petrol fumes in bilge

[sundancer9000]

Hello maybe im paranoid but i have had an awful thought. The boat is a MF925, recently i have aquired a small petrol generator for shore power use on isolated locations. I have stored this in the lazerette!! Im thinking there is 5 litres of petrol in the small tank on this, even though the fuel valve is switched off is there danger of a build up of fumes in the bilge? My webasto heating unit is in this lazerette (a potential source of ignition for fumes).
Am i being too paranoid or should i never store this in this enclosed space.
P.S i would never run this generator on board only 20 ft away downwind of boat.

 

[kashurst]

no you are not being paranoid, never ignore the smell of petrol. Sounds like the genny tank is venting. Out board motors with inbuilt petrol tanks can close off the fuel to the carbs and also seal the tank vent to prevent this happening. You also need to have a word with your insurance company because if the worst did happen you may not be covered.

I know a Boat Safety examiner and the BSS scheme is very cautious about petrol storage on boats. Worst he ever saw was an outboard motor wedged between the engines as a "safe place" to store the outboard while under way. Portable gennies stored below decks were also a big no no as well.

 

[sarabande]

Is the lazarette fully sealed off from the rest of the hull ? Does it have a drain open to atmosphere at its lowest point ?

If yes to both, and if you can't detect any leakage from the tank or carb (by smell or visible) then use the lazarette as a store, but keep the genny in a tough plastic bag - though this might cause condensation) perhaps taking the genny out when you use the Webasto.

Petrol fumes are heavier than air, so can be pumped out using a manual pump such as a dinghy pump, but a good drain is important.

 

[VicS]

Petrol fumes are heavier than air, so can be pumped out using a manual pump such as a dinghy pump, but a good drain is important.

They may be heavier than air and initially sink but being gaseous they will quickly diffuse throughout the entire locker.

To clear the locker of fumes you would have to pump several times it volume.
Just not practical with a bilge pump especially as such a pump is not likely to pump air efficiently.
( equally applies to trying to remove leaked LPG )
The only effective method would be a blower fan.

Many people would store a small outboard engine in a locker without second thoughts. Storing a petrol generator is no different but in a locker with a potential source of ignition would be unwise, both for an outboard or the generator.

 

[Spi D]

Give a thought to the way gas bottles are stored onboard: A separate, closed compartment with own, direct ventilation to the outside of the hull.

 

[sundancer9000]

Thanks everyone for the kind advice

Thankyou for all advice. Ill rethink this prehaps get a small plastic tub to keep generator bolted to deck open to the elements. Sealed unit will keep water tight and i will make a few holes in the bottom to vent out any fumes. Obviously this tub is only for storing the generator when not in use and is essentially only to keep this from rolling about and waterproof.