One of the advantages of a double-ender when running a bar ("inlet" down
there in Florida) is that a following sea will part around the sharp
stern, not getting as good a grip on it as it would with a transom.
The lack of buoyancy aft in Egret may be related to Colin Archer's ideas
about following seas, as demonstrated in his redningskoite's (sp?).
Archer's rescue boats had steep, sharp runs. His idea was that as the boat
came down the face of a big wave, the lack of bearing aft would cause the
stern to dig in, keeping the boat from going too fast and, just as
importantly, keeping the rudder deeply immersed where it would work best,
even in a broken sea. A boat with lots of buoyancy aft could lift its
stern quickly to a following sea, pulling the rudder partway out of the
water (even all the way out, if it's a shallow rudder like on a
motorboat), and pushing the bow down if it doesn't have a lot of buoyancy.
Not a good combination...
Archer's rescue boats are marvelously seaworthy, but they have a low top
speed because of their lack of bearing aft. You pays your money and you
takes your choice. <shrug> Most of us don't ever need a boat as seaworthy
as a redningskoite, but if I was gonna be sailing around Cape Horn, or
poking around other dangerous places, I'd sure feel more comfortable in
one, or one of Billy Atkin's closer adaptations of the type -- Eric,
Thistle or Ingrid (or even the plastic version of Eric/Thistle, the
Wetsnail 32, though I've heard that a Westsail will never sail as well as
a real Eric/Thistle due to changes in ballast and rig).
An interesting design for running the bars on the Northwest coast, which
make anything on the East Coast look pretty tame, is George Calkins'
Bartender. A planing double-ender! Despite the fat stern needed to plane,
they handle wonderfully on a rough bar:
On Mon, 27 Aug 2012 15:24:16 -0700, Bruce H wrote:
Part of my intent with the boat modeling I have done is to attempt to
the mind" of some master designers. Munroe's Egret is considered to be a
'master' design for a surf boat, and it certainly has reduced buoyancy in
the after part of the boat, so this kind of confirms things.
My conclusion after studying what master designers have done (including
PCB)...broaching is caused when the stern lifts (causing the bow to dig).
If the stern has low buoyancy relative to the forward portion of the
it can reduce the tendency to broach.