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What are I J P E and what do they mean to me?

bruceyp

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I know that these are the dimensions of my sail plan but what do they actually measure? And other than when I am ordering a new sail, when will I use this info? Are these numbers that I should be memorizing? (More likely, saving in my phone).  

JohnRPollard

Aside from when ordering sails, you will usually need to report them if you race and are applying for a rating certificate for your boat. But there's no real need to commit them to memory. Here's a good link that explains what measurement each letter pertains to: EDIT: Sorry, but SailNet seems to be having trouble with hyperlinks lately. Try this (you may have to cut and paste in your browser, preceded by www): (secondwindsails.com/measurement.php)  

sailingdog

sailingdog said: Here's JRP's Link : LINK Click to expand...

sailortjk1

Here is another useful link to have. Lots of good info can be found here. Sailboat Rig Dimensions and Specs  

My link to Mauri Pro appears to be working fine. Don't know why one works and one does not, don't forget, I am basicaly computer illiterate.  

Reason for the trouble with links to other sites While a bit late for this thread, this might help other people having difficulties trying to link to web pages outside Sailnet. The problem lies with the fact that Sailnet uses the BASE tag in the HEAD section of its web pages. The web browser then assumes any link that doesn't start with "http" followed by a colon and two forward slashes is a link to another page on the Sailnet forum site. The web browser then automatically adds the Sailnet forum address to the start of the link address, resulting in a broken link. Hover your mouse over a few of the links in the earlier messages above and look at what shows up in your status bar and you'll see what I mean. RULE: Always put "http" followed by a colon and two forward slashes at the start of an external link address. I've had to use "http followed by a colon and two forward slashes" in place of the correct protocol descriptor as Sailnet won't yet let me post with links. If you don't know what I meant by that, look at the Sailnet web address in the location box at the top of your browser- It starts with "http", followed by a colon and two forward slashes. Hope this helps someone. Slán from Ireland  

I just finished putting together a page with dimensions and sail area calculations for thousands of boats. Not a unique list but follow the link to a page specific to the boat with sail area calculations in addition to the boat dimensions. Boat Dimensions  

You mean like this site? SailboatData.com - sailboat database with specifications, drawings and photos, more than 8000 listings  

sailboatdata.com is another excellent site. My data source is completely independent of them so it is worth comparing them as errors can show up on any of these lists. Allen  

Great project Allen, but there are a number of problems with spinnaker square footages on several boats that I took a quick look at including my own boat, an Express 34. (you need to define builders... Alsberg Expresses are very different than the Canadian Expresses) Racing Symmetrical Spinnaker = 1.8 x JSP x ISP = 150 sq ft Racing Asymmetrical Spinnaker = 1.8 x JSP x ISP= 150 sq ft Cruising Asymmetrical Spinnaker = 1.65 x JSP x ISP = 137 sq ft I can tell you, all our symmetrical spinnakers are all much larger than 150 sq ft. That's even less area than our #4 jib. Am I not reading your information correctly?  

blt2ski

Mark, Probably the same reason my Jeanneau Arcadia has a spin at 124#, NO listing for the JSP or ISP. The program does not auto entry the P or J figure as the spin figure. Not sure HOW many boats are this way, but will swag a BUNCH! Marty  

The bug is fixed (I hope). Try it now. The program was auto entry I and J, but not correctly. Hopefully it is correct now. I apologize for the error and thank you for pointing it out. Please leave a comment on the page if you have any other suggestions for improvements or find any problems. Allen  

As I said before, there are a lot of sites with dimensions and all of them have errors as far as I can tell. It is best to compare them and see if they agree. While that doesn't guarantee accuracy, if every site is different, you know you have a problem. I added pages using the PHRF database so there is now another source of data. Some of what is given on the PHRF database is different as well so there is additional information on it. I included definitions of terms as well on the pages. Hope you find it useful. http://L-36.com/boat_dimensions_phrf.php  

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OntarioTheLake

Sail area calculations

Mainsail Area = P x E / 2 Headsail Area = (Luff x LP) / 2 (LP = shortest distance between clew and Luff) Genoa Area 150% = ( 1.5 x J x I ) / 2 Genoa Area 135% = ( 1.35 x J x I ) / 2 Fore-triangle 100% = ( I x J ) / 2 Spinnaker Area = 1.8 x J x I

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What Sail Dimensions are Required to Calculate Sail Areas?

The required sail dimensions for calculating the area of any triangular sails are usually its height and the length of its foot. But that only works for mainsails and mizzens with no roach, and jibs with a 90 degree angle at the clew - and what about high-cut headsails, spinakers and cruising chutes? Read on...

Foresail and mainsail dimensions are universally referenced with the letters 'J', 'I', 'E' and 'P' approximating to the length of the foredeck, height of the mast, length of the boom and the height of the main sail - but more accurately defined further down this page.

Yacht designers need these sail dimensions to calculate thought provoking stuff such as the sail-area/displacement ratios of their creations, and sailmakers need them before they put scissors to sailcloth.

If our sailboat's sails were perfectly triangular then, as every schoolboy knows, their area would be 'half the height, times the base' - but with the possible exception of a mainsail with a straight luff, generally they're not. Here's how it works...

Main and Mizzen Sail Dimensions

These are almost right-angled triangles except for the curvature of the leach (the 'roach') which increases the sail area. 

sail dimensions labelled on sailboat

It's usually calculated as:~

Area = (luff x foot)/1.8, or

Area = ( P x E )/1.8, where:~

  • 'P' is the distance along the aft face of the mast from the top of the boom to the highest point that the mainsail can be hoisted, and
  • 'E' is the distance along the boom from the aft face of the mast to the outermost point on the boom to which the main can be pulled.

For the mizzen sails on ketches and yawls , 'P' and 'E' relate to the mizzen mast and boom.

For more heavily roached sails, the increased area can be accounted for by reducing the denominator in the formula to 1.6.

Clearly calculating sail areas isn't going to be an exact science...

Jibs, Genoas and Staysail Dimensions

Parts of a sail named

For a working jib that fills the fore triangle - but no more - and with a foot that's parallel to the deck, then you've got a 'proper' right-angled triangular sail, whose area is:~

Area = (luff x foot)/2, or

Area = ( I x J )/2, where:~

  • 'I' is the distance down the front of mast from the genoa halyard to the level of the main deck, and
  • 'J' is the distance along the deck from the headstay pin to the front of the mast.

Genoas, by definition, have a clew which extends past the mast and are described by the amount by which they do so. For instance a 135% genoa has a foot 35% longer than 'J' and a 155% genoa 55% longer. Areas are calculated as follows:~

Area (135% genoa) = (1.44 x I x J )/2, and

Area (155% genoa) = (1.65 x I x J )/2

High-cut Headsails

The 'luff perpendicular' is needed for measuring the area of a high-cut jib

But these formulae don't work for a high-cut jib with a raised clew - unless you imagine the sail turned on its side such that the luff is the base and the luff perpendicular is the height.

It's still a simple calculation though, once you know the length of the luff perpendicular ( LP ), the sail area is:~

Area = (luff x luff perpendicular)/2, or

Area = ( L x LP )/2, where:~

  • 'L' is the distance along the forestay from the headstay pin to the front of the mast, and
  • 'LP' is the shortest distance between the clew and the luff of the genoa.

Spinnaker Sail Dimensions

Much like calculating foresail areas, but with different multipliers for conventional spinnakers and asymmetric spinnakers...

Conventional Spinnakers

Area = (0.9 x luff x foot), or

Area = (0.9 x I x J ), where:~

  • 'I' is the distance from the highest spinnaker halyard to the deck, and
  • 'J' is the length of the spinnaker pole.

Asymmetric Spinnakers

Area = (0.8 x luff x foot), or

Area = (0.8 x  I  x  J ), where:~

  • 'I'  is the distance from the highest spinnaker halyard to the deck, and
  • 'J'  is the distance from the front face of the mast to the attachment block for the tackline.

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Boat: Every boat has maximum sail dimensions that cannot be exceeded. They are defined as I, J, P and E, (also Py and Ey for Ketchs and Yawls). Unless you have existing sails to use as a reference, it is always best to physically measure the boat and not rely totally on manufacturers specifications. Occasionally rig sizes will vary even between the same make and size boat. Measurements can also be altered as a result of re-rigging.

Main Sails: Attach a tape measure to the main halyard and hoist to the maximum or to the black band around the mast if available. Measure to the main tack fitting for the P measurement. The E measurement is the length of the boom measured from the tack fitting to the clew connection or the black band around the boom if available.

Headsails (Spinnakers require I and J measurements): Attach a tape measure to the jib halyard (or top swivel of the furler) and hoist to the maximum. Measure to the deck sheer line for the I measurement. Also measure to the tack attachment point on the bow (or top of furler) for the maximum hoist measurement. Measure from the intersection of the deck and headstay to the front side of the mast for the J measurement.

Tip: tie a line to the halyard along with the tape measure in the event the tape should break you can easily retrieve the halyard.

Sails: Sails are defined by another set of terms. The luff is the leading edge of the sail. The leech is the trailing edge. The foot is the bottom edge. Jibs and Genoas have a Luff Perpendicular (LP) that is the perpendicular distance from the luff to the clew. The LP defines the sail size in terms of percentage increase beyond the J measurement as in the following examples. Headsails are designated as Number 1, 2, and 3.

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Sailboat Rig Dimensions

sailboat specs i j p e

I = Height of headstay termination above the sheer line. J = Distance between the headstay termination at the deck and the front of the mast at the sheer line. P = Distance between black bands on the mast, or the maximum luff length of the main. E = Distance between black bands on the boom, or the maximum foot length of the main. PY & EY are similar to P & E , but indicate mizzen dimensions.

sailboat specs i j p e

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Helpful Information

Rig dimensions primarily used by sailmakers to know how to size a sail..

"P" is the luff length of the mainsail, measured along the aft face of the mast from the top of the boom to the highest point that the mainsail can be hoisted or black band.

"E" is the foot length of the mainsail, measured along the boom from the aft face of the mast to the outermost point on the boom to which the main can be pulled or to the black band.

"I" is measured along the front of mast from the genoa halyard to the main deck. The main deck is where the deck would be if there were no deckhouse.

"J" is the base of the foretriangle measured along the deck from the headstay pin to the front of the mast.

"JSP" is the length of the spinnaker pole or the distance from the forward end of the bowsprit (fully extended) to the front face of the mast.

"ISP" is measured from the highest spinnaker halyard to the deck.

"PY" and "EY" are, respectively the luff length and foot length of the mizzen of a yawl or ketch measured in the same way as for the mainsail.

"IY" is the measurement from the staysail halyard to the deck.

"JY" is the measurement from the staysail stay to the front face of the mast.

"LP" is the shortest distance between the clew and the luff of the genoa.

If you need to know the I J P or E of your yacht or rigging diameter of wires which is useful if you are fitting a furling gear or changing your standing rigging send me an email, I have records of most boats.

The following formulas will give you approximately areas for:

Mainsail = (P x E) / 2 (add 10% for racing mainsail 155% Genoa = (( J x I ) / 2) x 1.65

135% Genoa = (( J x I ) / 2) x 1.44

100% Jib = ( I x J ) / 2

Racing Symmetrical Spinnaker = 1.8 x J x I

Racing Asymmetrical Spinnaker = 1.8 x J x I

Cruising Asymmetrical Spinnaker = 1.65 x J x I

Whisker sail image

What is a Whisker Pole?

Whisker Poles are used to "wing-out" the jib when sailing downwind. They extend between the mast and jib sheet at the clew to hold the jib out on the opposite side of the main in clean air, producing a greater degree of control and efficiency than you could possibly achieve without a whisker pole. Sailors who have attempted downwind sailing without a whisker pole can appreciate the value of being able to stabilise the jib, enabling the sail to work more efficiently.

Advantages of Using a Whisker Pole.

A whisker pole allows you to control the shape and position of the jib on a downwind run, exposing it to air that is undisturbed by the main sail, thus producing a very noticeable increase in efficiency and boat speed. Sailing wing-on-wing is much easier than handling a spinnaker and takes less people to handle equipment.

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Cruising World Logo

How Sailboats Measure Up

  • By By Jeremy McGeary
  • Updated: October 17, 2012

sailboat specs i j p e

Sailboats by the Numbers

Boat reviewers rely on numbers to describe some of the key attributes of their subjects, such as length, beam, draft, and displacement. And while judgments on interior layouts and decor are subjective, these figures describing dimensions are not. There are, however, other numbers commonly cited in spec boxes that can prove more elusive, since they attempt to put a numerical value on how a sailboat might be expected to perform while under way. The commonly used ratios are sail area to displacement (SA/D), displacement to length (D/L), and ballast to displacement (B/D). And though they’re so commonly used that a certain amount of dogma has accrued around them, these figures can, in fact, be misleading, or at least misunderstood. And the result is that a boat can be assigned attributes based on numerical values that don’t take into account how sailboat design has changed over the past several decades.

Here, then, is a look at those ratios, what they attempt to describe, and how they should be interpreted when you go off exploring new and used models. (Click to page 2 for a more in-depth explanation.)

Sail Area/Displacement (SA/D)** An automobile buff seeking a high-performance ride looks for a high power-to-weight ratio and compares the horsepower/curb-weight ratios of different cars. For a sailboat, the SA/D provides the same metric. The horsepower comes from the wind on the sails and is proportional to the sail area; a boat’s weight is its displacement (in pounds, kilograms, or tons).

Initially, the SA/D only really gives a measure of potential acceleration rates (in case any physicists are reading this), but since displacement is a key factor in the resistance a boat encounters when moving through the water, SA/D also has a bearing on potential maximum speed.

The traditional calculation for SA/D compares sail area in square feet to displacement in cubic feet. In the formula, displacement in pounds is divided by 64 (the density of seawater) to obtain cubic feet, which are in turn converted to square feet to make the ratio unit-free.

On a spreadsheet, the formula would be S/(D/64) (2/3).

Nominally, the higher the SA/D, the more lively the boat’s sailing performance. The vessel will accelerate more quickly and have the potential for higher speed. But to be able to compare boats with any degree of precision (or fairness), we have to use similar numbers. The displacement must be in the same condition, either light ship (nothing on board) or fully loaded, and the sail-area measurement must reflect the normal working sail plan. Racing boats have measurement certificates from which these numbers can be reliably extracted. The specifications provided in cruising-boat brochures might not be consistent between builders, but we have to assume they are.

Boats measured in the 1970s and the 1980s for racing under the International Offshore Rule for the most part had SA/Ds between 16 and 17, based on the sum of the mainsail triangle (M = P E/2) and 100-percent foretriangle area (100%FT = I J/2). The measurement system favored small mainsails and large headsails, and since designers of cruising boats stuck close to the IOR sail plan, the IOR value for SA/D became the yardstick. An SA/D above 17 said “fast boat,” and anything below 16 said “slow boat.”

After the IOR fell out of favor, cruising-boat design drifted away from raceboat design, and sail plans began to change. Today, many boats are designed with large mainsails and small jibs, and most builders publish a “total sail area” number that includes the standard jib (often as small as 105 percent) and the roach in the mainsail (which is significantly greater on modern boats with full-battened mainsails than on IOR boats).

These builder-supplied numbers are more readily comparable against competing models, but using them in the SA/D formula makes the boats look “faster” than older models. This is a false comparison, because the sail area used for the older boats doesn’t include the extra area in, say, a 150-percent genoa.

The table “Sailboats by the Numbers” (see page 79) illustrates this. It shows SA/Ds calculated for a selection of modern boats and boats from past eras, all about the same length, using different numbers for sail area. For each model, it shows five SA/Ds. SA/D 1 is calculated using the sail area provided by the builder. SA/D 2 is calculated using M (P E/2) and 100% FT (I J/2). SA/D 3 is calculated using M + 105% jib. SA/D 4 is calculated using M + 135% jib. SA/D 5 is calculated using M + 150% jib. The only SA/D that includes mainsail roach is SA/D 1.

Let’s look at some examples. The 1997 Beneteau Oceanis 411 has a published sail area of 697 square feet on a displacement of 17,196 pounds. That gives an SA/D 1 of 16.7 (the same as SA/D 2), which for decades was considered very respectable for a cruising boat.

In 2012, the current Beneteau Oceanis 41 has a published sail area of 902 square feet (453 mainsail + 449 jib) and a published displacement of 18,624 pounds, to give an SA/D 1 of 20.5. Wow! Super-high performance! But this is for the standard sail area, with the 449-square-foot jib (just about 100% FT and typical of the trend today toward smaller jibs that tack easily). Plug in the calculation using I, J, P, and E and SA/D 2 drops to 18.9 because it doesn’t include mainsail roach, which is about 16 percent of the total published mainsail area.

Go back to the 1997 model, tack on a standard-for-the-day 135-percent genoa, and the SA/D 4 becomes 20.7. (If we added in mainsail roach, typically about 11 percent of base mainsail area before full-battened sails, we’d have 21.4.) The 1997 boat has essentially the same horsepower as the 2012 model.

Looking at current models from other builders, the SA/Ds based on published numbers hover around 20, suggesting that designers agree on the horsepower a cruising sailboat needs to generate adequate performance to windward without frightening anyone.

The two boats in our chart that don’t at first appear to fit this model are the Hunter 39 and the Catalina 385, but they’re not really so far apart.

The Hunter’s SA/D 2 is 16.1. Its standard jib is 110 percent (327 square feet), and the rest of the published sail area is in the mainsail—664 square feet, of which 37 percent is roach!

Catalina is a little more traditional in its thinking. If you add the standard 135-percent genoa, the SA/D becomes 21.2—right in the ballpark. (It’s still there at 19.7 with a 120-percent genoa.)

The table shows that, for boats targeted at the “performance cruising” market, the SA/D numbers using actual sail area lie consistently around the 20 mark. To go above that number, you have to be able to fly that sail area without reefing as soon as the wind ripples the surface. To do that, you have to elevate stability—with broad beam, lightweight (i.e., expensive) construction, deep bulb keels, and fewer creature comforts.

Displacement/Length (D/L)** While sailboat builders and buyers are interested in displacement in terms of weight, naval architects view it as volume; they’re creating three-dimensional shapes. When working in feet, to get a displacement in pounds, they multiply cubic feet by 64, the density in pounds per cubic foot of seawater. (Freshwater boats displace more volume because the density of fresh water is only 62.4.) The D/L ratio is therefore a measure of immersed volume per unit of length—how tubby the hull is below the waterline.

According to conventional wisdom and empirical studies, the lower the D/L, the higher the performance potential. This is mainly due to wavemaking resistance being lower for slender hulls than for tubby hulls.

In the D/L formula, displacement in pounds is divided by 2,240 to convert it to tons to bring the values to manageable numbers, so D/L is displacement in tons divided by .01LWL (in feet) cubed.

In a spreadsheet, the formula would be D/(2240*(.01L)3), where D is the displacement in pounds and L is LWL in feet.

In the early days of fiberglass boats, the Cruising Club of America rule was the principal dictator of boat shapes. Because it was a waterline rule, designers kept waterlines short to keep ratings low and relied on long stern overhangs immersing to add “sailing length” when the boats heeled. Carbon fiber was available only to NASA, and boats had full interiors, so “light displacement” wasn’t really in the cards. A D/L of 300 was considered dashing, even risky. Many still-popular designs from the 1970s and 1980s have D/Ls as high as 400; see the Bounty II.

Fast-forward 40 years. Boats now have plumb bows and plumb sterns and waterlines almost as long as their LOAs—there are no rating penalties on a cruising boat. The boats’ weights haven’t changed much because, although builders try to save weight to save cost, the boats are so much bigger. The hull and deck surface areas are greater, and all that extra internal volume can be filled with furniture. The effect on D/L ratios has been drastic—just look at the table. A D/L ratio above 200 today describes a heffalump.

But do these lower D/Ls actually buy you any more speed? Yes and no.

Yes : Because speed is proportional to the square root of the waterline length. Today’s 40-footer has a much longer waterline than yesterday’s and ought to sail as fast as yesterday’s 50-footer. It might also benefit from reduced resistance due to a smaller cross-sectional area, but it also might have greater wetted-surface drag due to the longer immersed length. When sailing downwind in waves, though, the lower-D/L boat will surf more readily.

No : Because, as we saw above, the power-to-weight ratios (SA/D) of modern boats aren’t effectively any higher, and certainly aren’t in the realm that would allow our cruising sailboats to climb out of the displacement zone and plane. In most conditions, the lower-D/L boat is still trapped in its wave.

In the days of the IOR, a D/L of 250 was still pretty racy; see the 1978 Catalina 38. Today, even a D/L as low as 150 doesn’t make a boat a speedster if it can’t carry the sail area to make it so. To compete at a level with a Volvo 70, look for a D/L of about 40 and an SA/D of 65.

Ballast/Displacement (B/D)** The ballast/displacement ratio is simply the ballast weight divided by the boat’s total displacement. Since ballast is there to give the boat stability, it’s easy to jump to the conclusion that the higher the B/D, the stiffer the boat.

However, B/D doesn’t take into account the location of the ballast.

Take a boat that has a total displacement of 20,000 pounds and put its 8,000 pounds of ballast in the bilge. Now take the same boat and put the 8,000 pounds of ballast 4 feet deeper in a bulb at the bottom of a deep fin keel. Same ballast ratio (0.4), but very different stability.

When looking at B/D, therefore, we must ask about the configuration of the keel: How low is the ballast?

Stability analysis is complex and involves beam, hull cross-section, and length, among other factors, of which B/D is just one.

Since the late 1990s, builders of sailboats intended for sale in the European Union have been required to provide stability data, including a curve of righting arm at angles of heel from 0 to 180 degrees—far more information than anyone can divine from a B/D number and a much more useful measure of a boat’s inclination to stay upside down in the unlikely event (the way most people use their boats) that it exceeds its limit of positive stability.

CW contributing editor Jeremy McGeary is a seasoned yacht designer who’s worked in the naval-architecture offices of David Pedrick, Rodger Martin, and Yves-Marie Tanton and as a staff designer for Camper & Nicholson.

To read the related article, How To: Measure Sail Area, click here.

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Sailing coaching, consulting and instruction, crew training, sailing systems & techniques for solving sailing's challenges. call coop at 401-965-6006, sails-mainsail: the “p” dimension, defination and measurement of..

One of the things that gives most sailmakers gray hair is confirming the dimensions and details of fit for the sails they make. This selection of articles discusses the things sailmakers need to know and what the definitions are so the consumer can provide the correct information. There is nothing worse than getting down to the boat on that lovely Spring Saturday morning with the new sail only to find out the luff slides just don’t quite fit the track. Read on to find out how to help eliminate such frustrations.

Virtually all boats have their “rig plan” defined by four dimensions. These are called the I, the J, the P, and the E. The I & J define the headsail and the P & E the mainsails. There are some other subcategories but let’s start with these four first and we will start with the mainsail and what the P & E dimensions are NOT.

  • The P is NOT the luff length of the actual sail.
  • And it is NOT the maximum available hoist on the mast.
  • The P dimension is NOT anything but this:

The distance up the mast (from the top of the boom) that the designer has calculated as the maximum luff length that a sailmaker might build a sail to (which, in conjunction with the other dimensions, I, J, E) will give the boat the sail area the designer wants it to have.

In plain English, “P” is in the first place a mathematical construct. In practice on most boats, especially those sold with “racer” in the name, the P is measured “from the UPPER edge of a contrasting color band at the gooseneck UP to the LOWER edge of a contrasting color band at the mast head.” This (is an approximate, but close) quote taken from most sail boat rating handicapping rules, like for instance PHRF, IRC and ORR. Any class or make of boat that desires to limit or control the mainsail area will make some definition similar to this. An example of what this (commonly called the black band for obvious reasons) looks like is this on a Hallberg Rassey 31 footer.

The Black Band is located at the tack and P dimensions are taken from the top of the band to the underside of a similar band near the masthead.

Now the observant amongst you will say, “But the tack of the sail is a couple of inches above the upper edge of the black band!” Go to the top of the class- this is the nub of this article. That detail is called the tack set up and we will get to that detail. Another version of the black band is here.

Another view of the Black Band

And if the mast is black-Carbon or anodized-the band is white.

"Black Band" in White, on a Carbon spar

This “contrasting colored band” is at the gooseneck (so the lower) end of the P dimension.

The top end is of course at the masthead, more or less. There are a few variables related to the positioning of the Upper Band of P. One fairly important one is the length of the backstay crane. This is the structure at the top of the mast to which the backstay is attached. The design and installation of the backstay crane varies over  time and boat design and intended use. In the case of older boats, and in particular boats with wooden masts, there is for practical purposes no backstay crane. So backstay crane’s come in all manner of configurations. The one of most interest to the sail makers is the length, I.E. the extent to which the crane and in particular, the attachment of the backstay to the crane is aft of the aft face of the mast.

The detail I am thinking about when measuring  this boat is making sure the sail does not foul the backstay when set to full hoist.

1. The height (length) of the luff of the mainsail is determined first by knowing the boat’s “P” dimension.

The mainsail headboard needs to be able to clear the backstay at full hoist.

On many boats, especially “cruising” boats, like this Alajuela 33 pictured above there is no black band. Quite often the P is determined by consultation with any of the various compendiums of sail boat data sailmakers have at their disposal.The sailmakers must ensure that the mainsail headboard will not foul the backstay when the sail is at full hoist. The sail in the picture is actually at the “correct” height for the boat’s stated “P” dimensions (even though it looks “short”). This was confirmed, (reconciled really with data I had researched on the class of boat)  in advance of the new sail being made by measurement (by me) of the spar. If on the other hand the sail was built to full hoist, right up underneath the crane, it is most likely that the headboard would foul the backstay.

TIP: measure the spar fore and aft at your eyeball level standing on deck. Then eyeball the crane and visualize how long the crane is compared to the spar thickness. So if you reckon the mast is 8 inches long, fore and aft, and the crane is about 50% of the size of the spar, then a good estimate is the crane is 4″.

In this image, below, of an older wooden spar, there is no crane and no black band. Fortunately there is no backstay either. The line passing through the block is the topping lift.

Wooden mast with no backstay crane or backstay

2. The size (how long fore and aft) of the headboard and so how far aft the corner of the headboard may extend (including with all the luff hardware attached) aft of the aft face of the spar. The sail pictured below has a special headboard included with this luff hardware. On this boat the entire sail is about 1.5 inches further aft from the mast than it would be if the sail merely had “normal” slug slides.

Luff hardware has an impact on how far aft the headboard will extend

3. The position of the backstay attachment to the crane.

On some racing oriented boats, like this Pearson Flyer, pictured below, the “P” is literally at the bottom of the main halyard sheave. Indicated in this instance with a white band on the blue spar. The crane is fairly long, for a 30 foot boat. The backstay is led through a, so called, “backstay flicker”, so that in light air the backstay can be eased to let the roach of the sail pass thru. Refer to more information on this in the Full Batten posts.

Race boats have the band very close to the top of the spar

This absence of backstay crane is the main reason why there is often upwards of 18″ difference between the upper P measurement point and the “top of the mast” as is seen, below, on this wooden mast.

The shorter the backstay crane is (or if absent completely) the lower down the sail must be

When you lower your old mainsail examine the anodized aluminum headboard for scarring on the after corner and if it is so marked almost for sure the sail has stretched to the point where it is fouling the backstay. On some boats there is a backstay crane yet the band is still a ways down from the “max hoist” distance, as here.

Close up of black band on Olsen 34 masthead. The black track is a Tides Marine Strong Track

You will observe that in this picture I am measuring the backstay crane so as to make sure what even headboard we select it will clear the backstay. How we figure that angle will be discussed in greater detail further on in this series, but basically we take a dimension from the gooseneck aft to where the backstay passes the end of the boom.

A common default measurement sailmakers use for determining the size of the headboard, stems from racing rules and that is 4% of the boats E dimension. So for a boat with a 12 foot E, then the default headboard would be 5.76, or basically a 6 inch headboard. Unless the boat is racing, and this is a detail of the transaction though the headboard would be shorter, for all the reasons discussed above.

So, to recap, the “P” is “the distance between the top of the lower band and the bottom of the upper band.” It is not the luff length, the max hoist or anything else. The “P” dimension and the “E” dimension, discussed in the next article, are the two pieces of information the sail maker will need to have to even begin to think about figuring out all the things he needs to consult with you on a new sail. Subsequent articles will discuss the detailing at the corners, tack set back, tack set up, reef set back and clew set up battens roach and a few other details pertinent to buying a new mainsail.

Home > Resources > How to Measure for a New Headsail (Jib or Genoa)

How to Measure for a New Headsail (Jib or Genoa)

25 April 2017

Ask Precision Sails , Hardware , Headsail , Measurements , Sails , Technical Tags: Head Sail Measurements , How to Measure for a Head Sail , New Sail Meaurements

measuring for a new headsail

Purchasing a new Head Sail for your sailboat is one of those investments that every sailor will be faced with eventually. Sails don’t last forever, even if you treat them like gold. Once you have decided to invest in new sails you may get that feeling of being over whelmed by the choices and the details involved. When deciding on a loft to work with make sure you choose a loft that will offer a good consultation on the cloth and sail feature choices as well as a design consultation if you want one. Don’t be scared into paying extra for a sail just because your local loft tells you it’s hard to measure. You do not need the added expense of having someone come to your boat and measure for your new sail. If you can read a tape measure you can measure your boat for a new Jib or Genoa.

Measurements Required for a New Head Sail:

Rig Specs – The first thing that you are going to want to find are the General Rig Specs I,P,J,E for your boat. You can get these from your boat manufacturer, online or in your boat manual. These will be used to ensure that the loft you are working with has quoted you the correct size of sail and to ensure that when you take your measurements they are accurate.

Existing Head Sail – Measure your existing Jib or Genoa sail’s general dimensions. Luff (leading edge of your sail), Leech (trailing edge of your sail) and the Foot of your sail. These measurements will be used to compare the measurements that you take from your rig to ensure that everything is working out well. It will also give your designer an idea of what the current sail size is.  If you are ordering a sail that is going to add to your inventory of head sails the only measurement that is of benefit is the luff length.

Rig Measurements – Now we are going to get onto the boat and start to take the measurements of the rig as it sits today. This will ensure that your sail designer is designing a sail for your boat and not the boat that it started as. The two measurements that are required are the I measurement and the J Measurement. The I is the the distance from your the top of your halyard to the base of your mast. This is taken by hauling a tape measure up your halyard until it reaches the top and measuring straight down to the base of your mast.  While you have your tape at the top take the time to also measure the maximum luff length by measuring to the attachment on your furler or on the deck (hank on sails). The J measurement is done by measuring from the base of the mast to the attachment of your fore stay.

How to Measure the Maximum Luff Length of your Genoa or Jib

Now that we have the basic dimensions for your sail it’s time to get into the details that will ensure that your sail will fit the day it arrives.

Luff Specifications: Furling Head Sail or Hank On

Furling head sails attach to your furling system using luff tape.  It is a cord or rope warped inside of a tape.  Each Furling System will have a specific luff tape size that will slide nicely up the track without coming out while under force.

The best way to measure the tape is to use Calipers that can measure in millimeters.  If you don’t have a set use a set of drill bits and either slide them up the track in your furling system or hold them up to the luff tape on your existing sail to determine the proper size.

Luff Tape Specification chart below: 

Track Measurements:

Your sail designer will want to know where your tracks start and stop to ensure that the new sail will be designed with the proper sheeting angles. Attach your tape to the base of the fore-stay and measure to the start and the end of each set of tracks.

J Measurement Video:

Track Measurement Video:

Water Line Measurement:

A good measurement to provide your sail designer is the distance from the waterline to the fore-stay and from the waterline to the base at your chain plates.  These measurements will let your designer ensure the clew height of new Jib or Genoa.

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Working with Sail Dimensions

Why measure sails? Sailmaking is a complex discipline that blends elements of science and art. Perhaps you want to get a new set of sails made for your older boat, or perhaps you have a new to your boat with no sails to work from. However you attack the problem, you’ll have to start out with some measurements.

Table of Contents

Sail measurements and definitions, main sail dimensions, headsail dimensions — jib, genoa, or staysail, sails and sailing measurements made easy, sail dimensions faqs.

Sail dimensions

One thing to understand before diving in—sails are three-dimensional objects. You can lay them out flat on the ground, but a perfectly flat sail does not harness the wind. Instead, sails must have a curve built into them, and that makes measuring them much more complex.

The three sides of a triangular sail each have a particular name.

  • Leech — The rear edge of a sail that is not attached to anything
  • Luff — The forward edge of a sail, attached to the mast on a mainsail or to the stay on a headsail
  • Foot — The lower edge of a sail, it runs along the boom on a mainsail

Likewise, each corner of a triangular sail has a name.

  • Head — The top of a sail, where the halyard gets attached
  • Tack — The forward corner, on a mainsail it gets attached to the gooseneck
  • Clew — The aft corner, where the outhaul attaches on a main or the sheets attach to a jib

Sailboat Sail Dimensions

With those basic terms out of the way, it’s time to look at a few things that sailmakers consider when designing a set of sails. The most significant limits placed on the sailmaker come from the boat itself. 

Many makes and models of boats have their sail specifications online. It’s essential to break out the tape measure and measure your boat–if only to confirm that the numbers you found are genuine. Remember, at this point, many of our sailboats have had long and storied lives well before we owned them. Your boat may have been custom rigged, and you don’t even know it. 

Rig measurements also can change from year to year on one make and model as the manufacturer’s supplier changes. So you can’t be sure which numbers you find on the internet are correct and which apply to a different boat. 

The limiting dimensions for mainsails are the height of the hoist along the mast and the length of the boom.

  • P — distance along the aft face of the mast from the top of the boom (gooseneck) to the point of highest hoist at the maximum main halyard position
  • E — distance along the boom from the mast to the maximum outhaul position

Mizzen Mainsail Hoist Elevation and Boom Length

Mizzen mast sails on ketches or yawls will have similar shapes and measurements as a mainsail. Therefore, their P and E measurements are usually denoted Py and Ey to show it is the mizzen sail.

main and mizzen sail dimensions

Main and Mizzen Sail Area Calculation

When given P and E, the unknown factor is the length of the sail’s leech. The leech can be longer and curve out, giving the sail more shape and lift by adding roach. 

If the sail were perfectly flat, calculating its area would be straightforward. The area of a right triangle is equal to one-half of its two legs multiplied together. 

Since the main or mizzen is not a flat object, though, we do not divide it by two (or halve it). Instead, we use a multiplier to estimate its area. For a regular mainsail, divide by 1.8. If the sail has a larger roach, divide by 1.6.

Mainsail Area = (P * E) /1.8
Mainsail Area (heavily roached sails) = (P * E) /1.6

The key measurements for a headsail are the distance up the mast that you can hoist the sail and the distance from the base of the headstay to the mast.

  • I — The height along the front face of the mast from a point level with the headstay pin to the point of maximum hoist
  • J — Foretriangle horizontal distance measured from he distance along the main deck, from the tack attachment to the mast

Headsail Area Sail Measurements

Assuming that the headsail is roughly a right triangle, the area equals those two sides multiplied together and divided by two.

Working Jib Area = (I * J) /2

However, it’s important to note that many genoas are designed to overlap the mast. Therefore, using the J measurement does not account for the extra sail area that projects aft of the mast.

135% Genoa Area = (1.44 * I * J) /2
155% Genoa Area = (1.65 * I * J) /2

jib or genoa dimensions

Luff Perpendicular

In the case of a high-cut jib or genoa that does not form a right triangle, the luff perpendicular measurement is used. 

  • L — (Luff) The distance of hoist from the attachment of the sail’s tack to the point of the maximum hoist, as measured on the forestay (i.e. the length of the sail’s luff)
  • LP — (Luff Perpendicular) The shortest distance from the sail’s clew to the luff

The same area measurement formula applies.

High-cut Jib Area = (L * LP) /2

While it’s fun to work out all the specifications that set one boat apart from another, it’s of little use to the cruising sailor. Measuring sails is a simple task as long as you know what to look for and the limits that your boat places on your sails. Keep in mind that as long as a sail fits, it will probably work. Most sail lofts and second-hand sail dealers work on the “try and see” plan. So hoist the sail and give it a shot—you might be surprised. 

How do you measure a sail?

Sails are measured based on the limitations presented on the boat. For example, a mainsail cannot be hoisted taller than the mast. So a critical measurement for a mainsail is the luff length, denoted by the measurement “P” in sail dimensions. Similarly, you cannot mount a mainsail on a boom that is too short. So the foot of a mainsail is denoted as “E.”

What is sail size?

Sails are sized based on the fixed dimensions from the boat they are made for. In other words, nearly every sail is custom-tailored to the rig on the boat. You can take specific measurements from the rig that will dictate the size of the final sails. Within those boundaries, sailmakers can tinker with a few other ways to add sail area, like adding roach to mainsails or creating overlapping headsails.

How are sail luffs measured?

The luff of a sail determines its draft, or how much curve the sail has. As such, there is no straight-line measurement for the luff of a sail. Instead, sailmakers used the fixed measurements from the leech and foot of the sail to determine its overall size. The luff, in the end, may be curved outward to add roach and more draft.

Too much luff is not a good thing, however. If the luff is too long on a mainsail, the boom may sit too low to clear the bimini, hardtop, or boom gallows.

What is the formula of sail?

The area of a sail is calculated by multiplying the luff or vertical by the foot and dividing by 1.8 for mainsails or 2 for headsails.  Mainsail or Mizzensail Area = (P * E) /1.8 Jib, Genoa, or Staysail Area = (I * J) /2

sailboat specs i j p e

Matt has been boating around Florida for over 25 years in everything from small powerboats to large cruising catamarans. He currently lives aboard a 38-foot Cabo Rico sailboat with his wife Lucy and adventure dog Chelsea. Together, they cruise between winters in The Bahamas and summers in the Chesapeake Bay.

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Rigging specs for Grampian 26, I, J, P, E

  • Thread starter Harry Phillips [email protected]
  • Start date Sep 19, 2006
  • Brand-Specific Forums

Harry Phillips [email protected]

Need the I, J, P, E measurements for a Florida Westcoast PHRF rating. Is a '74 model with a fixed kkel. Also, if possible, the range of ratings.  

Scott21120

Here is a site with Rig Dimensions for lots of boats - just pick the letter your boat starts with from the top ( G for you) and scroll down the list that comes up to your boat.  

[email protected]

PHRF and specs Here is a link to Bacon Sails. They have all the measurements that you need. http://www.baconsails.com/database/boatspec.php As far as the PHRF. I can tell you I received a rating of 242 with my 26. With that rating my son and I placed 4th in our class at a recent race. We were very proud of that being there were about 25 boats in that class. Maybe Gramp's are not really as slow as they look.  

More info on G-26 PHRF PHRF-LO has given us a rating of 219 (same rating as PHRF New England gives for a G-26). Yes, very comfortable and fairly fast boat for a cruising type. Having won the division championship trophy for 4 years straight now, and beating out C&C, Mirage, Tanzer etc. they are nailing us with the faster ratings. Here is a site you might find interesting - lots of Grampian links as well.  

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Sail Measuring

sailboat specs i j p e

You will notice, as you read the sail listings, that many sails have no boat class shown. This is simply because we just do not know. If all three edge dimensions are appropriate, the sail will fit. A sail does not have had to be made for your class boat to fit and work well. For over 60 years, we have gone by this principle and it has worked very well.

Measuring Your Boat Remember, every boat has maximum sail dimensions that cannot be exceeded. Establish the I, J, P & E for your boat, also the Py and Ey, if yawl or ketch rigged. It is a good idea to measure, to confirm your boat is rigged to specifications, as many boats are re-rigged or the specifications have been changed by the manufacturer. CAUTION: When measuring, ease up against mast top sheave; do not cause “jam.”

Luff A sail’s forward edge. The luff of the mainsail is usually hoisted up and attached to the mast. The luff of the headsail is attached to the forestay / furling extrusion.

Leach/Leech The back edge of a sail.

Foot The bottom edge of a sail.

Mainsails The P and E ( or B) refer to the mainsail luff and foot respectively. You will want to check if you have a tack setback; if so, note this dimension. E = setback and actual foot of sail. Also, check to see how much the luff and foot can vary; note the travel of the outhaul car and the gooseneck fitting if it slides. Now that you have found the minimum and maximum luff and foot dimensions, check the leach dimension. Hoist your tape measure on the main halyard and measure to the outhaul fitting. Remember, too long a leach will cause a droopy boom. Confirm the boom will clear any special fittings you have, such as boom gallows, dodger, etc. Do note the minimum and maximum dimensions acceptable to you.

Jibs and Genoas The I and J are the controlling dimensions for headsails. The luff of the working jib is usually 80% to 90% of the I. The foot usually overlaps the mast by one to two feet. The leach is determined by the location of the jib lead block. See the paragraph below for “trying on sails.” In many cases, the best way to find the leach and foot dimensions is this trial method. 150% and larger genoas are usually full luff sails. The I on many boats equals the maximum luff, but it’s best to measure to insure a proper fit. Hoist your tape measure on your regular genoa halyard and measure to your regular tack fitting. If you want a 150% genoa, measure 1.5 x J from the tack fitting to the rail. Working from this position establish the minimum and maximum leach and foot dimensions. Again, the trial method works best. Keep in mind your sheet lead block positions.

Spinnakers If you are racing, we urge you to check your class rules on the allowable spinnaker size. Some racing classes, such as Lightnings, Solings, etc. have very strict rules. Most cruiser-racer classes use the I.O.R. rule. This rule allows the spinnaker luffs (leaches) to be a maximum of 95% of the square root of (I 2 + J 2 ). The sail width may not exceed 1.8 x J. The spinnaker pole length should equal J. Larger sails can be used, but expect a rating increase. Many boats that do not race like to use spinnakers. The rule of thumb for the spinnaker size is the luffs = I. The foot should be between 1.6 x J and 2 x J. Many cruising boats are now using “Poleless Spinnakers.” The luff on poleless spinnakers should not exceed the I or the full size genoa luff. The foot should be between 1.6 and 1.8 x J. The leach is usually 90% of the luff. No spinnaker pole is used with these “Poleless Spinnakers.”

To “TRY ON” any sail on the list, tie three ropes together to the exact three edge dimensions of the sail. Hoist the “sail” outlined by the ropes. If a jib or genoa, this will include putting a sheet rope on the ”clew.” If the “pretend sail” can be sheeted in so that ropes representing the leach and foot can be pulled taut at the same time from your lead block, the ACTUAL SAIL should fit OK.

Remember all dimensions shown on the list are fully stretched, as would be the sail when sailing.

NOTE: There is a maximum dimension for any sail that you can use on your boat. The boat itself is a limiting factor. The minimum dimension can be your decision, based on many facts, the sails available or the price.

Our staff has many years of sailing experience. If you have any question, please let us know.

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Rig Dimensions

The following abbreviations are often used to describe various measurements on a sailboat. Precise technical definitions exist for each abbreviation, but the following is a list of simple descriptions.

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sailboat specs i j p e

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Sail Plan Dimensions

Sail plan dimensions, figure out your rig dimensions when it comes to your sails.

sailboat specs i j p e

The basic rig dimension for a yacht are generally understood. However, there are some differences in how some sailors describe these dimensions. Here is how we define them at North Sails.

I – Height of Foretriangle Elevation of Forestay, measured down to elevation of main shrouds at sheer line.

J – Base of Foretriangle Horizontal distance measured from front face of mast at deck to position of headstay at sheer line.

P – Mainsail Hoist Elevation of upper mast band or maximum main halyard position, measured down to lower mast band or top of boom.

E- Mainsail Foot Horizontal distance measured from aft face of mast at top of boom to boom band or maximum outhaul position.

Is – Height of Inner Foretriangle Elevation of Forestay, measured down to elevation of main shrouds at sheer line.

Js – Base of Inner Foretriangle Horizontal distance measured from front face of mast at deck to position of inner headstay at sheer line.

Py – Mizzen Mainsail Hoist Elevation of upper mast band or maximum main halyard position, measured down to lower mast band or top of boom.

Ey – Mizzen Mainsail Foot Horizontal distance measured from aft face of mizzen mast at top of boom to boom band or maximum outhaul position.

ISP – Elevation of Spinnaker Halyard Measured down to elevation of main shrouds at sheer line.

SPL – Spinnaker Pole Length

STL – Spinnaker Tack Length Horizontal distance measured from front face of mast at deck, forward and horizontally to position of spinnaker tack attachment point.

sailboat specs i j p e

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  2. Balboa 20 Details

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  3. Sailboat Rig Dimensions

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  5. Helpful Information on I.J.P.E

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COMMENTS

  1. What are I J P E and what do they mean to me?

    P-distance from boom to top of mast. E-length of boom. Mainsail area is approximately (P * E)/2. This is only approximate, since most main sails are cut with some roach. Jib area is approximately (I * J)/2. This is also only an approximate because some jibs are cut with a high clew, to help the helmsman see under the sail or other slight ...

  2. Sailboat Rig Dimensions Official Website

    Sailboat rig dimensions official website will help you calculate sail area. Sailboat Rig Dimensions Database ... Mainsail Area = P x E / 2 Headsail Area = (Luff x LP) / 2 (LP = shortest distance between clew and Luff) Genoa Area 150% = ( 1.5 x J x I ) / 2 Genoa Area 135% = ( 1.35 x J x I ) / 2 Fore-triangle 100% = ( I x J ) / 2 Spinnaker Area ...

  3. Understanding Sail Dimensions and Sail Area Calculation

    Primary dimensions for calculating areas of triangular sails. It's usually calculated as:~. Area = (luff x foot)/1.8, or. Area = ( P x E )/1.8, where:~. 'P' is the distance along the aft face of the mast from the top of the boom to the highest point that the mainsail can be hoisted, and. 'E' is the distance along the boom from the aft face of ...

  4. Rig Dimensions

    The following rig dimensions designated by " I ", " J ", " P ", and " E " are needed to produce a price quote. They are convenient names to use because they are short and are understood throughout sailmaking…. " P " is the luff length of the main-sail, measured along the aft face of the mast from the top of the boom to the ...

  5. Sail Measurement Assistance

    Links. Sail Measurement Assistance. Boat: Every boat has maximum sail dimensions that cannot be exceeded. They are defined as I, J, P and E, (also Py and Ey for Ketchs and Yawls). Unless you have existing sails to use as a reference, it is always best to physically measure the boat and not rely totally on manufacturers specifications.

  6. Information Sail Data

    Sail Pack Kit - Standard Sunbrella® Color (10' Boom) Spinnaker Sock Kit 21' 1" to 24'. Foredeck Sail Bag Kit - Standard Sunbrella® Color (For Boats up to 20') Complete Sail Plan Data for the Information Sail Data. Sailrite offers free rig and sail dimensions with featured products and canvas kits that fit the boat.

  7. Sailboat Rig Dimensions

    Sailboat Rig Dimensions. I = Height of headstay termination above the sheer line. J = Distance between the headstay termination at the deck and the front of the mast at the sheer line. P = Distance between black bands on the mast, or the maximum luff length of the main. E = Distance between black bands on the boom, or the maximum foot length of ...

  8. Helpful Information on I.J.P.E

    If you need to know the I J P or E of your yacht or rigging diameter of wires which is useful if you are fitting a furling gear or changing your standing rigging send me an email, I have records of most boats. The following formulas will give you approximately areas for: Mainsail = (P x E) / 2 (add 10% for racing mainsail 155% Genoa = ( ( J x I ...

  9. I,J,P,E

    Jun 13, 2002. #2. IJPE. I and J describe your foretriangle:u000bu000b- I is the vertical distance from the highest hoist point of your jib halyard to the boat's sheerline abaft the mast (basically, down to the deck level)u000bu000b- J is the horizontal distance from the front of your mast to the jib tack attachment point.u000bu000bP and E ...

  10. I, J, P, E

    Hunter 35.5 LI, NY. Nov 5, 2004. #5. Re: I,J, P,E. Bob, The "J" is measured from the front of the mast to the point where the headstay intersects the deck. The "I" is measured from the mast base to the 'hounds' (the point where the headstay attaches to the mast)u000bScott, you've got it right!! B.

  11. Hands-On Sailor: How Sailboats Measure Up

    It shows SA/Ds calculated for a selection of modern boats and boats from past eras, all about the same length, using different numbers for sail area. For each model, it shows five SA/Ds. SA/D 1 is calculated using the sail area provided by the builder. SA/D 2 is calculated using M (P E/2) and 100% FT (I J/2).

  12. Sailboat Calculator

    Use the search bar to look up dimensions for boats currently in our database. You may also enter a boat's dimensions directly in Part 2. Part 1: Search Database. Search. ... PART 2: BOAT SPECS. US IMPERIAL. METRIC. You may edit the boxes below from your selection above or add a boat from scratch. BOAT NAME: LOA: LWL: BEAM: DISPLACEMENT:

  13. Sails-Mainsail: The "P" dimension, defination and measurement of

    A common default measurement sailmakers use for determining the size of the headboard, stems from racing rules and that is 4% of the boats E dimension. So for a boat with a 12 foot E, then the default headboard would be 5.76, or basically a 6 inch headboard. Unless the boat is racing, and this is a detail of the transaction though the headboard ...

  14. How to Measure for a New Headsail (Jib or Genoa)

    If you can read a tape measure you can measure your boat for a new Jib or Genoa. Measurements Required for a New Head Sail: Rig Specs - The first thing that you are going to want to find are the General Rig Specs I,P,J,E for your boat. You can get these from your boat manufacturer, online or in your boat manual.

  15. Working with Sail Dimensions

    Mainsail Area = (P * E) /1.8. Mainsail Area (heavily roached sails) = (P * E) /1.6. Headsail Dimensions — Jib, Genoa, or Staysail. The key measurements for a headsail are the distance up the mast that you can hoist the sail and the distance from the base of the headstay to the mast.

  16. Rigging specs for Grampian 26, I, J, P, E

    Sep 19, 2006. #4. More info on G-26 PHRF. PHRF-LO has given us a rating of 219 (same rating as PHRF New England gives for a G-26). Yes, very comfortable and fairly fast boat for a cruising type. Having won the division championship trophy for 4 years straight now, and beating out C&C, Mirage, Tanzer etc. they are nailing us with the faster ...

  17. SailboatData.com

    SailboatData.com …is a database that contains information on over 9000 production and semi-production sailboats dating back to the late 1800's. COMPARE BOATS To compare up to three boats at one time, click the (+) Remove a compared boat by clicking (-)

  18. Sailboat Data

    Us 33 Sail Data. Ericson 33 7/8 Rig, Holland Sail Data. Gulfstar 44 Motorsailer Ketch Sail Data. Seaclipper 34 Sail Data. Hunter 37 New Sail Data. Beneteau First 285 Sail Data. Search for sail data such as measurements and rig dimensions for your sailboat in Sailrite's Sail Plan Database.

  19. Sail Measuring

    Measuring Your Boat Remember, every boat has maximum sail dimensions that cannot be exceeded. Establish the I, J, P & E for your boat, also the Py and Ey, if yawl or ketch rigged. It is a good idea to measure, to confirm your boat is rigged to specifications, as many boats are re-rigged or the specifications have been changed by the manufacturer.

  20. Rig Dimensions

    Rig Dimensions. The following abbreviations are often used to describe various measurements on a sailboat. Precise technical definitions exist for each abbreviation, but the following is a list of simple descriptions. LOA. Length Overall - overall tip-to-tip length of the boat. LWL.

  21. PDF Mac 25

    Specifications I J P E L.P. MacGregor 25 21.75' 10.50' 25.5' 9.83' 15.75' Hull speed in knots Displacement to length ratio Sail area ... Maximum heel angle is 10 to 15 degrees, more or less and the boat will sail slower. There should be no lee or weather helm in light to moderate conditions. When other than neutral

  22. Sail Plan Dimensions

    Measure the distance from the top of this new forestay mark to the middle of the forestay pin. On most boats this is the load sensor pin, the pin that the tack of the jib attaches to. The next step for tuning the rig is to make sure the mast is square in the boat. Set the shroud tension close to base tension and loosen the D1's (& D2's).

  23. J/70

    S# first appeared (that we know of) in TellTales, April 1988, "On a Scale of One to Ten" by A.P. Brooks . The equation incorporates SA/Disp (100% fore triangle) and Disp/length ratios to create a guide to probable boat performance vs. other boats of comparable size. For boats of the same length, generally the higher the S#, the lower the PHRF.