Flanged seacocks installation with Beneteau grid liner?

[kodiak1120]

I am about to start replacing the thruhulls and seacocks on my 2009 B37. I know the recommended approach is to use a backing plate and a flanged seacock. The current thruhulls are installed through the structural grid matrix, but the holes they cut are only big enough to fit the existing thruhull, backing washer and nut, so there isn't enough space for a full backing plate. I'm trying to figure out what to do. I think there are two options:

1. Enlarge the existing hole with a Dremel in order to fit the larger backing plate.

2. Fill the existing hole with thicked epoxy and install the backing plate on top of the grid.

Does anyone have any experience with this? Seems like a common issue, but there is very little online about the proper way to deal with the grid.

 

[dlochner]

How far back does the filler between the hull and lining go? A few small test borings might be necessary.

 

[Mark Maulden]

What’s wrong with them?

 

[kodiak1120]

What’s wrong with them?

They are 14 years old. They are brass. And they don't have proper backing plates or flanges.

 

[Ralph Johnstone]

Wow ! With ideas like that, it pretty well goes without saying that you're travelling with the wrong crowd . Maybe try reading some well received books by Calder and other similar authors.

They are 14 years old.

In the life of a thru-hull, not worth mentioning.

They are brass.

Extremely unlikely. Have you had a metallurgical test done to prove they are brass and not bronze ?

And they don't have proper backing plates or flanges.

Unfortunately, almost 100% of thru-hulls on production boats skip the flanged construction thru-hulls. Do try to avoid falling on one with your full weight. Having said that, they are almost always in locations where you can't posibly fall on them with your full weight.

 

[BigEasy]

They are 14 years old. They are brass. And they don't have proper backing plates or flanges.

I have recently replaced the last two thru hull assemblies. I too was not comfortable with Beneteau’s selection of hardware. The thru hull fittings, valves, & tail pieces are some version of “red bronze”. I used Groco bronze fittings with BSPP threads on all to eliminate mis-matched threads. I did not use seacocks, adaptor plates, nor backing plates because of the factors that you described. I am not crossing oceans or the Gulf of Mexico so the factory configuration is good enough for my situation.

 

[colemj]

In the life of a thru-hull, not worth mentioning.
...............
Extremely unlikely. Have you had a metallurgical test done to prove they are brass and not bronze ?

In a 2009 Beneteau, they are brass. You can even see dezincification beginning on it.

Beneteau explicitly states these seacocks have a 5 year lifespan. The CE certificate it is built to only requires a 5yr lifespan on seacocks.

This is well-known.

The OP should cut the liner back as far as needed to install a new seacock. There is nothing structural to worry about, as these are not installed on stringers - just the connecting liner. It looks like the fill around it is just caulking, and is only there to prevent things from finding their way into the liner irretrievably.

Mark

 

[colemj]

The thru hull fittings, valves, & tail pieces are some version of “red bronze”.

They are DZR brass.

Mark

 

[dLj]

They are DZR brass.

Mark

This is a good alloy for that use. Not all brasses are "bad". Not all bronzes are "good".

DZR brass is often used in Europe.

I wouldn't say 12 years old is necessarily trivial - it depends upon too many factors.

If the OP wishes to change them due to their current condition, it's not a bad thing. It may or may not be necessary based on actual condition but as none of us are at his boat none of us can know.

As far as going through all the work to put in flanged seacocks, I'd suggest the structure that is making it difficult to do that is actually helping to minimize the likelihood of side loading which is what the flanged seacock's advantage is. Plenty of boats work perfectly well without them. The expression "Better is the enemy of good enough" comes to mind.

dj

 

[Ralph Johnstone]

Beneteau explicitly states these seacocks have a 5 year lifespan. The CE certificate it is built to only requires a 5yr lifespan on seacocks.

I'm not doubting you on this but I'm going to have to see some authentification from the manufacturer of the boat before I'm going to believe the thru-hulls are not bronze.

Would an intelligent person buy a new boat with thru-hulls that have to be replaced in five years ?

 

[Richard19068]

..... I'm going to have to see some authentification from the manufacturer of the boat before I'm going to believe the thru-hulls are not bronze.

Would an intelligent person buy a new boat with thru-hulls that have to be replaced in five years ?

Beneteau Responds to Seacock Query - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.

www.practical-sailor.com

 

[colemj]

This is a good alloy for that use. Not all brasses are "bad". Not all bronzes are "good".

For a long time I agreed with that and defended the use of DZR brass for this application. However, I changed my opinion after seeing way too many boats with failures of them after 4-7yrs. The internet is rife with failure stories and complaints of these fittings on these boats. The CE requires that seacocks need to last 5yrs, and the big EU builders seem to have achieved this, but no further. I don't know if Beneteau/Jeaneau and the like source inferior quality DZR, or if DZR in general is unsuitable for longer than 5yrs in the water. It doesn't seem likely that so many boats have stray current or galvanic issues.

Frankly, I don't understand why anyone would use metal seacocks on a plastic boat, but in this case suspect the DZR choice was for cost reasons.

Mark

 

[colemj]

I'm not doubting you on this but I'm going to have to see some authentification from the manufacturer of the boat before I'm going to believe the thru-hulls are not bronze.

Would an intelligent person buy a new boat with thru-hulls that have to be replaced in five years ?

Someone posted a response by Beneteau saying they are duplex brass - which DZR is one. But even without that, would you expect bronze to look like this? Even after 16yrs? Half of the threads that held the valve on it are pitting, peeling, and dezinced.

It is possible that this isn't what I'm thinking, and that pink and pitting/peeling is just residual thread lock compound, but the yellow color isn't something I've seen in marine bronzes.

Mark

 

[Davidasailor26]

It doesn't seem likely that so many boats have stray current or galvanic issues.

Generally the Beneteau thru hulls are not bonded or connected in any other way to the ground system, so I don’t think the failures are associated with stray current or galvanic issues anyway. I think it’s just the metal choice that causes the problems.

I have the same model boat as the OP and I agree with the above that the filler is probably just cosmetic and nothing really structural. I’m not even sure mine has that filler around all the thru hulls; I’ll confirm next time I’m at the boat. Assuming it’s not structural epoxying an extra platform in the inner circle area won’t really help. Someday when I replace mine I figure I’ll just use the same style non-flanged thru hulls but with real proper bronze, or marelon.

 

[dLj]

For a long time I agreed with that and defended the use of DZR brass for this application. However, I changed my opinion after seeing way too many boats with failures of them after 4-7yrs. The internet is rife with failure stories and complaints of these fittings on these boats. The CE requires that seacocks need to last 5yrs, and the big EU builders seem to have achieved this, but no further. I don't know if Beneteau/Jeaneau and the like source inferior quality DZR, or if DZR in general is unsuitable for longer than 5yrs in the water. It doesn't seem likely that so many boats have stray current or galvanic issues.

Frankly, I don't understand why anyone would use metal seacocks on a plastic boat, but in this case suspect the DZR choice was for cost reasons.

Mark

I'd really like to see those failures. The CDA lists that alloy as an excellent alloy for the application. I've looked over the chemistry and it should be. But real world is a better teacher...

We could have a long conversation about bronze vs plastic thru-hulls. I personally would never use plastic.

dj

 

[dLj]

Someone posted a response by Beneteau saying they are duplex brass - which DZR is one. But even without that, would you expect bronze to look like this? Even after 16yrs? Half of the threads that held the valve on it are pitting, peeling, and dezinced.

It is possible that this isn't what I'm thinking, and that pink and pitting/peeling is just residual thread lock compound, but the yellow color isn't something I've seen in marine bronzes.

Mark

View attachment 229747

Your comments and indications i don't agree with at first blush, but one would really need it in hand to know

dj

 

[Ralph Johnstone]

This is taken from the above link referring to the responce from Beneteau to Practical Sailor courtesy of @Richard19068 :

It exceeds the requirements of ISO 6957. Attached below is a test of ISO 6957 done for a major valve supplier whose products I am very familiar with. Pretty much cinches that argument..

Beneteau explicitly states these seacocks have a 5 year lifespan. The CE certificate it is built to only requires a 5yr lifespan on seacocks. This is well-known.

After reading the above unembellished statement, this is exactly why I wanted to see some form of authentication. Thank you @Richard19068 for this article.

Further taken from Beneteau's above reply :

​

Having a professional perform an inspection may be a bit of an over-reach on Beneteau's part but no more than CYA. If a cleaned and polished section looks like shiny yellow metal, you're good to go.

I'm not a professional in this area but every time I have the boat out sitting on the hard for a bottom painting, I will file and emery a small section of a different (each time) mushroom flange on the bottom of the thru-hull to check its integrity. So far, so good.

You might want to find out exactly what DZR brass is before banishing it to the scrap heap :

The Different Types of Brass: A Comprehensive Guide | The Federal Group USA

 

[colemj]

We could have a long conversation about bronze vs plastic thru-hulls. I personally would never use plastic.

By "plastic", I meant glass filled polymer like Forespar and Trudesign uses. They have a track history much better than the DZR used in the boats we've been discussing.

Mark

 

[colemj]

View attachment 229751

This is taken from the above link referring to the responce from Beneteau to Practical Sailor courtesy of @Richard19068 :

View attachment 229749​

It exceeds the requirements of ISO 6957. Attached below is a test of ISO 6957 done for a major valve supplier whose products I am very familiar with. Pretty much cinches that argument..



After reading the above unembellished statement, this is exactly why I wanted to see some form of authentication. Thank you @Richard19068 for this article.

Further taken from Beneteau's above reply :

View attachment 229750
​

Having a professional perform an inspection may be a bit of an over-reach on Beneteau's part but no more than CYA. If a cleaned and polished section looks like shiny yellow metal, you're good to go.

I'm not a professional in this area but every time I have the boat out sitting on the hard for a bottom painting, I will file and emery a small section of a different (each time) mushroom flange on the bottom of the thru-hull to check its integrity. So far, so good.

You might want to find out exactly what DZR brass is before banishing it to the scrap heap :

The Different Types of Brass: A Comprehensive Guide | The Federal Group USA

Believe anything you want. At first you didn't believe they were not bronze and now you know better. Now you want to believe they are not failing in these boats in spite of all of the evidence available for the googling.

I know exactly what DZR brass is. As I stated, I was a proponent of it, and defended its use in this application for a long time. I've been disabused of this opinion from seeing many examples of these boats, talking to many owners with problems, and reading about them in forums for many years.

That standard you posted is a test of the properties, not a long-term test or suitability test for thruhulls. Beneteau itself state they only have a 5yr useable lifespan, which just matches the CE requirements.

Your scratch test is good for the immediate surface you scratched, but you have no idea what is going on in the threads or valves in the system. Dezincification is usually a concentrated or localized phenomenon until it totally eats out the part or the part suddenly fails at that spot. Besides, if yours are bronze you have little to worry about - particularly if they are unbonded.

Mark

 

[dLj]

By "plastic", I meant glass filled polymer like Forespar and Trudesign uses. They have a track history much better than the DZR used in the boats we've been discussing.

Mark

I am fully aware of what materials we are talking about.

If you would like a long discussion, fine. I just don't think this is the thread for it.

dj