How big a sail can I put on this thing...?

Squidd · #1 (**permalink**) 01-13-2012

Genoa Sail.. My I measurement is 34', my J measurement is 11'8"

That makes a 150% or 151% at about 18' foot (at least according to my calculatiions)

Bacon is selling some 150-151% (listed) with a 19' foot..generally with a 33' Luff and 31' Leach, no matter what the foot layout was...110s-130s etc...

I also found a sail locally that is 31'8" Luff, 30' Leach and 21' foot...

I scaled it out on a sail plan drawing of my boat and it "looks like" it will fit... foot is parrallel to deck (on the same plane as 151%) clears safety rail but about a 1'6" longer...

My aftmost sheet lead block is on the toe rail, so I can adjust leach and foot tension...

So is there any problem running a 170% genoa...? (I understand clearing the Mast on a tack, but so too the 151%)

jameswilson29 · #2 (**permalink**) 01-13-2012

I rely on the sailmakers for that figure - I am not sure how they calculate the maximum percentage, but I understand it usually is not worth increasing after about 150-155%, so a 170% is not necessarily faster than a 150%.

Too large and your increase in drag is greater than your increase in lift - you are working on the trailing edge of the sail which does not necessarily generate any more power. Of course the sail becomes that much more difficult to handle as well.

Squidd · #3 (**permalink**) 01-13-2012

Not neccessarily looking for "faster" just useable/cost effective...

The Genoa that came with the boat was shreaded at the head (unsalvageable) but was 19'3" at foot (33' luff 31' leach)

So this one is "shorter" (foot rides higher) but 1'6" longer...so what I've gained in length is offset by what I've lost in height so sq/footage isn't that big an increase..?

I can get the sail fairly reasonable, so I'm hoping it's workable...

py26129 · #4 (**permalink**) 01-13-2012

Squidd

I would think that the big sail would be fine. My dad's PY26 actually had a 180 genny and it worked fine.

Mine had a 150, no issues with that either. At the upper end of the wind range for each sail, the 150 provided a bit more of a balanced helm while the 180 produced more weather helm.

Matt

treilley · #5 (**permalink**) 01-13-2012

Answered at SBO.

blt2ski · #6 (**permalink**) 01-13-2012

The issue is not the foot length, but the LP or length perpindicular to the luff. For sq footage, that is the number with the luff to figure out actual sq foot of the sail.

But as I think you are pointing out, the sail you want has a longer foot by a foot of so, and a leach of about 1' less, so in a round about way, the SQ ft of the sail is probably about the same, the new one frankly would probably be a 155 vs the old one a 150 or some other equal'ish type measure. Not sure either is what most would call a 150 or 155, probably an LP 14x if you will. But might be 150% of the foretriangle as some rating rules go by.

marty

mxracer19 · #7 (**permalink**) 01-13-2012

When you consider what the sail is...an airfoil...generally speaking high-aspect ratio airfoils generate more lift at slower speeds with less drag. Take the example between a glider and an F-15 Eagle. The 15's wing is more triangular, the gliders wing looks like a surfboard. Take this rough comparison and apply it to your sail, because in effect thats what were talking about. A taller thinner rig will generally give you less speed than a shorter wider rig when considering equal area. HOWEVER...the key is the hull. Hulls have a maximum speed and there comes a point where no amount of sail will help you.
A displacement hull is limited by the wave it produces. The key is to measure sails to fit the hull. After a certain point, the power gained with a short, broad sail is capped by the max hull speed and with an increase in wind you'll only develop increased drag and heel. This is because the speeds at which a short broad sail become efficient are unattainable due to hull design.

I cant answer your actual question. I just wanted to provide food for thought. Considering that we're all just harnessing the wind, basic aerodynamics cannot be overlooked.

-Matt

Squidd · #8 (**permalink**) 01-14-2012

Quote:

Originally Posted by py26129

Squidd

I would think that the big sail would be fine. My dad's PY26 actually had a 180 genny and it worked fine.

Mine had a 150, no issues with that either. At the upper end of the wind range for each sail, the 150 provided a bit more of a balanced helm while the 180 produced more weather helm.

Matt

Do you remember off hand the measurements of your 150 and your dads 180...?

py26129 · #9 (**permalink**) 01-14-2012

Squidd

I'm sorry to say I do not. What I do remember is that the 150 ended more or less even with the companionway and the 180 went to at least mid copckpit, if not further aft.

If it helps, I may be able to dig up a photo of the `50, sheeeted in.
Matt

Squidd · #10 (**permalink**) 01-15-2012

OK thanks, still looking for options...

The more I ponder on this the more i "think" I'm starting to visualize it...

I was/I am prepared to go into my first season with this boat with just the main and working jib (100% I believe, I'm going to pull it out tomorrow and measure again to be sure) ...

But in reading reviews, and looking at the rating numbers for this boat I'm under the impression that while it'll handle heavy conditions, it "struggles" a bit in low wind...Hence the quest for a second option headsail...

The opening question then, rather than being "how big" a sail can I get...should read..."What would be my best option for a second headsail for my boat in light wind conditions"...???