Running Wires In Aluminum Boats: A Step-By-Step Guide

Wiring an aluminium boat is a complex task and it is recommended to hire a professional marine electrician to do it for you. However, if you are planning to wire your aluminium boat for lights, accessory plugs, and a trolling motor, it is important to note that you should not ground any wires to the boat. Instead, use a heavy-gauge ground wire from the battery ground (-) and connect your minor grounds for lights and accessories to this wire. It is also important to use marine-grade primary wire and to ensure proper circuit protection to prevent fires.

Do not connect grounds to the aluminium boat body

When wiring up an aluminium boat, it is important to never connect grounds to the aluminium boat body. Always connect the ground to the negative battery post. Grounding to the boat body will cause electrolysis and, over time, your boat will develop pinhole punctures all over it.

The reason for this is that when the engine chassis is grounded to the hull, an electrical current can run from the hull through the seawater to the bronze and steel in the engine's saltwater cooling system and back to the hull through the connection. This setup forms a battery, and the least noble metal—in this case, aluminium—will be eroded.

If you connect the ground to the boat body, it also increases the risk of crossing the hot side of the battery with the boat, which is now the ground. This can cause blown electronics, ignited fuel fumes, or even melt metal objects like rings.

To avoid these issues, run a large-gauge ground wire from the battery up to the area where you are installing electronics, and connect several grounds to it if needed. This will ensure that the ground is properly connected without causing any damage to the aluminium boat body.

Run a large-gauge ground wire from the battery

Running wires on an aluminium boat can be a complex task. It is important to understand the basics of boat electrical systems before attempting any wiring work.

In this case, we are focusing on running a large-gauge ground wire from the battery. This is a critical component of the electrical system, ensuring that the boat's electrical devices have a direct path to the negative terminal of the battery.

Firstly, it is essential to determine the correct wire gauge for the ground wire. The gauge should be based on the amperage of the electrical devices you will be using. For example, a 14-gauge wire can handle up to 15 amps, while an 8-gauge wire can handle up to 50 amps. It is crucial to choose a wire gauge that can safely handle the amperage of your devices to prevent overheating and potential fires.

Next, you will need to run the large-gauge ground wire from the negative terminal of the battery to the area where you plan to install your electrical devices. This may be a long wiring run, depending on the layout of your boat. Ensure that the wire is securely fastened and does not come into contact with any sharp edges or moving parts.

Once you have reached the installation area, you can connect multiple grounds to the large-gauge wire if needed. This centralised ground point ensures that each device has a reliable connection to the battery's negative terminal.

It is important to note that the aluminium boat body should not be used as a common ground. Always connect the ground wire directly to the negative battery post. Using the boat body as a ground can lead to issues such as electrolisis and increased risk of crossing the hot side of the battery, potentially causing blown electronics or even igniting fuel fumes.

By following these steps and taking the necessary precautions, you can safely and effectively run a large-gauge ground wire from the battery in your aluminium boat.

Run wires under the floor or along the gunwale

When it comes to running wires in an aluminium boat, there are a few options. One is to run them along the gunwale, and the other is to run them under the floor. Here are some things to consider when making your decision:

Running Wires Along the Gunwale:

• This option may be more convenient if you need to make modifications to your boat in the future, such as adding rod storage or other accessories.
• It is generally easier to access wires that are run along the gunwale, which makes it simpler to fix any issues that may arise.
• To protect the wires, you can use a conduit or tubing, such as PVC piping. This will also make it easier to replace or add new wires in the future.
• When using a conduit, avoid sharp bends and allow enough room for multiple wires. This will ensure that you can easily pull new wires through without damaging the existing ones.
• You can use self-adhesive clips or cable ties to secure the wires along the gunwale.

Running Wires Under the Floor:

• This option provides a cleaner installation, as the wires are hidden underneath the floor.
• If you decide to run wires under the floor, it is recommended to use a conduit to protect the wires.
• When running wires under the floor, make sure not to block the drainage path to the bilge.
• Keep the transducer cable as far away from power leads as possible, and consider running it in a separate conduit.
• If you use tinned marine wire and avoid connections below deck, water exposure will not be an issue for your wiring.

In summary, both options have their advantages. Running wires along the gunwale provides easier access for future modifications and repairs, while running them under the floor results in a neater installation. Whichever option you choose, using a conduit and avoiding sharp bends will make it easier to pull new wires through in the future.

Use marine-grade primary wire

When wiring up an aluminium boat, it is important to use marine-grade primary wire. Marine-grade wire has a higher copper content than SAE-grade automotive wire, which is better for boats as it reduces electrical resistance and enables the delivery of more amperage for a given gauge size. Marine-grade wire also has better resistance to chafe and heat.

Marine-grade wire is designated AWG (American Wire Gauge) and is measured in AWG. It is important to use the correct wire gauge when wiring a boat to ensure that there is sufficient "ampacity" to power all the electrical appliances. The wire gauge should be chosen based on three factors: the current draw of the device, the total length of the run, and the allowable voltage drop.

Marine-grade wire is also tinned, which increases corrosion resistance. Tinning also makes it easier to solder connections if needed. While untinned wire can be used in boats, tinned wire is better able to resist corrosion at terminals and along the wire.

Marine-grade wire can be purchased from online marine stores or specialist websites such as TinnedMarineWire.com. It is important to choose the correct type of wire for your boat to ensure the safety and performance of your electrical system.

Use stranded wire

When running wires in an aluminium boat, it is important to use stranded wire. Stranded wire, also known as high-strand count wire, is a flexible wire that is less likely to break out of crimps or connectors. This type of wire is ideal for boats as it can withstand the constant vibration and movement of the boat without breaking. Stranded wire is also easier to run through conduit, as it can be fed through more easily and is less likely to get caught or snagged.

Stranded wire is also preferable due to its high strand count, which provides greater flexibility. This flexibility is essential in boat wiring, as it allows for easier routing of the wire through tight spaces and around obstacles. The flexibility of stranded wire also reduces the risk of chafing and other damage caused by vibration.

Another advantage of using stranded wire is the ability to solder connections. Soldering creates strong, reliable connections that can withstand the harsh conditions of a marine environment. It is important to use the proper type of solder and flux when soldering stranded wire to ensure a secure connection. Additionally, coating the soldered joint with liquid electrical tape or heat shrink tubing can provide extra protection and insulation.

When running wires in an aluminium boat, it is crucial to use the correct type of wire to ensure safety and reliability. By using stranded wire, you can be confident in the durability and longevity of your boat's electrical system.

Frequently asked questions