Sail Dimension Help - SailNet Community
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post #1 of 7 Old 06-23-2009 Thread Starter
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Sail Dimension Help

Looking to get a new headsail for my boat. I would like to get a new "used" one that is in excellent condition, maybe a lightly used race sail, to save money over a true new one.

The issue that I ma having is trying to figure out if the dimension of the headsail from the dimensions of the rig.

The P dimension of my boat is 40.5, the I=46.0, J = 14.2, and E=11.0. So to get the max. luff dimension, along the headstay, with out measuring my current sail, I calculated Max Luff equals Square root of (I^2 + J^2) = 48.14 ft. That assumes that I tack the sail right to the deck. I am guessing that the RF tack fitting is about 12 inches off the deck, so now the Max Luff is around 47.14.

If I wanted a sail that was between 130 and 140% of the foretriangle, I am guessing that the headsail foot dimension is between 18.46 and 20.

So when looking for a sail The Luff measurement should be no more than 47.1, but best if between 47 to 46 ft, the leech no more than 46, and the foot (J) between 18.5 and 20 ft.

Are my calculations correct?



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post #2 of 7 Old 06-23-2009
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Go to Bacon sails
Bacon Sails & Marine Supplies

Towards the bottom of that page you can search for by boat

"Search our inventory by your boats factory specifications!!"

This will give you dimension if your boat is in their data base
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post #3 of 7 Old 06-23-2009
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More likely than not your dimensions bear little resemblance to what you will actually need. The calculation is not all that likely to produce an accurate forestay length off of the PHRF measurements. Boats vary quite widely from their class measurements.

But beyond that the difference between the forestay length and the luff length needs to include room for the stay connection/ swage, halyard box, some room for stretch, and clearance for the roller furler head swivel fitting.


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post #4 of 7 Old 06-23-2009
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Most sailmakers will measure your boat before building the sail - this assures the proper fit/set. Jib lead track/car locations, spreader angles/height, etc etc all combine to affect just how your sail should be built.

Having your sailmaker check out YOUR boat will result in a better sail. This is what makes me nervous about buying a sail from FX or other on-line lofts...


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post #5 of 7 Old 06-23-2009
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I agree, I ran into major problems trying to get online dimensions for a new headsail. You can measure for a new sail yourself, shoot me a PM and I'll forward you an email with what the sailmaker requires.

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post #6 of 7 Old 06-23-2009
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I draw a scale line drawing of my boat, (or use one I find online.) You need to know the mast height, and distance from the mast to the head stay plate. The head stay length is also needed. The luff, leech and foot measurements of the used sail, can be compared to the scale drawing to see if it will fit. The used sail is converted to the same scale as the drawing. I've bought a couple of head sails using this method, that fit well. Draw in the position of your genoa tracks to be sure the lead angles will work.

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post #7 of 7 Old 06-23-2009
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Finding a used headsail that will fit a furler is not going to be easy. If the sail luff is too long or too short you are going to have problems with the furler. With hanks you can use a sail that's not full hoist, but not on a furler. Both FX and North Sails Direct will give you quick quotes based on your boat model, but you will need to make a number of measurements before an order can be placed. I ordered a main from North when they were called Cruising Direct 7 years ago and it fit perfectly and is holding up well.

Last edited by JimsCAL; 06-23-2009 at 05:41 PM.
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