VP Saildrive- Seacock Material?

[CJ13]

I'm replacing the below waterline seacocks on my 2006 Bavaria 39.
The seawater intake for the engine cooling comes thro the 130S-B saildrive leg. In the engine bay there's a threaded pipe into the sail drive to which the seacock screws. The threaded pipe looks in good condition.
Does anyone know what material the threaded pipe is made from & if it's plain Brass where can i get a Bronze/ DZR fitting to replace it?

Thanks,
John

 

[Sans Bateau]

Haa ha! I tried to find this out last year, no one seems to know. I tried VP but no data exists. In the end it was assumed that VP would only use a material suitable for the job. Short of doing the various tests on the metal, thats as far as I got.

 

[savageseadog]

I've wondered the same about Yanmar saildrives too.

 

[Ripster]

I have a 2011 130 and have been wondering the same thing. Look forward to finding out.

 

[PeterR]

I've had the same thoughts. My boat is 2008 and I took the pipe off this year. It proved impossible to separate the ball valve from the tube into the 130 saildrive or to remove the tail pipe from the ball valve - at least without using so much force that I was in danger of damaging something. There were no markings on either tail pipe or tube but I filed across the ends of both and there was no sign of dezincification in either so I have put the assembly back for the time being. May be they are bronze or perhaps they gain protection from the zinc saildrive anode?

 

[macd]

PeterR: Apologies if this is old news, but what surface treatment does the ball valve housing have? If it's bright plated (but not polished) it's almost certainly regular brass (cf Vyv Cox's excellent info on the subject: http://coxengineering.sharepoint.com/Pages/Metallurgy.aspx

 

[vyv_cox]

PeterR: Apologies if this is old news, but what surface treatment does the ball valve housing have? If it's bright plated (but not polished) it's almost certainly regular brass (cf Vyv Cox's excellent info on the subject: http://coxengineering.sharepoint.com/Pages/Metallurgy.aspx

Thanks for the plug(!) but despite the title the OP is asking about the pipe, not the valve. No easy way to find out, I'm afraid. I can arrange an analysis for anyone who wants one but it could cost £100.

 

[Martin_J]

When I replaced the diaphragm in my 120SD a couple of years ago I bought all the parts from Keypart.

At the same time I wanted to replace the stiff blue plastic seacock with a more robust version.

Keypart sold the adapter tube (that you mention although it is called a nipple) together with the flat washer and the valve.

At the time I am sure I asked if it was DZR and they said yes. Perhaps it is worth a call to Keypart to see what their 'replacement part' is made of.

It is shown here as part number 33 - nipple!

Perhaps they or volvo will answer the question given the part number.

 

[Sans Bateau]

At the time I am sure I asked if it was DZR and they said yes. Perhaps it is worth a call to Keypart to see what their 'replacement part' is made of.

Now thats interesting as when I asked the same question, they would not commit, as I suggested in my earlier post, they 'assumed' it would be. Big difference.

 

[Sans Bateau]

Thanks for the plug(!) but despite the title the OP is asking about the pipe, not the valve. No easy way to find out, I'm afraid. I can arrange an analysis for anyone who wants one but it could cost £100.

That sounds rather cheap, it is VOLVO PENTA you know!

 

[CJ13]

I've contacted RK marine who sent me a data sheet, for the material the 'Nipple' is made from- it looks as if it's either CW614N or CW617N.
I haven't been able to attach the data sheet to this post, but i have emailed it to Vyv at the address given on his web site, so hopefully he'll be able to tell us wether it good or bad brass.
John

 

[PeterR]

PeterR: Apologies if this is old news, but what surface treatment does the ball valve housing have? If it's bright plated (but not polished) it's almost certainly regular brass (cf Vyv Cox's excellent info on the subject: http://coxengineering.sharepoint.com/Pages/Metallurgy.aspx

Thanks, Yes I am only too well aware that the ball valve itself is nickel plated brass. My guess would be that the tail pipe is as well. However, as the pipe into the saildrive is supplied by Volvo there is a sporting chance that might be bronze or DZR brass.

The vast majority of brass fitting failures have been in skin fittings or the tail pipe as these are much thinner than the ball valve. My problem, and I guess its the same for others, is that there is little point putting a nice bronze valve and tail pipe on a brass pipe into the saildrive leg when the pipe is the most likely point of failure.

All the pictures I have seen of failed fittings show a progressive layer of dezincification, starting in the lumen of the pipe and working outwards. Having filed the ends of both pipes I am certain there is no such dezincified layer as yet. Now if both pipes are bronze that does not tell me anything about the state of the valve. However, if either are brass that implies that the valve is probably still sound as well. It certainly still copes with being put in a vice!

Like the OP I intend taking all the valves out over the winter and if there is any sign of dezincification they will be replaced. However, if they appear sound they will go back in for a few more seasons. After all, neither bronze nor DZR brass fittings will last forever so delaying their placement a while if the present fittings are still sound will reduce the chance of requiring further replacements.

Before anyone replies and tells me their bronze fittings have lasted a lifetime - yes I know they can - but equally a neighbour in the marina has just had to replace his seven-year-old folding bronze prop because the teeth have become severely dezincified.

 

[Ripster]

On a previous French boat I had a seized valve (main engine inlet 2") replaced by a well known dealer that many would instantly recognize. This was in 2006. They replaced it with a CW617N valve. At the time, far less was discussed about the composition of these valves, but if you google CW617n you will find it is Nickel plated Brass not DZR and it clearly states that this material is not suitable for use in Sea Water - this is something that I only really became aware of (the importance of it) two years on. I do agree that its the skin fitting threads and the pipe tails that are the weak points, rather than the chunky valves themselves.

Its worth doing a Forum search on this subject as it has come up many times over the last few years.

 

[vyv_cox]

I've contacted RK marine who sent me a data sheet, for the material the 'Nipple' is made from- it looks as if it's either CW614N or CW617N.
I haven't been able to attach the data sheet to this post, but i have emailed it to Vyv at the address given on his web site, so hopefully he'll be able to tell us wether it good or bad brass.
John

Both of those specifications are for leaded brass. There must be some subtle difference between the two but they look very similar to me. Nothing special about it at all for corrosion in seawater. It will dezincify.

 

[CJ13]

It's clear from Vyv's reply that the 'nipple', seacock and tail are all subject to dezincification. Presumably every VP saildrive unit has the same fittings.
Could it be that they're actually protected by the aluminium saildrive / anode?
Has anyone heard of the nipple, seacock, tail etc failing?

John

 

[Tranona]

Before anyone replies and tells me their bronze fittings have lasted a lifetime - yes I know they can - but equally a neighbour in the marina has just had to replace his seven-year-old folding bronze prop because the teeth have become severely dezincified.

That is not necessarily translatable to DZR or bronze used for seacocks. You do not know what the composition of the "bronze" is and the dezincification is often caused by the use of other metals in the prop such as the pins plus inadequate anodes. Skin fittings are not mixed metal so will not corrode if made of DZR or Bronze, but may if they are brass.

 

[vyv_cox]

Before anyone replies and tells me their bronze fittings have lasted a lifetime - yes I know they can - but equally a neighbour in the marina has just had to replace his seven-year-old folding bronze prop because the teeth have become severely dezincified.

There is no zinc in bronze*, so genuine bronze most definitely did not dezincify. Many 'bronze' propellers are actually manganese bronze, which is a 60/40 brass with a few minor additions of other elements. I have even come across one specification that had no manganese in it!

*There may be up to 5% for deoxidation purposes when casting but this plays no part in the alloy.

 

[Lucky Duck]

There is no zinc in bronze*, so genuine bronze most definitely did not dezincify. Many 'bronze' propellers are actually manganese bronze, which is a 60/40 brass with a few minor additions of other elements. I have even come across one specification that had no manganese in it!

*There may be up to 5% for deoxidation purposes when casting but this plays no part in the alloy.

The prop was the standard Volvo three blade Saildrive folding version. The teeth had become so badly erroded that the blades would no longer fold/unfold in unison providing interesting results when trying to berth.

New anodes installed at the begining of the season and then a new set installed during the mid-season scrub.

 

[vyv_cox]

The prop was the standard Volvo three blade Saildrive folding version. The teeth had become so badly erroded that the blades would no longer fold/unfold in unison providing interesting results when trying to berth.

New anodes installed at the begining of the season and then a new set installed during the mid-season scrub.

I'm sure there is no doubt that it had corroded or worn or failed by some other mechanism. All I am saying is that if it was bronze it did not fail by dezincification. Volvo claim that some of their propellers are constructed of nickel aluminium bronze but it seems highly unlikely that this alloy would suffer severe corrosion.

 

[Tranona]

The prop was the standard Volvo three blade Saildrive folding version. The teeth had become so badly erroded that the blades would no longer fold/unfold in unison providing interesting results when trying to berth.

New anodes installed at the begining of the season and then a new set installed during the mid-season scrub.

That particular prop is well known for suffering from corrosion, although there have been changes in the alloy and anodes over the years. Not all folding props suffer in the same way, indeed some such as the 2 blade Flexofold do not have anodes as standard, although they are an option.