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Comparing different chine hulls

Please comment on a comparison of the Crowther multi chine and similar wider V-hulls such as Crowther amas and Cross 12 m hard chine with approx. 45 degree chine hull. Waterline is below chine so turbulence should not be a factor in fairly smooth seas. I have also heard of monohull aficionados preaching the value of chines.

Without having the actual lines plans in front of me, it's hard to make a direct comparison, but please refer to my article on 'Basic Ways to Use Plywood' for general trends and relative complexities.

As far as chine-built boats in general—yes, I am also somewhat of a fan. IF well designed—and they not all are!—they can perform surprisingly well and look good too, as the chine lines (if kept with fairly straight) can really help to make a boat 'look' fast. They also work well for monohull planing forms but add resistance for most multihulls if the chine is allowed to become 'too banana shaped' or if the hulls end up too Vee'd, giving an increase in frictional resistance compared to a round bilge boat. Vee'd hulls also tend to pump surface water out horizontally as they pitch and this adds resistance. The banana chine (or buttock) shape also offers less resistance to pitching, which further spoils performance. In my personal view, chines are the guidelines for how the water is divided by a hull in motion. If this is done BELOW the watersurface, there is far less surface wave, so I like chines to start as low as practical at the bow, and be as straight as possible. Designers such as Van de Stadt and Phil Bolger knew this well, but in what might be considered 'misguided efforts to simulate round bilge bows', this now often seems to be forgotten.

Veed hulls do 'track' well and may slip less to leeward. Multi-chines can also help to gently break up waves though this generally makes the boat slightly slower in the process. (Just like a Lapstrake boat can have a very kindly ride in waves—but then be slower. The lapstrake Folkboats being but one example.)

Today, there are also some interesting round bilge alternatives that are no harder to build than the early chine ply boats (see the various METHODS articles—particularly the Radius Chine, Strip Hulls, KSS and Hybrid. One aspect of round bilge is the common association with professional boatbuilding. IF you build to high quality, a round bilge boat will typically have greater resale value than one with a hard chine—and will be faster in light-wind conditions. However, if the hull can be kept narrow (as for a multihull), the vertical flat sides of a deep 'U' or box section can be remarkably efficient in the mid-speedrange due to low wavemaking resistance. (see the W17 as just one example).


Mike Waters NA

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