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Old 04-02-2020, 19:41   #136
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Re: Seacock warning, probably most relevant to Australians

Brass is an alloy of copper and zinc. Just like with sacrificial anodes, the zinc molecules in the alloy sacrifice themselves, leaving a Swiss cheese like copper material that is bound to fail.

This is why brass has no place here, unless completely encapsulated like by plating it with chrome. That protection ends as soon as the plating fails due to wear or aging.
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Old 04-02-2020, 20:43   #137
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Re: Seacock warning, probably most relevant to Australians

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Originally Posted by Dockhead View Post
Only the cheap skin fittings lack the "ears". You have a stepped wrench which engages the "ears" to hold the skin fitting in place from the outside of the hull when you snug the nut down.


HOWEVER, having changed a lot of these, and owning the wrench, the usual approach is different. Well bedded down in Sika and snugged down, the skin fittings don't go anywhere. So I generally don't use the wrench when replacing ball valves. In one out of ten cases, the skin fitting turns in the hull when you are loosening the ball valve, and I take that as a sign that the bedding was not good enough, and so then I replace the whole lot including the skin fitting. If the skin fitting is solidly bedded in enough to take all that turning, and passes the dezincifiation test, it stays.
but what if your in the middle of the atlantic solo sailing and you have to do this? this is why a thru bolted , flanged seacock is so critical. there is no haul out if the thru hull sealant breaks free far offshore because you had to replace a damaged or leaking valve, and you certainly are not going to be able to dive and secure the thru hull while trying to remove the valve from the inside at the same time...

I guess it still boils down to how the boat will be used but for any offshore work I would personally never consider anything but thru-bolted flanged seacocks made of all bronze.
they are expensive but not prohibitively so...
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Old 05-02-2020, 03:48   #138
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Re: Seacock warning, probably most relevant to Australians

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but what if your in the middle of the atlantic solo sailing and you have to do this? this is why a thru bolted , flanged seacock is so critical. there is no haul out if the thru hull sealant breaks free far offshore because you had to replace a damaged or leaking valve, and you certainly are not going to be able to dive and secure the thru hull while trying to remove the valve from the inside at the same time...

I guess it still boils down to how the boat will be used but for any offshore work I would personally never consider anything but thru-bolted flanged seacocks made of all bronze.
they are expensive but not prohibitively so...

Why would you ever need to remove a ball valve in the middle of the ocean? Have even ever heard of such a case? Do you carry spare ball valves? I have about 1000kg of spares on board, but I don't keep those. Also, only a flanged adapter would allow you to possibly change a ball valve at sea -- what it touted as the best solution of all, a proper integral flanged sea cock, also does not allow you to change the ball valve like that. If the ball valve goes bad, you have to haul out.

And why would the sealant break free just from sailing? And even if it did, how would that be different with a flanged sea cock or flanged adapter?

These are non-existent problems.

Look, we've discussed this ad nauseum, and there is no objective answer to this question which satisfies everyone.

Flanged sea cocks and flanged adapters are stronger but have other disadvantages. Some people really want that extra strength -- great! Your boat; your choice. How much strength do you think you need, and why? 1 tonne? 10 tonnes? Where does it end? A small normal skin fitting holds 400 pounds of force according to MaineSail's testing -- that means it will withstand more than two of me standing on it sideways. That's plenty strong enough for me and for the entire community of European sailors too. So I don't feel any compulsion to drill 17x3 more holes in the bottom of my boat in order to change my normal European skin fittings to flanged adapters. My boat, my choice.

The best is the enemy of the good, and you can't stop there in making a rational decision about what to go for. The rational choice is not always the strongest or best possible thing you could buy or install.

I also think it's odd that we focus on this one aspect of the design of sea cocks. Flanged sea cocks are stronger, but they're still bronze, and bronze is not the perfect material, so neither are they actually the "best". If you are so hungry for the absolutely perfect sea cock, why are you satisfied with bronze, which is subject to dezincification and corrosion under some circumstances?

Your answer is that bronze is "good enough" -- it's much better than brass and it often lasts 50 years in this application. And it IS good enough, in the same sense as normal skin fittings, which often last 50 years in this application, are good enough. But bronze is not perfect just like normal skin fittings are not perfect -- there are better choices. Only question is whether the better choices are worth it, and everyone has to make his own judgement.

The PERFECT sea cock would be made out of titanium, not bronze. And a titanium sea cock would be a rather big leap forward, a much bigger difference than the difference between normal skin fittings and flanged adapters, all of the same compromise material. I'm not much interested in flanged adapters, but I would definitely be interested in titanium underwater fittings, and changing to that would be worth some trouble and investment to me. But again, your boat, your choices!
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Old 05-02-2020, 06:12   #139
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Re: Seacock warning, probably most relevant to Australians

Except that one does not drill any extra holes in their hull for flanged adapters or seacocks. Actually reading MarineHowTo articles that are so important is helpful to at least understand the point of view and how to implement the actual installation procedure. Only then such decisions can be made insightful.

Then the 400lb loading. Why would the ABYC fail an installation that can withstand 400lb sideways loading? You must understand that before being able to judge it. They did not come up with their numbers for just withstanding a static loading; most incidents are caused by shock loading like during a fall or an engine breaking loose off itís mounts etc.
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Old 05-02-2020, 12:47   #140
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Re: Seacock warning, probably most relevant to Australians

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Originally Posted by Dockhead View Post
Why would you ever need to remove a ball valve in the middle of the ocean? Have even ever heard of such a case? Do you carry spare ball valves? I have about 1000kg of spares on board, but I don't keep those. Also, only a flanged adapter would allow you to possibly change a ball valve at sea -- what it touted as the best solution of all, a proper integral flanged sea cock, also does not allow you to change the ball valve like that. If the ball valve goes bad, you have to haul out.

And why would the sealant break free just from sailing? And even if it did, how would that be different with a flanged sea cock or flanged adapter?

These are non-existent problems.

Look, we've discussed this ad nauseum, and there is no objective answer to this question which satisfies everyone.

Flanged sea cocks and flanged adapters are stronger but have other disadvantages. Some people really want that extra strength -- great! Your boat; your choice. How much strength do you think you need, and why? 1 tonne? 10 tonnes? Where does it end? A small normal skin fitting holds 400 pounds of force according to MaineSail's testing -- that means it will withstand more than two of me standing on it sideways. That's plenty strong enough for me and for the entire community of European sailors too. So I don't feel any compulsion to drill 17x3 more holes in the bottom of my boat in order to change my normal European skin fittings to flanged adapters. My boat, my choice.

The best is the enemy of the good, and you can't stop there in making a rational decision about what to go for. The rational choice is not always the strongest or best possible thing you could buy or install.

I also think it's odd that we focus on this one aspect of the design of sea cocks. Flanged sea cocks are stronger, but they're still bronze, and bronze is not the perfect material, so neither are they actually the "best". If you are so hungry for the absolutely perfect sea cock, why are you satisfied with bronze, which is subject to dezincification and corrosion under some circumstances?

Your answer is that bronze is "good enough" -- it's much better than brass and it often lasts 50 years in this application. And it IS good enough, in the same sense as normal skin fittings, which often last 50 years in this application, are good enough. But bronze is not perfect just like normal skin fittings are not perfect -- there are better choices. Only question is whether the better choices are worth it, and everyone has to make his own judgement.

The PERFECT sea cock would be made out of titanium, not bronze. And a titanium sea cock would be a rather big leap forward, a much bigger difference than the difference between normal skin fittings and flanged adapters, all of the same compromise material. I'm not much interested in flanged adapters, but I would definitely be interested in titanium underwater fittings, and changing to that would be worth some trouble and investment to me. But again, your boat, your choices!
**** happens unexpectedly mate. You seem to be arrogantly confident in the fact you got it all figured out. Good luck to you.
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Old 05-02-2020, 13:48   #141
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Re: Seacock warning, probably most relevant to Australians

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**** happens unexpectedly mate. You seem to be arrogantly confident in the fact you got it all figured out. Good luck to you.

Well, let me understand you. So you think that it's critically important that your seacocks be configured so that you can change a ball valve without hauling out. Did I get that right?


But then what about the classical flanged seacock, valve integral with the flange, which is considered the best of the best? You can't change that without hauling out either.


So you're saying the only acceptable solution is the flanged adapter with the separate screwed on ball valve? And the classical flanged sea cock is unacceptable?


You carry spare ball valves for such an eventuality?
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Old 05-02-2020, 13:56   #142
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Re: Seacock warning, probably most relevant to Australians

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Originally Posted by s/v Jedi View Post
Except that one does not drill any extra holes in their hull for flanged adapters or seacocks. Actually reading MarineHowTo articles that are so important is helpful to at least understand the point of view and how to implement the actual installation procedure. Only then such decisions can be made insightful.

Then the 400lb loading. Why would the ABYC fail an installation that can withstand 400lb sideways loading? You must understand that before being able to judge it. They did not come up with their numbers for just withstanding a static loading; most incidents are caused by shock loading like during a fall or an engine breaking loose off itís mounts etc.

Well, fair enough, and I have plenty of respect for ABYC, which I cite often in arguments about gas safety.


But still -- what is strong enough? 400 lbs isn't strong enough, then why is 500 lbs strong enough? Why not 800 lbs? 1500 lbs? 50,000 lbs? Where does it end?



Just because something is stronger doesn't mean you can't live without it. You have to figure out what is strong enough for your purposes. That is basic engineering by the way.


My sea cocks are not located where someone can fall on them or a runaway engine can fall on them (and I'm absolutely sure that a runaway engine would bust even the best integral flanged sea cock anyway). There is no way any of my sea cocks can be subjected to shock loads, and 400 pounds seems quite adequate to me. I worry more about dezincification and dream about titanium.


You may come to different judgements, and that's fine! Your boat, your rules.
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Dash me with amorous wet . . . . I can repay you."
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Old 05-02-2020, 14:30   #143
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Re: Seacock warning, probably most relevant to Australians

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How old were the fittings when this happened? And which brand or supplier?


They failed between 4-8 years after installation. The supplier/manufacturer was Guidi.
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Old 05-02-2020, 15:53   #144
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Re: Seacock warning, probably most relevant to Australians

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Well, fair enough, and I have plenty of respect for ABYC, which I cite often in arguments about gas safety.


But still -- what is strong enough? 400 lbs isn't strong enough, then why is 500 lbs strong enough? Why not 800 lbs? 1500 lbs? 50,000 lbs? Where does it end?



Just because something is stronger doesn't mean you can't live without it. You have to figure out what is strong enough for your purposes. That is basic engineering by the way.


My sea cocks are not located where someone can fall on them or a runaway engine can fall on them (and I'm absolutely sure that a runaway engine would bust even the best integral flanged sea cock anyway). There is no way any of my sea cocks can be subjected to shock loads, and 400 pounds seems quite adequate to me. I worry more about dezincification and dream about titanium.


You may come to different judgements, and that's fine! Your boat, your rules.
The failures related to engines breaking free come from the attached water hose, not impact from the engine. The exhaust and water hoses are what hold the engine. One of the best kept secret upgrades is steel wire straps around the engine mounts for backup in case the rubber splits
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Old 05-02-2020, 16:47   #145
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Re: Seacock warning, probably most relevant to Australians

[QUOTE=s/v Jedi;3068381]Except that one does not drill any extra holes in their hull for flanged adapters or seacocks. Actually reading MarineHowTo articles that are so important is helpful to at least understand the point of view and how to implement the actual installation procedure. Only then such decisions can be made insightful.

I don't understand, never seen a flanged thru hull, but the article I read says you through bolt the flange thru the hull into the thru hull fitting. And countersink the holes from the outside.
So now we have a big hole and two or three little ones in the same area for each thru hull right?
On a glass hull this seems like an answer to a problem that doesn't exist and I would think the degradation of hull strength in these areas would be more of an issue than any perceived problems with a standard thru hull.
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Old 05-02-2020, 18:12   #146
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Re: Seacock warning, probably most relevant to Australians

[QUOTE=NevilleCat;3068758]
Quote:
Originally Posted by s/v Jedi View Post

I don't understand, never seen a flanged thru hull, but the article I read says you through bolt the flange thru the hull into the thru hull fitting. And countersink the holes from the outside.
So now we have a big hole and two or three little ones in the same area for each thru hull right?
On a glass hull this seems like an answer to a problem that doesn't exist and I would think the degradation of hull strength in these areas would be more of an issue than any perceived problems with a standard thru hull.
I have 4 of these flanged installations and none of them are through bolted to the hull, all are fitted with GROCO backing plates with press threaded inserts, no need to drill through the hull so absolutely ZERO extra degradation.....





....the beauty of this installation is i have no fear of breaking the seal on the thru-hull when removing the valve for servicing while the vessel is in the water....
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Old 05-02-2020, 21:27   #147
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Re: Seacock warning, probably most relevant to Australians

[QUOTE=IslandHopper;3068793]
Quote:
Originally Posted by NevilleCat View Post

I have 4 of these flanged installations and none of them are through bolted to the hull, all are fitted with GROCO backing plates with press threaded inserts, no need to drill through the hull so absolutely ZERO extra degradation.....



...the beauty of this installation is i have no fear of breaking the seal on the thru-hull when removing the valve for servicing while the vessel is in the water....

That looks nice, very strong, with the backing plate glassed into to the inside of the hull, but a lot of labor to install.



But still -- you remove your ball valves for servicing while the vessel is in the water? Really? What kind of ball valves need that kind of service? Why in the world would you do it in the water when you would have to take the hoses off and deal with the fountain of seawater coming into the boat, rather than waiting for your next haulout? I never heard of anyone servicing ball valves like that and I can't imagine what the purpose could possibly be. Quality ball valves don't need any service except a squirt of grease every year or so when the boat is out of the water, and I actually doubt whether even that is needed since the chromed balls run in PTFE seals. What they really need is to be regularly worked so growth doesn't form in the seals.
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Old 05-02-2020, 21:29   #148
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Re: Seacock warning, probably most relevant to Australians

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The failures related to engines breaking free come from the attached water hose, not impact from the engine. The exhaust and water hoses are what hold the engine. One of the best kept secret upgrades is steel wire straps around the engine mounts for backup in case the rubber splits

That's a good tip, really something to think about. Maybe I'll put that on my list.
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Cushion me soft . . . . rock me in billowy drowse,
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Old 05-02-2020, 22:41   #149
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Re: Seacock warning, probably most relevant to Australians

[QUOTE=Dockhead;3068855]
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Originally Posted by IslandHopper View Post


That looks nice, very strong, with the backing plate glassed into to the inside of the hull, but a lot of labor to install.



But still -- you remove your ball valves for servicing while the vessel is in the water? Really? What kind of ball valves need that kind of service? Why in the world would you do it in the water when you would have to take the hoses off and deal with the fountain of seawater coming into the boat, rather than waiting for your next haulout? I never heard of anyone servicing ball valves like that and I can't imagine what the purpose could possibly be. Quality ball valves don't need any service except a squirt of grease every year or so when the boat is out of the water, and I actually doubt whether even that is needed since the chromed balls run in PTFE seals. What they really need is to be regularly worked so growth doesn't form in the seals.
Plenty of people service seacocks in the water on a regular basis including the PO of my boat, he installed the first 2 and i did the other 2, not difficult at all. Like many others I don't haul out every year, the state of my antifoul usually dictates that not some date on the calendar, and the less i have to do on the hard the better. In 2 months time it will be 2 years since she was last on the hard and after recently inspecting and scrubbing the hull i doubt she will be coming out for at least another 6 months unless something untoward happens.

My 8 year old quality GROCO's operate like brand new off the shelf units and i like to keep them that way, a couple of hours preventive maintenance here and there is bugger all and is great peace of mind.

So as your fond of saying......Your boat, your rules.

Oh, and as for the fountain of water, don't you have a set of these? they sell enough of them worldwide to stay in business so quite obviously plenty do remove while in the water.

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Old 05-02-2020, 22:56   #150
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Re: Seacock warning, probably most relevant to Australians

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Ouch!

Iím paid through to the 17th, I am determined to leave by then.
The Trudesign seacocks, thruhulls etc are made in New Zealand.
They should be readily available on Oz.
They are ABYC certified.
They don't seize.
They will never corrode.
They are available in both tapered and straight threads.

Why stay with bronze on a plastic boat?
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