Near disaster - broken thru-hull fitting - your comments appreciated

[scubaman]

After a five hour cruise yesterday we moored up in Hanko. Roughly fifteen minutes later the bilge pump started going and I went down to investigate. Following the alarming sound of gushing water it transpired that one of the through hull fittings had broken and we were taking on water at an uncomfortable rate.

The fitting is for draining one of the storage lockers in the cockpit and is situated on the side of a trim tab ‘tunnel’ in the aft port side.

As a first aid, I blocked the hole with a plastic bag from the outside and later replaced that with a wooden bung. After a while the bung did it’s job and the leak was reduced to a few drops so it was time to calm down...

I’m now waiting for a lift-out at around 3 pm this afternoon for replacing the fitting and to have a good look at the other fittings with an endoscope.

The fitting has sheared right from the bottom. Initial analysis of a marine services guy who visited the boat was that it might have been over tightened and due to the weight of the ball valve has slowly given in. We’ll know more once it’s removed and we can have a proper look.

The other fittings seem ok externally, the broken one shows signs of a prolonged leak which I had missed in the spring (white powder).

I would really appreciate any and all comments you might have on things to take into consideration when fitting the new one, causes of the breakage, etc.

I’m just happy it didn’t happen when we were out in the middle of the sea...

Thanks in advance!

 

[oGaryo]

Unless I misunderstand, can the risk of reoccurance be avoided completely by doing away with the drain if that's all it is doing and find another way to drain the locker (via the bilge pump or routed through to another area of the boat that has a drain). just thinking the more underwater holes you have in a boat exponentially increases the risk of another near disaster occuring

 

[boatingdave]

Hi. Through hull fittings do actually have a 'life'. They erode slowly anyway. Normally they are checked and if there is excesive oxidisation then they need to be replaced. Given the cost of a lift our versus the cost of the valve any that show excessive erosion/corrosion should be replaced. They can also be impacted by dissimilar metal errosion. There are different variants out there. I would suggest its unlikely to be stress related fatigue although they have been known to fracture if overtightened but that normally manifests itself quite quickly.

 

[cloud7]

It's worth considering bronze through hull seacocks , a lot manufacturers fit brass which have a sort life span . I had a similar experience on a 5 year old boat , the brass seacocks had a lot corrosion .

 

[Tranona]

In your first photo that looks like dezincification of the skin fitting. The skin fitting is probably brass and when you replace it use either DZR or bronze to avoid that in the future. You may want to consider changing all of the skin fittings (and probably the valves as well), although the valve looks like it is DZR as it has CR (corrosion resistant) cast into the body.

The easiest way to replace the skin fitting is to grind off the outer flange and push it through as you will find it is not easy to dismantle the assembly with it in place.

 

[MapisM]

Wow K, glad that it remained a NEAR disaster, eventually!
Not much to add to what has already been said re. the material of these things, but was that a factory installation?
A hole under the waterline just for draining doesn't seem a good idea to me...

PS: Fwiw, I'm also a bit skeptical about overtightening as a reason for failure.

 

[vas]

In your first photo that looks like dezincification of the skin fitting.

+1

cut area looks very carotty to me K.!

If that's the case, I'd go through the trouble of undoing and scrapping ALL THE SKINFITTINGS and replacing them with decent ones. If you're unsure of brass bronze et al, go for GRP as I did with MiToS and fitted Trudesign ones, extremely strong, flexible and unlikely to rot dezinc or whatever

I'd be very afraid to keep travelling with unknown condition of skin fittings!

cheers

V.

 

[Nick_H]

Yep, that pink colour on the broken edge of the fitting is a clear indication of zinc leaching.

Here's a brass fitting that I removed from my boat after only 2 years. It's the same pink colour. I could break pieces off it with my fingers.

 

[Ripster]

Lots of information here: https://coxengineering.sharepoint.com

AGree with others that your pics show pinking on the broken fitting which indicates dezincing. Again, as others have said, change your other skin fittings as well - the valves may OK still as they are much larger lumps, but for what they cost, worth doing them all or at least those BWL.

 

[Pinnacle]

K

Glad you were there to stem the flow!

We carefully inspected the skin fittings on our boat when it was ashore and to our alarm, I was able to break several without any real effort. At that point, the boat (a Beneteau) was about 9 years old. They all looked like Nick_H's photo above.
I think it would be a good idea to look at every one carefully - including giving it a bit of a wiggle - and if all seem to be ok, then plan to take every one apart over next winter. If you can take it apart and it is in good condition, it will go back together again. If its getting weak, then the act of trying to take it apart will almost certainly break it. The modern "plastic" ones seem to be fit-and-forget, but may not be suitable in the engine room (if you have any fittings located there).

Best of luck.

 

[vas]

The modern "plastic" ones seem to be fit-and-forget, but may not be suitable in the engine room (if you have any fittings located there).

Best of luck.

I agree with all the points made, but why plastic fittings are not suitable for e/r?
If it's risk of fire/heat related, the hoses from them to the filters and engine waterpumps will surely melt before the fittings, so don't see any difference tbh.
That is unless I'm missing something

cheers

V.

PS. I wouldn't sleep at night fearing that the other skin fittings are in similar condition...

 

[jimmy_the_builder]

I'm agreeing with everyone else that your failed skin fitting looks like it has dezinced (Nick_h's photo is a great reference). While the boat is out of the water it would be worth firmly tapping all the other skin fittings with a small hammer - you should get a dull sound from your failed fitting, and a clearer 'ting' from sound fittings. You can also scrape them from the outside with a screwdriver to see if they are soft/pink.

When the worst happens, wooden bungs are good but this might have been easier and quicker to deploy:
http://www.seabung.com/

I replaced one of mine with bronze late last year - but at the time I did wonder if Marelon would be a better long-term choice; I'd be interested to know if there are any compelling reasons to *not* switch to non-metallic skin fittings.

Good luck with it though, and very well done for catching it in time to prevent a bigger problem.

 

[Bandit]

Looks carotty which is pink and also crumbles or breaks in your hand.

de zincification looks like the cause .

The valve is marked cr which should be corrosion resistant but it's the skin fitting not the valve which has broken.

You are late in the season for you, replace any that are showing signs of leakage or are suspect now.

when she comes out of the water for the winter I would consider replacing all skin fittings and valves with DZR.

how old is the boat and how many years has she spent in salt water.

 

[volvopaul]

I know the ones you mean, they constantly blocked up on my Phantom 43, a real bad design to drain the storage locker on the port side and the cockpit drains, why ther not sited just above the waterline I don't know, I ended up pouring brick acid down mine to unblock it as it was impossible to do otherwise.
I'd guess as it sited next to the trim tabs it's acting as an anode as well, and it's not earth bonded to the rest of the system.

 

[julians]

I don't know the manufacturer of the boat in question in this thread,but why do reputable manufacturers fit brass fittings?

And how do we allow them to get away with it?

Does anyone know what windy used back in 2006?

 

[scubaman]

Thank you everyone for your input, your comments have been thoroughly read and much appreciated. The boat was lifted today and I replaced both the fitting and the ball valve at the same time. I'll post pics tomorrow but it would seem that dezincification as you have described has been the problem, although the parts weren't as brittle as described. There has been a prolonged leak through the fitting and I'm wondering if that could have contributed to the matter?

I also unscrewed the bolt from other fittings (which look perfect externally) and gave them a good wiggle but they appeared solid so for now I'm confident that they will be ok until the end of the season and the winter lift out.

I agree that the design is a bit daft and Gary's suggestion to drain the locker into the bilges makes a lot of sense.

Also as I commented on an earlier thread on a similar topic, the non metallic fittings and valves would seem like a good solution. In that case I noted from one manufacturer's website that the operating temperature was limited to 80 C, which may not be enough for all engine rooms. Would be fine on any other use though.

That Seabung looks very interesting. Seems a much better solution that wooden bungs.

My boat (Fairline Phantom 43) is from 2003 and has spent first nine years of it's life in the uk, and the rest in the Lake Saimaa or in the baltic sea which has a very low salinity.

On a more general note, just the experiences on this thread do make one wonder how is it possible that boat builders use that cr@p to keep their boats afloat... Pardon my french...

But for now it seems that the situation is under control, the boat is back in the water and I have a nice cold beer next to me when I'm typing this. Thank you again for all your comments.

 

[Pinnacle]

I agree with all the points made, but why plastic fittings are not suitable for e/r?
If it's risk of fire/heat related, the hoses from them to the filters and engine waterpumps will surely melt before the fittings, so don't see any difference tbh.
That is unless I'm missing something

cheers

V.

PS. I wouldn't sleep at night fearing that the other skin fittings are in similar condition...

Vas

I can't find it now, but not long ago there was a thread on this very point. IIRC, it was jfm commenting on the marelon fittings. I guess it comes down to a burnt out hose won't sink you - you simply close the sea cock. If the skin fitting comes off in your hand when you try to shut the valve, you have a much bigger problem.

In any event, I am delighted Scubaman is now happy and drinking a beer!

 

[petem]

On a more general note, just the experiences on this thread do make one wonder how is it possible that boat builders use that cr@p to keep their boats afloat

Wash your mouth out with soapy water!

What causes de zincification (is it electrolysis)?

Anyhow, in the pics above, the valves look OK so surely it wouldn't be expensive just to change all the thru-hull skin fittings as a precaution?

Here's the previous thread on the same subject http://forums.ybw.com/forums/showthread.php?457886-Seacock-broke-in-my-hand!/page3&highlight=marelon.

 

[MapisM]

Wash your mouth out with soapy water!

C'mon P, you can't expect Fairline to be praised for drilling holes below the w/l to drain storage lockers, regardless of the skin fitting material... :ambivalence:

 

[petem]

C'mon P, you can't expect Fairline to be praised for drilling holes below the w/l to drain storage lockers, regardless of the skin fitting material... :ambivalence:

I'll concede on that point!