Question:
My dad was trying his "new" used Thompson tri-hull for the first time when, all of a sudden, he heard a loud pop from the Chevy I/O engine (inline-V6, I believe) when he adjusted the trim lever while going about 20mph. He and my mother and brother turned to see flames shooting out of the engine. The fire extinguisher was not enough and they all took a dive (life jackets secured around them) and watched the new purchase go up in flames. Thanks to full gas tanks there was no explosion but the boat was still a total loss. Thank God, everyone escaped physically unharmed. (We were to take my four-year-old son on the boat the same weekend!) We are all new to this boating thing so here are some newbie questions: 1. Are there known problems with this type of boat? It was a 1977 model and Dad had looked over the engine pretty good and did limited testing out of the water. 2. Are there other old boats to stay away from? He plans to get another tri-hull of some type. 3. Are there more exotic fire extinguishers for the engine compartment? Can't say enough about having life jackets - my family was hundreds of yards from shore and had little time to react. Kind boaters plucked them out of the water.

Answer: Q: my mother and brother turned to see flames shooting out of the engine. The fire extinguisher was not enough and they all took a dive (life jackets 1. Are there known problems with this type of boat? It was a 1977 model and Dad had looked over the engine pretty good and did limited testing out of the water. A: I can't comment on the known problems with the boat, but I would speculate that if the boat was 19 years old, then it couldn't have had very many basic flaws. Q: 2. Are there other old boats to stay away from? He plans to get another tri-hull of some type. A: I suspect that the real problem was not from the design of the boat, but from the maintenance and repairs done over the years. A common temptation is to replace the expensive "marine" parts with much cheaper, rebuilt automotive equivalents. Over a period of 19 years, it would be reasonable to assume that the fuel pump, alternator, or starter may have been replaced. You can ignore the starter as the culprit, as the engine was running when the fire started. But I would be very suspicious of the fuel pump and alternator. Marine engine parts are made to prevent fumes from escaping (in the case of parts dealing with fuel) and to prevent igniting any fumes that may be present (for the case of parts that deal with electricity). The common automotive fuel pump will spill gasoline when their diaphragm fails. An automotive alternator will ignite an explosive air/fuel mixture. The two together can result in the situation you just experienced. It may be rather hard to do, but when looking at an older boat, try to determine if the alternator, starter, and fuel pump are marine parts. The carburator, distributor and voltage regulator should be marine parts as well, but these don't fail as often, and hence are more likely to be original. Another generic problem can be the gas tank. There have been lots of problems with aluminum tanks that suffer from corrosion and develope leaks after years of service. Gas tanks in runabouts are especially prone to failure due to the pounding that they are often subjected to. Q: 3. Are there more exotic fire extinguishers for the engine compartment? A: Yes, there are. You can get automatic extinguishers that mount in the engine compartment, and when they get too hot, will flood the compartment with whatever chemical they use. In my opinion, Halon is the best, but safety seems to be taking a back seat to protecting the ozone layer, so these are being phased out. Without the automatic extinguisher, you can basically forget fighting an engine fire on most boats. It can be *VERY* hazardous to open the engine hatches if there is a fire in the compartment, and spraying a dry chemical in through the vent openings has little or no effect. A hand held halon or CO2 extinguisher can be effective at fighting a compartment fire by spraying it into the vents. But CO2 extinguishers are large and heavy, and Halon is being regulated out of existence. They are still available, however, so if you are really interested in protecting yourself, the Halon units are the best bet for fighting this type of fire. Now, before someone jumps in to offer the counter argument, I might as well say that the dry chemical has advantages too. A disadvantage of Halon is that it goes away fairly quickly, and doesn't prevent flashbacks. Dry chemical, on the other hand, stays around and helps keep the fire from flaring up again. But as I said before, dry chemical only helps if you can get the chemical to the source of the flames. Where Halon will flood an entire compartment, dry chemical must be applied to the base of the flames.