24 ft trimaran

[John Perry]

Originally Posted by SeaDrive

If you take a conventional tri shape, and pull all the bows out longer and thinner, but with the same volume, then the LCB will be aft and the danger of pitchpoling about the same.

Surely if you do that you will have reduced the danger of pitchpoling because you have increased the lever arm of the reserve bouyancy (meaning the bouyancy which is not actually used when the boat is in a flat calm) in the bows. In other words you have the same amount of reserve bouyancy but it is further forward. If you stretch out the bows without making them thinner that would be even better.

However by stretching the bows you have made the whole boat bigger and increased the 'through life' cost - harbours tend to charge by length and many other boat costs are also length related.

The problem is to find the optimum ratio of length to beam and the longitudinal position of the C of G, taking into account over turning moments about both axis and I think that is where plots like Tom has produced are very relevant. From the point of view of resisting pitchpoling the CoG should be as far aft as possible, but there is a limit to that because if you take it too far aft the hulls have to become a funny shape which unlikely to be good for hull drag.

John

This boat is a prototype and improves upon some of the design ques of the F24 II. It is slightly shorter in length, lighter, and easy to fold. I would keep my eye on this builder - I have a feeling he is going to produce some nice boats in the future.

Andrew

http://www.multimarine.com/L-7/L-7.html

[oldsailor7]

For a DYI 24' Trimaran design you can't go past the Lock Crowther designed Buccaneer 24.
See the Buccaneer 24 thread on these forums.