The Essential Volvo Penta Anode Fitting Guide

We’ve collated some top tips for anode fitting, maintenance and identification of anodes specifically for Volvo Penta saildrives and engines. This manufacturer is one of the most popular brands and types of kit fitted on boats. Due to the range of designs suiting different vessel requirements, it also means there are are quite a few anode types to sift through. We often get asked about general anode fitting and maintenance, which anodes are required, where to fit them, how to match the original part numbers. This guide will help you cover off all of the questions above, and if it’s not covered in this article, it’ll be covered in another one within our Knowledge Base. We’ve tried to include as much as possible in this piece including photos of the different types, part numbers, links to the anodes and diagrams showing where to fit them whenever possible. What more could you need? A cup of tea perhaps?

Top Tips For Fitting and Maintaining Your Anodes

• Start by ensuring you get the correct anode for the job! Enter the Volvo original part number into our search facility to find the correct part. A few original part numbers have changed over time so there maybe a couple of different numbers for the same part. If you’re not sure, you can often find the correct part by using our guide to the different saildrive types, engines and propellers, and by entering the model into the search box.
• Clean the area where the anode is to be fitted ensuring there is no oil, debris or paint.
• Ensure the surface of the anode has a good electrical contact where it is positioned, both on the metal surface and through the bolts.
• Start to consider replacing the anode when it has corroded by 30% and definitely replace it when it has reached 50% as there will not be enough surface area or capacity in the anode mass to protect effectively.
• Never paint the anode or the area underneath, but do repair or repaint any area that was factory painted to ensure the anode is not being required to protect additional areas.
• Only use premium, ideally US MIL Spec grade anodes to protect your investment; never use home made or sub-standard alloys. For new vessels, check your warranty will still be valid using aftermarket anodes, you may not be covered regardless of whether they are exactly the same specification or not.
• Use the correct metal type for the water your vessel is in. Use aluminium or zinc for salt water, aluminium for brackish water and only use magnesium in fresh water. If you use magnesium in salty water types it will corrode very quickly and leave your vessel unprotected VERY rapidly
• Remember that the anode has only been designed by Volvo Penta to protect the part it is fitted to eg. saildrive. If you have additional metal equipment fitted below the water line then that will also require protection
• Use the same anode metal type across the whole vessel; you don’t want to create additional problems by mixing metal types. The only exception we’ve seen if on the IPS drive which has a combination of zinc and aluminium
• Anodes work by sacrificing themselves instead of the more noble metals. The whole hull set up should be tested while in water with a reference half cell to ensure that the vessel is protected on a holistic basis, not the individual component parts
• Check for stray currents in and around the boat; stray voltages and other metals in your water area will also affect the corrosion potential on your vessel. Volvo’s configuration does not require a galvanic isolator to be fitted unlike some other engine manufacturers but it is always best to check
• Lastly, inspect your kit as often as physically possible, that may mean a quick dip or with a camera. All it takes is for the boat alongside to be under-protected and you could well be left cathodically protecting their vessel and your anodes disappear