Anodes

Anodes are an easy and relatively cheap method of protecting your expensive underwater metal marine gear. We all know that water and certain metals don’t mix so to prevent unnecessary corrosion and electrolysis, anodes are fitted to the vulnerable areas. On steel boats this is the hull, rudder and props. For GRP cruisers such as Naughty-Cal these are the stern drive or outboard motor and trim tabs.

There are three main materials for bolt on anodes that are widely available:

Magnesium – For fresh water use
Zinc – For salt water use
Aluminium – For brackish water use

Up until now we have used Magnesium, fresh water anodes on Naughty-Cal. The odd forays into the brackish waters of the lower Trent, lower Ouse and Upper Humber have caused the anodes little harm with no signs of excessive wear. However since we have started using the boat more in coastal, salt water areas the anodes are starting to wear at quite an alarming rate. The anodes we replaced in April are now ready for changing again after just six months of use.

The time has come to consider changing to Aluminium anodes. These will still work just as well in fresh water, allegedly lasting up to six times as long as magnesium anodes in similar conditions, but will also stand up to salt water immersion much better than the existing magnesium versions. According to the manufacturers they will last up to three times longer than zinc anodes in salt water.
Aluminium seems to be a win, win situation for us, so what the cost of this upgrade? Surprisingly, for once, this seems to be a cost cutting exercise as well. Aluminium anodes are actually considerably cheaper than their magnesium counterparts, with a cost saving amounting to roughly a third. Bonus.