Blakes seacock help

[maej]

Sorry about yet another thread on blakes seacocks. The 3 on my boat in the heads all looked really horrible, one was leaking badly and another siezed so I assumed they were beyond repair and set about removing them to replace them. That took an awful lot of force and mallet strikes that they have survived undamaged.

Since they survived that so well I set about cleaning and regrinding them and they have come up nice, but they do have some patches of pink/reddish colour on the bodies, like skin blemishes, and one is pinkish around the top of the neck. Being 1984 fit without the grease nipple I thought they would be bronze and couldn't dezincify?

Also the top of the hose tail on the heads outlet looks like it's been nibbled at, and the tail has some pitting inside, I guess thats bacterial corrosion at work, but the tail survived being used as a lever to twist them off so must still be strong.

Below are some pictures, though they don't show the colours very well. Do you think these are good enough to put back in service or should I just replace them? (the sheared bolts are my ignorance, I didn't realise the nuts on the back were lock nuts ). The last pic shows why I thought they needed replacing.

If I should replace them, do the mounting holes still line up on the current versions from blakes?

What sealant should I use to refit them? sikaflex will likely make it impossible to remove them again for 20 years without damage to the boat since they are in a recess that prevents any tools prising under the flange.

Thanks

 

[Gordonmc]

I would have no worry about putting the valves back into service with new bolts.
For peace of mind you could treat them with something like Owatrol to keep the surfaces visible.
A non-setting mastic would be better than Sikaflex. I used red-lead putty on my (previous) boat... but that had a wooden hull. Life-Caulk or butyl on a FG hull.

 

[Tranona]

They look fine. Lap the cones in with grinding paste (in the little two ended tins) to remove the surface discolouring and re-assemble with grease. Adjust the locking plates so the handles turn with pressure of two fingers an re-install with new genuine Blakes bolts (close your eyes when you see the price!) and they will be OK for another 30 years. Use a Polysulphide such as Life Caulk which sets to a still flexible state, leaving the final half turn of the nuts until a couple of days after installation.

 

[Frankie-H]

We have about 10 Blakes sea cocks on the boat and I withdraw the centre valves about every 2 years. They are fool proof and servicable, unlike the average ball valve.
A quick shine up with fine wet and dry and a waterproof grease and off they go again. Be careful not to overtighten. No damage but have to reloosen and start again.

The redish blemishes you describe are electrolysis, taking the brass out of the copper. If this gets severe the remaining, mainly copper units, will become very fragile. Also the nibbling you describe is classic electrololysis.

You should check on your annode protection as it sounds as though there is some stray current. Do your annodes get eaten quickly and is there one close to the skin fittings. If this seems to happen in your marina, you could hang an old annode over the side and see if it gets eaten and over how long.

 

[Frankie-H]

Further thought. I would certainly bed all skin fittings into Sikaflex. Perhaps a cranked flat bladed screwdriver will help to get them out. Or a tap from the outside, when you are out of the water of course

 

[maej]

You should check on your annode protection as it sounds as though there is some stray current. Do your annodes get eaten quickly and is there one close to the skin fittings. If this seems to happen in your marina, you could hang an old annode over the side and see if it gets eaten and over how long.

I only bought the boat in November so I don't know the full history, but in terms of anode protection there were 2 shaft anodes and no hull anode. The shaft anodes were being eaten away but it seems there was no bridge over the flexible coupling. None of the seacocks are electrically bonded. The boat was kept on a swinging mooring on the Beaulieu river for as far back as I have history. The P bracket dezincified in just 10 years, but it too was not protected by an anode.
I'm having a hull anode fitted to help protect everything, but I thought seacocks shouldn't be linked?

 

[Ex-SolentBoy]

A new set of Blakes bolts looks to be about £50.
A new seacock with the inbuilt grease nipple looks to be about £100.

Tough call.

 

[Tranona]

I only bought the boat in November so I don't know the full history, but in terms of anode protection there were 2 shaft anodes and no hull anode. The shaft anodes were being eaten away but it seems there was no bridge over the flexible coupling. None of the seacocks are electrically bonded. The boat was kept on a swinging mooring on the Beaulieu river for as far back as I have history. The P bracket dezincified in just 10 years, but it too was not protected by an anode.
I'm having a hull anode fitted to help protect everything, but I thought seacocks shouldn't be linked?

No need to use anodes on the seacocks as they are not connected to anything electrically and they are all the same material. The nibbling on the toilet outlet spigot is almost certainly urric acid from human waste lodged on there for 34 years! The surface discolouring is the action of salt on the bronze, and as you have seen goes with cleaning.

No need for a hull anode or bridge across the coupling if the shaft anode is doing the job of protecting the prop. If there are signs of corrosion on the P bracket it might be worth wiring a hull anode to that through the bolts inside, but if the current one has lasted 24 years without problems, probably not necessary.

 

[Poignard]

The pits

My heads discharge seacock is 45 years old and shows pitting as described above.
About 12 years ago I cleaned it up and filled in the pits with epoxy resin thickened with graphite. That lasted many more years and I was going to do it again but then I realised that even if the pits began to corrdode right through there would only be a slight leakage, giving me plenty of warning that it was time to do something about it. The boat is not suddenly going to sink without warning.

 

[maej]

A new set of Blakes bolts looks to be about £50.
A new seacock with the inbuilt grease nipple looks to be about £100.

Tough call.

On my boat (Sadler 34) the blakes seacocks are held in with recessed counter sunk stainless steel bolts that are filled over on the outside so they are not exposed to salt water. Once I broke the filler out covering the heads they unscrewed easily and are still shiny coloured. I'm very tempted to reuse them, is that a stupid idea?

[Edit] In the picture, seacock one peeling machine nil

 

[maej]

Do the fitting holes on the new blakes seacocks line up with those on the old ones?

I've heard some comments either way and wondered if anyones knows the definitive answer?

 

[Tranona]

Pretty sure they are the same. The dimensions of the current ones including bolt spacing are on their website. No reason not to use 316 fastenings in the way they have done on your boat. Make sure there is sealer in the bolt holes to islolated the fastening from the body, then no water can get in. The key things of the Blakes ones are the material and the shape which fits the external cover plates, which presumably you are not using.

 

[maej]

The key things of the Blakes ones are the material and the shape which fits the external cover plates, which presumably you are not using.

There are no cover plates fitted, before she was peeled all I could see outside was the hole that is the seacock. If they hadn't accidentally tried to peel one of them I would not have known the screws were accessible under filler.

Thanks, it's good to know I can fit a new one without having to drill new holes.

 

[Boo2]

Since they survived that so well I set about cleaning and regrinding them and they have come up nice, but they do have some patches of pink/reddish colour on the bodies, like skin blemishes, and one is pinkish around the top of the neck. Being 1984 fit without the grease nipple I thought they would be bronze and couldn't dezincify?

I think Blakes themselves would be the best people to ask about the material. When I serviced my Blakes seacocks last summer there was signs of pinkishness about the valve but I lapped them back in with grinding paste ahd the colour returned to bonze very easily. I doubt I removed more than a half a thou so if you want to test how deep your pink colour goes you could try gently wiping with some fine grade emery cloth.

I'm also interested to know about the hole spacing, AIUI Blakes may have changed from an imperial thread to a metric one too at some point so that might possibly have some bearing.


Boo2

 

[Frankie-H]

No need to use anodes on the seacocks as they are not connected to anything electrically and they are all the same material. The nibbling on the toilet outlet spigot is almost certainly urric acid from human waste lodged on there for 34 years! The surface discolouring is the action of salt on the bronze, and as you have seen goes with cleaning.

No need for a hull anode or bridge across the coupling if the shaft anode is doing the job of protecting the prop. If there are signs of corrosion on the P bracket it might be worth wiring a hull anode to that through the bolts inside, but if the current one has lasted 24 years without problems, probably not necessary.

Tranona. I hate to disagree with you but I feel that the OP should to talk to a marine manufacturer as there is a danger that he may find himself with too many divergent oppinions.

Some experts say that you should bond and link. all thru hull metal fittings. Some say that this is not necessary. I don't think I have ever heard that this is a bad system. Mine have been linked for at least 30 years and I would hesitate to change.

Electrolysis will attack the least noble metal if there is stray current. Bronze is way down, on the list and not much higher than the aluminium alloy, which annodes are made from. It has nothing to do with skin fittings being made or assembled from different materials.

The dezincified copper will certainly never polish out. You might be able to remove the damaged part but this is certainly not the same as cleaning a corrosion off.

Uric acid might cause gout but , as far as I know, it will not attack bronze. I am sure there are chemists, who will correct me, if I am wrong.

Blakes bolts are bronze and it may just be that your problems are due to bi-metalic reaction from stainless steel bolts. I would certainly prefer to replace them with the correct bolts, as supplied by Bakes.

 

[doug748]

On my boat (Sadler 34) the blakes seacocks are held in with recessed counter sunk stainless steel bolts that are filled over on the outside so they are not exposed to salt water. Once I broke the filler out covering the heads they unscrewed easily and are still shiny coloured. I'm very tempted to reuse them, is that a stupid idea?

[Edit] In the picture, seacock one peeling machine nil

I think this may have been standard practice on Sadlers and probably Contessas as well. My boat certainly used the same method.

I have not noticed any problems with mine and have reused the stainless screws, but have taken the precaution of putting fibre washers under the nuts. I always bed these things on silicone stuff from the pound shop but wait for it to cure before giving the nut a final nip. I have found this method to be perfectly adequate. In my view Sikaflex is overkill.

I have only scanned the thread so forgive me if I am repeating stuff.

Those seacoks looks fine, I would not bond them, but would regrind.

Only a short time ago the standard advice put forward on these forums was to throw out the nasty, leaky, old fashioned seacocks and buy nice new ones with ball valves - just like on smashing new boats. It is no longer a fashionable view.

 

[Deleted member 36384]

There are no cover plates fitted ....

I always assumed that the cover plates were optional extras. On my own yacht the loo inlets have cover plates but not the sink outlets, neither does the raw water inlet have a cover plate. All have a flange around the outlet spigot which the bolts go through irrespective of cover plate or not.

Details here: http://www.blakes-lavac-taylors.co.uk/blakes_seacocks.htm

Mine are much older than the modern model represented above but the cover plate, ring option is the same.

The seacocks used to be bonded to a common earth but they are not bonded now and I don't see the need to. I believe the previous owner removed the bonding when a shore power supply was fitted with galvanic isolator.

Mine also looked a bit like the OP picture but cleaned up well. I don't remember a pinky hue but I did give the sea cocks a good battering with a panel pin hammer.

 

[Tranona]

Tranona. I hate to disagree with you but I feel that the OP should to talk to a marine manufacturer as there is a danger that he may find himself with too many divergent oppinions.

Sorry you disagree, but there is general agreement that there is no need to bond seacocks to avoid galvanic action. The reason for this is simple - assuming non metallic hoses are used they are not connected electrically to any other metals. The proof for the OP is that is seacocks are in excellent condition after 34 years. What possible reason is there for bonding them now? The same applies to the re-euse of 316 fastenings, this was common practice at the time and again there is no suggestion it causes any problem. You are right to suggest bronze fastenings - if the seacocks are installed in the usual way with an external backing plate, although it is also common to use 316 in this case as well. Provided the bolts are set in sealer there is little chance of any interaction between the bronze and the 316, but to my mind there is always the possibility of crevice corrosion if the seal is not perfect, so I would always use bronze. BTW The staining is not dezincification as it easily polishes out. Blakes bronze seacocks will last indefinitely if they are serviced regularly. That is why they are so popular with some people despite their price.

The pitting on the toilet outlet spigot is common as parsifal reports, and I had on the same place on my boat. The inlet and things like sink drains do not seem to suffer in the same way which suggests it is something in the waste that is causing it. However as parsifal also says the pitting is superficial and does not affect the strength of the fitting.

 

[vyv_cox]

If your seacocks are original as fitted Sadler they are almost certainly DZR, which your photos seem to confirm. There may be minor dezincification but nothing worse. My 1984 Sadler 34 has bronze bolts, imperial size. Your stainless ones do not sound like the standard fit, although the way in which they are installed is as mine.

Bonding seacocks is now generally frowned upon. If, for example, you had DZR, brass and bronze fittings on the boat,by no means unusual, corrosion of the brass would be accelerated by the bonding, I understand even if an anode is connected.

Your valves look good to me. Follow the suggestions about grinding in and rebedding and they are good for another 25 years.

 

[maej]

Thank you everyone, I feel happy to refit the existing ones now, though I might have a second go at grinding the outlet one to try to clear that rough area.

So to bed them in, polysulphide, silicone and sikaflex have all been suggested and I'm confused to what I should use. Is it a case of just use any of them as they all do the job, or are there particular advantages / disadvantages to any?

I can't find Boatlife Lifecaulk for sale, Arbokol 1000 is available, is that just as good? Dow Corning Marine Sealant is a silicone sealant I can get. If sikaflex, 291?