zoidberg
Well-known member
Huh! What's it like being right all the bleedin' time....?
Through Hull Advice Needed
- Thread starter Frayed Knot
- Start date
superheat6k
Well-known member
Haven't visited the OP's boat to observe close up the precise circumstances.
But hardly complicated, and the OP was seemingly keen on composite. I simply suggested another option to consider.
Up to him what he does, as is aways the case with readers on here. Some might prefer not to take my advice, or indeed yours !
Tranona
Well-known member
Somewhere earlier in this thread I made an observation about "logic and evidence" seemingly having no place in the debate about through hulls and seacocks (and double clipping hoses!). This has resulted in the idea that yellow metal alloys are an inappropriate material for this application - despite the hundreds of thousands (probably millions) of such items in use in boats without any evidence that such items are failing and boats are sinking. The "moral panic" - to use an idea common in social psychology derives from a misreading of the 1997 RCD requirement that such items should have a minimum service life of 5 years. Somehow this gave rise to the notion that builders were suddenly given licence to save money by fitting cheaper items. Nothing of the sort happened. Most builders were already using plain brass plumbing fittings and valves and had been for many years (and are still doing the same). While plain brass can dezincify it can take a long time and even in advanced state does not necessarily result in failure until the fitting assembly is dismantled and dezincification noted, usually in threads of skin fittings and hose tails rather than valves. Logic will explain why this is the case once you understand the process of galvanic action.
With regard to alternatives - there is a reason why composites were developed in the the US and down under. There was no domestic supply of better alloys such as DZR and particularly down under the imported bronze was very expensive creating a potentially profitable gap in the market. Much the same in the US - just look at the price of bronze fittings there. Not surprising that the 2 main composite makers promote their products as "solving" a problem with metal fittings that really does not exist. Their case is helped by some "professionals" and journalists who exhibit a woeful lack of understanding of the subject not helped by some (mainly British) builders who festooned their boats with anodes connected to through hulls - again to solve a problem that does not exist. This creates an environment that sees corrosion as a problem with metal fittings.
We are all guilty of colluding with this - even me. My 2015 Bavaria had plain brass through hulls (as they all do). Worked perfectly and would, like my previous Bavaria, would likely still be sound after the 15 years I had it. However when I sold it in early 2022 the surveyor noted some pinkness on the external flange of the toilet outlet. You can guess the rest - a £500 contribution to replacing all the through hulls rather than get into an argument that might risk a near £100k sale. Perhaps I should have stood by my principles and proved there was nothing wrong with them by hauling the boat again and taking them all out to prove the point.
This is just one example of where we get ripped off because of misinformation and effectively get forced to buy products or replace items unnecessarily. Not difficult to think of others as they come up regularly here. Once these non evidence based ideas get a hold it is very difficult to dislodge them simply because there is a real lack of reliable data to either prove or disprove them. I come from a background informed by Popper's view that everything should be questioned to move forward, particularly when it is being used by somebody with "skin in the game" - be they manufacturers, surveyors, journalists, insurers and so on.
Getting back then to why my advice to the OP (and anybody contemplating similar) to use DZR. Non metal alternatives sell at a premium , typically 25% more because they are appealing to people who have bought into the idea that they are superior to metal fittings - when they are not - they just claim to solve a problem that doe not exist. They are rarely seen at least in Europe as OE, even by high end builders.
Of course, I understand why some would ignore my advice and appreciate why non metallic through hulls are intuitively attractive, but I hope the above explanation explains the basis for that advice.
With regard to alternatives - there is a reason why composites were developed in the the US and down under. There was no domestic supply of better alloys such as DZR and particularly down under the imported bronze was very expensive creating a potentially profitable gap in the market. Much the same in the US - just look at the price of bronze fittings there. Not surprising that the 2 main composite makers promote their products as "solving" a problem with metal fittings that really does not exist. Their case is helped by some "professionals" and journalists who exhibit a woeful lack of understanding of the subject not helped by some (mainly British) builders who festooned their boats with anodes connected to through hulls - again to solve a problem that does not exist. This creates an environment that sees corrosion as a problem with metal fittings.
We are all guilty of colluding with this - even me. My 2015 Bavaria had plain brass through hulls (as they all do). Worked perfectly and would, like my previous Bavaria, would likely still be sound after the 15 years I had it. However when I sold it in early 2022 the surveyor noted some pinkness on the external flange of the toilet outlet. You can guess the rest - a £500 contribution to replacing all the through hulls rather than get into an argument that might risk a near £100k sale. Perhaps I should have stood by my principles and proved there was nothing wrong with them by hauling the boat again and taking them all out to prove the point.
This is just one example of where we get ripped off because of misinformation and effectively get forced to buy products or replace items unnecessarily. Not difficult to think of others as they come up regularly here. Once these non evidence based ideas get a hold it is very difficult to dislodge them simply because there is a real lack of reliable data to either prove or disprove them. I come from a background informed by Popper's view that everything should be questioned to move forward, particularly when it is being used by somebody with "skin in the game" - be they manufacturers, surveyors, journalists, insurers and so on.
Getting back then to why my advice to the OP (and anybody contemplating similar) to use DZR. Non metal alternatives sell at a premium , typically 25% more because they are appealing to people who have bought into the idea that they are superior to metal fittings - when they are not - they just claim to solve a problem that doe not exist. They are rarely seen at least in Europe as OE, even by high end builders.
Of course, I understand why some would ignore my advice and appreciate why non metallic through hulls are intuitively attractive, but I hope the above explanation explains the basis for that advice.
lustyd
Well-known member
While I agree with the general idea of your post it’s simply not true to say brass fittings don’t fail. There are many examples of them snapping off in peoples hands. Few examples of boats sinking I agree but that’s largely a result of people treating them with kid gloves while afloat because they know there may be a problem.
I moved to TruDesign because they are made of something similar to my boat that won’t degrade over time, is resistant to chemicals, is exceptionally robust, and more importantly I could see from the state of my failing metal fittings that they were not a good solution for a boat. Just because metal is the incumbent doesn’t mean it’s the right solution and using your own logic you should be questioning why you’re so sided with the metal over newer and better options.
I moved to TruDesign because they are made of something similar to my boat that won’t degrade over time, is resistant to chemicals, is exceptionally robust, and more importantly I could see from the state of my failing metal fittings that they were not a good solution for a boat. Just because metal is the incumbent doesn’t mean it’s the right solution and using your own logic you should be questioning why you’re so sided with the metal over newer and better options.
vyv_cox
Well-known member
Indeed so. There are several examples of fitting fracture on my website and I know of many more. Some of these occurred for 'real', when people fell on the hose or fitting when sailing, to be faced with a massive inrush of water.
Unfortunately as so often happens, surveyors interpret slight natural pinkness in fittings as imminent failure
lustyd
Well-known member
If only surveyors could say anything so conclusive and useful. In my experience they say things like
"some pink discolouration found on skin fittings which could indicate dezincification so the fitting may need replacing."
I can't imagine a world where they'd say anything else since they'd be liable if the fitting failed and they said it was safe. Would you confidently say there definitely wasn't a problem? Either way, we can be certain that the FRP fittings won't suffer from dezincification, corrosion, galvanic action etc. and neither will they cause condensation to the same extent, so a more confident answer can be provided. I wouldn't rush out to replace proactively, but at the first sign of trouble I think it's a worthwhile investment.
"some pink discolouration found on skin fittings which could indicate dezincification so the fitting may need replacing."
I can't imagine a world where they'd say anything else since they'd be liable if the fitting failed and they said it was safe. Would you confidently say there definitely wasn't a problem? Either way, we can be certain that the FRP fittings won't suffer from dezincification, corrosion, galvanic action etc. and neither will they cause condensation to the same extent, so a more confident answer can be provided. I wouldn't rush out to replace proactively, but at the first sign of trouble I think it's a worthwhile investment.
Tranona
Well-known member
While there may be examples (as Vyv says) of fittings breaking off when things fall on them - but that is more of an issue of crap design which locates them in vulnerable locations. I would defy anybody to fall on the through hulls on most modern boats where they are usually located inside a locker in the loo compartment. Of course some boats have seacocks located in storage lockers and under bunks, but that is a daft place to put them. Note that I have clearly stated that plain brass potentially dezincifies but it is the consequences (or not) that matters. They are not under any stress in their normal role and therefore highly unlikely to break. I note that TruDesign also have concerns about the robustness of their skin fittings, recommending the fitment of a support collar on the exposed thread to guard against it breaking off if a load is applied sideways.
Anyway the dezincification problem is solved by using DZR fittings which have all the properties you list and indeed better particularly in terms of robustness (see above!). Really cannot see why you think that metal fittings are not compatible with a GRP boat. Both materials are inert and the two are not joined together chemically, but mechanically (as are composite through hulls) so really this is a non issue.
In answer to your last question, while composite valves are newer than metal, although not as new as you might think having been around for 30 years or so, my questioning leads me to whether these products are any "better" than the existing products. My conclusion is no, they have no discernable advantage and when you add the 25% price premium it is difficult to justify fitting them. Just to reinforce this view, my 1979 GRP boat still has its original metal (DZR, but maybe bronze) fittings in place, and a bronze outboard bearing carrier for the propshaft. All bolted with sealer to GRP, none with anodes and all perfect. You could have achieved the same potential longevity and security for your boat by using all DZR fittings at a substantially lower price.
lustyd
Well-known member
Not just when things fall on them, when under operation. You've obviously made your mind up already so perhaps not so keen on questioning things as you thought. They can be under stress in normal operation for a number of reasons, people put things in cupboards, valves get stiff, hoses can add a surprising amount of leverage too. What about replacing a hose while in the water? Having just replaced all of my hoses I can tell you it puts enormous strain on the skin fitting and valve, and would quite easily snap a bad one. Then you're not just dealing with a dodgy hose, you're dealing with rapid water ingress. Depending where it breaks you may also be dealing with the reality that wooden bungs can't be pushed into a half closed seacock that's seized.
So yes, I do think the FRP ones are better in every way. There's nothing in them to corrode or seize, they're warm to the touch so don't cause condensation which can rust jubilee clips. True, they are slightly more expensive and if you can't afford them that's a good reason to stick with metal. As they become more popular the price will come down with economy of scale, and if they become equally priced I don't see a case for metal fittings on a plastic boat.
So yes, I do think the FRP ones are better in every way. There's nothing in them to corrode or seize, they're warm to the touch so don't cause condensation which can rust jubilee clips. True, they are slightly more expensive and if you can't afford them that's a good reason to stick with metal. As they become more popular the price will come down with economy of scale, and if they become equally priced I don't see a case for metal fittings on a plastic boat.
Tranona
Well-known member
All sorts of things "might" happen - but they don't. Given the enormous number of metal through hulls in use even a tiny proportion of failures in the way you describe would be a very large absolute number. Where are they all? I think you have already made up your mind that your decision is sound maybe because you have already made the expensive investment. I do hope you have not used clips that rust. The proper (expensive) clips don't rust.
It is not a question for me of not "affording" to buy the more expensive products - it is about whether the extra cost gives any advantage and you have yet to show there is any real advantage. No, the price will not come down. The makers are not interested in the mass market. They recognise that it is a niche product that will never gain wide acceptance with the real volume users simply because they, like me see no advantage and don't see a problem to be solved.
lustyd
Well-known member
But they do, that's what we're trying to tell you. Lots of examples.
And yes, the number is quite low, but that doesn't mean it's not worth thinking about or moving to a very clearly better option.
The proper clips do rust. The very nature of the installation lends itself to stainless corrosion.
The makers are now selling at volume into both aftermarket and OEM. No idea why you think they're niche, it's already widely accepted and being fitted on many new production boats (not the cheap ones yet). Every through hull conversation on these forums and Facebook groups mention TruDesign and from what I can see they are usually chosen as the best option.
Mistroma
Well-known member
I suspect it is because of the leverage if you jump on the end of the valve tail.
It's easier to apply a huge force when valve is at 90 degrees to the hull. I can see that it is safer to have the valve on the skin fitting but it isn't always possible.
Just a guess but seems reasonable.
I fitted a 2" TruDesign valve on a 90 degree elbow last year. It is in a small covered space and impossible to fit directly without cutting the liner. No chance of standing on it. In fact it's difficult to apply a lot of force at all. One reason for using TruDesign instead of DZR.
lustyd
Well-known member
I would think it's maintainability. The purpose of the valve is to shut the water off in order to work on the things that the through hull serves, or to mitigate leaking plumbing. As such you want it able to close off the through hull as close to the through hull as possible because everything on the outside of the valve cannot be maintained while afloat, and if it leaks there's no way to stop it.
superheat6k
Well-known member
Tranona
Well-known member
That is a gate valve and a good illustration of why it is not recommended and why it is suggested that the OP replaces his with a DZR or bronze ball valve. The failure is nothing to do with the material of the body, but the construction and materials used in the operating mechanism. That is common in gate valves with other materials used for the body.
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Tranona
Well-known member
Not sure why you have so much difficulty in differentiating between plain brass valves such as were fitted to your Jeanneau and DZR which is the preferred replacement. There is dispute that plain brass can dezincify (how many times have I emphasised this? - but maybe nobody reads it!) but even then the failure rate is extremely low.
The valves and fittings suggested for replacement are DZR or bronze and they have exactly the same properties as composite valves - strong, durable corrosion free and resistant to chemicals (not that it is important. Why do you have so much difficulty in recognising this?
316 clips do not rust. There is a remote possibility of crevice corrosion, but not in a modern boat which should be dry. You just have to make sure that all the components are actually 316 as many 2cheap" ones often have mild steel screws which of course are prone to rusting.
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lustyd
Well-known member
I don't at all. We're not just talking about dezincification though.
316 can and does rust. Modern boats are not dry where cold metal through hulls cause condensation in the humid environment. Plastic through hulls do not suffer from this issue, and so yes will be very dry. I did say this previously, I guess you must have missed that part
The Bronze and DZR fittings often have brass balls.
langstonelayabout
Well-known member
Yes, I had a number of 20yo Marelon seacocks literally jam and break or flake apart. They had been fitted as original equipment on my last boat, a Catalina 270.
Plastic seacocks. Never again.
Tranona
Well-known member
316 does not rust in the conventional sense. There may be staining and there is a possibility of crevice corrosion. However that would occur independent of whether the valve or fitting was metal or composite because the stainless is not in contact with the fitting. Read up on the causes of crevice corrosion and you will see why it is highly unlikely in this situation. Do you have any evidence that "cold" metal fittings cause condensation to the extent that it would create suitable conditions to start crevice corrosion? Suspect you are clutching at straws here.I don't at all. We're not just talking about dezincification though.
316 can and does rust. Modern boats are not dry where cold metal through hulls cause condensation in the humid environment. Plastic through hulls do not suffer from this issue, and so yes will be very dry. I did say this previously, I guess you must have missed that part
The Bronze and DZR fittings often have brass balls.
Yes, ball valves normally have nickel plated brass balls running in Teflon. Millions in use without any problems. The brass is not in contact with water and does not suffer from dezincification.
I think you have fallen for the misinformation and searched for spurious reasons to justify your choice. I must again say that I have no problem with people choosing composite valves and fittings - where I take issue is with the simple untruths that are spread to justify the choice.
You have to remember that valves and fittings (except for Blakes) are not unique to marine applications. The vast majority are derivatives from the plumbing and fluid handling industry where extensive research is carried out to minimise corrosion. Even the basic 60/40 brass (copper and zinc) is reasonably corrosion resistant and way exceeds the RCD 5 year requirement which is why it is still used extensively by boatbuilders as it was before the RCD. DZR is a product that was developed for the water distribution industry 40 years or so ago to deal with extreme environments. It is still a copper/zinc alloy but with less zinc and the addition of arsenic and antimony to prevent the wasting of the zinc that happens with 60/40 (and similar zinc rich alloys). It is, for example compulsory for underground installations. The problem for the marine industry is that it is the unique marine fittings (skin fittings, elbows and to an extent hose tails) that until relatively recently were not available in DZR because of the low volume, so expensive bronze was needed to make the whole installation totally corrosion resistant. Now that these fittings are also available in DZR at lower cost than bronze (or composite) it really is difficult to justify the premium price for composite as it no longer offers any advantages - indeed as replacement for existing metal fittings there can be problems because of the extra bulk.
Frayed Knot
Well-known member
I didn’t feel a need to contribute to this thread any further - my original question was answered and I received some helpful advice but then I saw this on the Hallberg Rassy owners group site just now. Thought it might be of interest…
lustyd
Well-known member
Sailing groups on Facebook are littered with posts just like that, it’s very common.