Keep your Blakes seacocks in top condition with a regular service. Marine surveyor Ben Sutcliffe-Davies shows us how
I know of some owners who have serviced their Blakes seacocks in the water by pulling the taper out and stuffing a bung in, but they are far braver than me. Servicing seacocks is much better done when out of the water and should be a routine part of winter maintenance.
The seacock consists of a skin flitting flange, a body and two holes – one for the taper and one on the side for the hose tail. The taper, open at the outboard end, has an aperture opposite to the with the handle. The seacock is open when when the handle is pointing away from the hose tail, and closed when it is turned 180º (not 90º) alongside it. The taper is held in place with a collar, tightened by two bolts into threaded castings with a locking nut each sitting just under the collar. To take it apart, loosen the locking nuts, undo the screws and lift off the collar. The taper will pull straight out.
If the valve is seized it can be difficult to remove the tapered valve. You can try taking a short length of dowel as a drift, pushed up from the outside of the hull and tap gently with a hammer. In the worst cases, some heat on the valve carefully applied will sometimes help as well.
Once the valve is out, clean off any fouling and old grease, but don’t use anything that could gouge the metal. Check the casting condition externally and internally. If there are stainless steel fastenings, change them for bronze fastenings.
At this point, the key to a good seal is having the faces of the body and the taper perfectly seated together. Re-benching the taper into the cast valve body, is done working cutting into the assembly with the taper in place. Blakes cutting paste comes in a tub with two ends for coarse and fine.
Firstly apply a small amount of coarse paste and then refit the taper into the body and turn and turn and turn. You will see a blackness to the paste the squirts out as the body casting and gets stiffer to turn as the valve creates a nice amount of contact. The most important part is the section above the aperture is properly benched in.
Once whizzed around a number of times and good contact to the surfaces is confirmed, then clean and apply the fine paste and repeat the benching in. Once it starts to get tight then clean down everything down with a soft rag and apply a good spoon of Blakes waterproof valve grease or waterproof pump grease if you can’t get any.
Before refitting, make sure the handle is correctly positioned with the pressure plate correctly fitted so it’s clear if the valve is open or shut! Gently refit the valve and turn it around several times again to ensure the internals get a good covering before refitting the bolts and lock nuts. Once the craft is relaunched check them and if necessary gently tighten down the bolts to get more of the wedge pulled into the valve body, but don’t over tighten.
Your Blakes seacocks are then good to go for another year.