Next time you’re hauled or on your trailer, count the holes in your hull and make notes as to their location and function.
Now see if you can find each one and its
seacock. If you can’t, do some exploring.
It’s better to explore now than when the
sea is flooding in. Unless it’s far above
the waterline, every thru-hull should
have a seacock, which should be readily
accessible and obvious or well labeled.
Most seacocks today are of the ball-valve
type. From fully open to fully closed is
one-quarter turn. The handle opens the
valve when it’s in alignment with the
direction of the flow and closes the valve
if it’s positioned across the flow. Quality
seacocks have bronze bodies with a
stainless or chromed ball inside. Some
have nonmetallic composite bodies, such
as Forespar’s Marelon valves.
Seacocks should be specifically
These valves are essential
components that keep water
on the outside of your boat.
Ignore them and you could
be sunk – literally
manufactured for the purpose. Don’t try
to save money on cheap ones; they can
fail when you need them most. Gate
valves shouldn’t be used for seacocks.
These usually have a wheel to turn and
a gate that opens and closes inside,
and unlike a proper seacock, there is
no visual indication when it is either
open or closed. Gate valves are prone to
blockage and corrosion.
While most seacocks can be disassembled for inspection and repair, this
often involves removing them from the
hull and requires steps unique to the
particular valve, which is beyond the
scope of this article. But there are some
important things you can do to help
ensure that your seacocks let water in
when it’s needed and keep it out when
Each seacock on your boat needs regular
inspection. Check for signs of galvanic
during servicing, avoid using
graphite. Graphite is at the
top end of the
and will lead to
82 | BoatU.S. Magazine DECEMBER 2017
BY TOM NEALE