How to Identify the Correct Anode: Part Number, Shape and Fixings

Buying the wrong anode is easy if you rely on guesswork. The good news is that correct anode identification is straightforward when you use a repeatable process.

This guide shows you how to identify the right anode using the three best signals: OEM part number, shape, and fixings.

Step 1: Search by OEM part number (best method)

If you have the OEM number from the old anode, your manual, or parts diagram, use it. OEM part numbers are the fastest path to an exact match.

Tip: Numbers are often stamped lightly or may be on packaging if the old one is gone.

Step 2: Match the shape (second best method)

Anode shapes are designed for specific locations:

• Trim tabs, cavitation plates, ring anodes, collar anodes, plates, blocks

Take note of:

• Overall shape and profile

• Any curves or recesses that match a drive housing

• Whether it is a ring/collar style

Step 3: Confirm fixings (the deal breaker)

Fixings matter more than people think.

• Bolt spacing

• Hole diameter

• Countersunk vs flat holes

• Clamp bolt style for shaft collars

If the fixings do not match, the anode will not fit properly, even if it looks similar.

Step 4: Measure (quickly but correctly)

You do not need engineering precision, just accurate enough to avoid near-misses:

• Length and width

• Thickness

• Hole spacing centre-to-centre

• Shaft diameter for collar anodes

Step 5: Confirm material for your water type

Once fitment is correct, ensure the anode material suits your environment:

• Saltwater: zinc or aluminium

• Brackish: aluminium

• Freshwater: magnesium

If you are unsure

The fastest solution is often to send:

• Engine/drive make and model

• A photo of the old anode

• The measurements and fixing layout

That usually allows a confident match without guessing.

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