Galvanic Corrosion
In general, the term “corrosion” refers to the unwanted loss of metal from the hull and /or under-water metal fittings of the vessel. There are three main types of corrosion – mechanical, electrical and environmental corrosion. Under the electrical category, there are three common subcategories: galvanic corrosion, stray current corrosion, and crevice corrosion. Galvanic corrosion occurs when two dissimilar metals are connected together electrically in the presence of a conductive electrolyte. Atoms in the less noble metal give up their electrons to the more noble metal and are released to flow (corrode) into the electrolyte in the form of positively charged ion
Due to either Galvanic or stray current corrosion these photos show what could be happening to your under water fittings at this present time totally unaware by anyone.
Galvanic or stray current depending on the severity can have an alarming effect and can cause the above damage in as little as three months.
Most owners think that because they have renewed the Anodes they are safe.
Unfortunately most owners and boat yards just replace Anodes with the same as before, this may be insufficient or even over protecting which could also have a detrimental effect.
This maybe ok until the situation changes !!
The problem is when your boat is moored and connected to the marina shore power the conditions can completely change at any time.
Basically your boat is now connected to every boat in the marina plus the dockside and pilings which all have different effects at different times. Some of the boats that are in the marina may have electrical faults due to poor wiring, moisture issues or some with more noble fittings, the pilings and dockside may also have earth leakage faults or contain more noble minerals.
Its not just underwater fittings and machinery that can be affected by this situation, any internal fittings that are in contact with sea water for example, engine components and cooling system, Head pipework, water makers, Bilge pumps and deck washers etc.
Any one of these fittings can be corroding totally unaware by the owner and only apparent when it is too late and your safety could depend on them.
Corrosion of fittings
This Skin fitting along with its multi combination of metals and its poor earth bonding is a perfect example and a disaster waiting to happen, with the even greater potential of sinking the boat.
The above photo shows skin fittings after the affect of corrosion again leading to a potentially life threatening situation should you be out at sea.
This Elbow fitting connected to a bilge pump system corroding away unaware by the owner again potentially leading to a serious situation when it fails.
Galvanic Corrosion / Stray Current Corrosion
HOW WE CAN HELP
The only one way to know exactly what is happening with your boat and prevent costly and time consuming repairs or serious safety issues whilst at sea, is to carry out a full galvanic Corrosion Survey, on board at the mooring regularly.
We can visit your boat at its berth to carry out a full Galvanic Corrosion Survey for underwater metal work along with internal fittings and all Hull skin fittings.
Being a qualified electrical engineer we will carry out checks for any Galvanic or stray current readings that are above the tolerated limits for each of the metals that could be affecting your boat and damaging fittings.
All readings are logged for future reference.
Having studied IIMS marine surveying materials and corrosion coarse we are happy to give you our advice of any incorrect materials used and related issues such as earth bonding etc.and to recommend remedies.
We can also carry out an underwater ROV CCTV Surveys/inspections to assist with the above to check fittings, hull and Anodes etc.
The best way to avoid an unnecessary and unexpected large repair cost is to continue with a regular ongoing monitoring programme to make sure your boat is always protected.
Marine Elecrician
Full Electrical Survey
BATTERIES / ANODE INSPECTION / GALVANIC CORROSION / CHARGING CIRCUITS