Join Date: Feb 2000
Location: Annapolis, Md
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Re: Full or fin keel?
Sea Hunter- Could you please explain what you are talking about? It may be a linguistic issue but much of what you have written has little, if anything, to do with the way that these terms are normally used in yacht design or design theory, or with the behavior of a vessel.
For example: "Certainly while loading has all to do with reserve buoyancy" The way that the term "reserve buoyancy" is classicly used, loading has little, if anything t0 do with reserve buoyancy. As I read your sentence, I would suggest that you are mistaking (reserve) "carrying capacity" for "reserve buoyancy". These are two very different and not necesarily related concepts.
Or, "I believe that the CG has more to do with keel design." CG is only affected by weight distribution. While the type of keel and the profile and section of the keel affords the designer more or less ability to move the CG around, the type of keel and the profile and section of the keel does not in and of itself impact the CG of the boat. To provide an example to explain this, you could have an three boats the identical type of keel and with the same profile and section of the keel, but one uses cast lead, the second cast iron, and the third has a timber keel. Obviously each of these materials would move the CG around vertically, and in most cases, longitudinally as well.
Similarly, "A long broad keel offers a more forgiving ride yet becomes more stiff on the reach, regardless of reserve buoyancy." A broad, meaning a transversely wide keel in conventional yacht design useage, while more forgiving in terms of stalling has litte or nothing to do with stiffness (form stability), reaching ability or reserve buoyancy.
None of the rest of "Designers alleviate this by cutting back the keel. Reserve buoyancy may have more significance in boats with finely shaped fin keeps where the shape of the hull changes the shape of their hulls at speed, but displacement is displacement." makes any sense or has any accuracy, except that "displacement is displacement."
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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay