Dodgy through hull picture - should I panic?

[vyv_cox]

J

Maybe we can get this back on track by taking another look at a seacock please? Since the earlier picture I've been round them all and cleaned them up. One fitting appeared quite pink before wire brushing but afterward cleaned up nicely, see photo below. There is still some evidence of pink in the threads but interestingly the more I wire brush it the less significant is the pink. I'm assuming therefore that the pinking is on the surface and perhaps therefore not the problem that it might otherwise be?

Your thoughts would be welcome and appreciated.

Rob

The pinkness of dezincification is the result of corrosion by seawater. You are looking at the exterior of the skin fitting that has probably never come into contact with seawater, or at worst very briefly. Brass fittings sometimes look rather pink, especially on the surface of threads, for a reason that I do not know but presumably some sort of reduction in zinc content caused during thread forming. You have absolutely no cause for concern.

When skin fittings and hose tails fail by dezincification it is because the loss of zinc occurs inside the fitting to pretty much equal depth. However, the external thickness of the fitting varies because it is threaded. If you could see red colouration at the roots of the threads but not elsewhere it would be worth investigating further. However, the most effective test is the one I mentioned several pages ago - heave on the hose. Very many people who have suffered failure of seacocks due to dezincification did so when they leaned on the hose when doing something else and it snapped off.

 

[prof pat pending]

There's nothing wrong with the fitting, my advice would be to leave it be.

As for the pink surface, you obviously keep everything very clean in there. Do you clean the seacock with anything?
There is evidence of Patina (green coating) under the outlet, but nowhere else on the fitting.

 

[GrahamM376]

Maybe we can get this back on track by taking another look at a seacock please? Since the earlier picture I've been round them all and cleaned them up. One fitting appeared quite pink before wire brushing but afterward cleaned up nicely, see photo below. There is still some evidence of pink in the threads but interestingly the more I wire brush it the less significant is the pink. I'm assuming therefore that the pinking is on the surface and perhaps therefore not the problem that it might otherwise be?
Your thoughts would be welcome and appreciated. Rob

If you look at the photos I posted early on on the thread, you will see that very little pink showed up on the surface of mine and, like yours, it seemed to disappear with wire brushing. When I took the seacock and nut off, I repeated what I had done with the others, stuck the stilson handle down to give it a wiggle and break the sealant. The through hull just broke into pieces and, as can be seen from the other photo, pink virtually all the way through except for the threads.

For the sake of a few quid and an hour or two work, my advice is to change them if in any doubt - others obviously disagree.

 

[[2574]]

Was that just a wire brush --or have you used an acid or other sort of cleaner.

Just a wire brush, nothing more.

 

[TheOrs]

J

The pinkness of dezincification is the result of corrosion by seawater. You are looking at the exterior of the skin fitting that has probably never come into contact with seawater, or at worst very briefly. Brass fittings sometimes look rather pink, especially on the surface of threads, for a reason that I do not know but presumably some sort of reduction in zinc content caused during thread forming. You have absolutely no cause for concern.

When skin fittings and hose tails fail by dezincification it is because the loss of zinc occurs inside the fitting to pretty much equal depth. However, the external thickness of the fitting varies because it is threaded. If you could see red colouration at the roots of the threads but not elsewhere it would be worth investigating further. However, the most effective test is the one I mentioned several pages ago - heave on the hose. Very many people who have suffered failure of seacocks due to dezincification did so when they leaned on the hose when doing something else and it snapped off.

It does look pinker at the root of the threads than it does on the peaks. Could it be that the fitting has de-zincified from the inside out through the threads as Graham suggests below.

I agree with your suggestion of trying to break it with a little pressure in a controlled way.

 

[pvb]

It does look pinker at the root of the threads than it does on the peaks. Could it be that the fitting has de-zincified from the inside out through the threads as Graham suggests below.

I agree with your suggestion of trying to break it with a little pressure in a controlled way.

And what if this "controlled" semi-destructive testing results in an undetected fracture, leading to a subsequent catastrophic failure?

 

[30boat]

And what if this "controlled" semi-destructive testing results in an undetected fracture, leading to a subsequent catastrophic failure?

Better have the boat on the dry.

 

[TheOrs]

And what if this "controlled" semi-destructive testing results in an undetected fracture, leading to a subsequent catastrophic failure?

And what if not testing it results in an undetected fracture, leading to a subsequent catastrophic failure?

It's hard to know what's for the best. I've been reading (dangerous, I know!) a bunch of stuff recently about marine corrosion and de-zincification of brass fittings and personally I would be wanting to be very sure that fitting was ok. I think that if you heave on it, it will either break or be ok. I don't really understand how pulling on the fitting would result in a small, undetected fracture.

 

[ghostlymoron]

I think some of you are getting a bit paranoid.

 

[TheOrs]

I think some of you are getting a bit paranoid.

You're probably right!

Everything I fix on my boat; two more break! I'm starting to realise now that this is just the way it is.

 

[GrahamM376]

I think some of you are getting a bit paranoid.

I think it's more a case of what one's priorities are. Reading many threads over the years, ir seems some people (talking in general terms, no-one specific) are quite willing to spend their hard earned money on chart plotters, instruments, i pads etc. but ask for advice on how to avoid spending a few quid to replace items which, if they fail, have the potential to sink the boat or maybe bring the mast down. As has already been pointed out by someone in this thread, corrosion is a big get-out with some insurers so I prefer to think of it as playing safe rather than paranoia.

 

[rivonia]

I think it's more a case of what one's priorities are. Reading many threads over the years, ir seems some people (talking in general terms, no-one specific) are quite willing to spend their hard earned money on chart plotters, instruments, i pads etc. but ask for advice on how to avoid spending a few quid to replace items which, if they fail, have the potential to sink the boat or maybe bring the mast down. As has already been pointed out by someone in this thread, corrosion is a big get-out with some insurers so I prefer to think of it as playing safe rather than paranoia.

Excellent summing up. Take this advice. Do not take the risk.

 

[pyrojames]

Excellent summing up. Take this advice. Do not take the risk.

In that case you better replace your rigging, remove your gas, check all your engine wiring for chafe, but you might as well replace it anyway, check your diesel tank for water, and if there is any pull it out and fit a new tank, because you might never get rid of the bug and the engine might stop on a lee shore, check for any corrosion inside and out on you mast and if you can't get to all parts of it you better have a new mast, replace all your water hoses each spring in case the cold weather has made one brittle and fails while you are sailing, better get new life jackets each season in case the cylinders corroded over the winter, or the bladders chaffed in the car on the way home, you better get a new anchor chain in case that has imperfections that you can't detect with some serious NDT kit, then you will need to get a professional chauffeur in a large car to take you to the boat and back, because we know that is the most dangerous thing you a going to do on a sailing trip.

You know it makes sense. You just can't take the risk.

 

[pvb]

In that case you better replace your rigging, remove your gas, check all your engine wiring for chafe, but you might as well replace it anyway, check your diesel tank for water, and if there is any pull it out and fit a new tank, because you might never get rid of the bug and the engine might stop on a lee shore, check for any corrosion inside and out on you mast and if you can't get to all parts of it you better have a new mast, replace all your water hoses each spring in case the cold weather has made one brittle and fails while you are sailing, better get new life jackets each season in case the cylinders corroded over the winter, or the bladders chaffed in the car on the way home, you better get a new anchor chain in case that has imperfections that you can't detect with some serious NDT kit, then you will need to get a professional chauffeur in a large car to take you to the boat and back, because we know that is the most dangerous thing you a going to do on a sailing trip.

You know it makes sense. You just can't take the risk.

That's the reality - there are always risks.

 

[GrahamM376]

That's the reality - there are always risks.

Obviously there are always risks and it's funny that although pyro's list reads as if taking all his listed actions are over the top, several of them are normal items for inspection anyway. We'll obviously have to agree to disagree on when an item need replacing but the following is copied verbatim from my insurance documents:-

if an owner is aware of a defect in his craft (including defects due to corrosion) and takes little or no remedial action, or takes no action to inspect/regularly maintain the craft to prevent such even occurring, it would be unreasonable to expect insurers to pay for damage that could have been avoided had some very basic care and due diligence been applied to protect the craft

 

[prof pat pending]

But then again, is it a defect or is it just a bit discoloured?
If you're going to suggest that everthing that doesn't look brand new is relpaced, most of us will be looking for new boats

 

[duncan99210]

I think, looking at the pictures that there is no cause for replacement. However, when the boat is hauled, the external appearance of the fitting should be examined and if there is any cause for concern (significant pitting, discolouration) then it should be replaced. Perhaps a good heave on the pipe work when out of the water alongside the visual inspection would be a decider if there is no external evidence of corrosion: if it breaks, there's the answer, if it doesn't and there's no external evidence, then leave as is.

 

[ghostlymoron]

All the fittings are likely to be in the same condition so if you think that one is defective, you should replace them all. However, whilst i agree that the condition of skin fittings is important, I think you are being unnecessarily gloomy.

 

[rib]

just read from start to finish fantastic reading got every thing in it brill well done lads

 

[rivonia]

It would be most interesting if the OP started a survey on this topic, to find out which way the majority are voting?