installing deck hardware sailboat

Mounting deck hardware

Attaching fittings properly isn't difficult and protects your boat for the long term.

At some point in its life, every boat will need a deck fitting replaced or will develop a leak that must be corrected. And while replacing deck hardware is not a complicated operation, doing it incorrectly can cause serious damage down the road. Install a fitting properly and you have a sturdy piece of hardware set for the long haul. Do it incorrectly and you face rotten core or compromised bulkheads.

Owners may choose to replace a fitting because they want to upgrade to something stronger and lighter or because they have concerns about the age of a piece of hardware. A few basic steps can achieve a good, long-lasting seal between a fitting and the deck. 

Remove old hardware

The first step is to remove the hardware or fitting that will be replaced or rebedded. In most cases, removing fittings is not difficult as the sealant is often broken down enough to not put up too much of a fight. If the hardware was originally bedded with 3M 5200 adhesive sealant, you may have to go to drastic measures to remove the fitting. More on the best sealants to use later. 

Start by removing all of the nuts and bolts fastening the fitting to the deck, being careful, of course, not to lose any overboard. Then use a good metal putty knife with a one-inch blade that extends into the handle to gently pry under the fitting. Use a hammer to tap the putty knife between the hardware and the deck, working around the piece gradually until it breaks free. Do not use a chisel or screwdriver for this task as you risk damaging the deck and possibly the fitting. 

Whether you are replacing the hardware or mounting a new piece, it is important to thoroughly clean both the deck and hardware. The old sealant needs to be completely removed and the area should be degreased so that a good bond can take place between the sealant, deck and hardware. The putty knife comes in handy to scrape off as much of the old sealant as possible. Adhesive removers can manage the rest but need to be used with care as they can stain the gelcoat or paint. Tape around the area you’re working on to protect the paint and then use an adhesive remover to clean off the residue. 

Repair and seal

With the deck hardware removed, it’s a good opportunity to check on what’s lurking underneath. Check for wet or rotten core by using a screwdriver to feel around in the bolt holes or take a sounding by gently tapping and listening for changes in pitch. If you find a problem with the core, or the deck is damaged in the removal process, assess the best way to fix the issue and do that before moving on. Making those repairs is vital to the soundness of the boat.

Assuming that the deck and core are still in good shape, it’s a good idea to seal the core with epoxy to prevent any future leaks from soaking into the core. Tape around the bolt holes to prevent any drips from causing a problem and put a piece of tape over the bottom of the hole from inside the boat. Using a two-part epoxy, work it into the hole and paint it on the core with a small paintbrush or acid brush, coating the exposed core and allow the epoxy to cure.

If you are replacing the deck fitting with a new one with a different hole pattern you will need to fill the existing holes. To do this, dig out some of the core surrounding the bolt hole using a screwdriver, allen wrench or other sturdy tool. After cleaning out all the removed core with a vacuum, tape off the bottom of the hole then inject thickened epoxy from the top using a syringe, filling the hole from the bottom first and backing the syringe out as the hole fills to prevent any air bubbles (Figure 1). If you found a small amount of wet core around the bolts but are rebedding the same fitting, remove the damaged core and fill with thickened epoxy as described above. Once the epoxy is cured, you can clean up the hole with a drill. 

Drill new holes

If you are mounting a new piece of hardware, the hardware should come with a bolt hole template that is to scale. Place the template on the deck in the location you want and with a center punch, mark the hole centers on the deck. Once the hole locations are determined, drill a pilot hole all the way through the deck, being very careful to keep the drill perpendicular to the deck, which is not necessarily level. The next step is to drill the hole to the size that will match the bolt. To prevent the paint or gelcoat from chipping, run the drill backwards until you have a countersunk hole the size of the drill bit tip. Then drill the hole, maintaining the perpendicular angle to the deck. Run the drill about three-quarters of the way through the deck and then drill from the other side, again running the drill backwards at first to prevent chipping.

Backing plates

Do not underestimate the importance of backing plates when installing deck hardware. They can be as simple as using fender washers to disperse the load or as significant as aluminum plates or Garolite—compressed fiberglass sheets—cut to fit. Some applications, such as jib tracks, require channels or square stock for proper backing. The backing plate best suited for each piece of deck hardware depends on its usage, loads and deck construction. If you have a fitting that is prone to leaking, chances are that a deck issue, such as a wet core, or the lack of a proper backing plate are to blame. 

Once all the holes are drilled and the backing plate fabricated, it is a good idea to dry fit everything to ensure good alignment before you introduce a sealant into the mix. If there is any adjustment to do, now is the time to take care of that. To help in the cleanup of sealant after your final mounting, tape over the entire area, including where the piece of hardware will be mounted. When the piece of hardware is down during the dry fit process, cut around the piece with a sharp razor knife, being careful to only cut the tape and not the paint or gelcoat under the tape. When you remove the part, you can then remove the tape that was under the fixture leaving the rest of the tape in place. 

Final mounting

Once you have all the parts necessary to mount the hardware and you have checked that everything fits, it is time to put the part down for the final time. Put the bolts into the fitting and put tape over the heads to keep them in place (Figure 2). Then spread a thin layer of sealant on the underside of the fitting using the putty knife. By putting the bolts in this way, it keeps the end of the threads clean as they go through the holes, making putting the nuts on a lot easier. Once the sealant is on, put the part into place, go below and put the backing plate on and tighten the bolts. 

Sealant choices

There are a number of options for sealants and adhesives on the market. Look for something that is UV stable, long lasting and made for a marine application, such as 3M Fast Cure 4000 UV. It’s important to avoid adhesives that have more holding power than is necessary. The main function of the sealant when bedding hardware is to seal out water leakage; the bolts do the lion’s share of the holding. Products like 3M’s 4200 and 5200 (sometimes referred to as “52 million”) have more adhesion than you need and when it comes time to remove or rebed a part it will be nearly impossible to get them off the deck without causing damage. There are other good sealant options, so use what works best for the project.

Cleaning up

Cleaning up after you have bolted down the part is just as important as resealing the part in the first place. Not only does it look good to have all the excess sealant cleaned up but it also prevents degradation of the sealant. 

Whether you have taped around the part as described earlier or not, the first step is to remove as much of the excess sealant as possible with a putty knife. After that you can easily wipe up the rest with a rag and adhesive cleaner, again being mindful of the paint when using cleaners.

Allow the sealant on the newly bedded fixture to cure according to the manufacturer’s recommendations, usually about a day in optimal temperature and humidity conditions, before putting the fitting under any kind of load. With your deck hardware properly mounted you can rest assured that it will serve you and your boat well for years to come.

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Installing New Deck Hardware – The Right Way

As a first-time boat owner, at 18 years old, I thought nothing of drilling holes on the deck of my boat. I, like many others, believed sealants would do the trick of keeping the water out – after all, they are called sealants.

Fast forward, and now with over 30 years’ experience on and off the water, the thought of drilling any holes on a boat takes on a different light. It’s a much more thought-out approach. In this post, we’ll discuss one of the best methods for installing new deck hardware. 

First let’s look at a typical install. It usually goes something like this:

1. Drill out the holes for the hardware

2. Apply sealant

3. Mount hardware

4. Have a rum-based cocktail.

Besides number 4 on this list, there is a better way. The problem with the traditional installation method is that it doesn’t safeguard your boat against moisture intrusion. Should a leak occur later on down the road, your boat’s wood core will be compromised. Moisture intrusion leads to rot and rot leads to structural failure.

There is a better way, one that will ensure you will not get moisture into the wood core should a leak ever occur. To fully appreciate the need for a new approach, let’s first review how core decks are constructed.

Core decks are a layered construction and consist of something like this: gelcoat, fiberglass, wood core, fiberglass, gel coat. Many of today’s boats are using either end-grain balsa or plywood. Balsa is used for its strength and its light-weight properties. Both have their place in boat construction but the problem, like we mentioned above, is keeping moisture out of the core.

Now that the problem is clear, are you ready for the solution? Here you go:

The Best Way to Install New Deck Hardware

Below is a waterproof method of installing above the water deck hardware. Use this technique the next time you are adding another pole holder, downrigger, or other piece of hardware.

1. Mark Install Location

First, you will want to locate and mark where your new hardware will be installed. Ensure it will be out of the way of other hardware and won’t catch on any running lines or processes. Be sure that the installation location is strong enough to withstand the drill and will not crack. 

2. Drill the holes

Drill your holes the same size as the mounting hardware. Use the holes on the hardware to line up.

Next, drill those holes out about 2x larger with a step bit. Step bits are good to use for this as they will not chip the gel coat and they allow you to walk the bit down slowly. Step bits have a cone shape which provides a slight taper that will work well with the upcoming epoxy process.

Once the holes are drilled, it’s time for epoxy. Use a 2-part professional grade epoxy found at your marine supply store.

Tape off the holes on the underside (inside of your boat) with blue painters’ tape. To keep the area clean, use a disposable hypodermic-style syringe to apply the epoxy.

Fill the holes and wait about 3-5 minutes, then poke holes on the bottom (inside) tape covering the holes and allow for the excess epoxy to drain (use a plastic cup to catch the excess). This part will create a watertight seal that will prevent moisture from seeping into your core as well as act as a compression sleeve for your hardware.

Now re-tape the bottom or inside and mix a new batch of epoxy. This time, add some silica to thicken the mixture. Stay safe – when working around silica, remember to use a mask such as an N-95 particulate type. Put the thickened epoxy mixture into another syringe and fill the holes. Wipe off any excess or drips with a towel and rubbing alcohol. Allow to dry 24 hours.

Drill again

Re-drill the holes to the diameter needed for the mounting hardware just like you did in the first steps. Next, use a chamfer bit to recess the top of the holes. This specialty bit will create a 45-degree taper into the hole. Use the chamfer bit to create just enough of a recess that some of the sealant can set into the hole, but don’t overdo it and drill out half the hole.

A lot of people will then apply sealant right to the hole. Go ahead and apply a little here, but also run the bolts through the hardware you’re attaching and apply a small bead around the bolts where they meet the hardware. This will provide a better seal. 

The next step is to simply line up the holes and mount the hardware. Secure with the proper fasteners – tighten slowly to allow the sealant to spread, but do not overtighten.

Wrapping it all Up

Yes, this method will take you longer, but what it will do is keep all those holes you put in your boat properly sealed against moisture and water intrusion. You can be rest assured that that any potential future leaks won’t leave you feeling rotten at the core. We hope you have enjoyed this post. If you have any questions about mountain hardware to your vessel, simply send us a message through our contact form. 

M.B. Marsh Marine Design

Mounting hardware on cored decks: right and wrong ways.

Improperly mounted hardware is a constant source of frustration for boat owners. Sometimes it's water leaking in through a bolt hole, sometimes it's rust bleeding onto the deck, sometimes it's a cleat that tears off its mount under load.

Here's how to mount hardware on cored fibreglass decks correctly, so you won't have to deal with it again- and a few examples of why things go wrong otherwise.

The Right Way

( Can't see the pictures? Click here , then go update your browser- if you're running  a browser old enough to not recognize SVG, it's old enough to be a big security risk.)

A good hardware installation features:

• Solid fibreglass replacing the core underneath the hardware. On very high-load fittings such as windlasses, winches and mooring cleats, the solid area should extend well beyond the footprint of the hardware.
• Bedding compound between the hardware and the deck to stop water from seeping under the fitting.
• A hefty metal backing plate to spread the load of the bolts over a large region. I have seen some builders laminate the plate into the last layer of fibreglass, which works just as well but makes it a bit harder to repair if it rusts out later.

Sounds simple, right? Let's look at some common ways that it goes wrong, and what happens in those cases.

The Cheapskate Production Line Way

Cheap boats are cheap because corners get cut during construction. See if you can spot a few errors in the installation shown above. I'll wait.

Ready? The flaws are:

• Bolt holes go through core. Any water that gets in will get into the core. Wet core loses its strength and eventually turns to mush, allowing the deck to sag and hardware to rip out. This ends with a very expensive deck replacement- if not a total write-off of the boat.
• No bedding sealant , so water will have an easy time getting in.
• Washers are too small. Pull hard on this cleat and the washers will punch right through the inner skin, crush the core, and tear the outer skin from the deck. Composites don't handle point loads very well; they hold up much better when the loads are spread over large areas.

If a new boat you're interested in has a lot of hardware installed like this, just walk away. You'll spend far more time and money patching leaks than you would have spent to get something better in the first place.

The Overkill-In-The-Wrong-Places Way

This looks better, right? It's just like our "good" example, but with more sealant and without the solid glass.

Err, no. This installation is doomed to a very short life once the sealant starts to age.

• Sealant on the backside will trap water. Outer seals always, always fail at some point. In this case, their failure will allow water into the core. The inner sealant will stop that water from draining, so you won't know anything is wrong.
• The bolts will corrode through in short order. Water trapped against metal in an enclosed space is a recipe for rapid corrosion.Stainless steel in a damp, stagnant, oxygen-poor environment does not last very long. Your first clue that anything's wrong will be a slight rust weep if you're lucky, or a cleat whipping across the pier if you're not.

Never seal the back side of a through-deck fastener. If water does get through the outer seal, you want it to drain, and you want it to drip where you'll see it. That way, you know to fix it before things turn bad. (If you're buying a boat and its fasteners are back-sealed, you'd better remove a few of them to check for problems before closing the deal.)

No matter how much sealant you lather on, the core itself still has to be sealed against moisture with a chunk of solid fibreglass resin. Exposed core in the bolt holes is a recipe for expensive failure down the road.

The Good Enough For Low Load Way

Hardware that won't see high loads may not need the full, beefy solution. If you're mounting a VHF antenna, a cupholder or some other low-load fitting, this technique can work. You drill the holes oversize, ream out a bit of core, back the holes with masking tape, and pack them full of thickened epoxy. Then you re-drill the holes and mount the hardware.

It's considerably stronger than the cheapskate method, because the epoxy rings don't compress like core does and they'll share the load between the two skins. Don't use this for anything that'll see high loads, though. The stresses are still concentrated around the bolt holes- you need a backing plate to prevent that. If you mount a cleat like this and drive off from the dock without untying the line, the cleat will probably rip out of the deck, bringing the epoxy rings with it.

Topic: 

• Boat Building

Boats: 

This is a really nice.

This is a really nice article. Thanks!

Would it be reasonable to beef up the "good enough for low load way" with a backing plate?

Backing plates

Yes, a backing plate would certainly help in the final case, making it almost as good as the ideal case (although I would still go with solid laminate, or at least a few extra layers of laminate, around the really high stress areas like winch bases and mooring cleats). A large, stiff backing plate, which spreads a concentrated load over a large area is ALWAYS better than washers- and, similarly, large stiff washers are much better than small thin ones. The only downside to backing plates is that it takes extra time to measure and drill them.

Hardware mounting

Matt, this is excellent information that is very well presented to all. The dilemma with our project was to try to match the strength of the hardware. Therefore we replaced the core with ply around the hardware location, added a extra large ply backing area, both penetrated with 25mm glass/epoxy rods at each screw location. A 10mm plate was buried in a matching composite area under the large backing area. The epoxy rods were clearance drilled down to the plate, which was set drilled and tapped for the 12mm cap socket bolts resulting in a bulky but smooth are under the deck with no protruding nuts. If you have the time please see: http://scrumbleproject.wordpress.com/2010/11/18/preparing-for-the-wet/

Re: Hardware mounting

If you need to mount hardware to a cored deck without any protrusions (nuts, etc.) on the back side, Tom's way is probably the best way to do it. It's labour intensive but, if done properly, is obscenely strong. Liberal use of anti-corrosion agents (tef-gel, etc.) would be prudent when inserting the fasteners, just in case water does seep in at some point- it's important to ensure that there's no way for water to sit, stagnant, in contact with the metal.

Tom's Scrumble Project site is an excellent few weeks' worth of reading for anyone considering a large self-build boat. He and Judy have meticulously documented every detail of their big Oram cat's build process, the ups and the downs- it will give you a good feel for how much work is involved in a project like this, as well as being a useful reference for all sorts of tricky construction details.

Mounting Hardware on Teak Decks

When mounting hardware on a teak deck, do you cut back the teak and mount on the fiberglass beneath or mount directly on the teak. Does it make a difference if it is a high load piece of hardware like a cleat or a low load like a pad eye?

Cutting back the teak to mount on the fibreglass underneath would, I think, put the hardware in a recess that would tend to trap water. That seems like a recipe for corrosion and eventual leaks. I'd rather see the hardware mounted flush with, or slightly proud of, the surface of the deck.

If I were designing a moulded fibreglass deck to take a teak overlay, I'd probably include cleat mounting pads of solid fibreglass that stick up to the level of the surface of the teak. That way, you can repair the wood finish without removing and re-bedding the hardware.

Waterproofing hardware on teak decks

A very good article, we have always drilled, epoxied & redrilled for mounting anything on deck. Normally we measure for a large thick SS backing plate and find a machine shop to do the actual cutting and drilling for us. I always keep an eye peeled for scrap SS pieces others have discarded and use these for my backing plate stock. We also use SS nylon locking nuts and Loc-Tite (Overkill - I know) but I feel better when the ---- hits the fan.

Nice articles here, Cliff

Nylocks plus Loc-Tite? I wouldn't call that overkill. That's just being cautious. And yes, it's really quite amazing what you can find in the scrapyard.

I forgot to ask this question in my last post.

I am looking at purchasing another boat and it has teak decks. How would be the best way to re-bed the existing hardware on the teak? Cliff

As far as I know, it's perfectly OK to mount hardware on top of teak.

The holes through the fibreglass should, if it's a cored structure, be reinforced and sealed as described earlier. The portion of the hole that's surrounded by teak would be drilled a little bit oversize, just enough that the bolts aren't in direct contact with the teak. You'd seal the hardware against the surface of the teak, as usual, and the shaft of the bolt would be left bare (unsealed) so that if the seal does fail, the water will drip inside the boat- where you can see it- instead of pooling around the bolt where it can do damage without being noticed.

laminate thickness

I am using a pop up cleat on a boat with 2 1" diameter fastener holes. The load is 5,400 lbs (ABYC rule for 32 foot boat). How do I determine how thick the fiberglass should be?

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Installing deck hardware is relatively simple. However, if you are installing the hardware on a cored deck ( a deck that is a combination of fiberglass and a wood core) you will want to take precautions to protect the deck from moisture in case the hardware leaks. This video shows you every step for a worry-free installation

• The different components of a cored deck and how they are built
• How to drill “crack-free” holes through gelcoat and fiberglass
• Using epoxy and fillers for filling holes
• Using a syringe or a cake decorating bag with epoxy
• Prep mounting holes to create gaskets that help seal out water
• Tips on how to properly apply sealant

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Upgrading Sailboat Deck Hardware

• By David Schmidt
• Updated: October 22, 2020

As a lifelong racing sailor, I’m well familiar with the go-fast, lightweight sailhandling hardware and line favored by serious buoy chasers. These come in myriad sizes and setups, but they often involve low-friction rings rather than blocks, clever use of Spectra (or other exotic and semiexotic materials) for strops (spliced loops),  and freely articulating soft shackles to connect gear to the boat. While this evolution is partially bolstered by the advent of new rope-making fibers (see below), it’s also being driven by boatbuilders’ and consumers’ demands for lighter-weight and lower-cost equipment that looks cool and can handle big loads. Here’s a look at some of the benefits that they offer.

The Fundamentals

Let’s begin with sails and cordage. The past few decades have seen substantial evolution in the materials that are used to build cruising sails. While some sailors are still hoisting (relatively) stretchy Dacron sails, plenty of others have upgraded their inventory to low- or no-stretch sails that are made from Spectra or other exotic fibers that are woven or 3D-printed onto molds. Even some Dacron cruising sails are now being constructed using similar 3D-printing techniques to generate higher-performance, lower-stretch sails.

Likewise, there’s been a big jump in the availability of high-strength, low-diameter rope that replaces basic polyester lines which, by comparison, can be stretchy, thick and heavy. While there’s no question that these new sails and cordage offer much higher performance than the sails your grandparents bent onto their Hinckley Sou’wester, there’s also no question that these new materials put greater strain on your boat and its sailhandling equipment.

“The dynamic loading on all the gear and rigging is greater on boats with high-tech sails,” says Jim Andersen, Harken’s US sales manager. “There’s less shock absorption of such loading due to the more-stable sails and running rigging with minimal stretch.”

Others agree. “Shock loads are quite a bit higher with high-tech sails and with high-tech fiber ropes,” says Alan Prussia, Ronstan’s commercial manager of marine products. Particularly, he points to Dyneema and Spectra, among other minimal-stretch materials. When upgrading an older boat, Prussia says, “decks need to be inspected to make sure the core is good structurally and that proper backing plates are used.”

Dealing with these loads and lower-diameter cordage isn’t typically problematic so long as owners work with their riggers and sailmakers to eliminate weak links. “It’s very important to understand how one change can affect the performance of other products in the system,” says James Hall, Spinlock’s marketing and sales manager.

While line and sail-inventory upgrades commonly drive sailors to find better sailhandling options, these changes are also being driven by new models with modern sail plans, which typically use easier-to-trim-in, non-overlapping headsails—rather than the big, overlapping genoas of yore—and by a desire to create a new, cleaner-looking aesthetic.

Ring Things

A good example of this is the floating jib lead, which consists of a simple, low-­friction ring that “floats” above the deck. Its position is controlled by a keeper strop (typically a Spectra loop that’s spliced around the ring’s circumference and led through one or more deck- or cabin-top-mounted padeyes) and one or more barber haulers that replace an adjustable fairlead and deck track. Such a setup provides significantly more trim and sail-shape options. While this is standard-issue stuff on most racing sailboats, it’s a configuration that’s now gracing some more-mainstream designs. “Floating leads, soft loops and rings are all becoming more popular on cruising yachts, especially new builds, because they look modern, light and clean,” Hall says.

One important consideration for a sailor who’s contemplating an upgrade is that a jib lead that’s suspended in space by strops and sheeted-on loads offers more trim options—and because of that, more opportunities to make incorrect adjustments. “I think floating leads are difficult for many sailors to figure out,” Prussia says.

He advises that before upgrading or buying a boat with floating leads, owners should consider their sailing style and sail-trimming skills (or desire to bolster those skills). Some will enjoy the challenge of eking out perfect sail shape, but such a system might not be as appealing to passagemaking sailors who aren’t concerned about capturing 0.1-knot efficiencies.

Still, Prussia notes that low-friction rings can work well elsewhere on a boat.

“We have had many ­inquiries about using low-­friction rings for furling-line leads along stanchion bases, jib outhaulers (for better reaching angles) and boom preventers,” he says. “These are perfect applications for this type of product.”

Some experts remain ­skeptical though. “We’ve seen more people trying the ­apparent simplicity and less-expensive friction rings,” Andersen says, but he adds that the word “friction” is the sticky wicket. “Rings are really only appropriate for shallow deflection (less than 30 percent) or lead-angle changes. That’s why Harken calls them lead rings. They’re not an appropriate replacement for a proper pulley for a 45- to 180-degree turn or a multipart purchase system where efficiency is the aim, and where adding friction defeats the mechanical-advantage goal of a block and tackle.”

Friction is obviously a concern with any running rigging, but Siebe Noordzy, the owner of Euro Marine Trading and the US importer of Antal marine equipment, says high-strength, low-stretch cordage naturally helps ameliorate some of these concerns. “With the increased use of Dyneema lines, which are very slippery by nature, over the past three years, Antal has been concentrating on creating low-friction equipment, which is no longer using sheaves,” he says. The gear is light, strong and easy to install, and now it’s commonly seen on cruising boats.

Soft and Tough

Gear experts might be split on their thoughts concerning floating leads and rings, but most agree that spliced strops and soft shackles are racing crossover equipment that—if properly maintained—can be a lightweight and simple upgrade. “There’s an almost explosive trend toward using soft shackles,” Noordzy says. “They’re easy to mount, weigh less [than traditional hardware and] are very strong. One only has to be careful not to mount them around sharp edges.”

Soft Shackle

Prussia agrees: “The ­applications are endless, and they offer a lower-cost solution than traditional snap ­shackles, standard shackles, quick links and carabiner-style products.” But, as with all good things, soft shackles have their downsides, starting with the fact that they’re not easy to release under load (racer tip: make sure there’s a sharp knife on deck and in each watch captain’s pocket) and can be hard to mechanically evaluate. “Deformation, rust or wear on a stainless-steel shackle is something almost anyone can relate to, and understand that there may be a problem with overloading, underspecification or simply wear,” Andersen says. But with synthetic strops and shackles, “fiber plating, interfiber chafe and UV degradation is harder to identify without training or experience.”

This matters, of course, because soft strops and shackles can fail, just as worn or defective stainless-steel hardware can, often with similarly less-than-desirable outcomes.

The story here is that you have options. If you’re ­upgrading sails and running rigging to more-exotic ­materials, or if your boat simply needs a sailhandling refresh, consider some of these solutions. And while floating-jib leads could be best-suited for reformed racers, other technologies such as rings, spliced strops and soft shackles are all great, cruising-friendly choices that offer some weight-saving and possibly cost-saving gains while also adding a decidedly sleek aesthetic.

David Schmidt is CW ’s ­electronics editor and occasionally reports on other gear.

• More: deck hardware , Gear , print oct 2020 , sailing gear

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FIBERGLASS BOATBUILDING: Deck Hardware

This is an area of fiberglass sailboat construction that many owners ultimately become interested in, either because deck hardware installations on their boat start leaking, or because they decide to replace and upgrade hardware. Unfortunately, it is also an area where some builders often try to streamline their methods to save time and money, particularly when it comes to installing hardware such as winches, cleats, genoa tracks, travelers, stanchion bases, and the like.

As we’ve discussed earlier in this series , almost all fiberglass decks are cored these days, which presents two problems any time a deck is penetrated to receive a hardware fastener. First, the core must not be crushed; second, it must not be exposed to any moisture. Given the enormous number of fasteners needed to secure deck hardware and the enormous loads some hardware carries, it should come as no surprise that hardware installation is both critical and troublesome.

Damage to a deck, once hardware fasteners start leaking, can be substantial. First small areas of deck core may become saturated; over time these can become large areas, requiring major repairs. (To get an idea of what’s involved, check out these excellent blog posts by Paul Calder: Deck Repairs, Part 1 and Part 2 )

To prevent such nightmares, the traditional practice is to treat hardware fasteners individually. This can be done by drilling out an over-sized hole for each fastener, filling it with a plug of epoxy paste, waiting for the epoxy to cure, then re-drilling a proper-sized hole through the plug. The plug both seals the core, protecting its internal face against moisture intrusion, and acts as a compression post that prevents the deck skins from being squashed together. Another alternative is to drill a proper-sized hole for the fastener, ream out the core around the perimeter of the hole with a bent nail or router, then fill the cavity with thickened epoxy filler. Again, the epoxy both seals the core and resists compression as the fastener is tightened down. Yet another alternative, rarely seen, is to drill a slightly over-sized hole, seal the core perimeter with epoxy resin, then insert a metal compression tube to bear the load of the tightened fastener.

Few, if any, builders took such obsessive precautions in the early days of fiberglass boat production. Older boats thus often have deck hardware installed with fasteners piercing unsealed balsa-cored decks with no compression fittings of any kind. The assumption then was that the core would not be crushed if nuts on bolts were not over-tightened, nor would it get wet if the hardware was well bedded with sealant. But heavily loaded hardware may in fact crush a core even if its fasteners are only finger-tight, and even the best sealant, liberally applied, will eventually break down over time and allow moisture to creep in. In the end, it is often some poor boatowner (or a yard crew hired at great expense) who many years later must properly seal and secure the fastener holes.

The best and most efficient way to install deck hardware on a production basis is to properly prepare the areas in question when the deck is molded in the first place. For example, the deck can be molded with only solid laminate in areas receiving hardware. If this is done, transitions from cored to uncored laminate within the deck should be made gradually, with the core gently tapering down in thickness so hard spots are not created. Another more common method is to replace compressible core material under hardware with another firmer material. In the past plywood was often used for such inserts, because it is cheap and is not easily compressed. Plywood does, however, readily absorb moisture, so each fastener hole, again, should be sealed with epoxy. Another more common alternative core material these days is high-density plastic foam, which is lighter and less absorbent than plywood, but also more expensive. Yet another sensible alternative, which hopefully will become more popular over time, is StarBoard, a lightweight solid plastic faux wood that cannot be compressed and is entirely waterproof.

All fasteners should be threaded through-bolts with nuts on the end, as illustrated. This is the only reasonable option, unless the hardware in question is never subject to any load, in which case self-tapping screws may be used if they are well bedded with sealant.

Besides being through-bolted, all loaded hardware should be supported underneath the deck by substantial backing plates with generous margins extending beyond the hardware’s footprint abovedeck. This spreads loads over a much larger area of the deck. It is best if these plates are metal–either stainless steel or aluminum–although plywood is commonly used and is usually acceptable if large fender washers are also installed. Sheets of StarBoard are another excellent alternative. Builders, unfortunately, often omit backing plates and instead install fender washers that may not spread loads sufficiently. I myself have seen cleats secured with fender washers torn clean out of decks by docklines strained by passing boat wakes.

There is another method for installing deck hardware without washers or backing plates that is now popular with many builders. First, during the deck layup, aluminum plates are glassed into areas where hardware will be installed. Then holes are drilled and tapped into the embedded plate (this can even be done by computerized robots) and hardware is fastened in place with stainless-steel machine screws. The great advantage is the entire installation can be made from above the deck, which simplifies deck design, as no allowance need be made for access under the deck. It also saves manpower, as a second worker is not needed below deck to install washers or backing plates and thread nuts on bolts.

I have to believe that the long-term viability of such installations is suspect. The embedded aluminum plate, if appropriately sized, can act like a backing plate and help spread loads, but the load may be carried by only a portion of the laminate. Moisture may also cause problems. With through-bolted hardware, if moisture gets into fastener holes it eventually emerges in the interior of the boat, having done no significant damage as long as there is no unsealed deck core to absorb it. The resulting leak can be discovered and redressed by rebedding the hardware with fresh sealant.

But with an embedded aluminum plate, moisture may be trapped in the laminate, eventually causing a problem. It will certainly cause corrosion where the aluminum plate and stainless-steel screw are threaded together. Expanding powdery waste from the corroding aluminum (you often see this on aluminum masts and booms where stainless-steel fasteners are installed) may someday cause significant delamination.

This can be prevented by removing the hardware and rebedding it on a regular basis, before the sealant fails. Removing hardware will be hard, however, if the aluminum plate and stainless-steel screws have seized together, as often happens. Then it will be necessary to drill out the screws. To replace the hardware, the holes will have to be re-tapped to receive a slightly larger screw. This can probably be done only once or twice before the screws are too large to fit the hardware’s fastener holes. All of which only discourages an owner from trying to remove the hardware in the first place.

To forestall these problems any boat with deck hardware screwed into embedded plates should have its hardware mounted on elevated bosses or plinths that shed water and so make it harder for moisture to find its way into fastener holes. Indeed, this is very desireable on any boat, but unfortunately is rarely done.

Coping with Deck Liners (or Not)

Comprehensive one-piece deck liners that cover all the overhead in a cabin interior are common on production sailboats. Such liners usually restrict access to fasteners under the deck, making it impossible to remove hardware without first cutting away part of the liner. The best practice when a liner is fitted is for the builder to cut small access hatches with removable covers so fasteners can be reached easily. Often this is done after the fact by owners seeking to remove old hardware or install new hardware in new locations.

Alternatively, fasteners may pierce the liner, spanning the gap between the liner and deck. In this case, some sort of compression fitting should be installed so the liner is not warped or crushed by the fasteners. It is best, too, if a backing plate is also installed, though this is rarely done.

Ultimately, it is best if there is no deck liner. On well-built boats you’ll find instead a series of removable overhead panels in open areas of the cabin. These are often held in place with Velcro strips, which makes it easy to access under-deck fasteners, though the Velcro eventually wears out and needs replacing. Overhead panels can also be secured with trim strips and/or small screws, which are more permanent and reliable, but take much more time to unfasten if panels must be removed.

On simple boats (or on lightweight race boats), there may be no liner or overhead panels at all, in which case all the under-deck fasteners will be exposed to view. It may not look very pretty, but from a maintenance point of view this is highly desirable. Any leaking fasteners will be immediately apparent; they will also be immediately accessible.

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AGROUND AGAIN: Naturally

DEAD GUY: Charley Morgan

What’s best way to fit deck fittings with an old non cored half inch grp deck? How do you maintain a moisture seal with epoxy on such a deck fitting? If using stainless steel backing plates do you need a timber pad as well? What thickness stainless steel plate should be used on an old 8m cruising cat? Finally, should the timber backing pad be beveled to gradually transfer any stress to the grp deck – I’m thinking of using epoxy coated 19mm marine ply for the timber backing pads and steel plate instead of washers with through bolted fittings. Many thanks for your thoughts.

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Sailing Eurybia

Two Humans and a Dog sail Mexico on a Sea Maid Ketch

A day in the life: Installing Deck Hardware

June 4, 2016 Leave a Comment

And our other work? After we are done installing deck hardware, then the forepeak ceiling, shelves etc can be reassembled. The day tank reinstall is essential as we will need to motor. We could wait to put the chains back on board, but it seems safer to put those in – just in case we anchor in town before heading to our slip on the Canadian border.  The cockpit cushions are underway – another weekend or two to finish. The deck painting and non-skid is planned for after we’re back in the water. The rudder extension is welded on but needs faring; the new feathering propeller has arrived but needs installing. Painting the bottom is just a day or so, but the hull painting will be at least two days plus time for the striping. The list goes on and on…

*Ultra High Molecular Weight Polyethylene is a generic tern for a hard plastic. HDPE or High Density Polyethylene is similar, not as dense, and less expensive, but similar in performance. StarBoard is a brand name for HDPE. Here is what they say about HDPE, and is also true of UHMW polyethylene:

StarBoard® is the original marine-grade polymer and the industry standard. In marine and other outdoor environments StarBoard® has the ability to withstand the effects of salt water, moisture, and direct sunlight without rotting, swelling, splintering, de-laminating or discoloring like teak and other solid woods.

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Installing Deck Organizers

• Thread starter jmce1587
• Start date Dec 11, 2015
• Hunter Owner Forums
• Ask A Hunter Owner

Hi All: I want to run additional lines to cockpit and need to change from a double to triple deck organizers on my 84 H31. Since these are not thru bolted to the cabin for access and I do not have an access panel similar to where deck winches and rope clutches are located can you advise what I need to do in order to attach new organizers to the deck? Looks like organizers have a thru bolt with nut on the bottom but not sure how to tighten down on this if necessary. All help/comments are welcome. thanks, Jerry  

Attachments

Those look stackable. Buy the same ones and lay them on top of the existing. 2x2=4 a side. Same placement for bolts, just longer!  

Allan12210 said: What Jackdaw says! He's quick. Click to expand

DianaOfBurlington

• What happens when the aluminum backing plate parts from the 'glass, inside the headliner where you can't see it? This can happen due to water intrusion. (Also, what's holding the aluminum in place? --do you know? Trust me-- it could very well be the piece of hardware itself. Take the bolts out and listen for a dropping sound. Now what?)
• How can you tell if there's water intrusion? --when water is coursing down the outside edge of the headliner into your bookshelves? And how do you know where it's coming from? This is the well-discussed problem with all molded headliners-- and the reason why only the cheapest boats still use them.
• Cheek blocks, halyard stoppers, organizers and winches are under shear loads, not tensile loads. This means the load is trying to rip the hardware laterally off the boat, not upwards. You don't need a block large in area for a backing plate; you need one that's thick . The plate of aluminum is probably 1/4". This isn't good enough. The unthreaded section of the mounting bolt needs to lean up against something thick to stop it moving along with the load. This necessitates a thick block, adequately bonded to the underside of the deck, in which a thick deck layup won't hurt either. I seriously doubt either of these is present in 1980s Hunters. How thick do you think your deck layup-- minus the core, which provides no strength-- is? With the metal plate, this is what's holding the load of your cheek blocks. As I have so often said before, this is definitely a case for bonding the backing block with 5200, which is excellent in shear and tensile loads. Butyl tape under the hardware is okay here, given a proper backing block (which the aluminum plate is not ), because all it has to do is to temporarily hold out water (about all butyl tape is good for). 5200 under the hardware would be great; but the hardware needs to be replaced or upgraded someday, so it needs to be removable.
• Long fasteners under shear loads are more prone to bending than short ones. This means the longer bolt needed for a double-stacked cheek block is less than optimal (especially for the upper sheaves' lines). Handrails are under bending loads and have the same problem. The shorter the fastener, the stronger the hardware will be, in use. This is why you see teak handrails in which the mounting bolts are way down inside deep-bored plugged holes; and why you see stainless ones with mounting flanges.

Allan. How did you do that? I have the same setup and no way I can stack the deck organizer without the upper line running right into the lip of the opening. What gives?  

markwbird said: Allan. How did you do that? I have the same setup and no way I can stack the deck organizer without the upper line running right into the lip of the opening. What gives? Click to expand

My '87 Legend 35 came with Schaefer triple leads. I ordered replacement Schaefer 6 packs ( double stacked 3's). Same hole spacing. As noted above, there is an embedded SS plate in the glass, so it's an easy replacement. There are aluminum backing plates for most deck equipment on my boat. Chris  

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Rebedding Deck Hardware

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A leaking deck fitting can cause damage to deck cores and boat interiors. But rebedding may be all that's needed to keep the water out.

Cleats, deck fills, lights, handrails, and winches are just a few of the many deck fittings found on the average powerboat or sailboat. All usually require drilling holes to attach them, and all are usually bedded into some sort of compound when a boat is built. Over time, age, sunlight, water, and general wear and tear take their toll, and when the bedding starts to break down, water is able to find its way below or, worse, into deck-coring materials. (See the section “Dealing With Cored Decks” below.)

If you suspect that a fitting is leaking, smearing a bit of goo around the outside and hoping for the best won't cut it. You've got to bite the bullet, remove the fitting, and start fresh. Removing old bolts and screws that may have corroded is often the worst part of the job, but has to be done. Having a helper hold the bolt while you remove the nut from below will make the job go quicker, and having a little moral support won't hurt, either. First, let's look at how to rebed a fitting that may be leaking or loose.

Rebed An Existing Fitting

1. Smaller fittings may be held in place with screws, in which case you shouldn't need to get to the underside of the deck. (Consider, however, whether the screws are appropriate for the fitting and decking and whether replacing screws with thru-bolts and backing plates would be better.)

2. When the bolts or screws are removed, the fitting should come away from the deck. Pry it up with a putty knife or other thin blade if needed, careful not to damage the fiberglass. At this point, you'll be thankful if the original installer used the correct bedding compound. (See "Bedding Compounds" below) If an adhesive sealant such as 5200 was used, getting the fitting up can take longer, although there are products, such as DeBond , specifically intended to help with this issue. Don't rush if the fitting doesn't pop off right away; carefully work a blade underneath to separate it from the deck.

3. Remove the old fitting.

4. Clean all traces of the old compound from the mating surfaces on the underside of the fitting and deck, then wipe with a solvent such as acetone to remove grease and other contaminants.

5. Tape off the work area to protect surrounding surfaces, and apply a generous but not excessive amount of the chosen bedding compound to the area under the fitting. Don't just squirt a bead around the perimeter; cover the whole base.

6. Place the fitting in position, insert the bolts or screws, and tighten evenly. Use new fasteners if the old ones are corroded, the heads are chewed up, or they're suspect in any way.

7. If you applied the correct amount of compound, some should squeeze out all around the base, a good sign. Scrape up as much excess as possible.

8. Finally, wipe with the solvent recommended by the manufacturer.

Bedding Compounds

Marine stores present you with a bewildering array of mastic and sealants. Knowing which one to choose is key. The most common products available are either polyurethane or a polysulfide, both of which are excellent — but only if used for their intended purposes.

Polyurethane is an adhesive compound. 3M 5200 is perhaps the best-known product in this category. It shouldn't be used when there's a chance that you'll need to dismantle the joint later. Many manufacturers use 5200 for hull-to-deck joints, and it's perfect for that kind of application. Polyurethanes hold up well underwater and bond to most materials, but they can attack some plastics. They don't harm Marelon, so it's OK to use for bedding underwater fittings made of this material.

Polysulfides, such as BoatLIFE products, remain permanently flexible. These are my preferred choice for most jobs. They can be used above and below the waterline, and the joint can be separated later if necessary. Polysulfides are available in a variety of colors. I've found that the brown is a good match for teak and mahogany, but use the recommended primer first for the best seal with oily woods such as teak. A polysulfide product shouldn't be used for bonding polycarbonates such as Lexan or PVC because it will attack them. Most window frames and other components contain plastic so are best bonded using a silicone product.

Another product I favor is butyl tape. Popular many years ago, its use waned when polyurethanes arrived on the scene. Butyl tape never sets and remains flexible forever, cleanup is easy, and because it comes on a roll, you use only as much as you need. In many cases, it's more economical than the stuff in a tube.

But butyl isn't the right choice for every application. While it works well under cleats and stanchions held in place with bolts, it's less suitable under screws. Tightening the screw tends to drag at the butyl and makes it pill up, pulling it away from the fitting. Butyl works well with bolts in situations in which they can be prevented from turning and are secured from beneath with a nut. The one caveat is that not all butyl tape is created equal. Use tape that's recommended for marine use.

Even more old-school is Dolfinite bedding compound, which can be somewhat hard to find. I like it for applications in which I'm bedding wood to wood. It can also be used for hardware-bedding applications. Dolfinite remains flexible for years, won't dry out, and won't destroy the parts should you ever need to break the bond. A can of Dolfinite (available in white, gray, brown) lasts for years.

Marine Sealants, Caulks & Mastics: Which One Do I Use?

Dealing With Cored Decks

When boatbuilders first began using fiberglass, almost all boats were built from solid laminates. As the years passed and builders began to better understand the material, they incorporated coring into decks. Cored decks — now the norm rather than the exception — are lighter, stiffer, and have significantly better thermal and acoustic insulation. However, water that finds its way into the core can cause myriad problems, so it's critical that hardware is installed properly.

Cored decks are a sandwich of layers: the outer layer of fiberglass, which may have a nonskid pattern or other features and is the part everyone sees; a core, which may be one of several materials but often is end-grain balsa; and a thinner interior layer of fiberglass, which often forms the cabin interior overhead.

Balsa is an ideal core material in many ways: It's comparatively cheap, very lightweight, stiff, and offers some measure of thermal and acoustic insulation. Its one major downfall is that it will suck up water at an alarming rate. Ensuring that deck fittings are correctly installed and bedded will do much to prevent water from getting into the core material.

Visit BoatUS.com/­Stubborn-Fittings for advice on dealing with stubborn fittings.

Fittings simply bedded into some form of mastic compound that is expected to keep the water out is insufficient. While it might work for a time, eventually all bedding compounds break down to some degree. As soon as the smallest cracks develop in the bedding, water will find its way into the core. Water that comes into contact with a balsa core may not initially have much effect because the water is absorbed into the wood. As more and more water finds its way into the core over time, it combines with the air in the cells of the balsa. Mold starts to grow, and the core eventually breaks down.

Problems are further exacerbated when moisture in the core freezes and expands the deck, forcing the core and laminates apart and allowing more space for water to enter as the temperature rises. As the temperature drops, everything freezes again and so on, each time doing a little more damage. Even though core material is very stiff for its weight, bolting down a winch or cleat willy-nilly crushes the core and deforms the deck. Fitting anything to the deck needs to be done properly and takes time. This initially might seem overkill, but you can rest easy knowing you've done everything possible to avoid problems and preserve the structural integrity of the deck.

1. Use a bent nail to ream out the core. 2. Drill the epoxy-filled hole for the bolt. 3. Tighten bolts — snug but not overly tight.(©2021 Mirto Art Studio (3)

There are other ways to install deck hardware, but the methods mentioned here have served me well. Here's how:

A. First, decide where to put the fitting. If it's heavy, it probably will stay in place by weight alone. Small deck cleats and those on vertical surfaces might require a piece of double-sided tape if you need to stand back to check placement. When you're happy with placement, mark the position of the bolt holes with a marker or pencil so you can easily see where to drill the mounting holes.

B. Using the marks as a guide, drill 1/16-inch pilot holes through the deck. This serves two purposes: You can go inside the boat or look under the deck to be sure holes and bolts won't interfere with anything. Plus, drilling the larger holes will be easier and more accurate because the drill has something to follow. If you have to make adjustments after drilling the small holes, filling them with epoxy is no big deal and will make them almost unnoticeable.

C. If everything checks out, carefully drill a hole twice the diameter of the bolt hole through the top layer of fiberglass and core only. (You'll feel it when you're through core and reach the inner fiberglass skin.) This hole will be filled with epoxy and will seal the core and offer solid posts that won't compress as the fastener holding the fitting is tightened. For the neatest appearance, the epoxy should not be visible around the edge of the fitting after it is installed.

If it looks as if this will happen — a few measurements can confirm it — an alternative method is to drill the correct size clearance hole for the bolt, though still going only through the outer laminate and core. Then cut the head off a nail, bend the last inch 90 degrees, and tighten it in the chuck of the drill (see Figure 1). Feed this into the hole and grind away, removing the core as an undercut.

D. With the holes drilled, put tape on the underside to prevent epoxy from running through the small pilot hole. Mix some unthickened epoxy and brush a little into the hole. You're not filling the hole at this stage, just wetting the surface as a sort of primer. With this done, carefully mix colloidal silica into the remaining epoxy until it is the consistency of thick mayonnaise. (Be sure to wear a respirator for this!) Force the mixture into the hole, using a small scraper knife or other suitable tool. Make sure there is no trapped air and that the epoxy is level with the surrounding deck surface. Allow it to cure for 24 hours.

E. Remove the tape from the underside of the deck. Using the pilot-hole mark, drill a small hole back through the cured epoxy. Then, from the top, drill down using the correct size bit for the bolt hole (see Figure 2).

F. When all holes are drilled, insert the bolts and dry fit (see Figure 3).

G. If everything lines up and looks good, add suitable caulking to the underside of the fitting, reinstall it and the bolts, and tighten the nuts so they're snug, not overtight.

Easy Masking Tip

Here's a way to save time and make cleanup a snap.

1 . (Not shown) With the fitting sitting over the fixing holes, draw a pencil line around its base , then remove the fitting and put to one side. Stick down masking tape so it covers the pencil marks.

2. Replace the fitting in the correct location , then cut around the base with a sharp knife or razor blade.

3. Remove the fitting, and peel up the tape on the inside of the cut line.

4. When you bed the fitting down, any excess bedding compound will squeeze out onto the tape and will be removed when you peel up the tape. This method is faster in the long run and produces very little mess.

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A marine surveyor and holder of RYA Yachtmaster Ocean certification, BoatUS Magazine contributing editor Mark Corke is one of our DIY gurus, creating easy-to-follow how-to articles and videos. Mark has built five boats himself (both power and sail), has been an experienced editor at several top boating magazines (including former associate editor of BoatUS Magazine), worked for the BBC, written four DIY books, skippered two round-the-world yachts, and holds the Guinness World Record for the fastest there-and-back crossing of the English Channel — in a kayak! He and his wife have a Grand Banks 32.

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• Attaching Hardware to Your Boat

Taking the quick and easy way out by just ramming in a few screws through a cored structure can and does cause thousands of dollars of unexpected damage. You either take the time to do it right, or pay the price when it comes time to sell your boat.

by David Pascoe

While we've been warning boat owners for years about the dangers of making holes in cored decks and other boat structures, it's become clear that large numbers of boat owners simply aren't aware of these potentially very costly self-inflicted wounds.

Table of Contents - Show/Hide

Can screws be sealed, what bedding to use, why stainless steel rusts, doing it right.

In the last month or so, we've run across no less than six larger boats where deck and superstructure cores were badly damaged as a result of water intrusion into the cores. The water intrusion came about as the result of the indiscriminate attachment of hardware -- anything from canvass snap fasteners to antenna mounts, windlass foot switches and tender cradles -- while failing to properly bed the fasteners to prevent water leakage. In other cases, hardware was removed and holes left wide open, and in many cases all the owner did was to smear some putty over the hole with no more concern than a person filling a hole in the living room wall with toothpaste.

In all of these cases, major damage to the boats occurred to the tune of thousands of dollars each. In one astonishing case, a ten year old 50 foot sport fisherman was effectively destroyed, damaged beyond the possibility of economic repair. The fore deck, house sides, bridge deck and aft cockpit deck were all rotted out and utterly beyond repairing. This was undoubtedly the worst case we'd ever seen, and yet the ruination of the boat was entirely the fault of its owner who had made dozens of holes throughout its cored structures.

Apparently many boat owners have not made the connection that making holes in decks and other boat structures is no different than drilling a hole in the roof of their house. They are unaware that putting a screw into a deck has exactly the same result as doing the same thing with a building roof: it is going to leak for certain.

While the risks to balsa cores are widely known, many people think that closed cell foam cores are impervious to water.  We assure you that they are not. They are subject to the very same problems that cause blisters on boat bottoms. While water itself does not directly affect most foams, water does react with the plastic resins and bonding agents used to adhere the foams to the laminate skins. Just as with bottom blisters, styrene precipitates out of the polyester matrix.

Styrene is a solvent, and it will soften or even dissolve foam. So once water gets into the core, this chemical reaction then goes to work on the core, softening it to the point where the deck gets spongy and eventually the foam separates from the fiberglass. The end result is exactly the same as a rotted balsa core. The core turns to mush.

To prove the point, we have taken fluid removed from bottom blisters and applied to various core materials. And guess what? Yep, the core dissolves in the blister fluid.

Okay, so now that you know this, you can no longer tell yourself, "Hey, my decks are foam cored, no problem. It's the latest and greatest space age material." Maybe so, but it is extremely unlikely that your superstructure is made with vinylester or epoxy resin, meaning that it is orthopthalic resin, which means that it's subject to the very same problems as all boat hulls made with this plastic. It is unstable when in long term contact with water.

Typical result of screwing hardware to a deck with no bedding. For a windlass  foot switch, this amateur installation,  done by a boat dealer, is going to cost about $5,000 to repair since the core is water saturated and delaminated.

When it comes to water leakage, it seems that many people do not understand what is known as the capillary effect, the uncanny ability of water to pass through micro-fine spaces between two objects -- like a screw and deck, or window frame and house side. But the fact is that very small fissures and openings can transmit very large amounts of water because the capillary effect functions like a natural pump. This results in more than just leaks. Rather the capillary effect has the ability to generate a flow of water far greater than the usual gravity effect. In other words, where it may look as if a screw, by means of the screw pressure generated, should seal itself, actually can result in an accelerated leak. As you can see in the photo above, tight screws did nothing to keep the water from getting under it.

To make the matters worse, many boat builders, boat yards, dealers and canvass installers do not themselves understand how they are causing  serious damage to boats by cavalierly drilling holes and running in screws. Part of the reason why is that it takes years for the damage to manifest itself.

Snap fasteners? You mean those little snaps that hold my enclosures and covers on could be causing me a problem? Yep, that's exactly what I mean. Every single snap that is installed into a cored structure is likely to be allowing water into the core. One recent example turned up a 31' Tiara in which the entire deck and cabin trunk core was filled with water, so much so that water was running out from under the snap fasters, leaving nice trails of green slime. This happened because someone installed snap fasteners all over the cabin top to secure sunbathing cushions.

The reason for the extensive delamination of the house side of this yacht became obvious after the laminate was peeled away. Notice all the plugged holes. Water got into the core and caused extensive blistering.

For that rather insignificant pleasure, the boat owner had effectively destroyed his boat. Since no one is going to buy a boat like that, the boat ends up in a fire sale as a handy man special.

You are now asking yourself, "But how the hell is anyone supposed to attach covers and enclosures if you can't just screw these things into the boat?"

That's a very good question, indeed. In the past, this wasn't a big problem before builders started going hog wild coring every structure on the boat in their ill-advised attempts to save a few bucks and make boats cheaper. Back in the good ole days of solid fiberglass, it didn't much matter. But now it is a very big problem, one for which the effects and damage don't begin to show up for years  -- like when you go to sell the boat and the surveyor discovers the problem.

Lately, the job of the surveyor has come to resemble that of a physician who has to inform his patient, "Sorry, sir, but you are dying of cancer."

After a little exploratory surgery, the reason for the deteriorated core becomes painfully obvious. Note the water weeping out of these filled screw holes.

Installing snap fasteners is less of a problem when done in places like the tops of flying bridge coamings and other areas where the structure is not cored. But to install them on flat surfaces like decks and cored house sides and tops is an invitation to disaster. Unless the boat designer has taken this problem into consideration, and has created an area of only solid fiberglass into which the fasteners can be safely put, then there is NO solution for the problem.

Think about it, if a piece of hardware is under load, then something is always pulling at the fastener, attempting to loosen it. And, of course, screws into fiberglass have notoriously little holding power. It is easy to rip them out. Just look at how easy all those snap fasteners pull out. Look at any boat and see how many of them have already come out.

So, yes, you could use some caulk under the fasteners, but that isn't going to help much. What does help is to through bolt all stress loaded hardware. That includes everything from antenna mounts to hand railings to rod holders.

The right way to do it. Note that there is no core around this hardware mount, and the 5200 bedding squeezing out from under the back up plate and around all the bolts. There is also not a trace of water leakage because it was done right.

I hear it over and over again: "I don't want to use 3M 5200 because it's messy and nearly impossible to get off." Sorry folks, but that is precisely why you should use it. 5200 is an adhesive: silicone and polysulphide are not good adhesives, which is why they don't work well. When mounting hardware, in my opinion, 5200 is the ONLY thing to be used that is highly effective.

Ever wonder why you see all those rust stains around screw heads and the mounting surfaces of hardware? You most often see this around rail stanchion bases. It's because there is water in the screw hole or under the hardware. This causes closed cell corrosion which will rust even the best stainless steel. In fact, some metallurgists say that it is the highest grades of stainless that are  the most vulnerable to closed cell corrosion. What many blame as low grade stainless is often simply the result of failure to bed the hardware properly. After all, it's called stain less steel not Stain proof steel.

When you see rust showing around fasteners or hardware bases, you can be sure that if it is a cored structure to which it is attached, there is water going into that core. The rusty hardware is waiving a red flag at you saying, "Hey Mr. Boatowner, there's water going in through these screw holes."

How to install hardware on a cored deck is easy in theory but hard in practice because of the accessibility problem to the underside of the deck or whatever you're attaching to. My advice is that  hardware should always be bolted, and never screwed, even if it's not load bearing hardware.

To do it safely, all you have to do is use a 2" hole cutter and remove the coring from the underside of the deck at the points where the bolts are to be installed. Then seal the exposed edges of the core with epoxy paste ( 2 part epoxy glue will work fine. Now you can drill your holes and mount the hardware with 5200 bedding and large washers on the underside (with 5200 under those, too) and presto! Now there is no chance of water ever getting into the core, plus the attachment is not going to leak or ever come loose.

So why not just bolt through the core? Because when you draw the nuts tight, this will crush the cored laminate, the part will come loose, and it will leak like a hole in the bottom of the Titanic.

Yes, it takes quite a bit more time to do it right. But if you figure the cost to repair serious core damage, say $3,000, then by whatever extra time you spend doing it right, you can figure that you've probably just saved about $1,000 per hour by that bit of extra time.

Just remember that when the time comes to sell your boat, that is the time these little chickens come home to roost. It's just a matter of pay now, or pay later -- with interest.

Posted August 14, 2000

David Pascoe - Biography

David Pascoe is a second generation marine surveyor in his family who began his surveying career at age 16 as an apprentice in 1965 as the era of wooden boats was drawing to a close.

Certified by the National Association of Marine Surveyors in 1972, he has conducted over 5,000 pre purchase surveys in addition to having conducted hundreds of boating accident investigations, including fires, sinkings, hull failures and machinery failure analysis.

Over forty years of knowledge and experience are brought to bear in following books. David Pascoe is the author of:

• " Mid Size Power Boats " (2003)
• " Buyers’ Guide to Outboard Boats " (2002)
• " Surveying Fiberglass Power Boats " (2001, 2nd Edition - 2005)
• " Marine Investigations " (2004).

In addition to readers in the United States, boaters and boat industry professionals worldwide from nearly 80 countries have purchased David Pascoe's books, since introduction of his first book in 2001.

In 2012, David Pascoe has retired from marine surveying business at age 65.

On November 23rd, 2018, David Pascoe has passed away at age 71.

Biography - Long version

Maintenance, Repair Articles At A Glance

• All about Bilge Pumps
• Battery Basics
• Corrosion in Marinas
• Dealing With Leaks
• Diesel Maintenance, Or Lack of It
• Electronics Outside
• Haul Out Basics
• How to Install an Aluminum Fuel Tank
• How to Prevent Your Boat from Sinking
• Tips on Electrical System Use and Maintenance
• How to Repair Window Leaks
• Is Your Boat a Leaky Tiki?
• Maintaining Stern Drives
• Maintenance Fundamentals Part I : Engines
• Myth of Condensation in Fuel Tanks, The
• Preventing Rot in Encapsulated Wood Structures
• Repairing Diaphragm Pumps
• Repairing Rotary Vane Pumps
• Solving Chronic Battery Problems
• Tips on Painting Fiberglass Boats
• Winter Lay Up
• Washing Down
• From Other Category
• Exhaust Risers (from Buying a Boat Cat.)

• What is Pre-Purchase Survey?
• Business Practices and Client Relations
• Sound vs. Seaworthiness
• Hull and Its Structure
• Surveying the Hull
• Using Moisture Meters
• Stress Cracks & Surface Irregularities
• Deck & Superstructure
• Drive Train
• Gas Engines
• Fuel Systems
• Exhaust Systems
• Electrical Systems
• Plumbing Systems

• The Marine Investigator Read Online Full Chapter 1
• The Nature of Investigations
• The Nature of Evidence
• Marine Insurance and Issues of Law
• Bilge Pumps & Batteries
• Finding the Leak
• Sinking Due To Rain
• Fire Investigations
• Machinery Failure Analysis
• Fraud Investigations
• Interrogation Techniques
• Deposition & Court Testimony

Published by: D. H. Pascoe & Co., Inc. Articles, Images: Copyright © 1997 - 2018 David H. Pascoe All rights reserved. Articles, Images: Copyright © 2019-2022 Junko A. Pascoe All rights reserved. Web site design & developement: Copyright © 1997 - 2023 Junko A. Pascoe All rights reserved. Web site: Maintained by Junko A. Pascoe

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• Boat Maintenance

A Better Way to Mount Hardware

Improperly mounted stanchion and pulpit bases are a major cause of gelcoat cracks in the deck radiating from the attached hardware. The cracks are usually the result of un­equally stressed mounting fastenings or inadequate underdeck distribution of hardware loads. Frequently, a boat is received from the builder with local cracks already developed. Once the deck gets dirty enough, these minute cracks start to show up as tiny spider webs slightly darker than the surrounding deck gelcoat While repairing these cracks is a fairly difficult cosmetic fix, the underlying problem — poor mount­ing — is fairly easy to correct in most cases.

For better or worse, production keep the cost of their boats com­petitive. Unfortunately, cutting cor­ners is the rule rather than the excep­tion in production boatbuilding. While you can’t change that situation, you can do a lot to correct the short­comings that are a function of corner- cutting, including poorly mounted stanchions and pulpits.

The most typical problem in stan­chion mounting is the base which straddles the inward-turning flange of the hull-to-deck joint. Frequently, the outboard bolts will go through both the hull and deck, while the inboard fastenings merely go through the deck. When a backing plate is instal­led that straddles the edge of the inward-turning hull flange under the deck, it is frequently distorted as the bolts fastening the stanchion bases are tightened. Tightening down the bolts when the backing plate doesn’t lie flush to the underside of the deck in­evitably causes local stresses in the deck, frequently resulting in the characteristic spider web of gelcoat cracks.

In order to avoid the problem, some builders simply use oversize washers under the nuts of through- deck bolts. These are not adequate to resist strong local loads, such as lean­ing hard against a lifeline stanchion. A backing plate of rigid material, at least the size of the base of the hardware to be attached, is the proper solution.

It is fairly common for builders to use fiberglass backing plates, cut from discarded sections of moldings such as cutouts for hatches. While a fiberglass backing plate is better than nothing, it can easily split or distort when bolts are tightened, reducing its effec­tiveness.

With stainless steel or aluminum hardware, fastened with stainless steel bolts, the best material to use for backing plates is aluminum, between 1/8″ and 1/4″ thick.

Aluminum has the advantage that it can be worked with ordinary wood­working tools with little difficulty. It can be easily cut with a sabre saw, is easily drilled, and sham corners can be quickly rounded with aluminum oxide sandpaper. It is also extremely light in weight.

You can usually buy scrap aluminum from a scrap metal dealer. Although the price may vary, you should be able to buy a lifetime supp ly of backing plate material for $10 or less.

If you’re making your own backing plates using a sabre saw, invest in a good supply of the correct type of metal cutting blade. About 12 teeth per inch is correct for clean cuts in aluminum up to 3/8” thick. Don’t try to use old blades, or blades designed for other uses. You’ll be amazed at the difference a sharp blade of the right type makes.

When drilling holes in backing plates, be sure to drill slightly oversize to allow for the bolts that are not perfectly perpendicular to the plate. To drill for a l/4” bolt, use a 9/32 drill for the backing plate holes. The easiest way to insure proper alignment for the holes is to clamp the backing plate to the stanchion base before drilling pilot holes in the backing plate by using the hardware fastening holes as a template. Don’t drill these pilot holes oversize, as you would enlarge the fastening holes in the hardware, making them more likely to leak.

Alternatively, you can drill the pilot holes, if you have an assistant, by simply holding the backing plate under the deck and removing the bolts from the already-attached hardware, one at a time. In the case of stanchions, this method may prove to be more effort than simply removing the stanchion base, but it may be less work than removing a bow pulpit or stern rail.

Whether you’re installing new backing plates, or simply correcting an improper installation, the installation method is the same. Once again, you’re going to take advantage of that wonderful mixture, epoxy and microballoons, that makes so much possible in modifying boats of all types of construction. If there’s any such thing as a panacea for the modern boatowner, epoxy resin filled with microballoons is it.

The epoxy and microballoon mixture is used to create a firm pad under the backing plate, straddling and smoothing out any irregularities in the underside of the deck surface, even irregularities as pronounced as the inside lap of the hull-to-deck joint.

First, make sure that the hardware fastening bolts do in fact line up with the holes in the backing plate. Next, thoroughly wax the surface of the backing plate that will lie against the underside of the deck; also wax the hardware bolts. Waxing allows you to remove the bolts and backing plate in the future. If you don’t wax them, your installation will be permanent, and few things on a boat should be that permanent.

Make a dry run to be sure that you haven’t overlooked anything. Then, mix only enough epoxy resin and microballoons to do one piece of hardware. The epoxy mixture must be fairly dry to keep it from running out of the gap between the backing plate and the underside of the deck. You’ll have about the right consistency when the mixture can be troweled onto the backing plate without sagging off.

Trowel the mixture onto the backing plate at least as thick as the largest irregularity to be bridged. Any excess will be squeezed out when the nuts are tightened. Be sure that you put bedding compound under the heads of the bolts, and under the base of the hardware if that has been removed.

With the plate, bolts, and nuts in place, evenly tighten the nuts using a socket and ratchet wrench, box end, or open end wrench. Do not tighten by turning the bolts. You’ll most likely turn out all the bedding compound under the heads, ending up with a nice leak.

It is not necessary to really torque down on the nuts. Tighten only enough to bring the plate evenly in position. When bridging the inside of the hull-to-deck joint, you may well end up with an epoxy pad that is l/2” thick at one end, and only thick enough to fill slight irregularities at the other.

Using a putty knife, clean up the epoxy that squeezed out when the plate pulled up to the deck. Most epoxy is water soluble before it kicks, so warm water and a sponge can be used around the edges for a perfectly neat cleanup. The neater you are, the better it looks.

If the epoxy is too thin, and wants to sag out of the gap between plate and deck, use masking tape to hold it in place. Pull the tape off as soon as the epoxy kicks off, and clean up any runs or dribbles with sandpaper.

When the epoxy is hard -this will vary with the type used and the temperature the nuts can be tightened a little more. Lock washers used under the nuts, rather than flat washers, will keep the nuts from backing off without excessively tightening the fastenings. If the fastenings protrude more than l/4” below the nuts, cut them off flush with a hacksaw blade. Do not use end nippers for this, as many boatbuilders do, because you may break the seal between the fastening and bedding compound while working the nippers back and forth to break off the end of the bolt.

This method can be used almost anywhere above and below decks to fill in major surface irregularities. When used above deck, the hardware and fastenings must be removed and bedded after the epoxy has cured, and the exposed edges of the epoxy “pad” should be painted to match the surrounding area.

A Word about Epoxy Resin

An amazing selection of epoxy resins is available to the boatowner: Chem Tech, Gougeon Brothers West System, Industrial Formulators, System Three, Travaco, Allied Resins, Tugon, and dozens more. Formulations are available in a bewildering variety, suited to different purposes. The simplest to use is Gougeon Brothers West System Epoxy, and the reason has nothing to do with the quality of the resin or any of its characteristics.

The reason is a simple device known as the Mini Pump, which mounts on the cans of epoxy resin and hardener, dispensing the proper amount of material with one depression of the pump. This is even simpler than 1:1 resin/hardner mixes, because absolutely no measuring is required.

Gougeon Brothers also market a variety of fillers to modify the characteristics of the resin, and even has a technical manual to help you solve most problems. Independent of product quality, the company’s marketing and packaging of epoxy resin and other products is superb.

For about $25, you can get a 21/2 pint kit of resin and hardener, plus a set of pumps. This may well be enough to see you through dozens of boat improvement projects.

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