Don’t Let a Through-Hull
Become a Sink Hole
Part 2: Seacocks, Initial Inspection, Annual Haul-Out
By Capt. Ken Kreisler — April 2003
All seacocks are valves, but not all valves are seacocks. As defined by the American Boat and Yacht Council, a seacock is “a type of valve...operated by a lever-type handle...[that moves] through a 90-degree arc, giving a clear indication of whether it is open or shut.” The rationale is twofold. The orientation of a lever-type handle tells at a glance whether the seacock is open or closed, so you can easily make sure that raw-water inlets are open before firing up a system. More important, if a hose or manifold breaks and you find the bilge awash, seacocks can be closed with just a flick of the wrist.
Inspection—Complete Survey of all Penetrations
When purchasing a new or used boat, check that all through-hull fittings are well-secured, with a backing plate inside the hull to reinforce the connection. Check that a seacock is installed on each fitting that penetrates the hull below its maximum waterline. There should be seacocks on all penetrations that could become immersed in any condition of loading, heel, and trim, not just those below the boot top. We know of a guy whose 42-foot boat sank at the dock when an unexpected storm dumped a foot of snow on his deck, trimming the hull and putting an unprotected opening below the waterline.
And make sure that each seacock is really a seacock. If you find a multiturn valve on a through-hull connection, replace it with a proper seacock, attached directly to the through-hull fitting. If a pipe or hose is installed between the through-hull and the seacock, it creates a failure point that the seacock can’t guard against.
Annual Haul-Out Inspection
Crawl through the bilge, inspecting each through-hull fitting and seacock. Be on the lookout for discolorations. Green or white powdery residue on metal fittings could indicate galvanic action or corrosion, so check for proper bonding and galvanic protection. Stains in the area surrounding a penetration could indicate a possible leak.
This article originally appeared in the March 2003 issue of Power & Motoryacht magazine.