1968Re: [AtkinBoats] Testing Billy Atkin's performance as stated by Atkin & Co
- May 30, 2008Hi Lon,
I am very familiar with the Atkin Seabright skiffs on the
website, but thanks for posting the links since it makes
them easy for others to find them.
I guess you are "assuming" that the tunnel-stern boats are
less efficient than the others based only on the figures
posted on the website, is this correct? Or do you have
factual evidence to support your conclusions?
In my opinion those figures you pulled off the Atkin website
are theoretical, not factual, and none of the folks who are
seeking the answers to my tests will accept those numbers
either. Besides, I'm talking about two hulls optimized for
15 knots, and there is no way to know if Atkin optimized
the hulls you mentioned for any particular speed -- or if
they were optimized for anything else for that matter.
In my opinion as well as the opinions of others, it is
possible that the tunnel-stern version traps some of the
moving, energy-filled boundary layer water under the hull,
then it re-uses this trapped energy by funneling it toward
the propeller where it is further accelerated. The
non-tunnel-stern versions simply let this energy-filled
boundary layer water drift away, and the energy it already
contains is basically wasted.
Although this is just a theory,it clearly supports the
possibility that the tunnel-stern boats may be more
efficient than the others. This is why, until I see some
actual evidence one way or the other, I simply cannot
accept yours or John Kohnen's assumptions.
Regardless of which Seabright hull versions are more or less
efficient than the others, no tests have been done to
compare Seabright hulls with non-Seabright hulls as far as
I know. So perhaps I still have a valid reason to run my
own tests and learn the facts about the relative
efficiencies of these two hulls?
> The Atkin Seabright Skiff Tunnel hulls were designed
> for inboard use in shallow waters, Atkin also designed
> Seabright Skiffs that were not tunnel hull that did
> not sacrifice performance for shallow draft, below are
> two seabright skiffs about the same width and beam one
> tunnel hull (shallow draft and the other slightly
> deeper draft (5-1/2") but it requires less than half
> the horse power to achieve greater speed.
> Heron Seabright Tunnel hull
> LOA 17 WL 16'-7" beam 5'-5" draft 6" 25hp 17MPH
> Happy Clam Seabright Hull
> LOA 17 WL 16 beam 5'6" draft 11-1/2 10HP speed 20mph
> So there it is
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