It will be onerous to overstate the significance of sustaining the anodes in your boat. When an anode is lacking or largely wasted away, the steel element it was put in to guard begins to dissolve — assured.
How a lot zinc
Usually, nevertheless, you aren’t confronted with figuring out the suitable anode measurement (aside from diameter for a zinc shaft collar). Moderately, you’re merely changing depleted zincs with new ones of the identical measurement. Examine all zincs at the very least yearly and change all which can be half depleted.
Electrical contact is important
The place the zinc is mounted on to the protected steel — bolted to the aspect of a steel rudder, for instance — it’s important to ensure the floor below the zinc is naked and brilliant earlier than the anode is put in. That is to make sure good electrical contact.
No paint
Sacrificial anodes can’t carry out their perform except they’re uncovered. Placing paint on an anode smothers it, rendering it ineffective. By no means coat anodes with backside paint, or the rest.
Props and rudders
Steel rudders and struts are most simply protected with zinc disks bolted on to the steel. Rudder zincs have a shallow dome form to streamline them and reduce their drag and turbulence.
Hull plates
Zinc hull plates are additionally fitted to steel boats to guard the hull. Evidently, such anodes should be fastidiously monitored.
Outdrives
Usually, these embody at a minimal a sacrificial trim tab (meant to warn you of depletion by a change in steering), a zinc plate or two hooked up to the gear case or the anti-ventilation plate, and maybe anodes within the exhaust cavity and within the cooling-water jacket. The combo of immersed metals makes stern drives and outboards notably susceptible to galvanic corrosion. It’s a good suggestion to seek the advice of your engine handbook to make certain the place each anode is positioned.
Zinc pencils
Some engines have an identical zinc pencil contained in the cooling-water jacket to guard dissimilar metals within the engine. To fight this, many warmth exchangers are fitted with a zinc “pencil” anode. Decide in case your engine and warmth exchanger are fitted with inner anodes, and if that’s the case, test them at the very least yearly.