I was very surprised by the seacocks that were installed presumably from new, particularly as dissimilar metal fittings were joined to the seacocks. While there were no obvious signs of decay, I was concerned of the risk as it was likely that the seacocks were original and now were 18 years old. If high quality bronze, not a problem, but they weren’t. They had to go.
If you want to read up on this subject, check out the following articles and also “Google” dezincification.
Reference articles
Yachting Monthly Seacock Failure
Corrosion in Through-Hull fittings : a comprehensive technical article
With Dragon II in Marmaris, far from home, this was not a job I had time for myself.
“Herman the German” and Erica who own and operate German Marine Service were my saviours. They did a great job and I can fully recommend them for all types of work if you are in the Marmaris area. Their email details are germanymarineservice@gmail.com
There are two main suppiers of “plastic” seacocks, TrueDesign and Forespar Marelon. Don’t be fooled by the reference to “plastic”. These are not some PVC ball valve that you might find at a plumber shop, rather a reinforced engineering plastic (nylon) that will never suffer from corrosion and the valve turns very smoothly.
Quoting from the TrueDesign website:
TruDesign Ball Valves are designed and made in New Zealand for use in marine applications above and below the water line. They comply with ISO 9093-2 and ABYC H-27 and certified by Bureau VERITAS and IMCI. They are ideal for controlling inlet and outlet water requirements.
The body of the Ball Valve is manufactured in glass-reinforced nylon composite with high impact and tensile strength resulting in a light weight unit, free from corrosion and electrolysis issues. The ball and sealing rings utilise a PTFE polymer to ensure a smooth action, and continuous ease of operation over many years. The Ball Valve is available in both BSP and NPS Parallel thread forms and can be locked in the closed position for use on toilet waste outlets.
I chose TrueDesign as the accessories such as tailpipes (to which you attach the hose) came in sizes and configurations that worked for me and Dragon II. Otherwise the two seacock designs seem equally good.
My major regret is I did not instruct Herman to follow the advise of Nigel Calder and remove some of the balsa core and replace with epoxy before installing the seacocks. Herman assures me that he was diligent with his use and choice of sealant, Sikaflex 291i.
Still…I wish.
A Dragon's Tale 