Originally Posted by waggy
Regarding the wet exhaust..
Are you suggesting to run drain lines into the exhaust lines? If so, how do you prevent the vessel from filling up with exhaust fumes?
The idea is to step the 2-3 inch engine exhaust up to 8-10 inches, after having run the exhaust gasses through a wet muffler
to cool them down. Run a splitter to divert a portion of the water from the raw water pump
to split what goes through the wet elbow
, to feed a gear
cooler and send it overboard
at the waterline on the side of the boat so you have a visual that your cooling
system is working.
At this point the flow going in the tubing flow is your engine displacement
* max RPM
and a Reynolds number. Work backwards to the diameter you need to keep ambient pressure, and you don't have anything different than having the drains go through the side of the boat.
Planing boats, with waterline discharge, will actually pull a negative pressure on through transom exhausts while running.
So long as the fiberglass tubing is sized sufficiently to accept the exhaust flow without generating back pressure, a loop in the drain line is sufficient to keep the exhaust out of the boat, as you've no more pressure than having an above the waterline side exhaust nested beside the sink drain. Having been stunk out of boats before with side exhaust and above the water sink drains.... I like having a trap on the drain even on gravity drain galley
For the lower heads and showers, install a sumpless diaphragm
pump and put the pumps valves between the exhaust and your drain lines, on a simple boat I'd run everything to the same sump.