Corrosion — it is the bane of many a boat owner. Let’s face it, metal surfaces and salt air, and seawater just do not get along very well! But, there are ways to protect your vessel from corrosion as much as possible, and minimize the damage.

Of course, the underside metal parts and surfaces of your yacht are those most subject to the corrosive action of water. Corrosion damage can be as minor as a somewhat pitted prop, to as disastrous as a completely rotted drive. However, following a few simple tips can prevent, or at least minimize, most types of corrosion.

What boat owners need to understand about corrosion is it is a chemical/electrical process. It does not happen suddenly, but takes time as your yachts metals react in various ways with the water and environment around them. Once you better understand the process of corrosion, you will see how easy it is to interrupt or prevent those destructive processes from taking place.

The Types of Marine Corrosion

There are several types of corrosion, or corrosive processes that can take place on your boat.

Galvanic corrosion – Galvanic corrosion is probably the most common form of corrosion. It occurs naturally whenever two different metals, such as steel and bronze, are in contact with each other and then are subjected to a common electrolyte, such as seawater or salty sea-air.  The chemical properties of the two metals react with the electrolyte to produce an electrical current.  The chemically produced electrical current will cause the “less-noble” (more likely to be damaged) metal to corrode, or “sacrifice” itself, while protecting the “more-noble” (less likely to be damaged) metal from corrosion. But, galvanic corrosion can be easily be prevented through the use of sacrificial anodes, called “cathodic protection.” The anode “takes one for the team” and protects your marine metals. However, the anodes must be closely monitored as the can wear out, and fail to produce sufficient charge after a while. Galvanic corrosion is the easy to avoid with a properly installed cathodic protection system.

The Red Arrow Points to a Sacrificial Anode Disk, installed to protect the prop

The Red Arrow Points to a Sacrificial Anode Disk, installed to protect the prop

Stray-current corrosion – Unlike galvanic corrosion which can be caused by any disparate metals in close proximity, stray current corrosion is caused by some source of external voltage, usually a DC power source. Preventing stray-current corrosion is best accomplished by checking your 12-volt DC electrical system for any loose wires or poor or inadequate connections, especially in bilge areas, which can be full of seawater that acts as an electrolyte.

An Alternator Fault Caused Stray Current Corrosion to This Shaft

An Alternator Fault Caused Stray Current Corrosion to This Shaft

Crevice or oxygen-depletion corrosion – Oxygen-depletion attack, AKA crevice corrosion, occurs in cracks, crevices or other hidden locations. It often takes boat owners unaware because it mostly attacks stainless steel, which many yacht owners mistakenly believe is impervious to corrosion. Not all grades of stainless are immune to corrosion, and only certain grades have been sufficiently modified to reduce susceptibility to crevice corrosion, and they should be used for any stainless steel parts of your boat that will remain submerged for any significant length of time.



Prevention Is Key

As always, “preventive medicine,” is the key to saving you money on costly repairs, and minimizing corrosion damage to your boat. From what we have described here, it may seem that preventing corrosion damage to your yacht’s metals may seem a complicated task, but enacting a pro-active maintenance plan is actual relatively straightforward, and can all be part of your routine maintenance when you become a member of our On Demand yacht management solution, or one of our charter income programs. Virtually all corrosion issues can be prevented before they occur through proper design, strategic cathodic protection, and a program of monitoring and maintenance

That is where having your yacht in our On Demand service program, or part of our Charter Fleet can help. In either scenario, your boat will be under a strict program of routine maintenance, and you will always be able to monitor your boat’s condition, and any repairs being done, by logging into your secure On Demand dashboard!




Operating a motor yacht can be costly. You can reduce your expenses, and avoid costly repairs by keeping her well maintained. On Demand yachting from FYM can help. If you would like to learn more, or if you have any questions or comments about this blog post, do not hesitate to contact our Yacht Management specialists, or call us at (954) 900-9968.