Originally Posted by capnward
Be attuned to the smell of gas, your nose is as good as any fume detector, use it often. You should not be able to smell gas, if you do there is liquid gasoline somewhere outside the air intake to the carb. Find the leak before using anything electrical. Sometimes there is a little gas in the bottom of the air intake to the carb, under the flame arrestor, but as long as it is not leaking out through the choke lever area and dripping into the bilge, you are probably ok. I am a great believer in using the hand bail on the mechanical pump and a fuel pressure gauge to see if there are leaks. Lots of ventilation is your friend. Even if there is a puddle of gas in the bilge, it may not explode if enough air is moving over it. It is the concentration of fumes with an ignition source that is dangerous. Air temperature is a big factor as well. Your reaction to the smell of gas should be alarm.
I will never forget the day in the 1980's when I opened the companionway and was hit by an overpowering gas smell. I had been gone for a few days. I had let an acquaintance borrow my portable gas tank, and when he returned it, he put it on something that tipped it over when the wind came up, and 5 gallons drained out of the air vent into the bilge. There was maybe an inch of liquid gas when I lifted the cabin sole to inspect. I immediately shut off the shore power at the dock outlet. In hindsight I should have done that before opening the bilge, but I was lucky. The amazing thing to me was that sitting on the cabin sole, directly above the puddle of gas but separated by three inches of air and 1/4 inch of plywood, was an electric ceramic disc space heater with a fan, happily blowing warm gas fumes around inside the cabin, and through the heating elements. It had been going constantly the whole time of the gas spill, and had evidently kept the fumes from being too concentrated. It may even have reduced the concentration by combusting fumes in the heating elements without igniting them, if that is possible. If it had been set to turn off and on to keep the temperature at a certain level, it may have blown up the boat. But as it was winter, and I was living aboard, it had been set on high, and stayed on. Once the power was off I opened up the boat as much as possible and started to remove the gas from the bilge using cups, sponges and oil pads. It was a plywood boat with a dry bilge, and the smell lingered for many days, but eventually stopped.
Ever since then I have been highly sensitive to the smell of gas. I would not be able to sleep, let alone run anything electrical, until I had found the source of the leak and fixed it. I always leave the engine compartment open so that the whole interior of the boat is the engine compartment, and air is flowing through it. Blowers are essential to ventilate the engine compartment, if it is enclosed. The blower hose should be led right up to the carburetor. But I don't use a blower unless I smell gas. I prefer to leave the engine completely exposed to all the air flowing through the cabin, and open up hatches fore and aft to maximize that flow when the boat is moving. I think it is important to keep fumes from concentrating in the first place. Plus, if fumes are contained in a closed engine compartment you can't smell them.
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