sailing yachts with lifting keel

What are the pros and cons of different keels?

We all sail for different reasons, in different cruising grounds and use our yachts differently, so it makes sense that there is no one-size-fits-all keel design. At Sirius, however, we like to make the perfect yacht for each individual owner. One of the ways we serve our customers is our choice of keels – at least six different options for each model. It’s one of the ways we stand out – or should that be stand up?

We offer three styles of keel: fin, twin and lifting swing keel. All of our keels excel in many ways, but every design does have drawbacks – this is not unique to Sirius, but the keel affects the way you use the boat, so it’s important to choose the right one for you.

These are the keels we currently offer:

Standard Fin (310 DS, 35 DS, 40 DS) Performance Fin (310 DS, 35 DS, 40 DS) Medium Fin (310 DS, 35 DS, 40 DS) Shallow Fin (310 DS) Shallow Twin (310 DS, 35 DS, 40 DS) Performance Twin (35 DS, 40 DS) Lifting Swing Keel (310 DS, 35 DS, 40 DS)

Does the choice of keel compromise ocean capability?

For Sirius yachts, absolutely not. It’s important to realise that choosing one keel style over the other does not affect the yacht’s righting moment or compromise its ocean-going capabilities at all!

Whichever keel you choose, deep or shallow, twin or fin, they all have the same stability. This is achieved by putting more weight in the bulbs of the shallower keels as the shorter lever can be balanced with higher weight. Most of the blue water cruising and circumnavigations in Sirius Yachts have been made with twin-keel or reduced/shallow fin keel yachts.

Does keel choice affect performance?

As our shallow keels are heavier the weight dampens the yachts’ motion at sea, but as a downside, you have more weight to move with sails or engine. Once you’re moving there isn’t a difference but when tacking or gybing, or when not steered well, you will lose a bit in sailing performance. The shallower draught yachts also lose a few degrees to windward compared to their deeper keeled sisters, but they are still good all-round performers. Our customers with racing backgrounds always try to go for a keel as deep and light as their sailing area permits, either with a single or twin keel.

Pros and cons of fin keels

The standard keel on our yachts is a fin keel. Most sailing boats today use a fin keel because it gives a good all-round performance on all points of sail. By keeping the ballast lower it gives the most comfortable motion. The main downsides are that the draught (the depth of water required to stay afloat) is the greatest, and it’s very important to avoid running aground on a falling tide. Fin keel boats cannot dry out without additional support, either from a harbour wall or by fitting a pair of beaching legs. Some fin keel yachts are not built strongly enough to stand on their keels when out of the water, so they can’t dry out alongside a harbour wall and they need to be kept in a special cradle when stored ashore to avoid the risk of the hull deforming under its own weight. By contrast, all Sirius yachts can stand on their keels for any length of time with no problem at all.

We offer four types of fin keel. The standard fin is available on the 310 DS, 35 DS and 40 DS and is fully cast-iron. It offers the best value, good performance, and excellent responsiveness. It is the deepest of our fixed-keel options, so if you want less draught you may want to look at our other fin keels.

We also offer a performance fin keel for all our models. This uses a cast iron fin with a lead bulb at the tip (bottom). The structural strength of cast iron means the fin is the slimmest profile, but lead is denser than iron so the same volume of lead will weigh around 1.4 times more than cast iron, giving more righting moment. The heavier, softer lead down low has less volume in the bulb so achieves a slimmer profile with less drag and therefore better performance.

A lead bulb is also safer if it hits something. Lead can absorb 60% of the energy in flexing and deformation so that only 40% of the force will be transferred to the laminated structure of the keel reinforcement. A lead bulb is very forgiving and easy to reshape and will not start to rust where the coating is damaged. We can use less volume of lead than iron, and achieve better stability than a wholly cast-iron keel. We can also reduce the depth of the keel and retain excellent stability. However, lead is more expensive than cast iron and the bulb must be attached very securely to the iron fin, so this option does cost more.

If you want less draught, we also offer a medium fin. This reduces the draught of the 310 DS and 35 DS by around 40cm/1ft 4in and 55cm/1ft 9in on the 40 DS. Like the performance fin, it uses a cast iron fin with a lead bulb. To retain the keel’s grip in the water it has to have a longer chord (the distance from fore to aft). While this gives the boat better directional stability, it does make her a little less responsive and a little slower to manoeuvre.

On our 310 DS, we offer a shallow fin option – a special version for very shallow cruising grounds. This fin keel offers the least draught of any of our fixed keel options at 1.15m/3ft 9in and draws 10cm/4in less than the twin keel version. The keel has a significantly longer chord (2.24m/7ft 4in compared to 0.7m/2ft 3in of the standard keel) so she has the reassuring directional stability of a long-keeled yacht but with better manoeuvrability.

Pros and cons of twin keels

Our twin keels are the most popular option. About 70-80% of all Sirius Yachts are delivered with them – and on the 40 DS it’s 90%. Some folk still believe there is a big performance penalty with twin keels. In the past this used to be true but it’s no longer the case with modern twin keel designs, from Sirius at least. We have conducted many two-boat comparison tests, often battling for hours, by ourselves, with owners, and for sailing magazines and we have found that there may only be one or two boat lengths of difference at the end of a long windward leg, if at all. At the end of many of these comparison tests, the crews could not point out which of the boats had the twin keel.

If you cruise tidal areas, twin keels will reward you time and time again. Not only do they give you a shallower draught than the typical fin keel, they also give you the ability to dry the yacht out, whether that’s for a motion-free night’s sleep, to explore cruising grounds others cannot reach, or just for cheaper mooring and maintenance costs.

We offer two styles of twin keels; performance and shallow draught. Both options have a cast iron fin with a lead bulb. The performance keels have a deeper draught and a thinner chord so they act and feel a bit livelier when sailing and manoeuvring. The shorter keels have a longer chord, but give you the ability to navigate shallower areas. Like all keel designs, twin keels do have some downsides. They are more expensive than fin keels, and when you’re sailing fast in choppy seas at a steep angle of heel, you can occasionally get a slapping sound when an air pocket is caught and pressed out under the windward fin. Lastly, we’ve yet to meet an owner who enjoys antifouling between the keels. Thankfully it only has to be done once a year and with twin keels you might get away with doing it less frequently. A twin keel yacht can be kept on a drying mooring, where fouling is reduced because the hull spends more time out of the water. And when you’re off cruising it’s easy to give the bottom a quick scrub while the yacht is dried out.

Our yachts will happily sit on their keels on a hard surface, like a drying grid, or for winter storage but on softer surfaces we use the rudder for additional support. The rudders on our twin keel yachts are specially reinforced for this: we use a Delrin sheave to take the weight of the hull and the tip of the rudder has a wide, foil-like foot to spread the weight.

A lifting swing keel

We are one of a few manufacturers to offer a lifting swing keel. There’s a lot of confusion with the term ‘lifting keel’, it seems to encompass all yachts that have centreboards, variable draught, lift-keels or swing keels. To us, a lifting keel boat should have all the ballasted weight of the boat in the keel, and that keel needs to be retracted into the hull.

Technically, a lifting keel is a keel that can be lifted or lowered and gives the boat the ability to dry out when the tide goes out. A lift-keel is a ballasted keel that raises and lowers vertically. A swing keel has a ballasted fin that has a single pivot point and the keel swings up into the boat. There are other variants of design, for example some have a lifting keel to reduce the draught of the vessel but they cannot dry out on it, others have a ballasted keel and ballasted grounding plate. All these examples have a keel that does two things: keep the boat upright and stop her sliding sideways. Our swing keel is designed with a NACA profile to give the most efficient performance.

Centreboard yachts have a centreplate to provide grip in the water and reduce leeway. The plate may carry only 15-20% of the ballast but the rest of the yacht’s ballast is within the hull and/or in the grounding plate. This is called an “integral keel” and is more common as it’s less complicated to build. The lower a yacht’s ballast is located, the better her stability, the more comfortable her motion and the better she stands up to her sail area. The most efficient place for the ballast is as low down on the deepest keel possible – this is why race boats have deep skinny keels with large torpedo-shaped bulbs on the bottom, but they don’t make practical cruising sailboats.

Our keel designs have more weight in the tip (bottom) – using a bulb on the fin and twin keel design and flaring the lower sections on our lifting swing keel yachts. You don’t have this with centreboard and integral keel yachts.

It might be surprising, but a lot of owners come to us thinking that a lifting swing keel is the best option for them. Sometimes it is, but about 98% of customers who approach us because we offer swing keels end up sailing away on a twin-keel Sirius.

The downsides of a lifting keel

A lifting swing keel does give you more cruising options. It will lift should you run into something and, of course, it gives you the shallowest draught. But that difference is only 40-50cm (1ft 4in to 1ft 8in) less draught than our shallow twin keel option. The lifting keel increases the complexity of the build and the final cost of the yacht; it also sometimes limits the internal layout and engine drive options, and you need to have twin rudders too. Twin rudders make the boat less manoeuvrable in a marina – you can opt for a third central rudder which does improve the handling, but again comes at an extra cost.

On the lifting swing keel, 40 and 310 owners are restricted to the use of a shaft drive, which is less efficient and you have to accept a bit more noise and vibration. When drying out, the drive is more vulnerable to damage, whereas it’s totally clear when taking the ground on twin keels. With twin keels, you also do not have to worry about something sticking out of the beach or stones lying around because the hull is high above the ground. With the hull up high, you do not have to dig a hole in the sand and slide down on your stomach to check or change your anodes as you would on a swing keel.

Sailors who are attracted to the idea of a lifting swing keel should carefully consider the pros and cons to compromise the least. When owners understand the repercussions of choosing a lifting keel yacht, many of them feel it restricts their options too much. They could have a lifting keel or they can sail with twin keels, dry out, have better close-quarters handling and save money in the process. Unless you need the shallowest possible draught – 0.75m (2ft 5in) on the 310 DS, 0.9m (2ft 11in) on the 35 DS or 0.95m (3ft 1in) on the 40 DS – a twin keel might well be a better option.

How are the keels attached?

The design of the keel is important but the way they are attached is just as important, if not more so. All of our fixed keels are through-bolted. Every keel has a wide flange at the root (top) of the keel and the flange sits into a reinforced recess in the hull. The flange and the recess work together to spread the loads of the keel/s into the yacht’s hull. The keels are bonded and bolted to the hull. We use up to twelve 20mm and 24mm bolts (per keel) and these go through rolled stainless steel backing plates inside the hull to spread the bolt loads evenly into the fully laminated keel grid which goes all the way up to the chainplates and also carries the mast support.

For our lifting swing keel, we laminate a substantial keel box as part of the hull to accept the keel and the hydraulic mechanism needed to retract the keel into the hull. Unlike most other boatbuilders we don’t use a grounding plate to take the weight of the yacht, our yachts sit on the length of the leading edge of the keel. Integral keels with the majority of the ballast in the grounding plates move the ballast (weight) from low down in the keel to inside the hull. This negatively affects the stability as the more weight you have lower down, the better.

We also don’t like grounding plates because they bring the hull in contact with the ground. By leaving 10-15 cm (4-6in) of the keel out of the hull when it’s retracted, most of the time the hull is kept clear of the beach and anything that could damage it.

The problem with too much form stability

With only 15-12% of their ballast in the centreboard, most lifting-keel yachts cannot rely on keel weight for stability so their hulls need to be designed with extra form stability instead. This means the hull sections have to be much wider and flatter. A flat-bottomed hull is not what you want for a comfortable ocean cruising yacht; it isn’t sea-kindly or easy to steer in waves and gusty winds conditions. We don’t make that compromise at Sirius. With all the ballast in the swinging part of our swing keel design, we can use the same seaworthy, ocean-capable hull shape designed for our yachts with fixed keels.

If you don’t know which keel would be best for your Sirius, contact us to discuss the type of sailing you intend to do, where you want to sail and what your cruising aspirations are.

General Manager – Torsten Schmidt SIRIUS-WERFT GmbH Ascheberger Straße 68 24306 Plön/Holstein

Fax: 0049 – 4522 – 744 61-29

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What is a Swing or Lifting Keel? 14 Pros and Cons Explained

If you need to know what a swing keel is, like me, this article is for you. I'm trying to decide what keel type is right for me, so I dove into the swing keel.

What is a swing keel? A swing keel, also called a lifting keel, is a type of sailboat fin that can be retracted through a slot in the hull, which reduces draft and allows swing keel sailboats to navigate shallow waters like rivers. The keel rests on a frontal hinge and is generally lowered using a hydraulic ram.

Having a swing keel has some unexpected advantages, and there's one I bet you hadn't thought of. Read on to find out what it is.

On this page:

How does a swing keel work exactly, the advantages of swing keels, the disadvantages of swing keels, important things to know before buying a swing keel sailboat, popular sailboats with lifting keels, other keel designs to consider, what is a swing keel.

A swing keel is the same as a lifting keel and is also known as a centerboard. These keels swing back along the centerline of the boat, reducing the draft and wetted surface below the waterline. Swing keels allow you to increase and minimize draft on command.

There are some misconceptions regarding the swing keel, which I'm going to set straight in this article.

Some people confuse the swing keel for a canting keel. The canting keel is called the swing keel, but most sailors agree that this name is wrong and that the swing keel refers to the lifting keel or centerboard design.

Centerboard keels are unweighted lifting keels while swing keels generally refer to the weighted lifting keels.

Please note: some websites mention that a centerboard is a vertical keel. This is wrong. A centerboard is a pivoting keel, also called the lifting keel. The vertical retractable keel is called a daggerboard .

So in this article, I'm describing the lifting keel: a swing keel that can swing from front to aft, resting on a frontal hinge. The keel can be either lowered through a cable or a strut.

In contrast, the canting keel swings from side to side, but that's another keel design .

Swing keels can be weighted and can be rather heavy, but you can also carry a simple and fairly lightweight fin (centerboard).

Depending on the size of the sailboat, a swing keel can weigh over 5,000 kg (5 tons). However, smaller sailboats use unweighted fin keels, which mostly reduce slippage to leeward. These are less effective in countering heel.

Swing keels allow you to sail both inland and coastal waters. You can use weighted swing keels as bluewater cruisers as well. However, there are a lot of other considerations when picking a bluewater cruiser .

Properties of swing keels

Swing keels share a lot of properties with fin keels , although it does depend on the exact type of swing keel (with or without ballast).

Weighted swing keels

• can be a choppy ride
• reduce heel quite well
• good prevention of slippage

Weighted swing keels share almost all properties with bulb keels and will reduce heel considerably and prevent slippage to leeward.

They are less comfortable than full keels, but they are as comfortable as fin keels. They can be quite shaky in heavy chop.

The maneuverability of swing keels is comparable to fin keels, with the added benefit that you can retract the keel to reduce draft, increasing maneuverability considerably.

Swing keels are as fast as fin keels, and when retracted, will be even faster since it reduces the wetted surface.

Centerboards

• choppy ride
• decent prevention of slippage
• don't reduce heel as much

Centerboards will reduce slippage greatly but won't have a large effect on reducing heel. They are faster than fin keels when retracted. Even when lowered, the wetted surface is pretty small, so it will be faster and more maneuverable.

These keels are great for weekend sailors that go in and out of slips often, sail inland waters like lakes, but also like to sail larger bodies of water (like the Waddenzee).

Understanding all keel designs in 10 minutes There are too many keel types to get into in this article. For a more detailed explanation of keel design fundamentals, I recommend you go through our Illustrated Guide to Sailboat Keel Types . It also contains a full list of the most common keel designs and their properties . Simply skimming it will help you understand the basics in ten minutes or less. Run down of all keel designs

Overview of swing keel advantages:

• You can determine the amount of wetted surface yourself
• Won't damage when you run aground head-on (will simply lift)
• Great upwind performance
• Variable draft
• Can be docked in alternative moorings or harbors
• Seaworthy thanks to lifting keel
• Can get closer to shore
• Easy to free when running aground

Overview of swing keel disadvantages:

• Pivot point requires maintenance
• Hinge can get stiff as it gets older
• Older swing keels can be noisy as the hinge develops play
• Lifting cable can break off, rendering all advantages worthless
• This can result in losing your keel by snapping off
• Requires more maintenance than regular keels

Swing keels have a couple of moving parts and are one of the more intricate keel designs out there. But this complexity provides you with a major upside. You get one of the most versatile keel types available.

There are two main designs.

The simpler centerboard keel consists of:

• pivoting hinge
• lifting line
• lifting cable
• retractable fin

Heavier swing keels will generally be supported by hydraulics, so that design is a bit more complex.

The weighted swing keel consists of:

• grounding plate
• hydraulic ram
• lifting pennant
• retractable weighted fin

The keel has an eye bolt on its top aft, which attaches to a steel cable. The steel cable runs up through the hull and generally attaches to a

Since you can lower and lift the keel, you can determine the amount of wetted surface yourself. This will allow you to make your boat faster, more agile, or more directionally stable as you see fit.

If the weather turns, and you find yourself in a storm, simply lower it and be on your way.

I've really enjoyed the flexibility of this setup sailing the Frisian lakes and IJsselmeer, where water depth greatly varies, and there are a lot of shallows.

Another great benefit is your keel will lift up when you run aground head-on. This reduces impact damage and may make the difference between having a lifting keel and a dangling keel.

Swing keels provide great upwind performance thanks to a much smaller wetted surface, compared to, for example, full keels.

The variable draft allows you to dock and moor in alternative places other boats can't reach. It also allows you to get really close to shore or even beach her comfortably (with centerboards that retract all the way).

Also, when you do run aground, it is way easier to free yourself since you can simply lift the keel and be on your way.

However, there are also advantages to fixed keels over swing keels. Matej's compared the centerboard and swing keel to fixed keels in-depth and goes over all the pros and cons here.

The main setback with swing keels is that they require a lot more maintenance than fixed keels. There are a lot of moving parts involved, and each of these can be a liability when in bad condition.

It is critical to check each crucial part regularly. Some owners' manuals ask you to check the keel bolts before every sail. I'll go into the maintenance points of swing keels below.

The most important liabilities are your cable, pivot bolts, and eye bolt on the keel. Swing keel cables can simply break off, and with a weighted keel, this can result in you leaving your keel at the bottom of the ocean.

Your hinge can get stiff or develop some play, which may result in noise and rattling.

With swing keels, you'll need to perform regular maintenance with the lifting mechanism. This includes the lifting cable, pennant, and hydraulic levels of the hinge.

You need to check the tension of the keel hinge bolts before each sail to be sure.

You also need to maintain the lifting winch (if you have one). The Cornish Crabber I've sailed just used a simple line on a cleat in the kitchen.

Things you'll need to maintain:

• fastening the keel hinge bolts
• the lifting cable
• the lifting winch
• the eye bolt
• the pennant
• hydraulic levels of the hinge
• the turning ball

Here's a very good article on swing keel maintenance at stingysailor.com (new tab ).

• Cornish Crabber
• Catalina 22
• Catalina 25
• Southerly 49
• Southerly 95
• Benneteau Oceanis 331
• Jeanneau Sun Odyssey 292
• Jeanneau Sun Odyssey 32

If you want more information on these models , you can read a more detailed discussion on popular sailboat models with lifting keels here .

If you're interested in sailboats with lifting keels that are also trailerable , please check out our list of the most popular trailerable lifting keel sailboats .

There are dozens of keel types out there and all serve a different purpose and excel under different conditions. To understand which keel type is best for your situation , I recommend you read our Illustrated Guide to Sailboat Keel Types , which contains the fundamentals of keel design and an overview for each keel type's characteristics (including diagrams). It will help you understand which keel designs to consider in ten minutes or less.

sandra olson

i am going to pick up my first boat, it is a 22 ft, catalina, with a swing keel It is in someone’s back yard, he is not able to use it anymore, so he is giving it to me, I will have to learn all about this boat, on my own, so i am a little nervous, but looking forward to this adventure, It is a concrete bottom boat, as far as i know, I will know more after tomorrow, Your site has been helpful, I understand she comes with some sails, i may need one or two extra and has no motor, but is sitting on its own trailor, More tomorrow

Robert Trimmer

I am more of a powerboat person but I have been given a Snapdragon 23 yacht and it has a lifting keel, thank you for the insight on how they work as I will be taking it out before the end of the summer hopefully, I am a novice but will be undertaking training with experienced friends, also I will be obtaining an outboard motor as her engine currently does not work so I can use her on rivers, Your site has been very helpful, thank you.

Can you address one issue I am really interested in?

Does a lifting keel need to be all up or all down, or can you choose the level of depth depending on sailing conditions.

I live and sail in the Cayman Islands, an area where we have plenty of shallow water, but variable depth across a lagoon. It would be very useful to be able sail a boat with the lifting keel say half way down, rather than fully extended. Is this possible.

Also, can you sail downwind under spinnaker with the keel drawn up to reduced wetted area and increase speed?

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