On Fri, 20 Jul 2007 15:59:50 -0500, Geoff Schultz
wrote:

My plan is to replace the existing mixing elbow with a dry stack.
Basically I'll cut off the big round can and replace it with a 10" high
stainless tube U that will have the raw water entering 1/2 down the side
that connects to the muffler. I'll wrap the whole thing in insulation to
reduce the burn potential and heat.

Does this sound like a reasonable solution to this problem?

Perhaps, but take note of Bruce's comments.

What you describe is not truly a dry stack but more closely resembles
a "riser" in power boat language. A true dry stack has no water entry
at all and usually exits vertically through the deck like a lobster
boat. Many commercial fisherman and some long range trawlers use dry
stacks and keel coolers to totally eliminate raw water cooling and
exhaust issues.