A leading marine surveyor is warning yachtsmen that their boats could be in danger of sinking because thousands of seacocks and through-hull fittings are made from brass rather than bronze.

Paul Stevens, 58, a founding member of British Marine Surveyors Europe, is ‘incredulous’ that some boatbuilders are fitting out yachts with brass ball valve-type seacocks which are designed for fresh water plumbing and piping systems.

In salt water, brass is prone to a form of corrosion called dezincification, which makes them brittle and subject to failure.

Mr Stevens has examined yachts where cheaper brass seacocks have corroded so badly that they snapped off in his hands on inspection.

‘It used to be the case that boatbuilders only ever fitted bronze seacocks which are virtually fail safe,’ he said.

But bronze and DZR brass – which is resistant to corrosion – is four times the price of ordinary brass.

Ordinary brass will probably last five years, Mr Stevens admits, but if you introduce other factors, like electrical current leakage and associated electrolytic action (especially with marina shorepower), the rate of dezincification of brass fittings will be rapidly accelerated.

For more on this story see the new June issue of Yachting Monthly in which Mr Stevens has written a special report on seacock safety.

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