How to Properly Splice Wires on Your Boat

There are many sides to splicing wires for electrical projects on your boat. Should you solder or should you use crimps? How should you address keeping the water out? What products and techniques should you use? What about those wispy, thin electronics interface wires? I have tried to answer these and other questions in this article.

Soldering

The ­American Boat and Yacht Council says that we can solder, but we must also use a mechanical connection. The thinking is that a ­soldered connection makes the wire brittle and, due to the natural vibration and movement on a boat over time, prone to failure if it is not backed up by another means. Basically, you need to support a soldered connection against flexing. Soldering also requires practiced technique, a thing many boaters lack. A poorly soldered connection is not acceptable. That said, shrink-wrapping the soldered connection and then supporting it with at least two tie wraps is a common way to inhibit flex. This is one way to connect small-diameter wiring, such as that used to interface electronics. 

Crimping

A properly crimped connection is ­relatively ­flexible. Like soldering, there is proper technique involved in making a crimped connection. ­Practice making good crimp connections on scrap. Strip just enough wire (about 3/8 inch) so that the insulation butts against the barrel and stripped wire is barely visible at the barrel’s other end. Crimp in the center of the barrel using the right-size die, and test to make sure the connection is robust. ABYC requires 16 AWG crimped connections to withstand 15 pounds of pull (10 gauge must withstand 40 pounds). For thin wires, such as 22- to 24-gauge interface wires, crimp connectors are available but are not common. An alternative for thin wires is to strip back twice as much insulation as required, and then double the wire back on itself to increase its diameter and provide a snug fit in more commonly available crimp ­sizes. Waterproof shrink ­tubing, Liquid Electrical Tape or heat-shrink crimps should be used in any case. 

Read Next: How to Create Proper Terminal Crimps

Terminal Block

A third way to make wire connections is by using a terminal block. A terminal block is a collection of screw terminals, tied in pairs, and mounted on stiff plastic. Connect one wire to one side and connect the other wire to the mating side, and the circuit is complete. Each wire connects to the terminal block using crimp-on ring terminals. Size the ring terminal for the wire gauge, and also choose the ring terminal in a size that makes a snug fit on the screws of the terminal block. Do not use fork terminals, which can pull out. The terminal block’s screws go through the ring, ensuring a strong, tight connection. A terminal block can be fussy to use, and might not be the best ­connection in wet ­spaces. ­However, a terminal block makes it easy to see the wires and ­connections for ­maintenance and ­troubleshooting when ­required. 

Good Tools Matter

If you choose to solder, make sure you have your technique down pat. And practice. I also recommend using name-brand 63/37 rosin core solder because it melts and solidifies in a narrow temperature range, almost immediately, helping to eliminate a bad joint. Solder that ­solidifies too slowly is prone to a bad joint should any movement ­occur while you work. And on a boat, you will not be working on a stable bench. As for crimpers, make sure it has the right die sizes for the types of crimps you need. Also, select a ratcheting model. ­Basically, avoid the $10 ­discount-bin special.

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