On Tuesday, April 3, 2018 at 12:31:59 PM UTC+1, Scott wrote:
On Tue, 3 Apr 2018 12:13:32 +0100, Chris Green wrote:

I have just detected a (small) gas leak on my boat using the Alde
bubble leak detecter I installed a while ago. I have fixed the leak,
just a compression fitting on a tap needed a tweak.

It was a very small leak, just a bubble a second or so or even a bit
less. It's LPG (propane) though and is thus heavier than air and will
sink into the bilge. The leak has been there for a few days (probably
three or four days) since the gas was turned on, I only just got some
propylene glycol to replenish the bubble detector. Presumably the gas
will eventually diffuse but should I do something to clear any gas
that may still be sitting down there and, if so, what?

The boat has a diesel engine (sitting immediately above the bilges)
which sucks air in from the outside and (presumably) blows it out of
the exhaust. The engine was running for several hours yesterday and
Saturday so that would, I guess, have cleared things a bit. So the
accumulation is probably only over the last 24 hours since yesterday.

My feeling is to let sleeping dogs lie and leave it to diffuse,
there's no source of combustion down there anyway.

I would suggest maximum ventilation. Surely you should not be running
a diesel engine in the vicinty of a suspected gas leak?

You need to clear it out as it will have gathered in the bilges. Get a small bucket and scoop up the air gas mixture and throw it over the side. You might think you look stupid doing it but not half as stupid if a spark sets it off