Can I use “regular wire” for my boat?
The answer to this common question is a qualified “yes,” if the wire is SAE (Society of Automotive Engineering) J378, J1127 or J1128. These wires are designed for “surface vehicles,” not for the special requirements of the marine industry, but meet the minimum standards for boats in limited circumstances.
Even if tinned copper, they should not be run in bilge spaces or other areas subject to moisture from spray or dripping. They should not be run in engines spaces, unless marked “oil resistant” and “75°C”. They should not be used in applications where subjected to vibration or frequent flexing and must never be used for 110 volt applications. For safety, use only wire that is marked with size and type.
Most importantly, SAE wire is up to 12 percent smaller than AWG Boat Cable which means that, in many applications, larger gauge wire must be used to stay within the voltage drop limits recommended by experts (see our West Advisor on Marine Wire Size and Ampacity). The wire charts found in Chapman’s Piloting and other publications are all for “AWG” wire like that made by our supplier, Ancor, not SAE type wire. In general, wiring on boats should be of the stranded type, not solid copper wire used in household applications, which does not withstand the vibration found onboard a boat.
Primary Wire Color Standards
The ABYC (American Boat and Yacht Council) recommends the following color standards for marine wiring of boat engines and accessories. Select wire color from the list below.
Making secure connections
Which is better, soldering or crimping terminals? Most wire problems happen at the connections, and the experts are mostly in agreement on this one. Connections should be mechanically connected, not just soldered. Per ABYC Standards & Technical Information Reports for Small Craft (E-188.8.131.52), “Solder shall not be the sole means of mechanical connection in any circuit”. Further, crimping provides a solid mechanical connection resistant to “cold joints” breaking under fatigue, and removes strain.
Waterproof spade connector.
Vinyl butt connectors.
Stainless cushion clamp.
NEVER twist wires together, connect wires together with household “wire nuts” or wrap a bare wire around a terminal screw to connect wires together. A proper crimp connection is essential for safety and current-carrying ability. Use a good quality crimper, like our West Marine Ratcheting Crimper, Model 8956906.
Put the terminal in the correct die in the crimper, insert the wire into the terminal, and squeeze until the jaws grip the terminal lightly and hold it in place without distortion. Check the finished crimp to see that the wire is firmly in place by giving it a good solid tug. Finish the job with heat-activated, adhesive-lined heat shrink tubing.
Terminals are color-coded to fit different gauges of wire: red for 22- to 18-gauge wire, blue for 16- to 14-gauge wire and yellow for 12- to 10-gauge wire. Select the proper terminal for your job. Below are some examples and their uses:
For permanent secure termination. Ring terminals can’t pull off, and for that reason are preferred over spade terminals.
Flanged spade terminals
For permanent termination when terminal screw is captive. ABYC recommends: “Terminal connectors shall be of the ring or captive spade types.” E-184.108.40.206
For connecting two wire leads of the same size. Step-down butt connectors join a pair of conductors to a third, all of the same size, or join two conductors of different sizes.
Disconnects and snap plugs
Quick-disconnect connectors, also called “disconnects,” are common as a quick connect/disconnect solution for electronic and digital equipment. The ABYC recommends their use for circuits of not more than 20 amps, with a voltage drop of less than 50 mV with a 20-amp current, and as long as they stay connected with up to a six-pound pull.
Wire support standard
The ABYC recommends that wires be supported every 18" along their path. This is to prevent repeated flexing, due to the boat’s motion through the water, or the engine’s vibration. Cable ties and clamps are approved methods of securing wires.;
Ancor heat shrink tubing specs
ABYC recommends: “The shanks of terminals shall be protected against accidental shorting by the use of insulation barriers or sleeves, except for those used in grounding systems.” E-220.127.116.11. Heat shrink tubing, lined with adhesive, creates water, oil and acid-resistant seal, preventing corrosion at the electrical connection. It shrinks to one-third of its original size (a 3:1 shrink ratio).
||Wire Range (AWG)
||16 - 10
||12 - 8
||8 - 4
||6 - 2/0
Wire gauge wizard
Blue Sea Systems’ DC Circuit Wizard performs calculations and recommends appropriate circuit protection options—fuse or circuit breaker—and wire size for just about all DC applications. DC Circuit Wizard
Design rule: a change in six gauge numbers is a four times increase in wire size. When the wire size goes down two numbers (from 14 to 12), the amount of copper in the wire goes up by 59 percent.