Valves for exhaust thru hull.

While anchoring in a bay, both exhausts disappeared several times in the waves of a large yacht.
That cannot be healthy, so I tried to buy add-on rubber flaps for my 2" stainless thru hulls. NOT for sale in Europe!

One UK supplier offers a complete through hull with valve, but plastic and not fitting the existing hole and the exhaust hose, for 35 UK Pounds plus unreasonable postage.

So I played a bit with some stainless leftovers and an old car tire.....

 

Those look pretty good. You could make a wax mold from the prototype and cast your own from high-temperature red silicone rubber with fiberglass re-inforcement.

 

looks nice,how's it works?

 

The price/performance ratio is as good as can be because it didn't cost anything.
Salt deposit in this extremely saline waters sometimes keeps them from closing after the engines are switched off. I need to press a metal bushing in the rubber to improve that.

 

Nice job CDK. I want to keep that idea in mind. Looks very useful.

 

Fine, that's make sense, Salt deposit could happen on any kind of thru-hull covers.

 

CDK, I feel very strongly that these type of devices are not the way to go. (they are readily available in the states).
Waves simply lift up the flapper as the boat goes down and the mass of water proceeds right where it wud have gone anyway. I watch it all the time while anchored next to boats with these. The are other, better means to keep water from getting ingested by your engine, e.g., surge tube, altitude, a flapper inside of the exhaust, a muffler,..

 

Mark, there is enough height difference between the exhaust and the turbo charger to prevent real damage. I just don't want the whole hose filling up with water.

This exactly does what it is supposed to do. The flaps firmly close when waves hit the exhaust.