Servicing Blake Seacocks by Steve Freeman

I’ve done this job a few times in my Centaur and just (late April) finished this year’s attempt. As you might expect it’s the sort of job that gets easier with practice (aren’t they all?) but may be daunting the first time. Why? Because if you get it very wrong you can sink the boat. Or at least, cause the inconvenience and expense of having to have the boat lifted out again just after you’ve had her put back in. Bad news! But it’s not difficult to get it right. (This diatribe is specific to the excellent seacocks made by Blake & Co. I suspect other makes are similar, but I have no experience of them.)
You will need:

  • a reasonably clear cabin to work in
  • a ring or socket spanner to fit the clamping bolt heads (mine is ⅝”)
  • a rubber or wooden mallet in case something needs persuading
  • a small hammer, ditto
  • possibly a lump hammer, a foot or two of broom handle and a heavy cloth
  • a margarine tub or two
  • a brass-wire brush for removing verdigris (steel will cause rust particles)*
  • a small half-round file*
  • some fairly fine sandpaper*
  • white spirit (preferred), diesel (smellier; handy) or petrol (dangerous) for removing grease
  • an old toothbrush for applying above
  • plenty of paper towels
  • two lolly sticks or similar pieces of stiff cardboard
  • valve grinding paste (a few quid from a motor factor/tool shop), fine grade for preference
  • grease – ideally Blakes’ own; failing that, Ramonol or similar; ordinary grease at a pinch

or, whatever you fancy for cleaning up all the bits of bronze

This is what you do:

  1. Get the boat out of the water. This is one of those jobs that absolutely needs it. Once you get good at it you may be able to do it on the beach between tides (if yours is the type of boat that takes kindly to this sort of treatment) but the first couple of times you want it in a nice dry boatyard.
  2. Clear the sink. You’re going to want to wash your hands
  3. Move whatever cabin furniture is necessary to gain access as fully as possible to the work site.
  4. Apply the spanner to the bolt heads on one of the seacocks and loosen. If it seems reluctant, have a feel underneath for a locknut and remove that first. If that doesn’t solve the problem, try harder. Tap the spanner or handle with a mallet to apply a jolt. (Fig. 1) Tap the head of the bolt with a small hammer (to try and break the corrosion that’s sticking it. Heat the surrounding collar that the bolt’s screwed into with a cloth soaked in hot water.
  5. Take the bolts right out (together with the locknuts, if any) and put them in the marg tub. (Fig. 2)
  6. It should now be possible to lift out the cone. (Fig. 3) It may well be stuck or even seized. Wiggle the handle. Tap the top with a hammer. Hit it with a mallet… If it seems irrevocably stuck, bring out the artillery. Drape a heavy cloth over the offending article. Go under the boat with a lump hammer and a length of stout wooden dowelling of a rather smaller diameter than the hole (I used the handle of the small hammer). Insert the wooden drift into the hole as far as you can (it should reach up into the cone). Thump it with the heavy hammer. With luck and sufficient welly the cone should suddenly come loose and with even more luck the heavy cloth should prevent it embedding itself in the deckhead; or anybody else’s!
  7. Once it’s out, add it to its friends in the marg tub together with the collar. You should be able to see through the fitting to the ground beneath. (Fig. 4)
  8. Repeat steps 4 – 7 with the other seacock, if you have time and can be sure not to get the parts mixed up. Otherwise continue as below and do the other one later.
  9. Use the toothbrush and white spirit to remove all the dirty old grease. Don’t forget the bolt threads. Wipe thoroughly clean with kitchen paper. Inside the socket too.
  10. Lightly abrade all the non-mating surfaces to remove as much of the verdigris as you can. I’m not sure it does much harm but it’d be better looking clean. But whatever you do, DO NOT SCRATCH THE MATING SURFACES of the cone and its socket or it will leak.
  11. Once it’s all as clean as you can get it (Fig. 5), we get to the crucial bit. Use a lolly stick to smear a little fine grinding paste (basically grease with a lot of fine grit in it) on the cone (Fig. 6 & 7) and carefully put it back in its socket. Rotate it backwards and forwards (some say in one direction only but I can’t see that it matters overmuch) with minimal downward pressure until you’ve had enough. Take it out again and clean it up. If it seems pretty smooth, stop. If not, put another small dose of paste on and do a bit more. I read somewhere that you can check for a perfect fit by drawing pencil lines on the clean cone and seeing if they’re uniformly removed when you turn it in the socket that is, if you have nothing better to do!
  12. When you’re happy that everything’s clean (check all abrasive material has been removed) and the mating surfaces are smooth (Fig. 8), use another lolly stick to slather the cone liberally with grease and put it all back together again. You may also want to lightly grease the bolt threads.
  13. When reassembling, do up the bolts little more than finger-tight then install and tighten the lock nuts, recheck the valve can be swung with a little resistance only (If not, try again with the screws backed off a tiny bit, etc.).
  14. When the boat goes back in the water, the cocks may leak slightly. If so, tighten the bolts and lock nuts just enough to stop the leak. Note: If they’re too tight you won’t be able to turn the handle at all.
  15. Clear up, wash your hands and either put the kettle on or pour yourself a stiff one: you’ve earned it!

I reckon this job can be done in an hour or two, provided everything goes well and nothing is stuck. And if it’s done frequently enough (annually is usual) nothing should be stuck. Particularly if you use good waterproof grease. And an hour or two could mean between tides.

Good luck – and don’t blame me if the boat sinks.