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Author Topic: Bristol Channel Cutter - Listed SA too low?  (Read 1830 times)
Lazy Jacques
Pick-up Crew
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Posts: 4

« on: May 27, 2012, 07:07:19 pm »

Hello,

SailboatData states the listed SA for this vessel at 367 sq. ft.

Sam L. Morse's website lists "total sail area" as 637 sq. ft.

http://www.samlmorse.com/?a=bcc_specification

Cape George Cutter's website (currently building the BCC) report a "working sail area" of 673 sq. ft!

http://www.capegeorgecutters.com/BCC28/index.html

Notice anything? Each of these figures features a different arrangement of the same numbers! Regardless, I believe your "listed SA" figure to be much too low. All agree the rig on this stout little ship is very strong, and your SA yields a paltry SA/D of 10.15, a pretty unreasonable number for anything except a trawler-type motorsailer.

Of course, I understand this is different from "calculated" SA, but I haven't found any precise rig dimension info to add to this listing.

Cheers,

Lazy Jacques in Vancouver, BC
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sonosail
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Posts: 1865


« Reply #1 on: May 28, 2012, 01:56:00 pm »

Thanks.
Yes. this may have been a typo.
The calculated SA should possibly be relabeled 'working' sa, or upwind SA.
When the specific rig measurements are available, and it's a standard, 'marconi' rig, only the area of the triangles is listed. (mainsail roach is not included and only %100 of the fore-triangle.
Sail Area is measured in so many different ways by different builders and designers, especially for new boats. I know a lot of knowlegable people swear by formulas like SA/Disp etc.  I  guess they might have some value when comparing the performance boats of a very similar size and  type.
A number of years ago there was a person on one the PHRF rating committees who decided to re-do all the ratings based on a Sa/Disp number which he felt was THE most important number in evaluating the speed of a boat.  It was complete disaster.
This is why so many MEASUREMENT  rating rules (of which PHRF is not one) are so complex and disappointing over time. 
Even using hundreds of measurements, and the most advanced computer software, it is still, to this day, very hard to evaluate the performance of a sailboat numerically. 
rb   
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