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 let you close and
tighten a through-hull connection.
that a seacock has been installed on each fitting that penetrates the
hull below its load waterline, not just below the boot top. In fact, there
should be seacocks on all penetrations that could become immersed during
any condition of loading, heel, and trim.
make sure that each seacock is really a seacock, which is defined by the
American Boat and Yacht Council as "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." If you find a
multiturn (ball) valve installed on a through-hull connection, replace
it with a proper seacock. A seacock should be attached directly to the
through-hull fitting. If a pipe or tube is installed between the through-hull
and the seacock, it creates a possible failure point that is unprotected
by the seacock.
It or Lose It
The best preventive
maintenance for seacocks, whether made of plastic or metal, is to periodically
open and close each valve. Leaving a valve in one position for a period
of time without moving the handle can allow it to freeze up. Manufacturers'
guidelines differ slightly, but the consensus is that you should move
the handle of each seacock throughout the full open-close path at least
once every 30 days, more frequently if possible. One school of thought
advocates shutting all seacocks each time you leave your boat unattended.
If you follow this diligent strategy, be just as methodical coming back
aboard, especially to make sure valves on the raw-water intakes are opened
before starting the engines. More than one of my acquaintances hangs a
placard on the ignition switches as a reminder.
If you have a
seacock that won't operate freely, you'll need to disassemble
and lubricate it. To lubricate seacocks while a boat is in the water,
Forespar Products Corporation recommends the following procedure:
Close the valve.
2. Remove hose or tubing from the inboard side.
Drain any remaining water from the inside of the valve.
4. Swab some waterproof grease on the inside of the valve mechanism.
hose or tubing, checking clamps or fittings.
Activate the valve several times to spread the grease.
When the boat
is hauled, perform steps four through six from outside the hull to lubricate
the opposite side of the valve mechanism. Use winch, wheel bearing, or
water-pump grease. Avoid lithium or other metal-based greases, which may
cause galvanic corrosion.
If a seacock is
completely frozen, it's best to haul your boat before attempting
repair or replacement. If it's not possible to haul out the boat,
then temporarily plug or seal the through-hull connection from outside
the hull before attempting a repair. Don't be like the guy we heard
about, who sank his boat at the dock while doing battle with a stubborn
seacock. The handle wouldn't turn, so he put a 20-inch Stilson wrench
on the valve stem for leverage and proceeded to rip the entire valve off
the through-hull fitting.
the "little things" like this that can ruin your day.
L. Petrie is a professor of naval architecture at the University of New
Orleans and provides maritime consulting services. His Web site is www.maritimeanalysis.com.
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