Blakes seacocks – to replace or not to replace?

[Rich the Scribbler]

I am making some mods to the heads on my 70s design plywood boat and one of the nuts holding on one of the Blakes seacocks literally fell off when I was cleaning it. The bronze bolt had corroded through, presumably as the result of electrolytic action. I can't afford new Blakes fittings at £200-plus a pop (even for the 3/4"). Due to space (height) considerations (the seacocks are under the toilet), I cannot replace them with a standard lever ball valve. I have found a Maestrini bronze, lever-action gate valve that looks the works.

The question is, do I need to replace the Blakes valves at all? Does the failure of one bolt mean I should scrap both seacocks just in case? Obviously safety is the major consideration here.

Thanks in anticipation.

 

[vyv_cox]

I suspect the bolt was brass, not bronze. At the date your boat was built Blakes seacocks were bronze, very unlikely to have corroded but a detailed inspection is recommended. You could replace the bolts with bronze, phosphor bronze (expensive), silicon bronze. Seacocks in all Sadler yachts were bolted in stainless steel. Mine are almost as old as yours and in perfect condition. Countersunk into the hull and sealed with mastic there is little to corroded

 

[Sandy]

Have you considered selling your Blakes seacocks for vast sums of money, I understand there is a large market for that sort of thing, and fitting new plastic through hulls and seacocks? And still have cash over for a night at the pub.

I am a big fan of quality plastic seacocks and through hulls.

 

[Tranona]

Have you considered selling your Blakes seacocks for vast sums of money, I understand there is a large market for that sort of thing, and fitting new plastic through hulls and seacocks? And still have cash over for a night at the pub.

I am a big fan of quality plastic seacocks and through hulls.

Read what the OP says - there is not room for a ball valve - whatever the material.

 

[doug748]

I am making some mods to the heads on my 70s design plywood boat and one of the nuts holding on one of the Blakes seacocks literally fell off when I was cleaning it. The bronze bolt had corroded through, presumably as the result of electrolytic action. I can't afford new Blakes fittings at £200-plus a pop (even for the 3/4"). Due to space (height) considerations (the seacocks are under the toilet), I cannot replace them with a standard lever ball valve. I have found a Maestrini bronze, lever-action gate valve that looks the works.

The question is, do I need to replace the Blakes valves at all? Does the failure of one bolt mean I should scrap both seacocks just in case? Obviously safety is the major consideration here.

Thanks in anticipation.

I would check them, grind in the cones and refit with either bronze bolts (expensive) or stainless, as post 2. Mine were also fitted with stainless bolts, 45 years ago, and are still going strong.

Lots of spares available on Ebay should you need them.

.

 

[Tranona]

I am making some mods to the heads on my 70s design plywood boat and one of the nuts holding on one of the Blakes seacocks literally fell off when I was cleaning it. The bronze bolt had corroded through, presumably as the result of electrolytic action. I can't afford new Blakes fittings at £200-plus a pop (even for the 3/4"). Due to space (height) considerations (the seacocks are under the toilet), I cannot replace them with a standard lever ball valve. I have found a Maestrini bronze, lever-action gate valve that looks the works.

The question is, do I need to replace the Blakes valves at all? Does the failure of one bolt mean I should scrap both seacocks just in case? Obviously safety is the major consideration here.

Thanks in anticipation.

As suggested, re-use the Blakes with 316 fastenings well bedded in sealant. Would not touch that gate valve as it is brass and the mechanism will fall apart in seawater.

 

[Snowgoose-1]

I am making some mods to the heads on my 70s design plywood boat and one of the nuts holding on one of the Blakes seacocks literally fell off when I was cleaning it. The bronze bolt had corroded through, presumably as the result of electrolytic action. I can't afford new Blakes fittings at £200-plus a pop (even for the 3/4"). Due to space (height) considerations (the seacocks are under the toilet), I cannot replace them with a standard lever ball valve. I have found a Maestrini bronze, lever-action gate valve that looks the works.

The question is, do I need to replace the Blakes valves at all? Does the failure of one bolt mean I should scrap both seacocks just in case? Obviously safety is the major consideration here.

Thanks in anticipation.

Blakes Seacock bolt. Silicon Bronze. 5/16" x 2 1/2" With nut | eBay
Any good ? Got mine from Classic Marine
. Me and the boat still above ground. Or is it still above sea level.

 

[Rich the Scribbler]

Many thanks for all the posts; some very helpful tips, there. It sounds as if replacing the bolts should be sufficient, then. Silicone bronze would be nice, but that's £80 for both seacocks – I think I should replace all eight bolts to be on the safe side. The 316 option sounds the most cost-effective solution.

If I had the room I would probably have gone down the TruDesign plastic route, as they are obviously immune to electrolytic reaction, and their prices seem to have come down a bit, but not possible in my situation as they are much too tall.

 

[vyv_cox]

If I had the room I would probably have gone down the TruDesign plastic route, as they are obviously immune to electrolytic reaction, and their prices seem to have come down a bit, but not possible in my situation as they are much too tall.

Electrolytic corrosion is the result of applying an electric current to a metal in water. What you have is corrosion, possibly dezincification or something else.

 

[Rich the Scribbler]

Hi Vyv. The boat was in Yarmouth Harbour for two seasons and I think they have a problem with current leakage, as I've gone through two props in short order (one on my previous boat), with large copper patches appearing on the blades. I assumed my seacock had fallen victim to the same issue. (I've found the tips on your website incredibly helpful, by the way!)

 

[Keith 66]

Electrolytic corrosion is the result of applying an electric current to a metal in water. What you have is corrosion, possibly dezincification or something else.

Electrolytic corrosion is the result of two or more dissimilar metals in an electrolyte ie Salt water, the electrical current is created by the galvanic difference. Add electricity from shore systems, or boat electrics & things get worse.

 

[burgundyben]

I am making some mods to the heads on my 70s design plywood boat and one of the nuts holding on one of the Blakes seacocks literally fell off when I was cleaning it. The bronze bolt had corroded through, presumably as the result of electrolytic action. I can't afford new Blakes fittings at £200-plus a pop (even for the 3/4"). Due to space (height) considerations (the seacocks are under the toilet), I cannot replace them with a standard lever ball valve. I have found a Maestrini bronze, lever-action gate valve that looks the works.

The question is, do I need to replace the Blakes valves at all? Does the failure of one bolt mean I should scrap both seacocks just in case? Obviously safety is the major consideration here.

Thanks in anticipation.

Detail suggests the gate might be brass?

It wouldnt be my choice.

I'd use new bronze bolts and the Blakes seacock.

I'm in Yarmouth, I've been there with several boats in different parts of the harbour, I've never thought there to be a problem.

 

[vyv_cox]

N

Electrolytic corrosion is the result of two or more dissimilar metals in an electrolyte ie Salt water, the electrical current is created by the galvanic difference. Add electricity from shore systems, or boat electrics & things get worse.

No it is not. What you describe is galvanic corrosion.

 

[Tranona]

Hi Vyv. The boat was in Yarmouth Harbour for two seasons and I think they have a problem with current leakage, as I've gone through two props in short order (one on my previous boat), with large copper patches appearing on the blades. I assumed my seacock had fallen victim to the same issue. (I've found the tips on your website incredibly helpful, by the way!)

Do you have anodes protecting your propeller?

 

[Rich the Scribbler]

I do now! Lesson learned.

 

[Tranona]

I do now! Lesson learned.

If your props dezincified without anodes then that is to be expected and probably nothing to do with the claimed "current leakage" in the harbour

 

[RivalRedwing]

For silicon bronze bolts Anglia Stainless was historically a good value source of them Stainless Steel Fasteners - Anglia Stainless LTD Suffolk, UK

 

[Rich the Scribbler]

Again, many thanks for the really helpful tips.

One further question on this topic - what is the best way of removing the original bolts from the hull? How much heat can plywood take? Or should I just drill them out? I'm guessing bronze will be quite soft so a HSS drill would work OK if they prove stubborn. 5/16 is pretty much bang on 8mm; should I go for a 6mm or 7mm drill bit to avoid damaging the hull? My past efforts at drilling out steel bolts have not generally been successful - the bit always seems to wander.

 

[vyv_cox]

Electrolytic corrosion is the result of applying an electric current to a metal in water. What you have is corrosion, possibly dezincification or something else.

For interest there is a page on electrolytic corrosion on my website, including some spectacular images.
Electrolytic corrosion

 

[vyv_cox]

Again, many thanks for the really helpful tips.

One further question on this topic - what is the best way of removing the original bolts from the hull? How much heat can plywood take? Or should I just drill them out? I'm guessing bronze will be quite soft so a HSS drill would work OK if they prove stubborn. 5/16 is pretty much bang on 8mm; should I go for a 6mm or 7mm drill bit to avoid damaging the hull? My past efforts at drilling out steel bolts have not generally been successful - the bit always seems to wander.

They should tap out reasonably easily. Assuming the bolt heads are on the outside of the hull it would be sensible to have an assistant there with a heavy length of pipe over the head while you tap them from inside.