Your Marine Cable Buying Guide

Nothing will test the limits of an electrical circuit quite like a boat. In optimal conditions, the terminals and cables in a boat’s connection should hold up to the constant vibration and salty atmosphere in its environment. During the worst of times, on the other hand, a boat’s electrical cables are at times submerged in bilge water, cooked at high temperatures or dripping with the engine’s oil.

There is no sense in installing the highest quality electronics on your boat and yet paying little attention to the cables used to connect them. Marine cable suppliers are your go-to option for the purchase of cables that will support the operation of the electronics on the boats you are building and the harsh environment of their operation.

Some engineers might assume that residential cables can also work, but these only cause deadly boating electrical issues. The following are some variables that should guide your choice of cables for your boat.


This is your cable’s current carrying capacity and denotes how many amps of electrical current can safely run through it. The ideal ampacity for your cable is determined by the device you are connecting it to, so this is easy to handle.

The amperage and width of wire generally go hand in hand. As such, a cable with high amperage is usually thick to minimise the risk of unacceptable voltage losses. But you should also leave room for extra current since a device might draw more current than is indicated because of an extra load or low voltage.

Environmental Temperature

This variable will influence the amount of current your cable can safely conduct. Consider you are using a marine cable in your boat’s engine room where temperatures are generally about 500 degrees Celsius.

Here, an average #6 AWG cable will only safely carry 46.4 amps compared to the 80 amps it will carry outside the engine room. The maximum current rating of cables is generally 15% less than indicated in boat spaces, which are about 200 degrees Celsius hotter than other areas.

Cable Bundling

navigation officer driving a ship

Marine cables are bundled to generate a cumulative heat amount and minimise their heat dissipation. Therefore, you should make sure that you account for this when buying your cables to avoid surpassing your needed maximum amperage.

If, for instance, you pick three bundled cables, reduce your required maximum amperage by 30%. With four to six bundled cables, reduce it by 40% and for seven to 24 bundled cables, reduce the amperage by 50%.

Voltage Drop

Each cable length has a set internal resistance level such that a certain energy amount is lost when turned to heat. If you opt for long cable runs, you should expect a high voltage drop as more energy is converted to heat. To avert this, opt for cables with low internal resistance. These are generally those with large diameters.

Picking the right cable for your boat’s electrical connections is no easy feat. Without the proper choice of the above variables, your cable will not last and might damage your boat’s electrical equipment from frequent short circuits. This will paint your company in the worst light and lead to a loss of business.

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