Exercise Your Seacocks
By Don Casey
Revised by BoatUS editors in April 2012
All underwater through-hull openings should be fitted with seacocks (not gate valves), but a seacock is worthless unless it works when you need it. To keep seacocks functioning reliably, they must be exercised regularly and lubricated at least once a year. Cone- and plug-type seacocks need to be disassembled to be properly serviced, but ball-valve seacocks are easily maintained by spreading a dollop of waterproof grease on both sides of the closed ball.
Outside the boat, the ball is usually within reach, but to lubricate the interior side of the ball requires removing the hose attached to the valve. Operate the valve handle a couple of times to spread the grease onto the seat, and make a habit of exercising the valve every couple of months.