Underwater exhaust

[Jeff Jones]

Since adding davits, dink, outboard on the sternrail, larger house bank, etc. we find that both our diesel exhuast and scupper drains are just submerged when three or more adults are in the cockpit (still at dockside). Although the exhaust is quiter at idle, due to the close proximity of the starboard scupper drain we have diesel fumes emminating into the cockpit! I don't believe that the small amount of back pressure on the exhaust is something to worry about, after all there is water in the muffler and exhaust loop. With the stern squatting under power the exhaust is forced under anyway. My question is, should I move the exhaust or the scupper drain? I would have posted on the deisel forum, but find it is 'temporarily closed'. Surely someone else has come across the same problem?!Jeff JonesEscapade

 

[Doug Dreyer]

Loop

Yes, I have experienced the same problem as you have. I added a short 1-foot long section of hose to the stbd cockpit scupper hose with a coupling (I used a one way valve which is basically just a rubber flap in a coupling and doesn't really do much). The added length enables the you to position the hose over the fuel tank and creates a low spot in the hose before it goes over the tank in which water is trapped. This prevents any exhaust back flow up the hose. Yes, it slows down the drainage but I am just a coastal cruiser and it works fine. Make sure you remove the added hose or reposition the hose (which is what I do) to prevent the water in the trap from freezing in the winter. A blocked scupper hose could potentially sink your boat!