Cathodic Corrosion

[IanD]

I have recently experienced some fairly extensive corrosion to my Mercruiser B3 outdrive at age two and half years. The boat is berthed in the water at Swanwick Marina. The outdrive has been serviced and annodes replaced by a Mercruiser agent from new. The only thing we have discovered so far is that the Mercathode does not appear to be working. I would be interested to here from anyone who may have experienced simmilar problems and who may know of a good electronic expert for advice!

[JIY]

Originally Posted by IanD

I have recently experienced some fairly extensive corrosion to my Mercruiser B3 outdrive at age two and half years. The boat is berthed in the water at Swanwick Marina. The outdrive has been serviced and annodes replaced by a Mercruiser agent from new. The only thing we have discovered so far is that the Mercathode does not appear to be working. I would be interested to here from anyone who may have experienced simmilar problems and who may know of a good electronic expert for advice!

I experienced exactly the same problem on the Mercruiser Bravo 3 installed on my last boat. The Mercathode "connector plate" on the leg had a small crack in it that the servicing mechanic did not spot and I was going through a set of anodes every 100 hours! When the leg failed and was replaced, the (new) mechanic immediately spotted the problem, replaced the Mercathode, and the wear on the anodes thereafter was minimal. Clearly the Mercathode makes a huge difference to the speed of corrosion, particularly in the chemical saturated waters of a Marina.

[IanD]

Has anyone seen or heard of a Mercruiser Service Bulletin recomending that two Mercathodes be fitted in series when used with B3 outdrive? (reference was made to it on a Forum in the US but I cannot find it).