SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Brass thru-hulls?

11K views 33 replies 12 participants last post by  Capt Len 
#1 ·
Really? They, Jeanneau,used brass for thru-hulls back in 2000?
 
#3 ·
A decade ago we wanted to add a thru-hull and started trying to dig out details from basically all the suppliers in the US as to what their yellow thru-hulls were. And it turns out that "brass" and "bronze" overlap in alloys, so what one foundry calls "brass" is exactly the same as what another calls "bronze". And then at least one top name simply refuses to say what their "bronze" alloy actually is.

No, you should use brass on a boat, but yes, there are in fact "marine brass" alloys that can legitimately be used and called "bronze".

We gave up and went with genuine Marelon.
 
#4 · (Edited)
No, you should use brass on a boat, but yes, there are in fact "marine brass" alloys that can legitimately be used and called "bronze".

We gave up and went with genuine Marelon.
Gentle disclaimer .... The metallurgy gets a little complicated so my opinions have been simplified for the purpose of this forum ....

This is incorrect , Brass is brass whether you call it plated brass, Naval bronze or admiraly bronze. These are largely marketing misnomers. True brass is defined by zinc content and the previously mentioned types have between 20% -39% zinc .... these are not bronze's

Various types of bronze's may have small amounts of zinc however the types preferred for marine use will have zero or close to it.

The issue with brasses is the "Dezincification" cause by galavaic corrosion. Think of it this way your "zincs" (anodes) are designed to waste by giving up electrons to more cathodic metals ..... Do you really want your brass thoughulls giving up electrons and wasting away like your zincs.

This whole brass throughull/seacock mess was caused by the CE standards stating that throughulls and seacocks should last 5 years. So what did Jeanneau, Beneteau et al do .... they bought the cheapest materials that would meet the standard :eek

These same builders saved even more money in many cases by fitting NPT valves on NPS throughulls ... Shocking idiocy !

Suggest you Google "dezincification, brass seacocks, NPT, NPS" lot and lots of stuff from legitimate authorities on this issue. Also some terrific photos of this stupidity on Compass Marine website (a frequent poster here).

Just to get you started read one of Paul Stevens articles in Yachting Monthly

PS. I am a Certified Corrosion Analyst and I believe this is verging on criminal.
 
#7 ·
DZR (DeZincification Resistant brass) is a better quality brass alloy witha lower zinc content than normal brass with a couple of other metals thrown in and will do the job but not for as long as a good quality bronze.

There is still a bit of a crap shoot even buying brand name bronze Groco who had a great product and reputation for decades screwed up badly some years ago when theY switched production to China and did not supervise closely enough ..... result a huge recall. Don't trust Chinese metallurgy :)

As to Marelon .... yes, I have no problem with sizes 1.5" and over but the smaller ones give me the creeps. In a survey I used to put my foot on seacocks and apply a little pressure as they are supposed to handle up to 500lbs. lateral force. Let me just say that I learned the hard way that the smaller Marelon units were not up to the 500lb. standard.
 
#6 ·
boatpoker-
I don't disagree with you, and don't need to google it. I went through all that and when the most respected names in the industry (US or otherwise) all played "he went that-a-away" like the three stooges used to, pointing to different names and alloys and contradicting each other AND metallurgy references, that's when I said **** this all, we're going plastic. Because a good glass filled nylon, kept below the waterline, will not take UV damage, will not corrode, will not de-zinc, and if it is in a place when gorillas and flying batteries can't land on it, it will be plenty sturdy enough. Not to mention cheaper.

Now, for you to suddenly reveal that a commercial mass-market boat builder would dare to cut corners and "build it to a price", that's just shocking. Really shocking. Next you'll be trying to convince me that they use stainless instead of titanium just to shave costs and keep the prices down. (We all know, stainless is shinier and shiny shiny pretty pretty is what really counts!)

I wonder, with online machine shops and CAD/CAM and all, what it would cost to either print or carve some truly durable titanium thru-hulls. You know, perfect xmas gifts for the racing, or fast cruising, set. And whether just any old titanium alloy would do?
 
#10 · (Edited)
Ditto ... 'gas' bubble pockets/blow-outs too, unless the inlet/outlet 'sprues' of the mold are engineered to 'perfect'. Most 'true' bronzes are very difficult to machine (re. threads, etc.). But that is all ancient metallurgy.

BRASSES THAT ARE NOT SUBJECT TO DE-ZINCING.
Just like true-bronzes that are formulated without tin such as NickelAluminum Bronze, there are various available forms of BRASS, with zinc, that are anti-de-zincable (DZR or DR) brasses that are alloyed with 'transitional metals' such as Tellurium, Selenium, Tantalum, Niobium, Arsenic, etc. that changes the entire molecular (grain) structure which in turn inactivates and prevents the de-zinc-ability of the brass. These formulations and 'sequences' were closely held proprietary secrets. Its going to take a very long time for asian foundries to recover them; hence, the current problem of zinc loss from asian produced DRZ brass. These DZR alloys were originally discovered/formulated in the ~1950s-1960s for critical navy, aerospace and chemical engineering applications. Their current usage is quite widespread, despite the almost total forced collapse of the US 'red metals' industry and other domestic 'foundry' activities.
Here's a brief technical explanation of how these 'de-zincing' BRASSES are formulated: http://www.jomarvalve.com/docs/lit-jv-dzr.pdf

Here's a bronze without tin and without the typical trace zinc that aids 'machinability' ... I worked for of the original discoverers of this alloy at that time as a student intern bench chemist (at Phila. Bronze & Brass Corp. / AMCO Metals): Alloy: C95500 Nickel Aluminum Bronze - Concast Metals
 
#9 ·
The big US manufacturers of seacocks & thru-hull fittings use 85-5-5-5 bronze almost exclusively. It has been the go-to bronze for seacocks as far back as the 1930's. I have many 85-5-5-5 seacocks out there beyond 50 years old. This list of manufacturers using 85-5-5-5 includes Groco, Apollo/Conbraco, Spartan, Buck-Algonquin and even defunct manufacturers such as Wilcocx-Crittenden... This is a far superior bronze than what the ISO/RCD builders use...
 
#11 ·
Boatpoker-
For the main engine water intake, that's often someplace (like in the bottom of a laz) where someone or something might step on it. But for "that *damned thruhull" under the forward washbasin that you have to secure for the head intake"...Regardless of size, you might want it is extremely resistant to being found by a 500# gorilla. Or even a clever capuchin monkey.(G)
All these technical details of "newer" alloys are the reasons that I got allergic to hearing the terms "brass" and "bronze" in any marine setting. Even ten years ago, they were being tossed around and the big guys were insisting everything was a Trade Secret. Which doesn't really impress those of us who have seen things like analytical labs. Used to be a properly timed pizza and six-pack could get you a fast analysis of almost anything in any college chem lab. So...
Brass? Bronze? Might as well say the boat is made of "plastic" and the spars are made of "wood". They're all the same, and well-defined, too. Right? (G)
 
#15 ·
I don't know the chem composition or maker of my thru hull or ball valves in some cases. Do I worry? What are the signs of impending failure? The ball valves are neither loose nor tight.

Should I consider replacing all or some of them in the Spring?
 
#16 ·
It should be embossed or etched into the body. Usually it is just part of the casting. If it says DZR then yes I would replace it. Keep in mind the parts are only supposed to have a service life of five years. So some will fail before that some after.

The EU standard has been a disaster, and it's a stupid way Tom save a trivial amount of money. But the series builders can shave a grand of the cost of a boat from the factory.
 
#18 ·
I'm not sure that is exactly what the certification standard means. While this seems to be a genuine quality problem, I believe the majority far outlive 5 years. I'm just not sure that majority is high enough. After the 5 years certification window, you become the test pilot.

I'm hoping to begin a swap out to Groco this spring. Don't think I stand a chance of getting to them all, but will start with those furthest beneath the waterline.
 
#24 ·
It's fairly easy to knockoff the skin fitting from the outside when the boat is on the hard, I use a 4.5" angle grinder to remove the mushroom, it's quick and easy provided you're not removing flush fittings. For mounting pads I use 1/2" G10 pre drilled for the through hull and the seacock already bolted to to it, G10 taps well. It's easy to insert the through hull and spin the new seacock onto it then bed it in an epoxy slurry. As long as the through hull is flush to the hull the slurry will fill any misalignment. After it cures I remove the bolts holding the seacock on, spin the seacock off, bed the seacock in a polysulfide, spin it back on and bolt it to the G10. Done...

Most of this is from Mainesail, he's great!
 
#27 ·
The problem for most of the ball valves on boats is the HANDLES that you use to open and close them... almost all are crappy metal and corrode eve of the ball valve is OK. Why don't they make SS or bronze or delrin or no corrosive handle???

They do... but matching them is a bummer!
 
#28 ·
I had no idea my feeble tonguein cheek glib attempt at subtle humour would be taken seriously. If you haven't got at least a visual on thruhulls it's not likely the tapered plugs on a lanyard nearby concept will help when the itch develops a rash. If stuff is in the way how about a big hole saw in the locker and clips to secure the cutout or make a new panel if you have to move the hole. Torquing the last thread onto mis matched puts a lot of sheer on the thread roots and causes an itch too.
 
#29 ·
That floppy handle can be replaced with a piece of SS strap, say 1x3/16 slot drilled and filed to fit. Quash a piece of hose in a vice and drive them together for a professional look. or bolt on an extender shaft handle for remoter operation if the angles cooperate
 
#31 ·
Glad some of you with more recent Jeanneau's are figuring this BIG issue out.
If you're like Minne, in fresh water, not as big a deal. BUT if in salt water in a HOT marina or your ground etc is not that good. You will have issues with the chrome plated brass fittings that came std from Jeanneau.
There have been multiple posts at the jeanneau-owners forum site on this issue.
I've bought all new thru hulls for my 85. These appear to be a normal bronze. I'm going with flush Marlon thru hulls and valves.

Marty
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top