Where to put the exhaust?

[Allan Jennings]

Does the exhast really have to go at the back of the boat? Why can't it go at the side in the middle - the boat only heels when it is sailing after all.

[jehardiman]

You can put it in the middle, just make a stack to get the exhaust port 12-15 feet above the last working deck like any other vessel.

Really, the reason for a transom exhaust on a sailboat is that normally you motor upwind, which means that the exhaust is carried away downwind, not back into the boat. The reason most high speed motorboats have it aft is that they make thier own wind which carries it away. Finally most slow speed motor craft, like tugs and fishing vessels, have stacks to get it up away from the decks as they have nether the speed or the direction to the wind to carry it away.

There is nothing more miserable than a slow motor in cross seas breathing exhaust fumes......

[Cliff Pope]

There are pros and cons of every location.
At the back it is vulnerable to following waves, and is probably not appropriate for a counter stern.
At the side is fine when motoring, but you may want to start the engine to assist the sails, and you may be heeling.
That would argue that the exhaust should be as high above the waterline as possible. But then there is no space under the deck for the swan-neck, to stop water flowing back straight down it. But if you put it near the waterline it gets waves slopped into it, and may go a long way under when heeling.
A funnel would get in the way of the boom.
The neatest solution would be to pipe it up a hollow mast.

[JimCooper]

Diesels have enough exhaust pressure to start with a fair amount of water in the pipe. I always liked the shortest route straight out the nearest side, most boats I have had put the exhaust at the waterline, running up inside a steel mast seems to work for a dry exhaust but 15 foot stacks on a sailboat with give you black sails. Trasom in often too far away to be realistic on a bigger boat that darn hose costs an arm and a leg.

[Allan Jennings]

I have plenty of space for the swan neck - inside the deck saloon, and it can go well above the water line although the paint would suffer. How about putting in a Y junction and allowing the water/exhaust to go both sides and then it doen't matter about heeling and I can keep them both near the water line