Bilge Safety

[Mark S]

Just operate your blower as instructed by the builder and turn it off after starting.

Keel,

There was some debate last year, maybe in this post, about running the blower continuously while the engine was on, hence my interest in a continuously operating blower. I think Dave was the principal proponent of continuous operation. As quoted above, however, you seem to think differently.

Can we resolve this debate? I'll stay where I am if I can turn the blower off after starting the engine.

Mark

[keelcooler]

John, Lots of torn low quality blower hoses out in service, and the owners have no clue because they are not inspecting. INSPECT,INSPECT,INSPECT, the life of you and your family depends on it. Make sure its not torn, shagging or fitted w/a birds nest. Marine centers for the most part sell only crap 3” hoses. Get your new blower hose at Lowes. I replaced my crap, torn hose years ago w/ the foil covered stuff for dryers…much better.

An auto haylon will not eliminate or reduce an explosive fume condition. A haylon only works once a motor box fire has started. It will activate around 250 degrees and displaces the oxygen. If the blowers running it might not starve out that fire. You must have the proper size unit for the space and then add 20% for naturally occurring venting. The auto haylon is effective in the event of an electrical or raw fuel fire in the box.

The posted a4 C&C story has a telling tale. Exploded and burned after refueling. So we had fumes and raw fuel. No fumes in the cabin that the capt or crew could detect. So the fumes were aft. If that carb or a fitting/hose near the motor was involved in all likely hood some one would have detected. She had run extensively during the day. Does not sound like the motor was involved; the blower was running prior to start. I would speculate fuel fill hose or deck fill fitting leak. If the tank was the problem I would think some one would have smelled the fumes early in the day. If the vent hose had failed or become detached it may have been an explosion only.

What Joe found recently is what I would find 90%of the time during postmortem inspections on an explosion after a refueling loss. FUEL FILLS…don’t let yours be out of sight and out of mind.

You would not believe how may times I’ve seen a broken/rusted out fill system fail after the owner inserted the fuel pump nozzle. “How much now honey…35 gallons…that’s imposable we have a 25 gallon tank” or the power boat that pumps 100 gallons into his bilge! Funny thing, when it’s that fuel rich of a mixture they rarely blow or burn.

Mark, I think with all of the above facts we can draw our own conclusions. I just can’t see how it does any good. I have a haylon and if a box fire erupts I want that haylon to do its job and not have all its flame smothering gas sucked out. I think the engineers at Jabsco or Attwood would advise to use as directed. I think Dave is the only member that has an heavy duty 4” extended run blower that can safely operate all day w/out over heating. The rest of us have intermittent use rated units. I recall the continuous heavy duty rated should be replaced every 10,000 hrs where in ours should be replaced every 100 hrs of use This spec is not because it might fail, its because the spark shielding degrades.

[rigspelt]

I installed a gas sniffer on a previous boat. It alarmed one day when we were all relaxing on lawn chairs at the dock. Got everybody jumping. Inspected carefully and could not find any sign of fuel leak or fume source. We never did find out why it went off, and it was OK after. Even tested it with a thimble of gasoline. I appreciated having it down there in the engine space. Two boat bucks ($200) and slight continuous drain on the battery.

Mark, I doubt there is a definitive answer about continuous blower versus what so many do in small sailboats: careful sniff and open hatches, then blower on before start, then blower off, and maybe ventilate the engine space with hatches up while running, especially on longer runs if heat builds up in the engine space, being mindful of carbon monoxide in living accomodations. I like Hanley's idea of adding passive ventilation in the high spots of the engine space to reduce heat in there if possible, but that isn't so easy for many of us.

The keys, as Keelcooler pointed out, are careful ongoing preventive maintenance and inspection of the fuel distribution system, spark-minimizing in engine space appliances, consistent sniff-ventilate practice when starting, and extreme caution after refueling.

[ArtJ]

I installed a gas sniffer on a previous boat. It alarmed one day when we were all relaxing on lawn chairs at the dock. Got everybody jumping. Inspected carefully and could not find any sign of fuel leak or fume source. We never did find out why it went off, and it was OK after. Even tested it with a thimble of gasoline. I appreciated having it down there in the engine space. Two boat bucks ($200) and slight continuous drain on the battery.

Mark, I doubt there is a definitive answer about continuous blower versus what so many do in small sailboats: careful sniff and open hatches, then blower on before start, then blower off, and maybe ventilate the engine space with hatches up while running, especially on longer runs if heat builds up in the engine space, being mindful of carbon monoxide in living accomodations. I like Hanley's idea of adding passive ventilation in the high spots of the engine space to reduce heat in there if possible, but that isn't so easy for many of us.

The keys, as Keelcooler pointed out, are careful ongoing preventive maintenance and inspection of the fuel distribution system, spark-minimizing in engine space appliances, consistent sniff-ventilate practice when starting, and extreme caution after refueling.

I had one of the xanrex gasoline alarms go off a couple of years ago
when it was knocked loose from its overhead mount under the cockpit sole]
and into bilge water. I was told that it needed to re replaced. The replacement cost for the sensor was in excess of $100
Regards
Art

[sastanley]

One disturbing trend I've noticed with my power boat friends is that most of them only turn the blower on a few seconds before turning the key. This tells me most of them have no clue what the blower's job actually is. Good thing most of the issues we are discussing here never actually occur.

[joe_db]

The C&C 35 uses what seems to be a hardware store 90 degree rubber elbow in the fill line. It was never intended for gasoline and surely never intended for ethanol-gas
Mine was coming apart and I only found out when I refueled from a 5 gallon can and noticed gas running into the bilge
I tracked it back to the top of the tank and the elbow. When I took that off the fill hose, which looked perfect on the outside, was discovered to be rotting from the inside out. I was initially alerted by a strong gas smell coming from the blower. The leaking fuel was going right past the blower hose, so it provided a very good warning in this case. It took me about 3 hours to get the fuel out of the bilge and the boat de-smelled to the point I thought she was safe to operate.

John, Lots of torn low quality blower hoses out in service, and the owners have no clue because they are not inspecting. INSPECT,INSPECT,INSPECT, the life of you and your family depends on it. Make sure its not torn, shagging or fitted w/a birds nest. Marine centers for the most part sell only crap 3” hoses. Get your new blower hose at Lowes. I replaced my crap, torn hose years ago w/ the foil covered stuff for dryers…much better.

An auto haylon will not eliminate or reduce an explosive fume condition. A haylon only works once a motor box fire has started. It will activate around 250 degrees and displaces the oxygen. If the blowers running it might not starve out that fire. You must have the proper size unit for the space and then add 20% for naturally occurring venting. The auto haylon is effective in the event of an electrical or raw fuel fire in the box.

The posted a4 C&C story has a telling tale. Exploded and burned after refueling. So we had fumes and raw fuel. No fumes in the cabin that the capt or crew could detect. So the fumes were aft. If that carb or a fitting/hose near the motor was involved in all likely hood some one would have detected. She had run extensively during the day. Does not sound like the motor was involved; the blower was running prior to start. I would speculate fuel fill hose or deck fill fitting leak. If the tank was the problem I would think some one would have smelled the fumes early in the day. If the vent hose had failed or become detached it may have been an explosion only.

What Joe found recently is what I would find 90%of the time during postmortem inspections on an explosion after a refueling loss. FUEL FILLS…don’t let yours be out of sight and out of mind.

You would not believe how may times I’ve seen a broken/rusted out fill system fail after the owner inserted the fuel pump nozzle. “How much now honey…35 gallons…that’s imposable we have a 25 gallon tank” or the power boat that pumps 100 gallons into his bilge! Funny thing, when it’s that fuel rich of a mixture they rarely blow or burn.

Mark, I think with all of the above facts we can draw our own conclusions. I just can’t see how it does any good. I have a haylon and if a box fire erupts I want that haylon to do its job and not have all its flame smothering gas sucked out. I think the engineers at Jabsco or Attwood would advise to use as directed. I think Dave is the only member that has an heavy duty 4” extended run blower that can safely operate all day w/out over heating. The rest of us have intermittent use rated units. I recall the continuous heavy duty rated should be replaced every 10,000 hrs where in ours should be replaced every 100 hrs of use This spec is not because it might fail, its because the spark shielding degrades.