Of all the many maintenance jobs on a boat, DC electrical problems were probably among my favorite to deal with on Tosca—100 times more enjoyable than painting the bottom or cleaning the hull. Except for a few tight spots in the bilge and behind the nav station, all of the wiring and connections on our gaff-rigged ketch were easily accessible, so trouble-shooting required no contortions.
A multimeter like the one that performed well in our digital multimeter test will suffice for most DC projects. When choosing a crimper, avoid the cheap combination crimper-cutters available in automotive stores.
Ancor, maker of testers’ favorite budget-priced tool for stripping insulation makes a popular (but not inexpensive) double-action crimper designed for insulated terminal fittings; this makes it much easier to apply the correct amount of compression to insulated terminals.
If you find extensive corrosion and need to run new wire, consider paying a little extra for pre-tinned, multi-strand “Boat Cable” labeled “UL 1426 Type III,” which indicates that a wire is finely stranded (Type III) and complies with Underwriters Laboratory (UL) Standard UL 1426.
We found that THHN machine wire held up just as well as tinned wire in our marine wire corrosion test, but if you buy in bulk, tinned boat cable is only slightly more expensive and will add to the resale value to your boat.
Your Marine Products Specialists Want to Make Sure You Have the Right Tools For the Job
Your marine products professionals know that most of the terminal fittings for our wire test were tinned copper fittings made by Ancor (ring crimp connectors and terminal blocks) or Ideal (heat-sealed crimp connectors and push-on connectors). Standard crimp connectors don’t do the job.
What about protective sprays or coatings? Twice, Practical Sailor looked at anti-corrosion sprays suitable for wire terminals. In 2007, we looked the best anti-corrosion spray treatments for electrical equipment, and our long-term wire test compared protected and unprotected terminals.
When rewiring or replacing wire terminals, here are some key points to keep in mind:
Match the Lug Terminal Size to the Cable Size. It matters. If you use too large a lug terminal, the air pockets or voids in the crimped joint (especially when using coarse stranded wire) will increase voltage resistance.
Rotten to the Core: The wire that you are terminating must be completely free of corrosion and oxidation. If internally the wire is black or green in color, you must cut back until you find virgin copper, or consider replacing the wire (with tinned wire).
Crimp Tip: Make sure that the strands of your wire don’t extend too far out the front of the lug and into the terminals eye or spade contact area.
Plastic Not Welcome Here: The best-insulated lug terminals are those with nylon insulator sleeves. Nylon resists UV, gasoline, and oil. Unlike the cheaper vinyl and plastic insulator sleeves, nylon will not punch through or crack and fall apart when the squeeze gets applied.
Solder vs. Crimp: National Marine Electronics Association standards state that solder shall not be the sole means of mechanical connection in any circuit (with the exception of certain-length ship’s battery cables). If inclined to add solder to a lug terminal, solder it after you apply the crimp. A good solder joint is bright and shiny.
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