Don’t Let a Through-Hull Become a Sink Hole Page 2

Don’t Let a Through-Hull
Become a Sink Hole

Part 2: Seacocks, Initial Inspection, Annual Haul-Out

By Capt. Ken Kreisler — April 2003


 More of this Feature

• Part 1: Hull Care
• Part 2: Hull Care
• Part 3: Hull Care

 Related Resources
• Maintenance Index

Mounted inboard of each through-hull connection, seacocks are your best defense against catastrophe in the event of a serious leak or rupture in your vessel’s piping systems. The seacock’s sole purpose is to allow a through-hull connection to be closed and made watertight.

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.

Initial Inspection—Complete Survey of all Penetrations
Whether you are a current boat owner or purchasing a new boat, conduct a thorough survey of all hull penetrations. Do this when the hull is high and dry so you can locate and check each fitting below the waterline. Note the location of every through-hull fitting, and make sure you know how to access and inspect each of them from inside the hull as well. Make a sketch, if necessary, to remind yourself exactly how to reach each one. When the water’s ankle deep and rising is not the time to start tracing your piping system.

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
Carefully inspect and clean the outboard side of all through-hull fittings at least once a year or each time your boat is hauled. Remove accumulations of barnacles or marine growth both inside and out, and inspect each fitting itself to ensure that water can flow freely in or out. If bronze fittings appear bright and shiny, watch out: That’s an indication that galvanic corrosion may be occurring.

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.

Next page > Hull Care, Part 3 > Page 1, 2, 3

This article originally appeared in the March 2003 issue of Power & Motoryacht magazine.

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