There is an old saying among experienced boatmen, when aboard a gasoline power boat, “Sniff often and always trust your nose”.
My first experience with the gasoline boat explosion left a vivid memory etched in my mind, that now over 57 years later, is still as fresh as the day I watched the old black wooden lap streak sport fishing boat blow in the Manatee pocket, in Stuart Florida, burn to the water line, and sink. I was 6 years old, and was standing in the early morning mist, on the shoreline about seventy five yards from the explosion, Snook fishing. The blast rocked the ground, and sent wood, glass and debri over 100 feet in the air. The captain that had started the engines was blown overboard, and suffered severe flash burns on his upper body.
Having been around boats of all makes and sizes all of my life, most of them gasoline powered, I learned that gasoline fumes, in any enclosed area, whether below deck, in a cabin, or even under an outboard engine cowling can act as a bomb. They can injure or kill boat occupants and can certainly burn your boat to the water line. A friend of mine was standing a cockpit hatch of a boat that blew, and he was catapulted over the top of two sport fishing boats and landed on the cockpit cover of the third boat over. The cover broke his fall and spared him from serious injury.
I don’t want to alarm here, for I have spent tens of thousands of hours aboard gasoline powered boats in my life, and if the popper precautions are observed, the odds of your boat blowing up are very slim. That’s the purpose of this blog.
While fishing a charter boat approximately 43 years ago, I spent an evening trip and a half day trip the following morning aboard a 40 foot sportfisherman, that was slowly spewing some of over 100 gallons of gasoline in the bilge, from a rear tank that had broken a seam. While docking the boat after the evening trip both the captain and myself got a small whiff of the gasoline fumes. We spent about an hour checking things, and could not determine the extent of the problem at night. We left hatches opened all night, and the next morning, the smell was mute. No fresh gasoline smell or presence was observed. We discounted the previous night’s sniff, and went fishing for what was to be an all day charter. Around noon, however, while three miles offshore fishing, I went into the cabin to make a sandwich. The gasoline fumes about knocked me down. I immediately told the captain, and he jumped into the engine room to inspect the problem. By that time, the split in the tank had increased and 2 inches of gasoline were floating in the bilge. We immediately canceled the charter and headed back to the dock to get the party off the boat and away from the boat slip.
The lesson learned from this experience was, that gasoline in a bilge needs a spark to ignite. The engines were running, the generator was running, the frig. in the cabin was running, and even the bilge pumps came on several times and pumped some gasoline overboard, but the boat never blew. We were very fortunate. The most dangerous time of that experience was after we docked, and the captain slowly turned off all mechanical items on the boat, and shut off all circuit breakers to all electrical components. Again, with raw gasoline in the bilge, she did not blow.
Here are some major considerations that need to be understood in order to minimize your risks of a gasoline fire aboard your boat.
The two most critical times when boats blow up are usually after a prolonged stay at the dock, or shortly after a refueling of the boat.
#1. When a boat sits for a long period of time, preventive maintenance is often neglected. If a captain is the least bit sloppy, and does not properly check things out before starting up the boat, he can ignite a boat laden with fumes.
#2. Immediately or shortly after a recent refueling, if a gas tank has a weakness, it will show up with the renewed weight and stress of the new fuel. If a captain again is sloppy in his refueling disciplines, he can create an unwanted disaster.
The first precaution is to NEVER turn on anything or attempt to start a gasoline boat without first lifting a hatch, over the lowest point where water or liquids may be in the bilge, stick your head in the bilge and sniff! If you smell any fumes that concern you- check them out thoroughly. It dos not take a lot of fumes to be a problem.
When going to the gas dock to refuel; Dock the boat, turn off everything on the boat, including the motors, the generators, and all electrical components, prior to bringing the fuel hose aboard the boat. Leave all hatches closed and sealed. Leave all cabin doors closed and close all portholes prior to refueling. If fumes are accumulating you want to smell them.
Fuel the boat, and be sure to clean up thoroughly any spills that might take place. Before starting or turning on anything mechanical or electrical, sniff the cabin and lift a hatch as described above and sniff the bilge. If any smell concerns you, CHECK IT OUT!
Just in the past year, this process saved my boat and possibly my life, when after refueling, a sniff in the bilge that concerned me, led me to find a pin hole in the same tank that I had just filled up with 135 gallons of gasoline. I was able to plug the hole with sheet metal screw temporarily, run the boat back to my dock, with all hatches open and later get the boat to a boat yard and hauled out for the installation of a new tank. Had I not done the sniff test, the tank would have slowing filled the bilge with gasoline, and who knows what the results might have been later.
A major mistake many captains make is to rely on their blowers to blow out gasoline fumes in the bilge. First of all, the blowers are electric motors. Even though Coast Guard approved and supposedly fireproof, one blower failure and the results can be tragic. If a tank is leaking, sizable amounts of gasoline in a bilge, blowers will be insufficient to vent the bilge of all those fumes. It does not take a huge amount of fumes to be explosive.
I also recommend that prior to starting a gasoline boat, a captain should check all gasoline connections, fuel filters, and fuel lines to see if any potential leaks can be observed. This should be part of any normal pre-operation maintenance like checking oil levels, transmission fluid levels etc. I once found a cracked glass fuel filter located next to the carburator of a big block 454. When the engine was crank up, the fuel pump was forcing gasoline to escape from the small crack, and puddling on the intake manifold of the engine. There is no substitute for being observant while operating gasoline boats.
A similar process should be observed prior to staring an outboard motor as well. Lift the engine cowling prior to starting the motor, snif and check all fuel fitting, the fuel pump and filters for any leaks. I just saw an outboard motor blow about three months ago, and the fire begin to consume a 22 foot Mako with six adults aboard. Fortunately the fire was exstinguished, and no one got harmed.
Enjoy your gasoline boat as I have enjoyed mine for many years. Be careful, be observant, be disciplined, and “Sniff often and always trust your nose.”