lapping blakes seacocks

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steve yates

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I have two very stiff blakes on my westerly, I have the cone out of the smaller one, but still working on getting the cone out of the larger one.
Am I right in thinking I dont need to be taking the aseembly out of the hull to service these? I just need to remove the locking collar and then tap the cone out with a drift?

So when it comes to lapping them, am I just lapping the cone? In other words, do I work the grinding paste around the cone with something or do I smear it on the cone, put the cone back in the seacock and work it in there? If so, can I work it in both directions as it may not be possible to keep going round? or should it really be done in one direction?

The other thing is, I have some spare ones to refurbish. So would it work if I put one of the spares into a vice and then inserted the cone from the boat into it and lapped it at home, taking it back to insert into the insitu seacock when done?

Thanks.
 
Yes you can do it in situ or take it out and take it home.
I would suggest removing one of the through hull bolts to check it's condition if you chose to lap it in situ.
 
I have found the cones to be interchangeable, in that I have fitted a used one into an existing body. Of course it is possible that the construction changed at some point so there is no guarantee. However I would always lap the cone into the body where it is going to live, it's part of the idea of doing it.

You don't need to do a full 360, or at least I can't and it has worked ok. Don't expect the lapping will give you a wonderful finish with all marks removed, the cock will work with a reasonable, consistent mated finish at top and bottom.

PS

Doh. Of course, the handles come off, so you can do your 360 if you want!
.
 
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I cobbled together a way to connect a cordless drill to the cones, it makes for an easier and better job. You can keep repositioning the cone, and changing the direction. I started with coarse valve grinding paste, then fine, then Solvol Autosol although the latter was probably not vital.
The job is a bit carp if you just use the handle on the cone..
 
It is not good practice when lapping to use continual motion in one direction so the fact you can not turn the cone 180 degrees is a help more than a hindrance. You just rotate to and fro through small arcs with light pressure having put a coating of paste over the cone surface, after a few motions back ad for you lift and rotate to another position and repeat having moved the handle a flat and so on till the cone has been lapped in through a full rotation. You might need to start with course paste. Keep inspecting the cone for progress and every so often clean the cone and the body and then with a carpenters pencil or an ordinary soft pencil put 4 thick pencil lines down the cone at 90 degrees then insert the cone in the body and when in position rotate a few degrees back and for and then remove and inspect the pencil lines. They should all have been smudged and or removed of things are good however sometimes grinding proceeds more at the small end and this will be shown by the pencil lines not having been smudged or removed at the small end. If this has happened then only apply the next paste coating where the lines were smudged and removed.

Many folk probably don t bother with this and just put up with minor leakage back through the cock although there may be no leakage at the neck and clamp plate.
 
Although the cones are interchangeable, the whole point of lapping them in is to match the cone with the body. You can tell when you have done enough because there is a smooth coating of paste around the cone and in the body with no hollows. No need to remove the body from the boat unless the bolts or the sealant have failed. To remove the cone, slack off but don't remove the keep plate and use a drift up to the cone from outside. Useful to put some penetrating oil at the top of the cone to try and break down the grease that is causing it to stick. Once it moves it will go with a bang, hence the need for the keep plate to stop it from flying around the boat!
 
I found it useful to slacken off, but not remove, the bolts on the locking collar before drifting the cone out, in order to avoid the possibility of the cone flying off into the very deep bilge when it came loose (a tip I think I got from someone on here in a previous similar thread).

I found the cone surprisingly easy to drift out with a piece of scrap wood dowel (bit of an old broom handle, I think) and a hammer, despite the cone seeming locked solid from a turning point of view.

Blakes recommend medium grinding paste for lapping in the cone and housing. Unfortunately most suppliers of small quantities of grinding paste, e.g. combination cans of two types, do only coarse and fine, so I had to pay a little more to get a larger container of medium paste. I've no idea how critical it is, but imagine medium paste gives the best combination of a close fit, but with retention of enough grease to seal and lubricate the joint.

Blakes do a grease sold specifically for this purpose, but I couldn't find mine at the relevant time, and used standard white waterproof grease. The cone has seized again since (and is on my to-do list), but I've no idea whether that would have been avoided with Blake's own grease.
 
LittleSister said:
I found it useful to slacken off, but not remove, the bolts on the locking collar before drifting the cone out, in order to avoid the possibility of the cone flying off into the very deep bilge when it came loose (a tip I think I got from someone on here in a previous similar thread).

I found the cone surprisingly easy to drift out with a piece of scrap wood dowel (bit of an old broom handle, I think) and a hammer, despite the cone seeming locked solid from a turning point of view.

Blakes recommend medium grinding paste for lapping in the cone and housing. Unfortunately most suppliers of small quantities of grinding paste, e.g. combination cans of two types, do only coarse and fine, so I had to pay a little more to get a larger container of medium paste. I've no idea how critical it is, but imagine medium paste gives the best combination of a close fit, but with retention of enough grease to seal and lubricate the joint.

Blakes do a grease sold specifically for this purpose, but I couldn't find mine at the relevant time, and used standard white waterproof grease. The cone has seized again since (and is on my to-do list), but I've no idea whether that would have been avoided with Blake's own grease.
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I have found that the best grease here is a copper based grease. I used to use oilfield drilling products however Halfords do Copperslip Grease which is fine. My Sea Cocks have been serviced with this for the last 30 plus years. and in that lime lapped in two or three times. They can be operated with just single finger pressure. The copper in the grease seems to help. Be interesting to see if they are still free after this lockdown.
 
Copaslip is a good idea which I haven't tried. The Blakes grease is good stuff, it hasn't gone stiff (in a couple of years anyway) but it's madly expensive.
 
When I was young and impecunious, (as distinct from old and impecunious :) ), I used to maintain and repair whatever motorbike or car I could just about afford at the time, which often included cylinder head overhauls, which I had to learn to do on the job. The instructions in the relevant Haynes workshop Manual always recommended, when lapping in poppet valves, to lap each one into it's individual port, and not to rotate a full 360deg, but to twist the valve grinding tool between the palms of one's hands, back and forth, achieving a turn of probably about 145deg. At intervals the grip would be adjusted perhaps a quarter turn, so as to ensure that the whole circumference was, eventually, equally ground.
When I owned a boat which had Blakes seacocks I by default, adopted the same technique when lapping them in, and always mating the same cone with the same body. Additionally when re-assembling, I found that it was beneficial to coat the cone with copious amounts of waterproof grease, tightening the bolts down lightly, just until the grease was being squeezed out right around the circumference. I could then subsequently check for any weeping, on opening the valve and tighten the bolts up a little more. This ensured that I had easily turning valves throughout the season with no binding, and they could be dismantled on liftout without recourse to violence.
 
Gary Fox said:
Copper slip is a good idea which I haven't tried. The Blakes grease is good stuff, it hasn't gone stiff (in a couple of years anyway) but it's madly expensive.
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Copper slip is not cheap but for some jobs the cost is worth it. Another place its use saves time and agro is joints around the cylinder head such as exhaust manifold joints and nuts and also I coat injector bodies with it. It makes dismantling an easy job and keeps injectors free in their sleeves. We really benefited from this when I was working at sea with Medium speed diesels where it use could save a lot of time. We had serious problems with a certain medium speed engine that came from Lincoln. and would sometimes have to change cylinder heads at sea. Once we adopted Copper slip as a standard on all gaskets and studs the time taken reduced by a great amount. Once valves of a better material were delivered life got easier but we still used Copper slip.
 
Bilgediver said:
Copper slip is not cheap but for some jobs the cost is worth it. Another place its use saves time and agro is joints around the cylinder head such as exhaust manifold joints and nuts and also I coat injector bodies with it. It makes dismantling an easy job and keeps injectors free in their sleeves. We really benefited from this when I was working at sea with Medium speed diesels where it use could save a lot of time. We had serious problems with a certain medium speed engine that came from Lincoln. and would sometimes have to change cylinder heads at sea. Once we adopted Copper slip as a standard on all gaskets and studs the time taken reduced by a great amount. Once valves of a better material were delivered life got easier but we still used Copper slip.
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Ruston and Hornsby!
 
Ruston Hornsby AO and they were the beginning and end of Ruston's into big ship medium speed diesels. Very interesting times and fitted to ships of Reardon Smith. Scottish Ship Management . British Rail Ferries and RFA. Happy times but hard work.
When St George did the morning run from The Hook to Harwich on a calm winters morning you could sea the plume of grey smoke right across the North Sea. Ours were replaced with a Pielstick 2.1 16 cylinder engine which had a few bugs as had only been run at constant speed running on diesel in power stations when we took delivery of ours in Japan. Seized up fuel pumps when we tried to run it on heated fuel oil.

There is a reference in this :-
http://reardonsmithships.co.uk/shipmates26.pdf

https://flic.kr/p/agJg9V
 
Gary Fox said:
The Blakes grease is good stuff. . . but it's madly expensive.
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Not if you 'inherit' a tub with the contents of a boat you've bought. :)

Tranona said:
A tub lasts a lifetime though if only used for your seacocks.
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At the current rate of consumption, it'll last more than my lifetime. :D

(Numerous lifetimes if it keeps hiding every time someone wants to use it! :whistle: )
 
When you reassemble, only light clamping pressure is required as the taper plug will easily lock up. It can be the difference between of 1/8" turn between finger tip operation and lock up. After getting the clamping pressure correct, be careful with the lock nuts, as they may just turn the bolt a bit more and lock up the cone again. Very little pressure is needed to keep the cone from passing water.
 
LittleSister said:
Not if you 'inherit' a tub with the contents of a boat you've bought. :)



At the current rate of consumption, it'll last more than my lifetime. :D

(Numerous lifetimes if it keeps hiding every time someone wants to use it! :whistle: )
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Yep, I inherited both a tube and a tub of blakes grease with the boat, not to mention a fully stocked bar! :)
 
Gary Fox said:
Copaslip is a good idea which I haven't tried. The Blakes grease is good stuff, it hasn't gone stiff (in a couple of years anyway) but it's madly expensive.
Click to expand...
I have just found my Blakes heads cock is seized solid, and will need battering into the boat with a drift from outside.
Despite using Blakes grease costing more than caviar :(
 
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