Can anyone give me a sanity check on the calculations/measurements I’ve done for a cruising chute for my 1989 shoal-draft fractional rigged Legend? I’ve calculated to give me a tack near the pulpit (I don’t want a decksweeper) I need a luff of 45’, A leach of 40’ (10% of luff) and a foot of 23ish (1.6 x foredeck). Does that sound in the ballpark? Can any owners share their luff dimensions? Many thanks. Richard s/v Soupy Twist II
Asymmetric spinnaker dimensions for Legend 37
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Not quite right. Your "I" is 49' which means the luff of your achute should be about 55' or I + 10%. Don't forget that the luff of an achute is a big curve not a straight line like a genoa. Achutes are never decksweepers, they are offwind sails used for close to broad reaching.
Racing restrictions
I am a little nervous wading in after Alan but what the hell. On another site I found while looking for a used A-spin they had some guidelines: For racing most rules allow the luff to be no greater than I. The foot could be 180% of J. For cruisers they basically said plus or minus 10% as a guide for the luff and up to 160-200 for the J.
I am a little nervous wading in after Alan but what the hell. On another site I found while looking for a used A-spin they had some guidelines: For racing most rules allow the luff to be no greater than I. The foot could be 180% of J. For cruisers they basically said plus or minus 10% as a guide for the luff and up to 160-200 for the J.
Racing restrictions
Don, I'm sorry if I was sounding intimidating, it wasn't my intension. Racing restrictions vary from one PHRF location to another. I was advising based on cruising recommendations which have no such restrictions. Basically you would be looking for the 'best' size for general purpose off wind work. A short luff woud mean a loss of sail area reaching where additional area can easily be handled. Also a nice full luff will make for better sail shape.
Don, I'm sorry if I was sounding intimidating, it wasn't my intension. Racing restrictions vary from one PHRF location to another. I was advising based on cruising recommendations which have no such restrictions. Basically you would be looking for the 'best' size for general purpose off wind work. A short luff woud mean a loss of sail area reaching where additional area can easily be handled. Also a nice full luff will make for better sail shape.
just bought a used one for my 420
talked to quite a few suppliers and following seemed consensus: Foot: 160-180% of J with 172% or so being ideal Luff: 92-108% of I with 105% being target Full Tri Radial cut is best. While I got mine used from Bacon Sail Traders, Doyle (from sail loft on this site) was very helpful and I would highly reccomend them as well. I flew it once without a sock and once with it and the (I have the 'chutescoop') sock .... the sock is a must have!
talked to quite a few suppliers and following seemed consensus: Foot: 160-180% of J with 172% or so being ideal Luff: 92-108% of I with 105% being target Full Tri Radial cut is best. While I got mine used from Bacon Sail Traders, Doyle (from sail loft on this site) was very helpful and I would highly reccomend them as well. I flew it once without a sock and once with it and the (I have the 'chutescoop') sock .... the sock is a must have!
my experience
I also have an 89 Legend 37 and have both asymetrical and symetrical spinnakers. Following are the dimensions of mine, I bought it from Doyle: Your APR-90 will have an area of 1060 sq. ft., with a luff of 51.3, and a mid-girth of 21.9. The area is close to the symmetrical, but the girth is smaller. This is due to the fact that the foot on your sail is 24.3 and that of the symmetrical is 23. The last measurement, the leech, is 46.74. Translated, this means you have a little more area down low than the symmetrical, and a little less up high, which is the nature of the asymmetrical sail. This should not pose any problems for you in your rating discussions.
I also have an 89 Legend 37 and have both asymetrical and symetrical spinnakers. Following are the dimensions of mine, I bought it from Doyle: Your APR-90 will have an area of 1060 sq. ft., with a luff of 51.3, and a mid-girth of 21.9. The area is close to the symmetrical, but the girth is smaller. This is due to the fact that the foot on your sail is 24.3 and that of the symmetrical is 23. The last measurement, the leech, is 46.74. Translated, this means you have a little more area down low than the symmetrical, and a little less up high, which is the nature of the asymmetrical sail. This should not pose any problems for you in your rating discussions.
Thanks for the feedback
Especially Del. I suspected my calculations were coming up short, hence the post. However, Alan’s seemed a little big. I think it stems from the fact that it’s a fractional rig. Since posting, I’ve been to the boat and made actual measurements (rather than guestimating from a line drawing). Interestingly, I used a measurement method suggested by North Sails. You measure your “hoist”, which is the distance from the spinnaker halyard sheave to the tack location. (That’s 48’ in my case). You then subtract the distance you want the sail off the deck. (I guestimated my pulpit height at 3’, it’s actually more like 2’). This leaves 45’. They call this the “Luff Chord”. North then suggest multiplying the Luff Chord by 1.04 to get the “Spinnaker Luff”. Which comes out at 47.84, still a little short sounding. Which is why I’m pleased to get Del’s measurements. 51.3 just seems right. And Guy’s 105% figure seems to reinforce that. Many thanks, Richard.
Especially Del. I suspected my calculations were coming up short, hence the post. However, Alan’s seemed a little big. I think it stems from the fact that it’s a fractional rig. Since posting, I’ve been to the boat and made actual measurements (rather than guestimating from a line drawing). Interestingly, I used a measurement method suggested by North Sails. You measure your “hoist”, which is the distance from the spinnaker halyard sheave to the tack location. (That’s 48’ in my case). You then subtract the distance you want the sail off the deck. (I guestimated my pulpit height at 3’, it’s actually more like 2’). This leaves 45’. They call this the “Luff Chord”. North then suggest multiplying the Luff Chord by 1.04 to get the “Spinnaker Luff”. Which comes out at 47.84, still a little short sounding. Which is why I’m pleased to get Del’s measurements. 51.3 just seems right. And Guy’s 105% figure seems to reinforce that. Many thanks, Richard.
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