Essential seacock checks

  • Tue, 31 May 2011

How to check your boat for safe seacocks


Yachting Monthly is campaigning for tougher rules on seacocks, which currently only have to last five years, according to a European directive.

Our whistleblower surveyor Paul Stevens, 58, a founding member of British Marine Surveyors Europe, blew the lid on the directive after finding a worrying number of yachts fitted with brass seacocks designed for domestic plumbing systems, instead of the longer-lasting bronze or marine brass.

The European Community's Recreational Craft Directive (RCD) of 1988 introduced an ISO standard for through-hull fittings stating they should be corrosion-resistant for a service life of just five years.

The Cruising Association has since backed our campaign and we have been contacted by yacht owners across the world for advice on how to check their boat's seacocks.

Here is surveyor Paul Stevens' advice:


What can be done to minimise the risk?

1.    If your boat is still ashore scrape the external flanges of the through hull fittings clean and examine them for pink spots and pitting (see Elan pic from first article). If this is found they are almost certainly ordinary brass and the only advice must be to replace them.
Examine all valves for numbers with CW or CZ prefixes, these are the only one that appertain to the material, and for the CR corrosion resistant logo found on genuine DZR valves. CW617N is for ordinary brass, whilst CW602N indicates DZR brass. In my experience genuine DZR valves are finished in their natural gold colour and not plated to give a silver appearance.
Lightly hit the body of the valves with a screwdriver and hammer. it hHMove the hoses back and forth to test the strength of the tails.

2.    Ask the builder the following questions:

Can you please confirm that ALL the components used in the seacock assemblies are in compliance with ISO 9093-1 in terms of their corrosion resistance.

Can you please confirm the European CW designation for the materials used in ALL the components in the seacock assemblies? (Once this number is known the exact composition of the alloy and thus the component's suitability for saltwater use can be established).

I cannot emphasise enough the need to establish the material used for all components, ie the through hull, the valve, any 90 degree bends etc plus the tailpipe for the hose.

3.    Disconnect all through hull fittings from anodes. There is a general consensus that a conventional bonding system may actually encourage corrosion of the fittings.
Experience shows that the most vulnerable fitting is the engine cooling water inlet and isolating this from the engine after any bonding wires have been removed is not as straightforward as it may seem. This is because most hoses used in this application are spiral wound with stainless steel wire to prevent them collapsing under suction, and this wire often provides continuity between the engine and its intake valve assembly. Test this with a simple circuit tester.

4.    Fit a galvanic isolator, this should mop up any stray currents and minimise the risk of electrolytic action.

See the August issue of Yachting Monthly for the latest on our campaign, as well as an real-life story from a reader who saved his boat after devising an unusual method of stopping his yacht's broken seacock at sea.

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