ANSWER:
The good news is that corrosion can be prevented! Marine corrosion is a fact of boating life, but you can protect your investment with diligence & proper maintenance. As the boat owner, YOU are the most important key to effective corrosion protection. Here are some things you should know:
All MerCruiser sterndrives come standard with aluminum sacrificial anodes a three-year warranty against certain types of corrosion (see your Operation, Maintenance and Warranty manual for more details). SeaCore models receive a four-year limited corrosion warranty.
Bravo sterndrives are also equipped with a MerCathode, optional on Alphas.
Magnesium anodes are suggested for fresh water use ONLY & can be purchased from your authorized dealer.
Anodes & sterndrives should be inspected on a regular basis for signs of corrosion. Do not paint anodes.
Not all anodes are created equal. Don't sacrifice your sterndrive's protection with the use of poor-quality aftermarket anodes.
The MerCathode should be tested annually by an authorized dealer for proper operation. Do not paint or power-wash the MerCathode.
Your particular boating environment may require that you install additional anodes or other protective devices.
Whenever you add stainless steel accessories (for example props or trim tabs) it's a good idea to have the corrosion resistance checked to make sure it is still adequate
If you use shore power, you should have an approved galvanic isolator installed to protect against stray current corrosion (electrolysis) from your dock, from your boat's accessories or from other nearby boats.
Corrosion can be caused by many factors, such as the wrong type or improper application of anti-fouling paint, marine growth, stray electrical current (electrolysis), an improperly wired or damaged MerCathode, etc. These types of conditions are not covered by the warranty.
Before you notice signs of corrosion, contact your authorized MerCruiser dealer to arrange for an in-the-water hull potential test where the boat is primarily moored. This test will help the dealer determine if your protection level is adequate.
See your Operation, Maintenance & Warranty manual for more information.
A very informative pamphlet on corrosion "Marine Corrosion Protection Guide" (#90-88181301) is available. Please call 1-800-MERCURY to request one.