[ndutton]

I don't recall if I posted this before but a few years ago I had this exact sphincter episode.

I was merrily walking down the dock to my boat when about 2 slips away I could detect the distinct smell of gasoline fumes. I thought poor sap, he's got a dangerous condition, hope he doesn't take out the rest of us in the process. By the time I stepped into my cockpit it was clear that I was the poor sap.

First thing I did was step off the boat and turn off the shore power at the dock breaker. Next was to open up the boat as much as possible and start looking for the culprit. I knew anything left on had to be switched off but not haphazardly, it had to be done so no spark was produced. The only things I leave on when I'm not at the boat are the bilge pump (controlled by a float switch) and refrigeration.

I reasoned that the bilge blower switch was located at the very stern of the boat and pretty high. Also the blower itself is mounted high and is supposed to be ignition proof. That seemed like the best thing to get going to evacuate the fumes so I said a little prayer and switched it on. OK, all good. I then turned off the battery switches except for the one feeding the blower. Those switches are supposed to be ignition proof too. That went well.

So, I'd done as much as I could do regarding minimizing an ignition source until I was comfortable the fumes had been exhausted.

Post sortie debriefing
The fuel level in a full tank on a Catalina 30 is a little higher than the carburetor and my float valve had a speck of debris allowing a slow siphon. I have a small catchment below the carb and that was full and overflowing into the bilge although not much reached the bilge. I sponged up the spillage and went after the residue with soap and water.

I admit I'd been too lazy to dig under the quarter berth to close the tank valve which was the real issue. Since that episode I've installed a Xintex MB-1-R fume detector that automatically operates the blower (it's left on when I'm not at the boat) but most importantly I've installed a manual fuel shutoff valve immediately ahead of the carburetor and accessible without opening or removing anything. It's now a routine part of shutting down the engine.