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post #1104 of Old 07-12-2013 Thread Starter
Jeff_H
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Re: Bob Perry's take on Wolfenzee's dream boat

To me this is really a trade off. Bob may correct me on this, but downwind its all about cutting drag by reducing wetted surface and wave generation. Stability does not matter much. Long light, narrow boats with rounded sections have comparatively low wetted surface (although they pay a wetted area price for their length) and make smaller waves. Its the same reasons catamarrans are fast.

But upwind, and reaching, stability becomes important to be able to stand up to enough sail area to go fast. To me, designs that sail well in a broad range of conditions and which are forgiving in changing conditions cannot be too narrow since its hard to get enough stability without adding weight (in ballast) and they cannot be too wide since on a boat that gets too wide, its hard to control wetted surface and wave making without doing the kind of ballancing acts that modern 'open class' style boats employ.

I think when it comes to cruising boats, that there needs to be some moderation when it comes to displacement as well. I also think that there is a L/D practical range in which speed can be accomplished while still having enough surplus carrying capacity to be useful as a cruising boat. My sense is that range is an L/D somewhere between 150 and 180 at least with our current technology. Designers are capable of designing cruisible boats with an L/D below 150 but these are somewhat like the space capsules. They either need to be very long to carry enough to supplies to be comfortable, or else one must be extremely disciplined about what the weight that is brought aboard. Race boats have naked looking interiors for a reason.

When I raced and cruised my Laser 28 (L/D somewhere around 125 if I remember right) I had 2 milk crates full of race gear and 4 milk crates full of cruising gear. When I went racing I would switch them out. I kept them in the trunk of my car which led my brother to ask upon seeing my trunk one day, "I know architects aren't paid very well but can't you afford a home?"

Jeff


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Last edited by Jeff_H; 07-12-2013 at 04:46 PM.
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