|Here is a photo of Black Skimmer, copied from Woodenboat Magazine - I hope I haven't infringed any copyright. She is close to being my absolute favourite design.|
Ross, I love it that you are discussing flat bottomed skiffs. I love 'em. My first sailboat was a Bolger Featherwind which exhibited the design principles you mention in your post. I am not so sure I agree about the curvature in bottom and sides. W/L length gets shortened, more of the bottom is exposed to waves and the pounding is obnoxious (this is not to say that the boat was not a blast to sail). How would John Atkin's Lark (14'3" sailing skiff) stack up to your discussion? It has a fine entry, but the stem is immersed. It has good flare and I would bet that it does not pound the fillings out of your teeth while sailing in a chop. While I have not built and sailed another flat bottomed skiff since owning the Featherwind, I will probably do so one day because the nostalgia of that first boat has a powerful draw. Best, Dennis
I know what Dennis is talking about, and it is a good demonstration of how everything in boat design requires compromise. The shape which provides the excellent sailing behaviour (adequate rocker, matched curvature of the topsides and the bottom panel, forefoot run above the waterline) is very likely to pound badly when floating level.
There are plenty of flat-bottomed skiff designs around which have the forefoot immersed, and scores of William and John Atkin boats provide excellent examples to study. One of my favourite Atkin designs is Ration and she shows exactly what we are talking about.
|Lines of Ration - courtesy of Motor Boating's Ideal Series - Chapman and Horenburger|
To get an appreciation of what I'm trying to describe, compare the shapes I show below: -
|A typical flat-bottomed skiff with the heel of the stem immersed, and the bottom of the transom coming to above the waterline. I'm only showing the body plan here, but the boat I've drawn as the example is fairly long and slim.|
|The same boat heeled 25 degrees. In reality, the stern would probably be forced a bit higher and the bow lower than I've shown here, which would make matters even worse.|
|A clearer view of the same boat. See how the chine line will generate turbulence and drag, and will tend to force the boat to round up.|
|For comparision, here is the underwater shape of the example I drew for the previous posting. While this is not a perfect shape by any means, it is vastly superior to the example shown above - but it will pound more when flat in a ripple.|