47ft Colin Wild Motor Launch

This client had a 47ft Colin Wild motor launch showing signs of wood electrolysis around the rudder and stern tube areas. Wood electrolysis is the breaking down of wood fibres due to the stray electrical current present in boat hulls.

This is predominantly caused by incorrect bonding of batteries and 12 volt or 240 volt systems and how they relate to the sacrificial anodes on the hull exterior. Through the 90s and 2000s, vessel owners started bonding all their underwater metals such as shafts, rudders and propellers together in a series which looked after the metal very well but was detrimental to wooden hulls.

NZ Kauri (which is a world class boat building timber) suffers badly from this type of problem, and the classic boat fleet is showing this to be a real problem if not dealt with.

This particular vessel showed antifoul burn around all through hull fittings, which made it very easy to identify the issue. Nautique removed the copper and bronze tubes from the hull and remade in composite (fibreglass) which looked identical, but is completely inert and does not conduct electrical current.

The timber underneath had turned in a soft rotten mess. New timber was scarfed and glued. New seal heads were installed and everything realigned. Nautique also removed the old rudder tubes and bearings and copied the old Chatfield engineering pattern (but made in composite). All bonding cables were removed from each fitting. Metal Skin fittings were replaced with plastic.

The net result has been a massive decrease in the amount of anodes on the vessel and now the timber is protected and shows no signs of electrolysis. Nautique has done over 12 vessels now and all have been very successful repairs.