Engine Exhaust Underwater?

[labatt]

So we loaded 2 months worth of provisions onto Pelican yesterday - lots of canned goods, 70lbs of meat, etc. The overall effect was yet another lowering of our hull into the water and the fact that we've submerged our raw water engine exhaust. Considering that we've used our engine while heeled over under sail, I'm thinking this isn't terrible, but I figured I'd ask here if anyone thinks this is a major issue. I'm about to add another 250lbs of batteries too.

[ewingengr]

Most boats have a loop that prevents water from backing into exhaust so you should not have a problem. Also I had a boat that had water siphon into engine head from sailing with exhaust submerged. After much aggravation and replacement of anti siphon valve all was good. Of course check for leaks in hoses.

[r.furborough]

The only possible issue is that the exhaust back pressure may increase if the exhaust is fully underwater, keep you eye on the engine water temperature.

[JohnRPollard]

Labatt,

I agree, there could be some extra back pressure there, but probably not much. The bigger concern to me is back-siphoning when the engine is not running, especially with overtaking, following seas.

Do you have a seacock at the thru-hull for the raw water engine exhaust? If so, it would be good to close that when you're not running the engine, even if you have a vented loop. Hang your engine keys on the thru-hull handle so you don't forget to open it before starting the engine.

If you don't have a seacock there, you really should consider adding one, since it's now a below-the-waterline through-hull.

How's the boat doing with all the weight? Have you noticed a loss of performance?

[labatt]

Our raw water exhaust is actually on the port side of the boat, AT the normal waterline, so when we're sailing it's regularly submerged. Good point on the seacock - I'll have to look to see if there is one. It's not in the most accessible of places. So far, the most we've noticed from the extra weight is that we heel over farther and faster, but we're solid once we get there. Our speed seems to have been reduced by a few tenths and our acceleration is slower. My guess is that we're also sucking up a bit more fuel when under power. The big test will be when we cross to the islands some time in the next couple of weeks.