On Tue, 23 Jun 2009 12:34:27 -0700 (PDT), Frogwatch
wrote:

YES, I'll start a real flame war here but I am serious about the
question.
HK says a cutaway transom allows the boat to drain if it is swamped,
seems sensible.
The designer of my Tolman says to have a high drywell in front of the
motor on a cutaway to make sure she does NOT fill with water.
A compromise seems to be to have the dry well but also have serious
cockpit drains, not the tiny ones you see on most boats, I mean at
least 6" diameter AND have the cockpit drains with flapper valves made
of thick rubber sheet attached to the transom with SS screws. This
would require the boat be decked with floatation underneath.
I am curious because I am considering in the long term what boat to
build next and am considering a modified 23' Tolman Jumbo with more
deadrise.

Despite loving to poke Mr. Science and Boating in the eye once in a
while, transom cutouts do make some sense depending on the boat
design. And it's not for water flow out the stern either whicih is
probably the dumbest thing I've heard - 2/3rds of the transom is still
in place which creates a water dam forcing water out the remaining 1/3
- which happens to be partially plugged by a engine?

It's more for matching available engines to the boat - 30" shaft
engines aren't a common beast and 25" shaft engines are pretty much
the norm - unless you have a boat like mine which is designed as a
short shaft boat, but has a long shaft engine on a jack plate. It's
about the engineering of applying the power to the hull and making it
go rather than emptying the boat of water in case you are stupid
enough to be out running in weather you shouldn't be running around
in.

Racing sailboats have open sterns, but they are a whole different ball
game - their sterns are entirely open, not partially open.

Use of a splash board or dry well is to keep water out of the boat
when backing down or having water come up over the stern in certain
weather conditions. Most boat companies offer an option for a splash
board - around these parts it's unusual to see an open boat without a
splash board in boats with open transoms.

Brackets are the usual solution for those who want to have full
transoms and outboard power. Brackets have the added feature of
actually lengthening the boat by a foot or so - the old axiom that for
any given horse power, extra length on the boat will create more hull
speed - plus not having the engine cluttering up the stern. The down
side to brackets is that you can, and I've done this on a Fish Hawk
and a Sea Pro, bury the engine halfway up the cowl on a hard back down
and abrupt change of running status from quick to slow. That's always
been the one feature of brackets that I've been a little leery of.

If I were planning on building a boat, I'd probably go with a full
transom and use a bracket rather than poking holes in the transom for
an engine. It also depends on how you plan on powering the boat -
outboard or inboard? It may be a mute question.