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  • Writer's pictureAndrew Lambert

Sacrificing Metal: Choosing the Right Anode for Your Boat

Updated: Nov 8, 2023

The Mobile Mariner | Jensen Beach | Florida | Anodes | Tech Tips

As a boat owner, you know that choosing the right anode is important.

If you find yourself walking around a boat service yard, you may hear one tech shout to another that they "need a zinc." As a boat owner, the term shouldn't surprise you. If you're unfamiliar with the term, many thoughts may come to mind as you wonder what they're talking about.

Lucky for you, this article will cover all that.

What Is a Zinc?

Officially known as sacrificial anodes, Zincs (made from actual zinc) are the metal attached to various parts of the boat for protection. This is why choosing the right anode for the job is very important. They are used to counteract the corrosion that submerged metals would in-turn face. The most common places to find zinc are on your propeller (shafts), hull bottom, and sterndrive.

Anodes Cannot Be Mounted Anywhere

Zinc anodes need to be placed against the metal it's going to be protecting as well as providing electrical contact. This is because salt water is conductive and when you place different kinds of metal in the water, you create an electric current that deteriorates them. Various parts of your boat need sacrificial anodes. Should you choose a "hanging anode" you will need to have a wire to connect your anode to the other metal it is protecting.

Not Always a Zinc Anode

While they will almost always be referred to as a "zinc," the sacrificial anodes also come in aluminum and magnesium, depending on what metal you need.

What Kind of Zinc Anode Do I Need?

Choosing the right anode is important. The zinc you need may depend on the zinc anode you currently have. Is your zinc new? Is it halfway gone? Are you changing a part out? Are you having engine work done? Do you need your bottom painted? Besides your timeframe and the environment, these factors all play a role when you need to choose a new zinc. Knowing what zinc you will need also helps when you go to have your boat serviced.

The Mobile Mariner | Jensen Beach | Florida | Zinc Anode | Tech Tips

Shaft Anodes:

Shaft anodes are collared and they wrap around your prop shaft. Bolts are used to hold them in place, and they are typically placed at the rear of the prop.

Rudder/Trim Tab Anodes:

Your rudder/trim tab anodes come in various shapes. Your most commonly used zincs for your rudder are disc-shaped, and they connect with a stainless steel nut. Your Bennet Trim Tabs, along with Ferretti trim tabs, have their own specific zincs.

Hull Anodes

Hull anodes can be welded on, bonded with wire, or bolted on. These typically come in plates but can also be found in tear-drop shapes.

Engine Anodes

Engine anodes are particular to the engine they go in. They are typically "pencil-shaped," located under a brass plug on the exchanger, and they have NPT thread. The make and model of your engine determine which zinc(s) you will need.

You are not limited to the only zincs mentioned above. There are multiple kinds of zincs your boat may (or may not) need.

Other zincs include:

Propeller Anodes

Sterndrive Anodes

Outboard Anodes

Bow Thruster Anodes

Saildrive Anodes

Keel Cooler Anodes

Hanging Anodes

Maintaining your zincs is another part of boat service, and knowing which zinc you will need is key. The Mobile Mariner can help you figure out your zinc (and other boat maintenance) needs.

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