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Old 27-01-2011, 16:44   #1
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Sail Area . . . Question ?

was looking at some statistics about similar boats and was wondering why my hinterhoeller 28 had so little sail erea compared to other similar boats...these are the figurs I dont understand...can anyone explain what they are and how they afect sailing??

Hinterhoeller 28...sail erea; 190.4...displacement to LWL; 340...sail erea to displacement; 8.49
Tartan 27...sail erea; 376...displacement to lwl; 336...sail erea to displacement; 15.84
Northern 25...sail erea; 305...displacement to lwl; 312...sail erea to displacement; 17.15
Triton... sail erea; 379...displacement to lwl; 359...sail erea to displacement; 16:33
Alberg30...sail erea; 410...displacement to LWL; 395...sail erea to displacement; 15.16
Challenger 7.4...sail erea; 230...displacement to lwl; 217...sail erea to displacement; 14.6
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Old 27-01-2011, 16:54   #2
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This says your SA is 357...
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Old 27-01-2011, 16:55   #3
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According to HINTERHOELLER 28 Sailboat details on sailboatdata.com the foretriangle on your boat is 190sf.

Total SA is 364 giving you a SA/D of 17.7 in the lightship condition.

Loaded the SA/D be less but in similar proportion to similar boats.
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Old 27-01-2011, 17:14   #4
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I have just looked at Sailboat data for my Moody 31 and they have the numbers wrong, the sail areas are larger. However, this depends on how big a genoa previous owners have decided on when replacing.

The details are, Moody 31(plain cruising yacht)

Combined sail area 553sq ft, displacement to LWL; 238...sail area to displacement; 20.1

So what does this mean? well in winds of F3 and under we could do with flying the big cruising chute. At F4 on a beam reach we hit hull speed and should consider a reef or we go sideways too much. By F5 we really need to have the first reef in and be considering the second.

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Old 27-01-2011, 17:24   #5
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Sail Area (SA) is not an actual area, It is P*E/2 + I*J/2 (As I understand it...)

It's the foretriangle area (like a 100% genoa) plus the main triangle area excluding any roach or foot. It's just meant to be a guideline.
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Old 27-01-2011, 17:45   #6
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This says your SA is 357...
this seems more appropriate...however I disregarded that info because that site has the displacement wrong, they say 6000lb when the boat is more in the 8000lb range.

the data I posted came from carls sail calculator.
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Old 27-01-2011, 18:22   #7
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Originally Posted by jobi View Post
this seems more appropriate...however I disregarded that info because that site has the displacement wrong, they say 6000lb when the boat is more in the 8000lb range.
I just did a search, and numerous sources list the displacement as 6,000lbs.

Official displacements are often light, and are often specked as a boat's dry weight. In other words, nothing in the tanks, and no dirty socks in the laundry.
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Old 27-01-2011, 18:41   #8
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Quote:
Originally Posted by jobi View Post
this seems more appropriate...however I disregarded that info because that site has the displacement wrong, they say 6000lb when the boat is more in the 8000lb range.

the data I posted came from carls sail calculator.
You got the displacement from Carl's?
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Old 27-01-2011, 18:57   #9
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Originally Posted by Pete7 View Post
I have just looked at Sailboat data for my Moody 31 and they have the numbers wrong, the sail areas are larger. However, this depends on how big a genoa previous owners have decided on when replacing.

(...)
But should not the SA/something factor calculate the 100% triangle ONLY?

Otherwise we could be comparing apples and oranges.

(?)

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Old 27-01-2011, 19:19   #10
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But should not the SA/something factor calculate the 100% triangle ONLY?

Otherwise we could be comparing apples and oranges.

(?)

b.
That's exactly what daddle's formula does. However, boat manufacturers publish their own specifications, and decisions on what to post are often being made by the marketing guys. Which is why a given manufacturer might want to post the actual sail area of a boat running a genoa. If you manipulate the numbers, a boat can seem more or less stiff than it really is.

I guess the rule is not to trust the SA/D unless you've got it from the architect, or perhaps the builder, rather than the dealer trying to sell you the boat.
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Old 27-01-2011, 19:39   #11
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From sail calculator:

Also all data included was entered by users
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Old 28-01-2011, 06:09   #12
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I just did a search, and numerous sources list the displacement as 6,000lbs.

Official displacements are often light, and are often specked as a boat's dry weight. In other words, nothing in the tanks, and no dirty socks in the laundry.
the boat was wieghted for transport and only the boat dry 4,43 tons...this number was engraved by the canadian governement on the bulkhead.

I think its accured
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Old 28-01-2011, 13:32   #13
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I think the 357 SA is about right, the 190 is 100 percent jib. I have seen displacement @6800#. The transport Canada number may be a theoretical number. Next time it is lifted you may be able to get a real number if the lifter has built in scale. If it was me I would want it to be 6800 not 8000 something, lighter will be faster in light wind and you can reef for the big wind. Anyway he was a great designer look at his shark 24 done in 59 I think in plywood first before fiberglass. Enjoy and good luck.
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Old 29-01-2011, 09:56   #14
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Daddle is correct.

But on modern boats with huge roaches it seems silly not to factor in the area of the roach so you have to make a subjective decision a some point whe to use total mainsail area and when to use E and P. They are just numbers.
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Old 29-01-2011, 12:05   #15
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..... I have seen displacement @6800#. The transport Canada number may be a theoretical number. Next time it is lifted you may be able to get a real number if the lifter has built in scale. If it was me I would want it to be 6800 not 8000 something, lighter will be faster in light wind and you can reef for the big wind.....
The tonnage spec'd in documentation certificates is not weight. It is an odd ball measure of volume. For a cruising boat you basically ignore that number.

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