Author Topic: Seacock / skin fitting  (Read 11140 times)

CRYSTAL

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Seacock / skin fitting
« on: January 13 2016, 16:11 »
See attached pics of my skin fitting on my bav33C ( 9yrs ).
This is the orig fitting totally deteriorated. Luckily it happened during its replacement while lifted out. This should have been replaced 2yrs ago if not more. Total crap brass. Mind you the valve is in excellent condition but the whole set will be replaced with bronze.

It broke away while at tempting to remove the 1.5" hose and split where the skin fitting joins the valve.

Textbook example of galvanic corrosion! !!!

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tiger79

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Re: Seacock / skin fitting
« Reply #1 on: January 13 2016, 17:20 »
Textbook example of galvanic corrosion! !!!

Surely it's a textbook example of dezincification, nothing to do with galvanic corrosion.

CRYSTAL

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Re: Seacock / skin fitting
« Reply #2 on: January 13 2016, 18:04 »
Isn't galvanic corrosion the overall mechanism by which dezincification occurs?
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JEN-et-ROSS

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Re: Seacock / skin fitting
« Reply #3 on: January 13 2016, 21:42 »
Encountered the same problem several years ago when one sheared off  :(( on the hard! phew! :)). Same pink de-zinced colour  :(.
Replaced them all with Forespar Marelon, so no worries now :). Incidentally they cost rather less than 'proper' traditional DZR or Bronze  ;).

Yngmar

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Re: Seacock / skin fitting
« Reply #4 on: January 13 2016, 22:00 »
I've replaced all of my 15 year old skin fittings and ball valves last year with Tru-Design plastic ones. The old looked similar to yours, although not quite as bad.

Very happy with the plastic ones, no metal, no worries - I've painted Coppercoat right into the inside of them just shy of the ball, so no fouling either.

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CRYSTAL

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Re: Seacock / skin fitting
« Reply #5 on: January 14 2016, 06:45 »
Yngmar, 15yrs??? I guess Bav used quality fittings back then?

Jen-et-Ross just out of curiosity, how old was the boat when you changed them?

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Lyra

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Re: Seacock / skin fitting
« Reply #6 on: January 14 2016, 07:32 »
My 2004 B36 were 11 years old when I replaced them last year.
I did not like the external discoloration that propagated during the last two years so decided to replace before something happens.
They also broke when I applied some force during dismantling and the cross section displayed severe dezincification.
Replaced with Groco bronze fittings and also added a substantial backing plate (also made by Groco for these fittings).
S/Y Lyra
B36 / 2004

JEN-et-ROSS

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Re: Seacock / skin fitting
« Reply #7 on: January 14 2016, 08:35 »
Jen-et-Ross just out of curiosity, how old was the boat when you changed them?

A 1991 Bavaria 38 Lagoon, So they were about 20 years old when we went 'plastic'. They're excellent, no corrosion worries and the sea-life doesn't seem to block the outlet or valve as badly as the original.

CRYSTAL

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Re: Seacock / skin fitting
« Reply #8 on: January 14 2016, 12:01 »
I hope anyone out there who has not changed theirs yet will not give a second thought.

BTW, good thing we didn't try to remove / replace the toilet hose while in the water!!!!

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Yngmar

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Re: Seacock / skin fitting
« Reply #9 on: January 14 2016, 12:30 »
Yngmar, 15yrs??? I guess Bav used quality fittings back then?

Not really, as quality fittings should last for several decades in my opinion. But perhaps slightly better? Although I'm sure there are other factors too.

They were all still sound enough to withstand the surveyors hammer test (in the slings) when surveyed 6 months prior to replacing, but he did put them on the list of things to be sorted. Oh, and two of them were seized in half-open state, with one handle spinning freely.
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Ripster

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Re: Seacock / skin fitting
« Reply #10 on: January 14 2016, 13:21 »
Replaced all mine last year (2011 - 36C) as they were all plain brass.   They didn't "need" doing at that time and were still al functional, though were already covered in pink spots.  It is still shocking IMO that BAV do not fit DZR or plastic as standard and instead fit something that arguably is unfit for purpose (yes I know they only have to last 5 years under the regs) for a Sea-going boat.   

CRYSTAL

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Re: Seacock / skin fitting
« Reply #11 on: January 14 2016, 19:09 »
It's really interesting that when you buy the boat new they provide tons of upgrades but what about equipment below the water line?

Thanks to all.
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Sweet As

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Re: Seacock / skin fitting
« Reply #12 on: January 17 2016, 22:34 »
The installation looks great Lngmar. Can you further explain the install? Is that a backing plate covered in sits at the base?
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Yngmar

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Re: Seacock / skin fitting
« Reply #13 on: January 18 2016, 12:21 »
The installation looks great Lngmar. Can you further explain the install? Is that a backing plate covered in sits at the base?

My installation includes the optional load-bearing collars, which makes the complete thing more like a real seacock instead of just a ball-valve screwed on top of a through-hull. Perhaps overkill, seeing how the previous brass valves have lasted 15 years without any support, but since there are some pots and pans in that locker that could fly around and since the load bearing collar didn't massively increase the cost, I've opted to go for them.

Only if you do so, you need the packers, depending on your hull thickness where your seacocks are (mine is only 9mm in that area - a bit surprising compared to the 1980s Oyster I've previously fiddled with, but clearly not a problem). The included manual tells you what the minimum hull thickness is and to add packers if too thin. So I needed packers and made them from 20mm HDPE sheet (off-cuts from an industrial supplier on eBay) - simply cut a disc the diameter of the collar and a hole in the center somewhat larger than the thread of the skin fitting. Then Sika it all together - the manual describes all this, including recommended sealants. The reason I used HDPE instead of plywood is that it will never rot, and these seacocks are meant to last the lifetime of the boat, whatever it may be. Hooray for plastics!

For cutting out the old skin fittings, I've found a Dremel with fibre cutting wheel ideal. If you don't have a used wheel, grind it down on some scrap metal until it fits straight into the skin fitting, then simply cut around the side once.
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njsail

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Re: Seacock / skin fitting
« Reply #14 on: February 09 2016, 03:42 »
I replaced every one of the original seacocks with new groco bronze fittings on our 2001 Ocean 40 about 4 or 5 years ago.  I sleep better knowing I did.  The original ones had steel handles that rusted and I thought it was a horrible for a marine fitting.  I didn't see any immediate issues with outside fittings bit since the plan was to cruise I opted to make the change. Was a lot of work to cut the old ones off and replace with new bronze units. 

geoff

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Re: Seacock / skin fitting
« Reply #15 on: February 17 2016, 11:17 »
Partly as a result of this thread, but also because it was in the back of my mind I have just removed all the original skin fittings and seacocks on my 2001 ocean 40. The skin fittings and seacocks showed no signs of dezincification at all but as they were cut out to remove them I will replace all with bronze.  Expensive scrap but peace of mind.  Geoff

Craig

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Re: Seacock / skin fitting
« Reply #16 on: February 17 2016, 21:54 »
I'm showing signs of dezincification on the raw water inlet fitting that attached to the seacock on the sail drive. At present, my seacocks seem OK. ( Bav 38 (2009) ).

What I am seeking is views on the relative benefits of the new "Plastic" seacocks as opposed to replace metal seacocks.

How do they compare in price?

How do they compare in performance?

How easy is it to determine if new metal seacocks are correct alloy?

Craig
"Shirley Valentine"
Gold Coast
Australia

Yngmar

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Re: Seacock / skin fitting
« Reply #17 on: February 17 2016, 22:32 »
I've asked my local chandlery for a quote, buying all the seacocks and a few other bits for the refit together. They ended up ordering them from two suppliers as neither had all the parts I wanted. You can look up individual prices here: http://www.leesan.com/index.asp?m=3&b_idno=23&t=Tru+Design+Plastics

The benefit of plastic over metal is obvious - it'll never corrode, dezincify or partake in electrolysis. The manufacturer also points out chemical (diesel, petrol, antifouling) and UV resistance. They also save a little bit of weight (if you're a racer who breaks pencils in half to save weight, that may matter). I also quite like the large wide handles, which are easier to move than the metal ones.

I don't think they've been around for 15 years yet, so long term performance will have to be seen. But in theory they should last for decades. I saw "lasts the lifetime of the yacht" being thrown around somewhere, but can't remember where.

And as for determining what your new metal seacocks are made of - you can't, you'll have to trust the labels and sellers claims and won't really find out until years later. There's a CR label to look for, but in the day and age of counterfeit products, that means little. Perhaps another advantage of plastic ones.
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njsail

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Re: Seacock / skin fitting
« Reply #18 on: February 18 2016, 01:19 »
One thing I neglected to mention in my choice to install bronze seacocks vs is a personal experience that left me a little shaken.  I had an island packet with Marlon thru-hulls on the transom about 2 inches above the water line.  They were several years old.  One day at anchor I was washing the transom while on the ladder standing in the water and as I was wiping around the thru hull it broke off in my hand leaving a 2 inch hole in the transom.  If this happened while under power the transom drops down and that would have been a massive leak and been a really bad day.  After discussing with the island packet owners group I learned I wasn't the only one who had that experience.  The uv protection evidently wears off and leaves the plastic brittle and weak an accident that waiting to happen.  I'm not here to preach or say one is better than the other just sharing an experience.   Underwater maybe it would work better without direct sun exposure.

Craig

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Re: Seacock / skin fitting
« Reply #19 on: February 19 2016, 23:11 »
Yngmar and njsail's comments echo other comments and views I have received.

Some plastics are more UV resistant than others. GRP is a plastic and fairly UV resistant.

My above waterline fittings ( sink, basin and shower outlets) all appear in pristine condition and the seacocks on these fittings have always opened and closed easily. I suspect the below water line fittings (heads, watermaker) will need to be replaced first and due to their location UV is not important anyway.

Knowing the metal used in seacocks can be difficult and therefore I will probably replace below water line fittings with plastic in future.

Craig
"Shirley Valentine"

dawntreader

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Re: Seacock / skin fitting
« Reply #20 on: February 21 2016, 07:47 »
I have been having increasingly difficult times with my holding tank not clearing properly (or not at all). This was usually remedied by forcing water or compressed air into the outlet with the valve open and moving back quickly. This is no longer working and I can only conclude that the inside of the pipework is calcified to the point where movement is severely restricted. I have decided to take the boat out and replace the outlet pipe and seacock. The skin fitting looks ok on the outside but I was shocked at the poor condition of the seacock when I took a side-on photo from the inside of the hull (see attached). For those of you considering this task I have also included a photo of the parts needed to effect this replacement (using metal fittings).

Note: 1.5 inches = 38mm

Nigel

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Re: Seacock / skin fitting
« Reply #21 on: February 21 2016, 08:49 »
That looks like my pipework, and the skanky locker floor, and the peeling tape on the wires.

Isn't it annoying that you can't get a bend with a male thread one end and a hose fitting the other.
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Lyra

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Re: Seacock / skin fitting
« Reply #22 on: February 21 2016, 09:10 »

Quote
Isn't it annoying that you can't get a bend with a male thread one end and a hose fitting the other.

Grocco has them - two types called PTHC and FFC (same outer diameters, FFC has larger inner diameter)
S/Y Lyra
B36 / 2004

Symphony

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Re: Seacock / skin fitting
« Reply #23 on: February 21 2016, 10:50 »
I have been having increasingly difficult times with my holding tank not clearing properly (or not at all). This was usually remedied by forcing water or compressed air into the outlet with the valve open and moving back quickly. This is no longer working and I can only conclude that the inside of the pipework is calcified to the point where movement is severely restricted. I have decided to take the boat out and replace the outlet pipe and seacock. The skin fitting looks ok on the outside but I was shocked at the poor condition of the seacock when I took a side-on photo from the inside of the hull (see attached). For those of you considering this task I have also included a photo of the parts needed to effect this replacement (using metal fittings).

Note: 1.5 inches = 38mm

That discolouration is quite common and although messy is not an indicator of corrosion as it is only on the surface. If you do replace them, cut through the castings as dezincification will show up as crumbly pink rather than clean shiny yellow.

Nigel

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Re: Seacock / skin fitting
« Reply #24 on: February 22 2016, 06:53 »

Quote
Isn't it annoying that you can't get a bend with a male thread one end and a hose fitting the other.

Grocco has them - two types called PTHC and FFC (same outer diameters, FFC has larger inner diameter)

It hadn't occurred to me that these could be NTP, perhaps I will revise my plan to reuse the internal fittings.
Nigel Mercier: Forum Administrator