Bavaria Yacht Info

Member Forums => Bavaria Yacht Help! => Topic started by: CRYSTAL on January 13 2016, 16:11

Title: Seacock / skin fitting
Post by: CRYSTAL 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! !!!

Title: Re: Seacock / skin fitting
Post by: tiger79 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.
Title: Re: Seacock / skin fitting
Post by: CRYSTAL on January 13 2016, 18:04
Isn't galvanic corrosion the overall mechanism by which dezincification occurs?
Title: Re: Seacock / skin fitting
Post by: JEN-et-ROSS 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  ;).
Title: Re: Seacock / skin fitting
Post by: Yngmar 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.

(https://sdfjkl.org/tmp/seacocks_galley.jpg)
Title: Re: Seacock / skin fitting
Post by: CRYSTAL 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?

Title: Re: Seacock / skin fitting
Post by: Lyra 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).
Title: Re: Seacock / skin fitting
Post by: JEN-et-ROSS 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.
Title: Re: Seacock / skin fitting
Post by: CRYSTAL 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!!!!

Title: Re: Seacock / skin fitting
Post by: Yngmar 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.
Title: Re: Seacock / skin fitting
Post by: Ripster 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.   
Title: Re: Seacock / skin fitting
Post by: CRYSTAL 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.
Title: Re: Seacock / skin fitting
Post by: Sweet As 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?
Title: Re: Seacock / skin fitting
Post by: Yngmar 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 (http://stores.ebay.co.uk/GFG-Plastics-ltd/_i.html?_nkw=HDPE+sheet&submit=Search&_sid=673167820)) - 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.
Title: Re: Seacock / skin fitting
Post by: njsail 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. 
Title: Re: Seacock / skin fitting
Post by: geoff 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
Title: Re: Seacock / skin fitting
Post by: Craig 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
Title: Re: Seacock / skin fitting
Post by: Yngmar 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 (https://coxengineering.sharepoint.com/pages/brassandbronze.aspx), but in the day and age of counterfeit products, that means little. Perhaps another advantage of plastic ones.
Title: Re: Seacock / skin fitting
Post by: njsail 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.
Title: Re: Seacock / skin fitting
Post by: Craig 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"
Title: Re: Seacock / skin fitting
Post by: dawntreader 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
Title: Re: Seacock / skin fitting
Post by: Nigel 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.
Title: Re: Seacock / skin fitting
Post by: Lyra 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)
Title: Re: Seacock / skin fitting
Post by: Symphony 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.
Title: Re: Seacock / skin fitting
Post by: Nigel 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.
Title: Re: Seacock / skin fitting
Post by: Lyra on February 22 2016, 11:22
These are the Grocco fittings/seacocks that I replaced in my boat
Title: Re: Seacock / skin fitting
Post by: Lazy Pelican on February 22 2016, 14:00
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

I had a similar problem. It wasn't the pipe work which caused the blockage- I'd replaced this when changeing the sea cocks ( to  Trudesign ). The problem was that huge amounts of calcium had built up on the inside of the tank and slabs of calcium fallen to bottom of the tank blocking it.
We were midway thro a cruise at the time. My solution was to open the access hatch and manually remove as much of the crud as possible, aided by periodic flushing the tank thro with a hose. It's a horrible job but I ended up with a bucket full of calcium and a tank which emptied -no problems 2 years on.
I'm not looking forward to doing the same job on the ensuite!

John
Title: Re: Seacock / skin fitting
Post by: dawntreader on February 22 2016, 17:21
Thanks John - I am expecting that too. However, for peace of mind, I am still going ahead with the replacement of the pipework/valve. I will post an update once the job is done. Scheduled for 2 week's time - can't wait!
Title: Re: Seacock / skin fitting
Post by: s/y Susanne on February 22 2016, 19:53
Can anyone advise on the sizes for each basin or shower outlet and for the head inlet and outlet?  This would be helpful as my boat is in Greece and I am in Scotland so can't just pop down to measure.

 It would be a good project to undertake on a 2032 B44 as the de-zincification in the pics really concerns me. I am assuming that all Bavaria skin fittings are more or less the same with a through-hull threaded fitting and back-nut followed by a ball-valve and then an elbow and hose or straight to hose ruff?

I am tempted by the tru-design plastic kit

Thanks
Stewart
Title: Re: Seacock / skin fitting
Post by: Yngmar on February 22 2016, 21:04
The seacocks were 1 1/2" BSP for head and holding tank outlet and 3/4" BSP for everything else (galley/head sink, shower sump, toilet intake) with hose tails 38mm and 19mm respectively. Galley had straight tails, heads all 90° ones. If you get Tru-Design, make sure you get the "Long Thread" tails.

In fact, here's my order list:

Code: [Select]
Description Tru-Design # Bainbridge #
Skin Fitting Installation Tool 90782
Load Bearing Collar (small) 90856
Load Bearing Collar (medium) 90857
Ball Valve (manual) 3/4" BSP 90276 Q133700
Ball Valve (manual) 1 1/2" BSP 90235 Q133703
Skin Fitting Threaded (white) 3/4" BSP 90432 Q133722
Skin Fitting Threaded (white) 1 1/2" BSP 90419 Q133725
Nut backing 3/4" BSP 90482 Q135025
Nut backing 1 1/2" BSP 90488 Q135028
Tail Long Thread 90° 1 1/2" BSP to 38mm Hose 90375 Q133778
Tail Long Thread 90° 3/4" BSP to 19mm Hose 90372 Q133775
Spanner Ball Valve 3/4" 90477
Spanner Ball Valve 1 1/2" 90478 Q133791

Forget the spanners, I never needed them, but the installation tool you'll want. The backing nuts were spares in case I'd cock one of the included ones up, which I did not.
Title: Re: Seacock / skin fitting
Post by: s/y Susanne on February 23 2016, 11:31
Yngmar
That's great info. Thanks.

Lee San who offer the Tru-Design plastic fittings have offered a 10% discount on all their products to members of this forum.

Enter KARL10 as a voucher code at checkout. They will deliver outside UK if necessary (I have no connection with this compant but I feel its always worthwhile asking for a deal!)
Stewart
Title: Re: Seacock / skin fitting
Post by: dawntreader on March 01 2017, 08:55
Yngmar
That's great info. Thanks.

Lee San who offer the Tru-Design plastic fittings have offered a 10% discount on all their products to members of this forum.

Enter KARL10 as a voucher code at checkout. They will deliver outside UK if necessary (I have no connection with this compant but I feel its always worthwhile asking for a deal!)
Stewart

Stewart,
I tried the code but no joy?
Title: Re: Seacock / skin fitting
Post by: tiger79 on March 01 2017, 09:32
As it's over a year later, perhaps the code has expired.
Title: Re: Seacock / skin fitting (promotion code updated)
Post by: dawntreader on March 01 2017, 10:07
I'll ask them again for one for forum members then  :P



Update: Please use promotion code KARL16 for 10% discount  :tbu  :)

NB: Lee San quote: "All seacock kits are bundled by ourselves here to create kits from Tru Design parts. All seacock kits include a long thread tail hosetail. "
Title: Re: Seacock / skin fitting
Post by: dawntreader on March 24 2017, 13:42
I went for the 38mm 90 deg kit. This is what you get:

Very pleased  :)
Title: Re: Seacock / skin fitting
Post by: Ziffius on March 27 2017, 22:15
Anyone know the size of seacock on the heads water/flush inlet for a Bav39 2005/6?
Title: Re: Seacock / skin fitting
Post by: Salty on March 27 2017, 23:53
The seacocks were 1 1/2" BSP for head and holding tank outlet and 3/4" BSP for everything else (galley/head sink, shower sump, toilet intake) with hose tails 38mm and 19mm respectively. Galley had straight tails, heads all 90° ones. If you get Tru-Design, make sure you get the "Long Thread" tails.

In fact, here's my order list:

Code: [Select]
Description Tru-Design # Bainbridge #
Skin Fitting Installation Tool 90782
Load Bearing Collar (small) 90856
Load Bearing Collar (medium) 90857
Ball Valve (manual) 3/4" BSP 90276 Q133700
Ball Valve (manual) 1 1/2" BSP 90235 Q133703
Skin Fitting Threaded (white) 3/4" BSP 90432 Q133722
Skin Fitting Threaded (white) 1 1/2" BSP 90419 Q133725
Nut backing 3/4" BSP 90482 Q135025
Nut backing 1 1/2" BSP 90488 Q135028
Tail Long Thread 90° 1 1/2" BSP to 38mm Hose 90375 Q133778
Tail Long Thread 90° 3/4" BSP to 19mm Hose 90372 Q133775


[/quote]


My B36/2002 uses the same size fittings as on Yngmar's boat, so I reckon that probably the boats all use the same size fittings, and particularly because the size of the fittings to which the plumbing connects is not dependent on boat size but more dependent on the size the plumbing manufacturer made the fittings.
Title: Re: Seacock / skin fitting
Post by: Ziffius on March 29 2017, 09:07
Cheers for that Salty
Title: Re: Seacock / skin fitting
Post by: dawntreader on April 04 2017, 07:45
The seacocks were 1 1/2" BSP for head and holding tank outlet and 3/4" BSP for everything else (galley/head sink, shower sump, toilet intake) with hose tails 38mm and 19mm respectively. Galley had straight tails, heads all 90° ones. If you get Tru-Design, make sure you get the "Long Thread" tails.

In fact, here's my order list:

Code: [Select]
Description Tru-Design # Bainbridge #
Skin Fitting Installation Tool 90782
Load Bearing Collar (small) 90856
Load Bearing Collar (medium) 90857
Ball Valve (manual) 3/4" BSP 90276 Q133700
Ball Valve (manual) 1 1/2" BSP 90235 Q133703
Skin Fitting Threaded (white) 3/4" BSP 90432 Q133722
Skin Fitting Threaded (white) 1 1/2" BSP 90419 Q133725
Nut backing 3/4" BSP 90482 Q135025
Nut backing 1 1/2" BSP 90488 Q135028
Tail Long Thread 90° 1 1/2" BSP to 38mm Hose 90375 Q133778
Tail Long Thread 90° 3/4" BSP to 19mm Hose 90372 Q133775
Spanner Ball Valve 3/4" 90477
Spanner Ball Valve 1 1/2" 90478 Q133791


Yngmar, what did you use (recommend) to seal the threads?
Title: Re: Seacock / skin fitting
Post by: Yngmar on April 04 2017, 14:16
Yngmar, what did you use (recommend) to seal the threads?

Sikaflex (291i or 292 - I forget) for the through-hull and ball valve connecting to it. PTFE tape for the tailpipes.

No problems at all with the Sikaflex part, but the PTFE tape I can only recommend for the straight tailpipes. If you have 90° ones, they tend to rotate when attaching the hose and then can leak ever so slightly (well, one of five does - a drip a day, but annoying). So I will have to undo that one again and will probably use an adhesive sealant to lock it into place and seal it.
Title: Re: Seacock / skin fitting
Post by: dawntreader on April 04 2017, 19:35
Yngmar,
Thanks for that - I had already planned to use Sikaflex and PTFE - it was the apparent weakness of the thread connections that concerned me. I may look towards one of the Boss sealants as an option too, with Boss White looking like a suitable product.
Jim
Title: Re: Seacock / skin fitting
Post by: Markus on July 08 2020, 19:38
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.

(https://sdfjkl.org/tmp/seacocks_galley.jpg)

I realize I am hijacking a very old thread here, the relation to this is that I believe the picture above is from Ocean 40 galley skin fittings. I am also replacing all of the original skin fittings to Truedesign on my Ocean 40. I am just wondering what is the point on having two skin fittings for two galley sinks next to each other? I would be tempted to just laminate one hole shut and perhaps go up one size for the other skin fitting and have a Y-connector for the sink drains, which would result in one hole less in the hull and a few parts less to purchase. I remember seeing this done in other boats so I suppose there's no clear downsides, or...?
Title: Re: Seacock / skin fitting
Post by: tckearney on July 09 2020, 10:45
My boat is B42 and twenty years old.  I have no idea if these fittings have been changed.  I bought it at 15 years old.    The previous owner seemed to be meticulous in his maintenance, I can tell by the modifications that have been made and the parts that have been renewed.  However I can’t tell if these valves have been replaced.  I’ll have a look next lift out.   Is there any signs in the bronze I could definitely look for, either from inside or after it is out of the water.   There is a bit of rust steaks but I assumed it from the jubilee clips. 

Thanks for the pics Yngmar I have already looked up the UK supplier and will think about the plastic type . 
Title: Re: Seacock / skin fitting
Post by: tckearney on July 09 2020, 10:46
 My boat is B42 and twenty years old.  I have no idea if these fittings have been changed.  I bought it at 15 years old.    The previous owner seemed to be meticulous in his maintenance, I can tell by the modifications that have been made and the parts that have been renewed.  However I can’t tell if these valves have been replaced.  I’ll have a look next lift out.   Is there any signs in the bronze I could definitely look for  There is a bit of rust steaks but I assumed it from the jubilee clips. 
Thanks for the pics Yngmar I have already looked up the UK supplier and will think about the plastic type . 
Title: Re: Seacock / skin fitting
Post by: Markus on July 09 2020, 11:17
Is there any signs in the bronze I could definitely look for, either from inside or after it is out of the water.   

If you abrade the outside of the skin fitting with a sand paper you can see if it is yellow or if there's some pink areas which is a sign of zinc loss in the fitting.

I fully think that going plastic (Trudesign) is the way to go.
Title: Re: Seacock / skin fitting
Post by: Symphony on July 09 2020, 11:59
My boat is B42 and twenty years old.  I have no idea if these fittings have been changed.  I bought it at 15 years old.    The previous owner seemed to be meticulous in his maintenance, I can tell by the modifications that have been made and the parts that have been renewed.  However I can’t tell if these valves have been replaced.  I’ll have a look next lift out.   Is there any signs in the bronze I could definitely look for  There is a bit of rust steaks but I assumed it from the jubilee clips. 
Thanks for the pics Yngmar I have already looked up the UK supplier and will think about the plastic type .
bavariayacht.org/forum/index.php/topic,2878.0.html

You might find this useful. There is a lot of "myth" surrounding seacocks. Bavarias, and most other European boats use brass fittings and seacocks, some chrome plated. They have done for many, many years with very few problems, despite the material not being deemed suitable for use in seawater because they potentially dezincify because of galvanic action. However in practice this is rare, mainly because the vulnerable parts are not actually exposed to seawater, except as I noted in the end fittings, particularly the hose tails. More common is seizure of the ball valve, but this is nothing to do with the material of the body, or the handle and spindle corroding. This is mostly related to lack of use, that is not operating the valve periodically.

Bob's boat is similar age to yours and as you can see the valves and fittings were mostly sound except dezincification in the threads. On my old boat, similar age, I changed the loo outlet after 8 years because it had seized, but found it and the fittings otherwise sound.

Even if the fittings do dezincify they are unlikely to fail in normal use. Where they are vulnerable is if they get stressed, for example by something heavy hitting the valve or hosetail. Most of the valves in a Bavaria are in well protected locations so this is unlikely to happen in normal use.

Having said all that I think you should consider replacing all the valves and fittings that are underwater. The choice is between metal and composite (Tru Design). The latter is a bit more expensive and involves a bit more work. Metal valves and fittings are direct replacements for the existing, but it is important to use only those labeled DZR (Dezincification Resistant) or bronze. DZR is now widely available and is clearly marked as such. Bronze is more expensive and now, because of the availability of DZR not so easy to find. Both are equally corrosion resistant.
Title: Re: Seacock / skin fitting
Post by: tckearney on July 09 2020, 12:12
Thanks symphony very informative and as an engineer it is just what I woulod expect.  I have attached a photo of the aft loo.  the fwd loo looks the same only it has got a lot of mildue and Im embarassed to show that !!!  What do you think are these original ?
Title: Re: Seacock / skin fitting
Post by: tckearney on July 09 2020, 12:13
and another pic
Title: Re: Seacock / skin fitting
Post by: Symphony on July 10 2020, 17:00
They look nice and clean. The green is normal, product of damp on brass which is of course a copper alloy. The whole of the bottom of my boat is that colour from the copper in the Coppercoat!