Replace the receptacles every 20 years. Don't use the backstab feature. And, if you don't have a good feel for torque, use an instrument. I just finished replacing all the 1988 recepts in my house, and saw a number of issues. A boat doesn't have that many recepts to be a $ issue, and the ones that do exist may get heavy use along with salted atmosphere.
I don't know if this is a rule, but I would not put any stranded wire directly under a screw head. Use devices that clamp the wire end. Also, use devices that are "marine" rated, or at least "WR" (weather resistant). The yokes will be made of a corrosion resistant material.
Some good advice here, and the stranded wire issue is worth expanding upon. It is a violation of ABYC standards for any screw to bear directly on any wire. Typically, in shore-side applications the wiring is solid, which works well under the head of a screw, however, solid wiring is prohibited in marine applications, as are direct-bearing terminals. Stranded wires should either be terminated with a solderless terminal, or captured in a non-direct bearing screw clamp.
On the subject of heaters, this issue was driven home for me as a result of two fatalities caused by a heater, being used on a boat in Deltaville, VA, minutes from my home, a number of years ago. It was fall, chilly, old boat, father and daughter sleeping aboard.
I find that marginal wiring can work fine for years without the operator having a clue there is an issue lurking. However, heavy loads like heaters, hair dryers, and microwave ovens place an especially high load on inferior wiring, which exposes its faults. My advice is to inspect the
back of any receptacle in which you intend to use one of these high current devices. Look for loose wiring, undersized wiring, discolored screws or plastic, and any evidence of overheating. If you find faults, then it makes sense to check all the receptacles.
As an aside, all receptacles must be installed inside enclosures; this is a violation I encounter on an all too frequent basis, on new and used vessels, just a few weeks ago I came across this on a new, multi-million dollar vessel, both inside bulkheads and under counter and vanity tops, where they could easily be touched by someone reaching under those areas. This is both a fire and electrocution hazard. A few years ago I encountered just such a violation, with the added feature of a small pile of saw dust piled on top of the exposed receptacle.
