What's Below Your Waterline?

Seacocks fall into the 'out of sight, out of mind' category for many boat owners ... until they are needed.

By Steve D'Antonio
Published: April 2014

The Bad

Photo of hard plumbing attached to seacock
Anything attached to a seacock adds leverage, weakening it.
Photo of a inline valve handle
This in-line ball valve uses a mild steel handle, which is rusting.

Beware of nickel-plated brass. This will appear silver and is often mistaken for stainless steel. Aside from the potential for dezincification of the brass, many nickel-plated brass valves rely on mild steel or aluminum handles, which quickly rust or corrode in a damp bilge environment.

Ideally, to avoid dissimilar metal or galvanic corrosion issues, alloys used in direct contact with each other — seacock, thru-hull fitting, and pipe-to-hose adapter — should be of the same composition, i.e. all bronze. Within seacocks themselves, more than one metal may be found — a bronze body and stainless steel ball — for instance. However, for seacocks to meet both UL and ABYC standards, these metals must be fully compatible and suited for raw-water use.

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