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Do-It-Yourself Gone Wrong


Our GEICO | BoatUS Marine Insurance claims files have plenty of examples of DIY projects gone awry. Here’s how to avoid becoming a statistic.

While shrinkwrapping his boat, an owner put down the heat gun while moving a ladder.

Boat owners love projects that involve repairs or upgrades to their pride and joy. And why not? DIY projects save money, help us learn about our boats, and give us a certain satisfaction when we flip the switch and see our new toy turn on, or when we get up on plane after an oil change and tune up.

But sometimes in our need to upgrade and improve, we might not realize we’re in over our heads or not really know the right way to do something. And sometimes that not knowing can put your boat, and even you, in danger. If you’re not 100% certain you know what you’re doing, consult a pro so you can avoid problems like these.

Missing Fuses

There have been plenty of BoatUS Marine Insurance Program claims filed after wires to an electronic accessory overheated and melted. In the more fortunate cases, the smoking insulation was detected before adjacent material ignited. In other cases, the boat was badly damaged or even destroyed.

The concept of fuses is pretty basic, but a lot of people don’t seem to get it. When installing new equipment, a fuse (of the proper amperage) must be located close to the point — preferably within 7 inches — of where the power lead connects to the electrical source, which is typically at the panel board. This serves to prevent the wire from overheating — not to protect the equipment. The device’s internal fuse or breaker will protect it from an internal short, but it won’t protect the wire that can overheat before the internal protection trips. (A panel circuit breaker may not protect a short in the wire because it may be rated to serve multiple devices.)

The owner of the boat (above) installed a new VHF but neglected to include a fuse at the power source. As the boat was bumping down the road, the wires chafed and shorted and began to burn. A passing driver warned him. Imagine the owner’s shock at suddenly seeing smoke billowing from his boat.

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Oil Change Fail

Sometimes maintenance is a pretty straightforward DIY job, and sometimes it makes sense to call in a pro. But even the simple jobs, like changing oil, take a certain amount of skill and knowledge. The owner of the boat above changed his oil and filter but neglected to run the engine to check for leaks when he was finished. Unfortunately, when he installed the filter, the seal never seated properly, so when the boat was taken out for the first time, all the oil leaked out and the engine was destroyed in a matter of minutes.

Hose On Hose

This photo above shows how not to tap into an existing hose. Proper fittings are available to do such a job. In this case, the smaller hose could have been attached to a T-fitting inserted into the larger hose. But the owner tried a shortcut that didn’t work. The boat partially flooded when the small hose came off the cockpit scupper hose, and rainwater from the cockpit leaked into the bilge, overwhelming the bilge pump.

Backward Battery Goofs

It’s smart to disconnect the boat’s battery when installing electrical equipment, but make certain that when you reattach the terminals, you put them on the correct post. The red lead goes on the positive terminal and the black one on the negative. Reversing the leads can instantly damage sensitive electronics or cause much more damage. The owner of this boat installed his battery cables reversed with no apparent signs of problems — until the shore power and battery charger was plugged in. Within five minutes, smoke was pouring out of the engine vents. The boat was a total loss.

Hot Lamp

The owner of 45-foot powerboat installed a halogen light fixture in the master stateroom of his boat. A surveyor who was inspecting the boat sent us these photos and said that with the light on and the door open, within about one minute the wood door began to smoke. He measured the temperature under the light at more than 400 F. Halogen lamps get very hot (they’re even used as heaters in some applications) and should not be used near flammable surfaces. Switching them to LEDs will reduce the heat, and with it, the risk of fire.

Making The Connection

Many boat owners are often confused about hose and fitting sizes. Hoses may be measured by their internal diameter (ID) or outer diameter (OD). Using a fitting that is the wrong size virtually guarantees a future leak — or massive frustration trying to put a too-small hose on a fitting. With a threaded fitting, on the other hand, it’s easy to tell if you have the right fittings because they simply won’t screw together if they are the wrong size. But what you can’t do is combine threaded fittings with bare hose. Here are two examples.

When the exhaust hose to his generator failed, the owner of this boat couldn’t be bothered to put the new one on correctly and simply attached the hose to the bronze threaded fitting — and only used one hose clamp (ABYC guidelines require two for exhaust hoses). The possibility of the hose slipping off and filling the boat with deadly carbon monoxide is high. The proper fitting would be a threaded spud that fits on the bronze fitting onto which a hose could be (double) clamped.

The owner of another boat decided to replace the washdown pump hose with a new one. (He gets props for using the correct reinforced type.) However, he tried to attach it to a threaded fitting. (The thread tape is a nice touch but useless in this application.) There’s almost no way this arrangement won’t eventually leak. The right way to do this connection is to get a correct size spud fitting that screws onto the bilge pump’s discharge, then attach the hose to it with a quality stainless hose clamp.

Which Marine Caulk Should I Use?

Deck Leaks = Core Rot

Caulk doesn’t last forever, and resealing deck fittings is a common DIY project. But not doing the job right is almost as bad as not doing it at all. In the photo above, the owner simply slathered on a blob of silicone sealant, hoping that would stop the leak. It didn’t. The only right way to do the job is to remove the fitting, clean off all surfaces (applying silicone like this makes that part much harder), use the correct sealant, and lightly snug the bolts. Only after the sealant has set should you tighten more (but not so much as to damage the top layer of fiberglass or crush the core).

The photo above shows what happens when you don’t seal the fitting correctly. Over time, water will get past the sealant and into the deck core. Once that happens, it’s only a matter of time before the core starts to rot from the inside and the fitting becomes useless. Repairing a rotted core is not an easy DIY project, and it’s not cheap at a shop.

Sleeping Carbon Monoxide Detector

When you leave your boat, you want to be able to turn off the 12-volt power — but not to everything. Bilge pumps and carbon monoxide detectors are two of the few exceptions. Unfortunately, someone wired this boat’s CO detector to the ignition, which means it was only on when the main engine was running. Tragically, two people died when the boat’s generator malfunctioned at anchor, filling the boat with carbon monoxide. While these should be wired directly to the battery (or have their own internal battery), they and anything else wired to the battery must also have a properly rated fuse within 7 inches of the power source. Also, keep in mind that if you buy a used boat, especially an older one, the detector may not have been wired properly, so inspect it to make sure. Better yet, replace any with newer internal-powered CO detectors that sound an alarm at the end of their life (usually seven to 10 years).

Stainless Steel Isn’t Always ‘Stainless’

Stainless steel hardware and fasteners are great for many boat projects, but stainless has an Achilles heel — it will corrode and even disintegrate if starved of oxygen, such as when it’s used below the waterline and painted over or exposed constantly to wet wood. These bolts were removed from the transom of a boat that had wet core sometime after the owner had replaced the swim step using stainless steel bolts. Eventually they failed, allowing the swim step to collapse. Bronze fasteners are a better choice for underwater hardware.

Unintended Consequences

Sometimes you really need to think through a project. Case in point: The owner of this bass boat added a trolling motor. In doing so, he blocked the all-important green navigation light. Running early in the morning or late at night could be way more dangerous if other boaters can’t see his navigation lights. In a crossing situation without the green light, other boats might not see him as the “stand on vessel,” which could cause a collision that the owner may very well be responsible for.

Things That Go BOOM!

Just because Uncle Henry was able to hook up the barbeque grill in the backyard, doesn’t make him capable of safely designing and fitting a new propane system for your boat or fixing a leaking valve. Fortunately, propane explosions on boats are rare, but when they do happen, the BoatUS Marine Insurance Program claim files have found the cause is often a do-it-yourself installation or repair.

Visit to learn how to handle propane on a boat safely.

The owner of this 34-foot trawler (below) had just installed a new solenoid shut-off valve. He then made himself breakfast on board and had shut off the solenoid when he was finished cooking. Just as he was sitting down to eat, the boat exploded. A fire investigator later found that the fitting on the solenoid had not been sufficiently tightened, which caused a leak that was ignited by an unknown source. The boat was completely destroyed, and two other boats nearby were damaged. Miraculously the owner was not killed. His mistake was not testing the system, which would have revealed the leak.

Shrinkwrap And Heat Guns

Almost every year there is at least one fire reported in the BoatUS Marine Insurance Program claim files that involves a boat owner who started the fire while using a heat gun to shrinkwrap his boat (see opening photo). In this case, the owner put down the heat gun for a moment while he moved a ladder. When he turned around, he saw flames and ran to get a hose, which, after fumbling around for a few valuable minutes, he discovered was too short. Back he went to look for a second hose. By the time he finally coupled the hoses together and turned on the water, the fire was so intense that he had to call the fire department. Even though they arrived within minutes and quickly extinguished the flames, the damage had been done; the boat was a total loss.

Charles Fort

Contributing Editor, BoatUS Magazine