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Thread: Displacement or plane hull? Reply to Thread
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  Topic Review (Newest First)
02-11-2009 02:02 PM
Jeff_H George,

Thanks for your kind words.

02-10-2009 05:56 PM
camaraderie Jeff...while you know I will always be of the BIG and HEAVY and Heavily built persuasion for cruising...thanks for an excellent few posts. Most interesting to read and understand.
02-10-2009 12:29 PM
Jeff_H A couple things that may be a little misleading in the Santa Cruz vs Cape Dory discussion is that the Santa Cruz is a much earlier generation semi-displacement design, and the newer semi-displacement designs are much more tollerant of weight and are constructed with more modern interior components that look a lot more finished than the 'scan' interiors of the 1970's. It is also my sense is that the Santa Cruz would actually tollerate more payload weight than the Cape Dory as a percentage of their displacement. What is often forgotten is that a boat like the SC40 would be raced with a crew of 8 or 10 in the Transpac race and that this represents as much as 3,000- 4000 lb of crew, gear, and consumables. I have a tough time thinking of a Cape Dory 30 carrying anything like that.

02-09-2009 03:33 PM

As you can see, the Santa Cruz 40 has every spare ounce pared from her construction - this requires very good engineering - no extra weight anywhere - the bulkheads are 3/8" ply without edge trim. It's the price you pay for travelling faster. The Cape Dory 30 (sorry no picture, but easy to find)
is much more traditional and an extra pound here or there is much less of an issue. Space is larger below on the Santa Cruz, you just can't fill it up and have the same performance. As boats get larger, it's easier to have speed and more amenities.
02-09-2009 03:25 PM
fast or slower?

As an example , take a look at these two similar displacement boats:
Santa Cruz 40 - from the stable started by Bill Lee who coined the phrase "Fast Is Fun"
40' loa
36' lwl
12' beam
7' draft
10,500 disp
5,000 ballast
760 sq ft sail area

and contrast this with:
Cape Dory 30
30'2" loa
22'10" lwl
10,000 disp
4,000 ballast
4'2" draft
02-01-2009 11:09 PM
JPerkins build baby build.
01-27-2009 10:15 AM
InetRoadkill I bet it would be smooth. But I'm not going on deck to hoist those sails.

Actually, I'm just trying to get familiar with different hull shapes and their advantages and disadvantages.
01-27-2009 04:23 AM
kaluvic Are you actualy thinking about putting a mast on a sub....?
Should be a smooth ride
01-26-2009 10:29 PM
InetRoadkill Can't really tell from that picture, but it might be.

A swath hull is roughly a pontoon boat in which the pontoons are submerged and torpedo shaped. I believe the idea is that they don't make bow waves so they are not limited by hull speed and since they are underwater, they don't care about waves. They are probably too unstable for use in a sailboat application since there is little change in buoyancy with depth.
01-26-2009 10:05 PM
Originally Posted by InetRoadkill View Post
I'm just exploring options right now. ....
... I've always had a soft spot for catamarans which is why I was asking ...the swath-style hull on a catamaran
Can't believe I'm posting a pic of a powerboat, but is this what you mean by "swath" design? This boat is a passenger ferry between St Maarten and Saba.

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