Draft too far forward?

Aug 2, 2010
502
J-Boat J/88 Cobourg
We are the boat in the extreme left of this shot taken shortly after the start. I thought the shadow on the luff of our jib looked odd and am wondering if I had the halyard tension too high for the conditions? It certainly looks like we have much less draft than the other boats in the shot.
I am not sure what night this was taken but it looks like 10 knots or so to me and we are close hauled.
Thoughts and observations?
Thanks, Dan
 

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JRacer

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Aug 9, 2011
1,331
Beneteau 310 Cheney KS (Wichita)
Pretty hard to tell without looking or a pic shot from the deck directly beneath the sail. In general, jibs deepest draft should be about 30-35 percent aft of the luff. Yes, you are correct that a halyard too tight would pull it forward.
 
Mar 26, 2011
3,399
Corsair F-24 MK I Deale, MD
The best bet is to add some draft stripes and take pics while lying on your back, looking up. Shadows can be misleading.

The best location will change with conditions.
 
Aug 2, 2010
502
J-Boat J/88 Cobourg
JR, that sail has no draft stripe but I have not noticed it looking odd when driving. I would say we have been struggling to point with some of the other boats though upwind speed seems OK...we always want more, right?
For sure that photo and a couple of others make it look like the deepest draft is way forward at least in the top of the sail.
Dan
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
The lower 1/3 of the sail looks fine. I'm betting your jib car is too far back.
 
Aug 2, 2010
502
J-Boat J/88 Cobourg
The lower 1/3 of the sail looks fine. I'm betting your jib car is too far back.
In light airs last night I did move the cars up and picked up some speed. This sail is new this spring and we have been wrestling with the car position by trying to get the telltales to break evenly but ignoring the fact that it looks to flat in the lower portion and not flat enough in the upper.
We keep learning because you folks keep taking the time to help us, thanks.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Indeed, good sail shape is is a very complex interactions, and frankly jibs are the hardest to get right. Their very high-aspect nature makes this this way. At the end of the day, the key is figuring out what is fastest. For sure look at your hali tension as well. As you have found, these setups will differ dependent on windspeed. Mark your cars and halyards, and start keeping track. We have rulers on the deck to note the marks on the halyards, which are whipping twine. On the Beneteaus we used a Fein tool to remove the nubby anti-skid where the rulers are stuck. They would not stay attached otherwise.

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