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post #5522 of Old 12-23-2013 Thread Starter
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15 years in hull design

Originally Posted by capt vimes View Post
Bora... Always good for some stress...
My favorite tough weather sailing video, even if older...
Rough Weather Sailing - BT Global Challenge 2000 - YouTube
Yes, not weather for amateurs. I love those guys sitting on a rail of a 40 000kg boat on those conditions. We can also see the differences in what regards boat design in 15 years and they are quite impressive between the boats from the Challenge and Clipper boats):

From a narrow 72ft boat with weight of 38 000kg ,a beam of 5.5m, a draft of 3.0m and a B/D ratio of of 27% we passed to a 75.6ft boat with less overhangs, more beam but mostly a larger transom, lighter, the same draft and with a superior stability: LOA 75’6’’, weight 31 190kg, beam 5.65m, B/D ratio of 39%. The draft is the same but the newer boat has a more efficient keel that allows for a lower keel CG (independently of the ballast, that is also bigger) and that translates in a bigger RM provided by the more modern keel.

This will make not only for a faster boat but also for a more seaworthy one with more stability and much less prone to pitch the frightening way the older boat does on bad weather, like you can see on the video.

The pitch movement will be much smaller due to the less overhang and superior buoyancy at the bow, at the transom and for a much more centered weight on the boat due mainly to the bigger ballast ratio and different building materials (steel versus GRP).

Many times sailors associate a superior seaworthiness regarding older hull shapes that they call " less extreme" but that is not generically true.

That big pitch movement is responsible for much of the hardship that we see on the video: When the boat has the bow fully buried at the water it is at the mercy of the next wave that just sweep the deck and cockpit.

A visual comparison between the two boats that it is a good reference in what regards hull evolution on the last 15 years, also look at the keel and rudders:

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Last edited by PCP; 12-23-2013 at 10:38 AM.
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