No matter how it happens, if gasoline gets into the bilge, it’s simply a spark away from an explosion. The injury to passengers and crew during an explosion can be devastating, even without a fire. Aging systems aboard all boats need continuous preventive maintenance. Fuel fill lines, feed lines, and vent lines are constantly subjected to heat and vibration. Inspection access to these components is critical. Hoses become hard and brittle over time, fittings corrode and shutoff valves stick and are left open or incompletely closed. Regular attention to these conditions is critical to your safety.
Fuel system integrity
For gasoline vapors to ignite, there must be a fuel leak somewhere, and something to ignite it. Re-move both of these things, and you eliminate the potential for explosion.
Inspect and replace old and brittle hose using USCG-approved A1-15 hose, which is burn-through resistant. This hose gives you enough time to put out a fire or abandon ship before the hose begins leaking. Additionally, check all fuel connectors and fittings for leaks.
Many vessels today use propane cooking appliances. Make sure that propane tanks are mounted in a compartment with a vent at the bottom to allow any propane that might leak from the tanks to go overboard. Exercise shutoffs regularly, and close them when not in use. Make sure that nothing that could possibly make a spark shares space with a propane tank and that there is an electrical shutoff in the galley near the stove that closes a solenoid on the tank.
The other side of preventing explosions is to have no way to ignite gas fumes that may have built up. Any starters, alternators, or pumps—or any other electrical equipment—in your engine room or generator compartment must state on their labels that they are “Ignition Protected.” Using ignition protected fuses, fuse blocks, circuit breakers, switches and motors in critical areas is not only a good idea, it is required by United States Coast Guard regulation 33 CFR 183.410. For additional detail, see ABYC standard E-11.4.15 or E-11.5.3.
Ignition protected devices do not ignite a surrounding air-fuel mixture if there is an explosion inside them. Additionally, they can’t reach a high enough surface temperature or generate enough spark to ignite an air-fuel mixture.
When you replace fuses and fuse blocks, install ignition-protected components. Never use automotive parts of any type below deck, even though your propulsion system may be an automotive-type engine. Make sure that any crimp terminals and splices are installed using a calibrated crimping tool and have waterproof shrink tubing shielding the mechanical connection to prevent corrosion. Corrosion introduces high resistance, causing overheating, insulation melting and a bare wire that can spark.
Make sure that any wire you install has an insulation temperature rating of 105°C (221°F). Do not use shore-side wiring.
Some raw water pumps or bilge water pumps may not be ignition-protected. A previous owner could have installed a non-ignition-protected pump that could spark on startup. If you store gasoline, whether for an outboard or a gasoline generator, in the same compartment as a non-ignition protected device such as a diesel engine, your vessel is at risk.
Check the condition of your bilge blower duct hose; these deteriorate over time and become no longer capable of removing dangerous fumes from the bilge. Remember that a bilge blower will not rid the compartment of spilled fuel, which continues to emit vapors. This is why a marine vapor detector should be installed in the engine room. Check these as well, since most have a lifespan of only 5 years. Know where your fuel shutoffs are, and check them regularly for complete operation. Make sure that bulkheads separating non-ignition-protected components are secure from areas with potential explosive fumes.
Use care with portable appliances
Portable appliances brought on board are hazardous sources of explosive ignition. Tools powered by batteries or by AC have sparking, brush-type universal or DC motors. These include electric drills, routers, saws and vacuum cleaners. Never even consider using a wet/dry vacuum to vacuum up a fuel spill in the bilge.
Fueling your boat correctly
Review regularly the proper procedure for fueling your boat:
- Shut down the electrical system (all battery switches, generators, etc.).
- Close all hatches.
- Disembark all passengers. Confirm the actual identity of the fuel fill (not a rod holder or the fresh water fill.
- After fueling, but before starting the engines, open all hatches and turn on the blower for four to five minutes.
- Check the vapor detector and also place your nose in the lowest part the bilge that is accessible.
If you smell gasoline, get off the boat and alert the dockmaster, call 911, and let the professionals deal with it, even though it may be expensive. Expense is simply part of boating, and your life is at stake.