Another Seacock Question - replacing through hulls and ball valves with Blakes?

[pvb]

As mentioned before I do not think that the external flange with through bolts is necessary. If a Blake seacock is well fixed with its internal flange glassed over with several fairly wide GRP mat/cloth layers possibly with epoxy resin, it will resist the famous test of standing on it with one's weight; the job must be well done, of course. My boat had all the seacocks fixed this way at build time and, if anyone has doubts, it suffices saying that she was certified by the Lloyd's Register.

That wouldn't be my choice of fitting method for Blakes seacocks.

 

[NormanS]

I had ball valves on the cockpit drains but these soon became stiff and eventually froze; I suspected that the nylon (?) seats were swelling very slightly. Replaced with Blakes. That experience diminished my enthusiasm for ball valves.

Thinking about cockpit drain seacocks, when do you close them, and why?

 

[ghostlymoron]

Thinking about cockpit drain seacocks, when do you close them, and why?

If the hose splits I would think. It's never happened to me fortunately.

 

[Kukri]

Thinking about cockpit drain seacocks, when do you close them, and why?

.

Almost always, because why take the risk of a hose splitting or coming off a connection? (It hasn't happened to me, but I have met two people to whom it has happened- one split hose, one hose coming off ( sister ship of mine, Minches, F7)).

Yes I keep them closed on the mooring; that is what the cockpit cover is for!

 

[NormanS]

.

Almost always, because why take the risk of a hose splitting or coming off a connection? (It hasn't happened to me, but I have met two people to whom it has happened- one split hose, one hose coming off ( sister ship of mine, Minches, F7)).

Yes I keep them closed on the mooring; that is what the cockpit cover is for!

They are one of the many things that I know nothing about. I've never had a boat with cockpit drains, other than a steel sloop where the massively strong s/s drain tubes were part of the structure, and didn't have seacocks.

I had assumed that cockpit drains would be normally open, hopefully with the outlet above the WL.
But if yours are closed on the mooring, and presumably closed as a precaution while sailing (cf friend in the Minch), when are they used? I have heard of people closing them, so that they could use the SD cockpit as a bath.

 

[macd]

I had assumed that cockpit drains would be normally open, hopefully with the outlet above the WL.
But if yours are closed on the mooring, and presumably closed as a precaution while sailing, when are they used?

Not much use having cockpit drains closed if you're pooped.
They vary, of course, but in a great many yachts they drain below the waterline. Most owners seem to regard their default position as open, and certainly when under way.

 

[Kukri]

Not much use having cockpit drains closed if you're pooped.
They vary, of course, but in a great many yachts they drain below the waterline. Most owners seem to regard their default position as open, and certainly when under way.

On a very beamy light boat they may be above the waterline but on older heavier boats the usual arrangement is that the drains cross under the cockpit and go to seacocks below the waterline. The conventional thing was (is, for the likes of me) to open the seacocks as a routine part of preparing for bad weather. This is mentioned in Adlard Coles' "Heavy Weather Sailing".

Some people keep the cockpit drains open on the mooring but then some people leave their engine cooling water and WC seacocks open.

Yes, we used to use close the seacocks and use the SD cockpit as a bath, very handy with muddy children!

 

[macd]

The conventional thing was (is, for the likes of me) to open the seacocks as a routine part of preparing for bad weather.

Ours also need to be open for when motoring. The engine has a very weak bladder

 

[Zing]

If modern-day Blakes seacocks (oxymoron?) are only DZR, you might equally go with the Maestrini DZR ball valves which Vyv suggested. Or you could go the whole hog and fit Perko bronze ball valves which have plastic balls - http://www.asap-supplies.com/fittin...pares/seacock-valves/perko-seacock-0835005plb

But why not go with all bronze valves instead? Plastic is weak and soft and some plastics are damaged by solvents and microbes even. Nothing defeats the sea for reasonable cost like a nil zinc bronze. A simple material to work and produce, with thousands of years of experience behind it.

As to DZR, how sure can you be that the material was made just right? It needs a precise amount of lead 2% ish and arsenic 0.15% ish and to be brewed at just the right temperatures to work.

I wouldn't be surprised to find that in a number of years bad batches are responsible for sinking boats, and all to save literally a few quid. Seems daft to me.

 

[Tammany]

It's a composite boat so why not a composite seacock. Replaced mine with trudesign seacocks. Composites are the way forward in my opinion.

 

[Tranona]

But why not go with all bronze valves instead? Plastic is weak and soft and some plastics are damaged by solvents and microbes even. Nothing defeats the sea for reasonable cost like a nil zinc bronze. A simple material to work and produce, with thousands of years of experience behind it.

As to DZR, how sure can you be that the material was made just right? It needs a precise amount of lead 2% ish and arsenic 0.15% ish and to be brewed at just the right temperatures to work.

I would be surprised to find that in a number of years bad batches are responsible for sinking boats, and all to save literally a few quid. Seems daft to me.

Your comments about nen metallic seacocks are simply nonsense. They are made of glass reinforced composite and meet all certifying bodies (ABS/ RINA etc). Similarly current DZR are perfectly reliable and certified.

While bronze is also suitable for seacocks, it is more than 50% more expensive than either composite or DZR with no significant additional benefits. That is why the two materials have largely superseded bronze in this application.

 

[macd]

1. But why not go with all bronze valves instead?

2. Plastic is weak and soft and some plastics are damaged by solvents and microbes even. Nothing defeats the sea for reasonable cost like a nil zinc bronze. A simple material to work and produce, with thousands of years of experience behind it.

3. As to DZR, how sure can you be that the material was made just right? It needs a precise amount of lead 2% ish and arsenic 0.15% ish and to be brewed at just the right temperatures to work.

4. I would be surprised to find that in a number of years bad batches are responsible for sinking boats, and all to save literally a few quid. Seems daft to me.

1. It's not so easy. As Vyv mentioned earlier, some "bronze" ball valves have plain brass balls. I've just checked out Perko's pages on their "cast bronze" seacocks, which helpfully tells you that "No technical information is available at this time". 'Pig' and 'poke' spring to mind.

2. "Plastic is weak and soft" is as absurd as saying metal is weak and soft on the basis of an encounter with lead. Composites (cf Marelon and TruDesign) can be very strong.

3. How can you know anything is made just right? Equally, there's plenty of stuff masquerading as bronze that isn't, and absolute mountains of 'bronzes' that contain no tin.

4. I presume you meant to write "wouldn't" rather than would. But most seacock valves on European boats aren't even DZR but plain old brass, yet there's not been the slightest hint of an epidemic of sinkings. (That said, I wouldn't dream of installing such a valve but neither would I panic if I had a boat with one fitted.)

 

[GrahamM376]

It's a composite boat so why not a composite seacock. Replaced mine with trudesign seacocks. Composites are the way forward in my opinion.

+1

 

[Zing]

Your comments about nen metallic seacocks are simply nonsense. They are made of glass reinforced composite and meet all certifying bodies (ABS/ RINA etc). Similarly current DZR are perfectly reliable and certified.

While bronze is also suitable for seacocks, it is more than 50% more expensive than either composite or DZR with no significant additional benefits. That is why the two materials have largely superseded bronze in this application.

No, I don't agree about plastic being strong. Bronze is many times stronger than even a strong,tough plastic like glass reinforced nylon, let alone the junkier ones that are in the cheaper plastic ball valves. And I wouldn't think much of compliance with certification bodies as being a measure of adequacy. After all the recreational craft directive allowed brass ball valves.

I don't agree that bronze costs a lot more. The percentage might be large, but a big increase on not much money is not much money. That cost should be irrelevant on a safety critical item where the wrong choice and the sake of a tenner might put your boat at risk.

 

[Zing]

1. It's not so easy. As Vyv mentioned earlier, some "bronze" ball valves have plain brass balls. I've just checked out Perko's pages on their "cast bronze" seacocks, which helpfully tells you that "No technical information is available at this time". 'Pig' and 'poke' spring to mind.

2. "Plastic is weak and soft" is as absurd as saying metal is weak and soft on the basis of an encounter with lead. Composites (cf Marelon and TruDesign) can be very strong.

3. How can you know anything is made just right? Equally, there's plenty of stuff masquerading as bronze that isn't, and absolute mountains of 'bronzes' that contain no tin.

4. I presume you meant to write "wouldn't" rather than would. But most seacock valves on European boats aren't even DZR but plain old brass, yet there's not been the slightest hint of an epidemic of sinkings. (That said, I wouldn't dream of installing such a valve but neither would I panic if I had a boat with one fitted.)

1. Yes, a lot of bronze ball valves have what are actually chrome plated brass balls. Not ideal, so the choice is limited. They also often have brass stems, so again not ideal.

2. Sorry, plastic is weak, as in wet lettuce weak compared to a good bronze. Glass reinforced nylon is better than most. Plastic grades are like Iceberg compared to Cos.

3. You can't. Man has the propensity to cock everything up sooner or later. This is a risk analysis situation. The probability of cock up X the consequence of that cock up and if the number is not brilliant, like I think it his here then you might do something different.

4. Thanks, corrected. Actually, there have been sinkings due to brass and a lot of near misses. It doesn't have to be an epidemic to be a problem I believe.

 

[ghostlymoron]

I'm fortunate in having only one seacock on my boat but it's a brass, domestic gate valve. I'm going to replace it before launch next year with a DZR ball valve from a reputable supplier - if I can find one. Are ASAP ones all DZR?

 

[GrahamM376]

After all the recreational craft directive allowed brass ball valves.

Of course it does, it was drawn up by manufacturers to give a minimum standard for each category, no doubt based on cost effectiveness. Items have to last only for 5 years but they don't remind owners to check them after that period.

 

[vyv_cox]

But why not go with all bronze valves instead? Plastic is weak and soft and some plastics are damaged by solvents and microbes even. Nothing defeats the sea for reasonable cost like a nil zinc bronze. A simple material to work and produce, with thousands of years of experience behind it.

See post #5. Few bronze bodied valves have bronze balls, they are brass, All of them rely on plastic (PTFE, not nylon) seats to seal.

DZR is widely used in the plumbing industry today, so manufacture of the material is no more problematic than it is for any other metal How do you know that your bronze contains 5% tin? Sometimes you just have to put your faith in the manufacturer. Incidentally the lead content is not important, the manufacturer puts it in for his benefit, not ours.

 

[neil_s]

I have stainless steel ball-valves (with ss balls) on the under-water pipework of my GRP boat. They were installed 13 years ago and have given no problems at all. I give them a squirt of sail slide lube once a year, but I'm not sure they need it!

 

[Tranona]

No, I don't agree about plastic being strong. Bronze is many times stronger than even a strong,tough plastic like glass reinforced nylon, let alone the junkier ones that are in the cheaper plastic ball valves. And I wouldn't think much of compliance with certification bodies as being a measure of adequacy. After all the recreational craft directive allowed brass ball valves.

I don't agree that bronze costs a lot more. The percentage might be large, but a big increase on not much money is not much money. That cost should be irrelevant on a safety critical item where the wrong choice and the sake of a tenner might put your boat at risk.

You do not seem to have a clue what you are talking about. "sTrength" is largely irrelevant in this application as seacocks are under no stress being firmly clamped to the hull. Indeed even a completely dezincified brass body (rare) will maintain its integrity unless it is hit or wrenched. This is a well known recommendation to test security of valve bodies when the boat is out of the water for maintenance. Anyway the composite that seacocks are made of is neither weak nor does it corrode so will last indefinitely in this application. Neither are they cheap, being broadly the same price as DZR. You may be thinking of plastic valves used in domestic or freshwater applications which are not suitable for seacocks. Equally as has been pointed out most builders use brass valves as original equipment and the hundreds of thousands in service are mainly trouble free. The RCD is a red herring as it does not specify any particular material, merely stating a minimum life which even brass valves exceed by a substantial margin.

Suggest you price up different types of valve before making a statement about relevant costs. Bronze is significantly more expensive and for a typical modern boat with an average of 10 valves the additional cost will be near £400 over DZR or composite and £6-700 over brass. You might then understand why builders fit brass - and European builders have by and large fitted them for decades with no significant problems.

There may well have been sinkings because of valve failure. The problem is that there is no systematic body of evidence to determine the extent. Also as has already been noted there is more than one cause of failure and all metal bodied valves have weak points such as hose attachment and mixed metal balls/spindle. As suggested above, I do not think that dezincification of brass bodies is a significant cause of sinkings.