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Discussion Starter #1
Hi,
I'm currently looking at small centerboard sailboats in the 14-18 ft range.
To get a sense of boats without sailing all of them, I've been looking up numbers like the D-PN handicap ratings published by US Sailing, as well as the sail area to displacement (SA/D) ratio, and comparing them to a JY15, which I have lots of experience sailing. The SA/D is essentially the power-to-weight ratio, so a higher SA/D should go faster, in (my) theory. The handicap basically measures how fast or slow the boat is in real racing situations, and is perhaps a more useful measurement(?). Ostensibly, a boat with a better (lower) handicap should have a higher SA/D ratio, I think.
However, sometimes this isn't true! Sometimes, despite a higher SA/D ratio, a boat has a slower D-PN rating. I'm confused as to why this is. Does a boat with a high SA/D but slow D-PN imply that the boat can't point well, or is otherwise lower performance? Or is it just wrong to use SA/D as an estimation for how fast the boat will go?
My best example of this is the Laser 2, which has an incredible SA/D of ~120, but a relatively poor D-PN of 92.8. Compare this to the Tasar, which has an SA/D of ~72.65, but a faster D-PN of 88.2. Which is the truly faster boat? Of course, I don't expect a black-and-white answer, but I'm at a loss right now.

Thanks in advance, everyone!


-willzone1
 

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Assuming the rating is on a well known boat the rating is a better gague. Just because a bot has a lot of sail area doesn't tell you much about how efficient the sail shape is, the efficiency of the hull, if the boat is a planing hull or always displacement, ect.

As a rediculious example, if you were to take the wing from an AC 72 and lay it down sideways on the hull the boat would have the exact same SA/D but be god awful slow.
 

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In order to balance the results, you need to take into consideration what they're measuring. Handicap ratings are based (theoretically) on performance over a racecourse, with more weight given to windward performance. SA/D might be more indicative of the comparative speeds of similar-sized boats on a reach. On a reach, a boat with a low rating might not be able to pull away from one with a higher rating, but a similar SA/D ratio. Upwind... different story.
 

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Discussion Starter #4
Thanks, Stumble and paulk! What the two of you have said makes sense, and is sortof what I suspected, but is very useful in narrowing down my search.


-willzone1
 
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