|Mercruiser Sterndrive Information|
Look up your Anodes and Anode Kits HERE.
Zinc Anodes are designed to protect your drive from Galvanic Corrosion. Galvanic Corrosion is a destructive force in the water surrounding your boat. Galvanic Corrosion is also known as Electrolysis. The corrosion will usually eat away at softer metals such as your aluminum housings although in extreme cases it can destroy harder metals such as stainless props and shafts.
Anodes used to be primarily made of zinc however newer anodes are constructed of aluminum, magnesium and other special alloys.
Every boat and every mooring slip will have different levels of corrosion. Your slip may have very low levels of galvanic corrosion one day and extreme levels the next.
Although anodes provide a certain level of protection, it might not be enough. For extra protection you should have a Mercathode system installed.
You must keep your anodes in good condition. It is not uncommon for owners to have to replace their anodes every month or two. Only a few days of no protection can cause thousands of dollars in corrosion damage.
Read your Engine Owners Manual for tips and suggestions relating to your anode system(s). Your manual has a wealth of information that will prove to be very helpful. Corrosion protection is YOUR responsibility and unless you take proper care, extreme damage can result. Galvanic Corrosion damage is NOT covered under warranty.
The best protection is to keep your boat out of the water. If you must keep your boat in the water be prepared to spend thousands of dollars from time to time to repair and maintain the vessel.
Bottom Paint (anti-fouling paint) does NOT protect against galvanic corrosion. In some cases it will actually accelerate the damage process. NEVER paint a drive with regular copper based bottom paint. The paint itself will eat the housings. Always use a tin based paint which has been especially formulated to coat aluminum. Most good sterndrive paints contain tri-butyl tin II which works great.
Your anodes will not protect the drive if you have a break in the Bonding System. Mercruiser ships the engines, gimbals and drives with a Continuity Circuit. This is basically a "daisy chain" of wires, cables, straps and washers which daisy chains the engine to the inner transom plate to the gimbal to the bell housing to the drive and trim cylinders. If the chain is broken in any one place it will lower the units level of protection. Make sure whenever a tech services your engine, gimbal or drive that he confirms the bonding system's integrity.
My Drive Already Has Pitting and Damage
Once an aluminum housing has been damaged by electrolysis it can not be painted or repaired. The electrolysis changes the molecular structure of the aluminum. It makes it impossible for primers and paints to adhere to the damaged areas. Replacement of the housing or component is recommended.
NOTE: Before replacing any damaged components you should isolate what the problem is and take action to prevent further damage. You don't want the corrosion to eat away at your new components!
Boats can explode. Moving parts can rip your off your fingers. Hot exhaust can burn you to the bone and props can slice you up. One spark near a battery can cause an explosion. You can never be too careful. Remove the battery from the boat before working with fuel. Always disconnect the batteries negative terminal first. Clean up any spilt fuel and let ALL of the fumes dissipate before installing the battery and starting the motor. Pulleys and Belts can grab your clothes and hair. Don't wear loose clothing and keep your hair up under a hat. Always wear safety glasses. Be smart.
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