Join Date: Feb 2000
Location: Annapolis, Md
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Re: Bob Perry's take on Wolfenzee's dream boat
The only thing I would add is your range of D/L's sooms a bit low if you consider offshore cruising boats.
Bob: I think that there are several things that I was considering when I wrote that. For better or worse, I was using the race boat convention of the big 'D', displacement in that calculation equalling the boat dead empty, while in reality I think that when designing offshore cruising boats the designers I have known use the half load, or partially loaded displacement when laying out the DWL. I think that in reality, most offshore cruising boats end up being 15-25% over the dead empty load, and in many cases with full tanks and lockers well over that.
I also perhaps was not as clear as I probably should have been when I wrote, "My sense is that range is an L/D somewhere between 150 and 180 at least [achieveable] with our current technology." My thinking is that kind of range is possible, but it requires careful engineering and a calculated use of exotic materials and design approaches such as vacuumed down matrixes, cored bulkheads and casework, deletion of liners, greater draft to allow less ballast for the same stability, maybe carbon spars and so on. My sense is that this level of weight attention is rarely practiced in offshore cruising boats, and frankly perhaps may not be appropriate in where high safety factors trump speed.
That said, my thinking was these kinds of L/D's would seem achievable. Outbound 46's published L/D is just outside that range.
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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
Last edited by Jeff_H; 07-13-2013 at 11:41 AM.