Cathodic Protection in Yachts
Cathodic Protection in Yachts
If you have two different metals physically or electrically connected and then you immerse them in seawater, they become a battery. Some current flows between the two metals and the electrons that make up that current are supplied by one of the metals giving up bits of itself-in the form of metal ions-to the seawater. This is called galvanic corrosion and can destroy underwater metals. The obvious casualty is the bronze or aluminium propeller on a stainless steel shaft.
In order to counteract galvanic corrosion you need to add a third metal into the circuit, one that gives up its electrons first. This piece of metal we call a sacrificial anode, and usually it is zinc. It cannot be emphasised enough the importance of maintaining the zinc anodes on your boat. When an anode is dead, the metal component it was installed to protect begins to die.
A professional yacht surveyor will check your yacht has cathodic protection.
Factors to bear in mind
The larger the surface area of a zinc anode the more protection, although this does depend on the metal it is protecting. Replace an anode when half gone do not nickel and dime.
Check your anodes at least annually and replace those that are half depleted.
For protection it is CRUCIAL that an anode must be in electrical contact with the metal being protected. Low-resistance, metal-to-metal contact is required so you can either by mounting the zinc directly to the metal being protected or connect the two with a wire.
Ensure that when an anode is mounted directly to the protected metal, e.g bolted to the side of a metal rudder, the surface that the anode is connected to must be bare and bright. Do not paint anodes.
What can go wrong?
Read about Skin fitting failures here
This Westerly Pageant had a nice shiny new anode but someone had removed the connection to the stern gear. The result? Dezincification of the propeller and the need for a replacement. Note the pink appearance? When sounded with a hammer the propeller did not ring like a bell, and when struck on it’s edge with a file a large piece of propeller blade came away.
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Here are some snippets of recent reviews. they can be seen in full on our testimonials page, or on the facebook and google+ links above
“Matt provided an excellent survey service when I was buying my first boat – always a nerve-wracking experience! He was very flexible with timings, arrived promptly and conducted a very thorough inspection, taking time to explain key points to me and offer general boating advice. The report came through very quickly and was comprehensive, clear and made sensible recommendations. I would fully recommend Matt. ” Nick Bournemouth, Review Jan 2016
We purchased our Dufour 36 from ‘Ancasta’ Chichester last April, and they recommended using Matt for our survey. We were travelling from Cardiff , and Matt was extremely helpful and easy to deal with. I attended for part of the survey, and he took time to talk me over the yacht andgave me a very detailed verbal description on the day. This was followed up naturally by a more detailed written report . Everything was dealt with very promptly , Matt was easy to contact throughout the process , and I would highly recommend his services .
“I was very pleased with the survey that you carried out for me,It was comprehensive and at a fair price ,done when I wanted and it was very useful to be able to discuss you findings with you” Chris Forsyth. Olympic 500C. December 2014
I had Matt survey my Rinker 232 in September 2014, he was very thorough and answered any questions I had. Overall an excellent service without fault or delay so if you are looking for a marine survey I would highly recommend Matt. Terry Goulty. Rinker 232 December 2014
“Living in Sweden I found an interesting Beneteau First 305 in the Southampton area. Searching for a surveyor I found Matt West. He made a pre-purchase condition survey to great value for me. He also taught me a lot about this boat model. Knowing the status of the boat we had a nice sailing trip home to Sweden.” Jörgen Haslum December 2014
… A really nice guy, very knowledgeable and helpful. The report was clear and easily understood and all findings were clearly put into perspective for me. Thoroughly recommended! Peter Bristow, Haywards Heath May 2014
Excellent survey at a very reasonable price and the report was received the following morning … Matt was also happy to offer further free advice on the phone several weeks later and I’m sure even years later he’d continue to do so. …. Gary from Fleet. April 2014
…Matt did a great job, supporting me from start to finish and coming up with common sense solutions to potentially tricky problems. I will certainly be instructing Matt for my future surveying needs.Paul Lovejoy, Emsworth Feb 2104
…His inch by inch and nut and bolt complete survey was broken down into easy to understand sections that graded the work to be done using a simple star grading system. ….. He gave me the confidence to make my purchase, undertake the repairs and to have a boat now which has given me many happy hours of sailing. Mark Wood Portsmouth
Our 1984 Sunseeker 25 XPS Portofino required a safety / condition report for insurance purposes. This was carried out very efficiently and without fuss. P. Crowther-Wilton, Banbury 1st January 2014
Matt West was recommended to me …. the service he provides is prompt, reliable helpful and efficient. From initial call to receiving my survey took just a week. I would have no hesitation in recommending Matt” Andrew Campbell
Sent from my iPad December 2013
The previous owner, ….. was very impressed with your level of detail and testing and has kept your details to use your services when he buys his next boat. ….. we are very happy with her and in the knowledge that she has had a very thorough and detailed survey performed on her by a very knowledgeable and professional company. Dave D. December 2013
As a foreigner, having someone local you can trust, acting as your eyes and your ears and helping you to keep you with both feet on the ground, is an investment that’s worth every penny. Joris Van Roy, Belgium December 2013
He went out of his way to be helpful and even accompanied us on the sea trial. He produced an extremely comprehensive survey report and so far 3 months on I have not found a single thing he has missed. He is an accomplished professional with an in depth knowledge of boats and has been an invaluable source of advice. I would have no hesitation in recommending him to you, you would have to go a long way to find anyone better.” Mike S. December 2013
I have used surveyors when buying boats previously and none came up to the standard of service provided by Matt. Peter V. Sea Ray 240 July 2013
A very friendly and exceptionally helpful service, I would definitely recommend them. Rosie T. 43′ Narrow boat June 2013