Prop blade lost through corrosion of retention pin
Alan Pollard, Director Vecta Marine, UK distributor of the Kiwiprop feathering propeller, is anxious to reassure customers who read the letter, “Check your Kiwiprop”, published in the September issue of Yachting Monthly.
He replies: ‘I can understand Ralph Seeley’s disappointment that he lost a blade through corrosion of the blade retention pin. I can also understand the difficulty for Kiwiprops, in New Zealand, to diagnose the precise cause from thousands of miles away.
‘Mr Seeley’s boat is aluminium and such boats and their fittings are at much higher risk from electrolytic corrosion. They are prone to stray electrical currents, which is why most Ovni’s have a meter to monitor any current leakage from the boat. Problems from adjacent boats in marinas can also be an issue and when mains shore supply is involved, corrosion can be fast and serious. I suggest all aluminium boats should be fitted with an isolation transformer to isolate the boat’s AC circuit from the shore side.
‘With over 3,000 Kiwiprops in service worldwide there are many boats sailing the oceans trouble-free with our older bronze boss models and nickel silver blade pins. Now we have a stainless steel boss and titanium pins, with the pins designed not only for the best possible resistance to corrosion but also for strength and lighter rotating weight. Corrosion is an increasing problem for yachts and when a small underwater component shows any sign, our experience is that it is usually a sign of potentially bigger problems developing elsewhere.
‘I agree that our Kiwiprops should be checked at every lift-out. It’s sensible to check all underwater components regularly.’