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Seacocks

Q Seacock Leaks
A Water bypassing worn or scored conical plug - re grind plug with medium grinding paste (the new surface created after grinding need not cover the whole plug, the top and bottom only has to make contact for an adequate seal), re-grease with Blakes Waterproof Seacock Grease and assemble with Keep Plate "finger tight". Corrosion on Conical Plug (toilet installation) - caused by bacterial action of sewage left in pipe, re-grind. Always try to ensure that system is pumped clear before closing seacocks.  Conical Plug too loose - slacken lock nuts and tighten keep plate bolts but not so as to make the handle hard to turn, then re-tighten lock nuts.

Q Seacock Seizes
A Lack of grease in conical plug - plug could need re-grinding with medium grinding paste (this forms a rough enough surface to hold the grease).  Keep plate too tight thus squeezing all of the grease out of the plug - loosen keep plate and re-grease re-assemble with keep plate finger tight.

Q Material specification used on the Blakes seacocks
A The body and plug are made of DZR1 (BSEN 1982 CC752C). A dezincification resistant brass for die casting
If zinc is leached from brass by sea water corrosion, the brass will become porous and fail. DZR1 resists the zinc removal and is approved by Lloyds if used in a marine environment.
The seacock bolts are manufactured from Phosphor bronze.

Q Seacock corroded
A Possible galvanic action on boat - consult a qualified surveyor with a view to curing galvanic problem (possibly with sacrificial anodes) and to check other metal fittings such as propeller shaft and propeller.

Many problems with Seacocks can be traced to incorrect adjustment of the keep plate - here is the correct procedure:

Slacken two lock nuts. Adjust the keep plate bolts until the handle can be operated with gentle pressure only. If the handle is difficult to operate, the keep plate bolts are over tight - this is not to be recommended as it will tend to squeeze out the grease and increase the likely-hood of later seizure.
When the keep plate bolts are correctly adjusted use a screwdriver to maintain the adjustment while simultaneously tightening the lock nuts.  Seized plug can generally only be removed by "drifting out" from the OUTSIDE of boat using a hardwood or soft metal "drift". Always have a suitable sized softwood plug available to plug a hole in an emergency if working between tides.  Check for leaks when the boat is back in the water.

PLEASE NOTE THAT IT IS ONLY ADVISED TO FULLY SERVICE SEACOCKS WHEN THE BOAT IS OUT OF THE WATER.

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Copyright 2001 Blakes Lavac Taylors
Last modified: August 26, 2004