Flanged seacocks installation with Beneteau grid liner?

[Richard19068]

'
I'm not trying to stir the pot but was reading an interesting article about this in "Marine Systems Excelence Emagazine"
and thought I'd pass along this excerpt:

Suitable Alloys
The requirement for corrosion resistance limits the range of materials from which seacocks and their related components may be made. Only bronze, DZR (more on that in a moment) brass, glass-reinforced plastic and, in some cases, stainless steel may be used. The terms “brass” and “bronze” encompass a wide range of copper alloys. The primary determining factor is zinc content. Zinc is an especially ignoble metal; it corrodes very easily when in the presence of other metals and an electrolyte, such as seawater, which is why it’s used in sacrificial anodes. Zinc, however, also imparts strength to copper, mixing the two, often in about a 40-60 ratio respectively, results in a brass suitable for clocks, lamps and cabin hardware, but most definitely not, with few exceptions, for seawater plumbing.
Copper-zinc alloys used below the waterline undergo a process called dezincification whereby the zinc corrodes from the alloy, leaving behind a pink, porous and very fragile structure that’s almost certain to fail. For the most part, true bronze alloys are zinc-free, their primary elements being copper and tin. Other alloying elements include silicon and nickel (technically making them something other than bronze, but still acceptable for use in seawater plumbing). These are the best alloys for use below the waterline because they are not susceptible to dezincification

Unfortunately, a huge range of alloys lies between true bronze with no, or very little zinc and true brass which contains a high percentage of zinc. Two common alloys often used in marine applications are 85-5-5-5 (or C83600) and DZR.

85-5-5-5 contains 85 percent copper, 5 percent zinc, 5 percent lead and 5 percent silicon and can be used below the waterline.

Some European manufacturers use something referred to as DZR brass, a dezincification-resistant brass alloy. This alloy has a higher zinc composition than many other copper alloys (30 percent or more), but it also includes trace amounts of other metals meant to retard zinc corrosion or leaching.

Neither of these alloys resists dezincification nearly as well as the zinc-free or near-zinc free bronze alternatives; but as they are less expensive and unlikely to become a problem in the early years of the boat’s life, they can be an attractive alternative for more cost conscious builder.

 

[dLj]

Historically bronzes were considered Cu-Sn alloys but current day bronzes are no longer following that old designation. Here's a direct quote from a modern document from the CDA (Copper Development Association):

2.3 Bronzes Traditionally, copper-tin alloys are associated with the word ‘bronze’. However, today, the term refers to Cu-Sn alloys with further alloy additions to give improved strength such as Cu-Sn-Zn alloys (gunmetals) and Cu-Sn-P (phosphor bronzes). Importantly, it also now covers copper alloys which do not have a tin addition but are considered to provide the high qualities associated with the word bronze including Cu-Si (silicon bronzes) and Cu-Al (aluminium bronzes). Bronzes have superior resistance to ammonia stress corrosion cracking compared with brasses(3).

A good document published by the CDA is linked below. It is titled "Copper Alloys for the Marine Environment":

https://copper.org/applications/marine/cuni/pdf/pub206.pdf

dj

 

[Ralph Johnstone]

Beneteau itself state they only have a 5yr useable lifespan, which just matches the CE requirements.

I have presented a letter from Beneteau to Practical Sailor (courtesy of @Richard19068) which contradicts your claim of their saying five years useable span. Who should we believe ?

The applicable CE standard which requires that the material in question conform to ISO 6957 has been tested by an independant lab and found satisfactory. Do we believe them or you ?

So, from what you've presented to us here, you not only want us to believe you over the testing done by Practical Sailor but also want us to believe you over and above ISO 6957 as shown in your statement below :

That standard you posted is a test of the properties, not a long-term test or suitability test for thruhulls.

I'm quite sure the many people who belong to the worldwide federation of national standards bodies which in turn comprise the International Organization of Standardization (ISO) would be humbled to meet a self made genius such as yourself. Someone who does not bow down to scientific standards but relies on hand picked convenient anecdotes which suit his unsubstantiated thought of the day.

Unfortunately, I don't share their enthusiasm.

 

[dLj]

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.

It always makes me skeptical when the explanation of a corrosion problem in the marine environment is based on what people say on the internet. I've seen many levels of misinformation generated that way. I can't say one way or the other on this particular issue because I haven't seen these thru hulls directly. Until I can, I can't offer an opinion.

I will also make the observation that ISO 6957 is a test to look at the resistance against stress corrosion cracking in an ammonia based environment. While it is a good test for making sure stress corrosion cracking does not occur in a tensioned thru-hull - it does not appear to me to be a test that predicts dezincification. But I don't know what test would be used for that end.

dj

 

[colemj]

I have presented a letter from Beneteau to Practical Sailor (courtesy of @Richard19068) which contradicts your claim of their saying five years useable span. Who should we believe ?

The applicable CE standard which requires that the material in question conform to ISO 6957 has been tested by an independant lab and found satisfactory. Do we believe them or you ?

So, from what you've presented to us here, you not only want us to believe you over the testing done by Practical Sailor but also want us to believe you over and above ISO 6957 as shown in your statement below :



I'm quite sure the many people who belong to the worldwide federation of national standards bodies which in turn comprise the International Organization of Standardization (ISO) would be humbled to meet a self made genius such as yourself. Someone who does not bow down to scientific standards but relies on hand picked convenient anecdotes which suit his unsubstantiated thought of the day.

Unfortunately, I don't share their enthusiasm.

Look, I don't know what your problem with me is, nor why you insist I'm putting myself out as an expert. Nor why you intentionally misquote me.

Just do some of your own googling around. There are disproportionate numbers of boats having problems with the thruhulls used by Beneteau, Jeaneau, and a few others. I make no claims other than my opinion on DZR brass, at least that being used by the manufacturers in question, has been changed by personal observation and reading of experiences of others.

Yes, this is anecdotal, but not from just one or two observations. Yes, this could be "electrolysis" (I'm just matching Beneteau's terminology) like Beneteau insists, but it is a surprising number of boats experiencing it next to others who don't. I don't have DZR thruhulls, so don't really care - and I would be happy to go back to defending this material in this application if I see evidence that the failures are not due to the material.

As for your linked ISO, you don't understand what it is testing. As for your own thruhull, you don't understand how you are testing. As for the CE regulation being 5yrs useable life, you can simply read it for yourself.

I'm not sure what you "proved" with Beneteau's response. All they state is that they tested to an ISO standard (which isn't applicable to the problem presented), and that all of their thruhulls must be professionally inspected inside and out every year. This latter speaks nothing to your claims like you state. It is also an eye-opener to the opposite of your claims, as I know of no other manufacturer stating something like this. If you read Beneteau's warranty, you will discover that it is a 10yr warranty, with the exception of the thruhulls being warranted for 5yrs. That speaks volumes to me. I know of no other manufacturer that specifically states a warranty on their thruhulls, let alone that warranty being less than that for the boat itself.

Mark

 

[colemj]

It always makes me skeptical when the explanation of a corrosion problem in the marine environment is based on what people say on the internet.

To be clear, I've never seen anyone explain a corrosion problem of these thruhulls. They just present that their thruhull failed. These failures could have nothing to do with corrosion, and could be a manufacturing/design issue instead. Beneteau is the only one who has presented an explanation of "electrolysis". Ignoring the technicalities of that term, it seems unlikely so many would have this problem, and that only they have the problem when in the same marinas and local areas as others without.

The issue could be anything or many things, but the statistics seem to be that thruhull failures with bronze and plastic are rather rare, while that of Beneteau and other's DZR are not rare.

I don't know what B and others are currently using, and this issue may be in the past and limited to a period of time. But the examples and complaints are out there for anyone willing to look.

Mark

 

[Dave]

Hey Guys,

Debates and disagreements often lead to greater understanding of an issue, we all benefit from that. Just a gentle reminder to keep it civil and to the issue and not personal.

Thanks.

 

[Ralph Johnstone]

If you read Beneteau's warranty, you will discover that it is a 10yr warranty, with the exception of the thruhulls being warranted for 5yrs.

I still respectfully ask that you present something, anything presented by Beneteau that indicates their thru-hulls require attention due to excessive corrosion as you have stated previously:

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

A search of Beneteau's web site produces the following warranty information on new boats :

The Beneteau After-Sales Service | BENETEAU

In choosing BENETEAU, you are choosing a team of professionals, committed to acting as quickly as possible to meet your requirements. Whether you are in touch with a touring technician or our spare parts service, we are always ready to listen. Our commitment: a 7-year structural warranty and a 3...

www.beneteau.com

I think you will have to concede that this is nothing more than a typical warranty and certainly far better than I received from Hunter with my boat in 1998.

I do apologize, but without such validation from Beneteau I must label your statement as nothing more than disinformation.

 

[BigEasy]

As I mentioned previously, I changed out all my plumbing hardware over the past 18 years, including thru hull, valve, & tailpiece fittings because of the brass like composition. The last two fittings for the galley & head discharge were changed in July. None of the fittings showed signs of corrosion or signs of imminent failure. I now have “piece of mind” and a lighter wallet......what ever that’s worth.

 

[jbmia]

To the OP and others in a similar situation who may come along later,
I'm not here to debate anyone on this thread. I'm contributing because I own an '05 Beneteau 323, which has a similar production design regarding the hull grid liner/matrix system. Currently, I am in the parts acquisition and planning stages of a haul-out that includes thru-hull replacement, and I believe I can add something productive.

I'm not going to delve into the finer points of brass composition. However, based on my research and discussions with various sources at Beneteau in South Carolina and Sean at Groco, Beneteau used brass in the mid-2000s, presumable for cost reasons, designed to be replaced every five years due to CE rating requirements. At some point—perhaps around 12 years ago—they transitioned to sourcing Groco bronze fittings, at least for their U.S. boats (per Sean at Groco). In fact, if you visit your local Beneteau dealer and have them create an account for you, you'll find that the replacement fittings today are bronze Groco fittings. Spare Parts Beneteau USA

From my perspective, if you're hauling out a 20-year-old boat and still have the original or outdated thru-hulls, valves, and fittings, skip the microscopic examination of their metallic composition and proceed directly with a full replacement. The cost is trivial in "boat dollars" once you're already hauled out—far preferable to the alternative (e.g., a sinking boat).

My Choice of Fittings
I’ve chosen to use TruDesign thru-hulls and fittings where feasible and Groco BSPP valves and Guidi BSPP thru-hulls and fittings (all high-quality bronze, no DZR) where TruDesign fittings won't work.

• TruDesign with collar and 1/2" G10 back plates (see pics)
  • Engine cooling water intake
  • Stern/cutlass water cooling intake
  • Two of the head fittings I can make work
• Groco/Guidi fittings(for locations where TruDesign won't work due to space constraints or where modifying the liner seems be too invasive)
  • Both galley fittings
  • Two head fittings (see pics w/ 45 degree angle fitting)
  • I encountered the same issue with the galley sink drain (see pic) and debated cutting into the liner to accommodate a proper-sized backplate. I may still do that once I tear everything apart on the hard if it looks feasible. However, I already have the thru-hulls and valves on hand, allowing me to replace them with the same configuration as currently installed—just with much higher-grade materials.
  • These areas are protected from major impacts since they are either under the galley sink or the head sink in a cabinet. They’re not easily tripped over or stepped on (at least unintentionally).

Why BSPP?

• TruDesign sells both NPS and BSPP fittings, both of which receive excellent reviews (source: Gemlux). When installed with adhesive sealant, BSPP connections do not leak. A backing nut is also an option.
• This setup works well in bronze as well.
• There are no bronze NPS thru-hull/valve combinations sold in the U.S.
• However, Groco and European suppliers do sell BSPP thru-hull/valve combinations.
• To replicate what TruDesign does with their product and to align with European practices, I’m using a BSPP + adhesive sealant combination for the bronze fittings.

Benefits of BSPP:
Complete threading and seating of the fittings to each other
Avoids the NPT/NPS combination issue (which often results in a connection with only ~2 threads engaged)
Eliminates the Groco Combo NPT/NPS thru-hull issue with a valve (where you may get 4 threads, but then can’t cut the thru-hull down, leaving it unnecessarily long and protruding). By the way, per Sean, all their bronze thru-hulls are combo NPT/NPS, and of course cutting them down is not an issue if you're using their seacocks or their flanged adapter.

Why Guidi BSPP Thru-Hulls Instead of Groco BSPP Thru-Hulls?
Hint: Not because I prefer fancy, expensive Italian fittings…

• I originally ordered Groco BSPP thru-hulls and returned them all.
  Why?
  • The interior lugs were positioned at the inside thread end rather than the flange end (facepalm moment).
  • Because of this, you cannot cut them down to a smaller size without losing the ability to grip the lugs with a thru-hull wrench.
  • I called Groco and spoke with Sean about this. Given my relative inexperience with sailboats, I wondered if I was missing something.
    • Surprisingly, I was the first person to ask about this in the 12 years since Groco released them.
    • Sean had to put me on hold and check with the owner.
    • Turns out, they were made specifically for Beneteau—that’s how Beneteau wanted them.
    • Beneteau doesn’t bother cutting them down and assumes it's easier to tighten them from the inside.
  • So, I returned all the Groco BSPP fittings.

Why Guidi?

• They were the only manufacturer I could find in the U.S. that produces quality bronze BSPP thru-hulls and fittings with lugs on the flange end.
• Sources:
  • Aquastar
  • Environmental Marine
  • Note: The fittings from Aquastar were functional but pricey. Unfortunately, they arrived slightly dinged up, which was frustrating given the cost. I reached out to them about this but received no response.

I realize I haven’t directly answered your question since I haven’t crossed that bridge yet. However, these are my thoughts on the matter so far. Once I'm on the hard and have everything disassembled, I’ll take a closer look at whether cutting back the liner to accommodate a backing plate is feasible. Right now, I’m still waiting on a special order (drive shaft) from Beneteau before scheduling my haul-out.

On a related note, I’m also considering a DIY variant of a dry bilge solution that utilizes a sponge suction assembly and a low-amp, low-GPM pump on a timer to keep the bilge area beneath the liner as dry as possible. The challenge—similar to the question about cutting back the liner for the thru-hull—is whether it’s acceptable to remove a portion of the liner to accommodate one of the sponge suction assemblies used in these devices. It's really another topic, but still related and there are no examples of installations in matrix/liner hulls I can find as of today...

 

[dLj]

Interesting - good to know.

But I'm still stuck with the question as to what brass alloy did they use back then? Was it DZR? Or some other alloy? DZR is listed in many well recognized sources as being a good choice in this application. If it's not - I for sure want to know.

dj

 

[colemj]

But I'm still stuck with the question as to what brass alloy did they use back then? Was it DZR? Or some other alloy? DZR is listed in many well recognized sources as being a good choice in this application. If it's not - I for sure want to know.

Beneteau states it is a duplex brass. DZR is one type of duplex brass, and I think most assume they use DZR, but I haven't seen Beneteau specifically say DZR.

Mark

 

[colemj]

• TruDesign with collar and 1/2" G10 back plates (see pics)

Curious why the backing plate with the collar? Is the hull too thin there for the minimum thickness requirement of the fitting?

Mark

 

[jbmia]

Curious why the backing plate with the collar? Is the hull too thin there for the minimum thickness requirement of the fitting?

Mark

Currently there are wooden backing plates in that area... Not original OEM, so not sure what was there before... Haven't seen hull thickness there yet... Figured I'd just replicate what's there now, but with the G10 improvement. G10, in the quantity I need, is not a lot of money and I have a drill press, a few cheapy diamond hole saws from Amazon, some water and bob's your uncle.. Not hard, so figured I just go all in where I can.

 

[dLj]

Beneteau states it is a duplex brass. DZR is one type of duplex brass, and I think most assume they use DZR, but I haven't seen Beneteau specifically say DZR.

Mark

You know the old saying about when you ASSUME - you make an ASS out of U and ME

If DZR is not an appropriate alloy for this, then it should be brought to the CDA, ISO, and several other well known sources attention. But one doesn't stand up and whine about how "my thru hulls didn't last as long as I'd like, so bad alloy" when it isn't even known what alloy they used, nor have documented evidence as to why these thru hulls were failing. Don't get me wrong, I'm not ranting at you, in fact, I thank you for bringing this up - I'm ranting at the typical response of the marine world that never wants to actually look at why things break. The amount of misinformation that exists is amazing...

dj

 

[colemj]

I'm ranting at the typical response of the marine world that never wants to actually look at why things break. The amount of misinformation that exists is amazing...

The marine world in this case are just boat owners with failed thruhulls that were disappointd when they were told 5yrs is the useful life of them, and that the thruhulls needed to be professionally inspected inside and out on an annual basis. I'm sure all of them bought boats not thinking about thruhull material at all, but thinking that would not be a weak point. It would be beyond my expectations to insist an owner look into why they failed, outside of wanting to rule out any stray current or galvanic issues emanating from the boat itself. They just replaced with different material and moved on. Beneteau and others have refused to publicly determine why they failed, and apparently have now dropped them for more robust thruhulls. I've found no misinformation - just people saying their thruhulls failed in a relatively short time span, and these people owned specific boats. The closest thing to misinformation is Beneteau's insistence that electrolysis is to blame.

If one examined and determined root cause for every thing that broke on a boat, one would have no time for using the boat at all...

Mark

 

[Ralph Johnstone]

The amount of misinformation that exists is amazing...

How very, very, true. And it seems to be growing in SBO by the day.

Gentlemen, may I suggest that if you don't have the documentation to prove your statements, DO NOT put your own opinions forward as being factual. Just offer the information as your opinion. And when I refer to documentation, I don't mean some other clown's far fetched opinion. If Beneteau's made a statement, show us a screen grab of that statement and provide a link to it and DON'T TELL ME to go and look it up on the web. If I can't find it, what the hell does that prove ? You make the statement, you provide the proof. For example :

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

I have spent considerable time looking for requirements of the CE certification of sailboats presuming the classification to be CE-3. One of the better explanations of CE ratings I've found is contained in the following video :

Google Search

In further searches, I have not been able to find any reference to life expectancy of DZR thru-hulls although I did find a form for certification of through hulls for CE compliance as shown below :

https://www.imci.org/site/document/applications_checklists/Applications/Other/9093_2021_Seacocks_en240408.pdf

............................. which does mention DZR as shown :

Line 5 mentions testing to assure acceptance to ISO 6509-2:2017 standards which outlines a max. acceptable corrosion as a result of the test methods applied in ISO 6509-1 as shown below :

https://cdn.standards.iteh.ai/samples/59999/93e589f92ea549829c86322bc02dc02e/ISO-6509-1-2014.pdf

Not sure of the method of construction of thru-hulls so can't say whether (a) or (b) applies. Still, I can find nothing in ISO standards which limits the life expectancy of DZR thru-hull to five years. It doesn't mean they don't exist, it just means I can't find them.

Let's NOT turn this site into another SA which I sometimes suspect is an offshoot of the National Enquirer.

 

[dLj]

You appear to be loaded for bear... I'm not interested in an argument. I'm more interested in learning and expanding my knowledge in as many areas as possible. I also feel that we have an obligation to try to move into better knowledge and that as owners of boats, to keep an objective point of view.

In post # 8 you state:

They are DZR brass.

Mark

But now you say you don't know. Hmmm.....

The marine world in this case are just boat owners with failed thruhulls that were disappointed when they were told 5yrs is the useful life of them, and that the thruhulls needed to be professionally inspected inside and out on an annual basis.

This is actually good advice although most of us don't do it. I do it every time my boat is out of the water, but if I'm in the water for more than 1 year, obviously I'm not inspecting every year. I'm also a professional so I don't have the expense of hiring one...

I'm sure all of them bought boats not thinking about thruhull material at all, but thinking that would not be a weak point. It would be beyond my expectations to insist an owner look into why they failed, outside of wanting to rule out any stray current or galvanic issues emanating from the boat itself. They just replaced with different material and moved on.

Of course – there are too many things on a boat to worry about and 99%, or higher, of boat owners don't even have the expertise to worry about this. We are all relying on the manufacturer to be taking care of all these kinds of details.

However, if there are a large number of owners finding the same type of problem, maybe they ought to start thinking about hiring a professional that can actually make these kinds of determinations.

Beneteau and others have refused to publicly determine why they failed, and apparently have now dropped them for more robust thruhulls.

This is very common. It has to do with legal ramifications. But the real answer may be more complex or very different than one may think at first blush. It may be that the original thruhulls they were buying came from a supplier that simply did not provide what they had specified. It gets rather complex from a commercial point of view. There are many other possible scenarios.

I've found no misinformation - just people saying their thruhulls failed in a relatively short time span, and these people owned specific boats.

Don't you think that maybe when these kinds of things happen, it would be a good idea that owners go – “Hey, this seems to be happening to a lot of folks, how about we find out exactly what is happening?”

The closest thing to misinformation is Beneteau's insistence that electrolysis is to blame.

This is clearly a “marketing” publication...

Here's the definition of electrolysis written by “The Worldwide Corrosion Authority” and originally published as the Corrosion Glossary through NACE (National Association of Corrosion Engineers) which has now become AMPP (The Association for Materials Protection and Performance). I think you can still find it on AMPP's web site but I haven't looked in a couple years. I have my own copy as I helped edit the original document.

electrolysis—production of chemical changes of the electrolyte by the current flowing through an electro-chemical cell.

I'd be willing to guess anyone that can read and understand English would realize that the explanation as you've stated cannot be correct.

If one examined and determined root cause for every thing that broke on a boat, one would have no time for using the boat at all...

Mark

It seems a bit extreme to insinuate that I suggested “everything that broke on a boat” required a root cause examination. Obviously that is not realistic. However, it does seem realistic that when the same thing happens multiple times, that somewhere a light bulb should go off saying – maybe one should talk to a professional and find out if there is something here that needs to be brought to light. In fact it could actually make economic sense....

dj

 

[colemj]

You appear to be loaded for bear...

I'm really confused why you keep coming at me, since I haven't been trying to argue with you at all. You asked what the thruhulls were made of and I told you Beneteau said they were duplex brass, of which DZR is one type, but that Beneteau (to my knowledge) hasn't specifically said that. That is all. I thought it was a helpful comment.

Yes, I said DZR brass, because that is what Yachting Monthly called it, and is what many of the owners have called it. It has been described as such in the forums where the problem has been discussed. It may not be DZR, and I admit that, particularly after seeing that Beneteau just called it "duplex brass".

As for people with the problem gathering together and hiring a professional, these things happen in isolation over time. It's not like everyone has their boat pulled out together and finding the same issues with them and deciding to take collective action. Particularly since they have no legal recourse if the thruhull is 5yrs or older. If it was me with a failed 6yr old thruhull and no legal recourse, I'd just replace with a better one and go sailing. But sure, it'd be a good thing to do.

This whole thing started with the OP asking about his thruhulls and wanting to replace them because they were brass. When everyone refused to believe that, I posted that they were brass, and this has been a contentious issue with Beneteau, Jeaneau, Hanse, and several other manufacturers. That is when certain people here started taking the piss out of me. Then other owners of Beneteaus posted they are brass and that they found some issues with theirs.

So let's agree that there have been an unusual amount of failures of these thruhulls in these boats compared to other boat manufacturers not using them, and that we don't know the exact composition other than "duplex brass". After that, we are all free to speculate on what type of brass, whether it is normal for a thuhull to only last 5yrs, and whether these failures are to be blamed on the boat and not the material.

Mark

 

[colemj]

How very, very, true. And it seems to be growing in SBO by the day.

Gentlemen, may I suggest that if you don't have the documentation to prove your statements, DO NOT put your own opinions forward as being factual.

That's good advice, you should try it some time.

First, you argued that brass was not used at all. Then when you were shown to be wrong, you changed your arguments to ad hominem ones and posted nonsensical things like ammonia immersion requirements, along with a misreading of Beneteau's written response. Now you are posting what you think is the CE directive, but you don't understand that what you are posting is not the EU RCD ISO standard for thruhulls on a boat.

That standard is ISO 9093, and here is what it says for the version the OP's boat was built under:

See that? 5 years service life is all that was required by CE/RCD for these boats. Here's your link: https://www.iso.org/obp/ui/#iso:std:iso:9093:-1:ed-1:v1:en

Now, this standard has been recently updated, and that 5yr service life part has been removed. Coincidently, at the exact same time, Beneteau and all the other manufacturers with this thruhull problem stopped providing brass thruhulls and started using bronze and plastic.

To put this in perspective, the OP himself stated his thruhulls were brass and you refused to believe that. Then you jumped ugly on me for whatever reasons when I simply pointed out what the OP said was true and that it is a known issue. Then this all focused on whether DZR brass can corrode instead of the real fact that CE only required 5yr life, Beneteau built to that using whatever material they did, and it has been a widespread and public enough problem that I'm very surprised you and the people arguing this here have not heard about it.

Nobody with these boats having failed thruhulls care if it is DZR or not. They are only concerned that their thruhulls are failing after an unexpectedly short time,. and in ways that were not readily apparent from normal sight and use. Why you are arguing this is beyond me.

Mark