Some of the more interesting assignments I get in my profession are damage claims. In most cases I am hired by the insurance company, but sometimes by the boat owner. One of the two most common claims I investigate are sinkings. The most common cause for sinking is the do it yourself wiring or plumbing jobs.
Boating is an expensive hobby. Once you pay contractors to work at your house and to work on your car, the boat seems to be victim of the shortcut. Not to say that they DIY installer is not taking the time or putting in an effort, but they are doing so without the understanding that boats are subject to issues that cars and houses are not. A few examples.
CASE: Commercial / residential electrician installs a replacement bilge pump and float switch. Connection to the float switch (which of course lays in the bottom of the bilge) made with wire nuts and “sealed” with electrical tape. As you can see from the picture, the wires corroded in the wire nut which was not water tight by using electrical tape.
What to know: Wire nuts should never be used for marine electrical, anywhere. In addition to providing a poor seal and conductor splice with marine wire (stranded versus single strand e.g. Romex) , they are prone to backing off from the motor and system vibrations on a boat.
CASE: Underwater intake is replaced with a polypropylene thru hull fitting, no seacock, and single clamped. The fitting was leaking at the hose so the vessel owner’s “mechanic” friend snugged the hose clamp. When he snugged the clamp, he cracked the fitting without knowing it. The vessel owner woke up early the next morning to 2 foot of water next to him in the aft berth.
What to know: Using anything but metal (bronze, nibral, stainless steel, etc.) fittings below the waterline is a bad idea. Generally because they wear from heat and are susceptible to cracking from even a small impact. Thru hulls below the waterline should always be double-clamped. Unless your “mechanic” buddy is ABYC certified or at least works professionally on boats, his good will should not go unappreciated, but his work should be inspected and supervised by someone who knows the standards for marine applications. This might have been a $200 repair instead of a $500 deductible and loss of a boating season.
These are just a couple of examples of things we see every day, mostly before something goes horribly wrong. In each of these cases, no one was hurt, but many of these go the other way. DIY electrical work is responsible for a lot of fires and explosions.
Also, beware of the advice you get on the internet. Just as an example, The Hull Truth, a well meaning forum for boaters, is a source of a lot of bad information. Every once in awhile, when looking for information about a specific issue on a specific model boat, I come across and read the postings. Some make me cringe and are down right terrifying.
It is fairly easy to find the ABYC, NFPA, and USCG recommendations relating to marine systems. They can read like the state statutes, but they are generally based on real marine failures which have resulted in injuries or loss of vessels or lives.
The easiest and least expensive solution, consult with your local marine professional. Most will happily look at a job and advise you how to do it right. Pay them for an hour of their time to look at an issue and let you know if you can tackle it yourself. Take their advice if they recommend professional repair or installation, or get a second opinion if you think they are just trying to find work for their shop.
If you like to research the internet, seek out the experts. Call your manufacturer’s customer support or any of the following sources: