Is my thru hull bronze or brass

[Frederik283]

Hi can you help me identify the material?

[more]

clean i small part to metal with sandpaper.
Brass is yellow/gold color
bronze reddish brown

[Manateeman]

Looks bronze but old. Replace with Groco adaptor plate. Info at marine how to. com...nice guy, be generous, he’s ill.
We pulled all our Marelon plastic toy boat stuff and went Groco.
Just the opinion of professional boatbuilders.
The manatee crew.

[SVTatia]

Originally Posted by Manateeman

Looks bronze but old. Replace with Groco adaptor plate. Info at marine how to. com...nice guy, be generous, he’s ill.

We pulled all our Marelon plastic toy boat stuff and went Groco.

Just the opinion of professional boatbuilders.

The manatee crew.

Marelon is made of composits, stronger than the fiberglass boat using them.
I can understand the choice of replacing Marelon with bronze, but replacing a bronze fitting just because it is old? Bronze lasts a very very long time, as long as it is not turning pink due to metal loss.

Looks like the OP just need to clean the thru-hull for further checks, but it looks like bronze to me.
I have read here that some older european boats had brass fittings rather than bronze.

[Pete7]

Originally Posted by Manateeman

We pulled all our Marelon plastic toy boat stuff and went Groco. Just the opinion of professional boatbuilders.
The manatee crew.

Are the bits for sale?

[AA3JY]

If it’s a benateau built boat most likely brass..
https://www.practical-sailor.com/boat-maintenance/beneteau-responds-to-seacock-query?amp=1

[SVTatia]

Originally Posted by Pete7

Are the bits for sale?

Yes and for a very good price, check his post.

[Manateeman]

Sorry, we didn’t mean old, just old design...it’s not a seacock in our opinion. The strength is simply all on the thru hull. Seacocks to us, are things bolted to the hull. Supported ball valves, plastic, reinforced plastic...put them in your boat if you want, but that is not our opinion.
We built a vessel over 30 years ago with real solid bronze Apollo seacocks and they all still work perfectly. We love bronze. A good solid backing plate or additional hull layup and an all bronze real seacock...perfect.
The OP asked for a professional opinion. He can check our qualifications and make his own decision. So let’s see who you have worked for, how long and what you have built with your own two hands.
I don’t quote others...period. Let people decide about the advice given without comments on the advice of others.

Captain Mark

[Shanachie]

Actually, the answer to this is more complicated than many think.


Basically, bronze is an alloy mixing copper and tin. Brass uses copper and zinc. But there are all kinds of specific alloys with all kinds of properties.



Lots of rudder and prop shafts on sailboats are naval bronze, which is a type of brass. Yet it has good resistance to saltwater corrosion, although not as good as say silicon bronze.



Groco says on its web site that its through hulls are c83600 bronze and c84400 bronze. However, when you search for those alloys, you find them described as red brass with zinc in them.


As a respected manufacturer, I assume Groco knows exactly what it's doing and that the alloy endures fine in saltwater. I had no problems with them on previous sailboats.



Marelon is also a fine product. I have it on my current sailboat.



To the OP: If it ain't pink, it's fine. Pink means that the zinc has eaten away, reducing the strength of the alloy.

[Bowdrie]

For those interested, this is a pretty good PDF on metals for marine usage.
http://www.kastenmarine.com/_pdf/mbq...2C%20and%20tin.

[SVTatia]

Originally Posted by Manateeman

Sorry, we didn’t mean old, just old design...it’s not a seacock in our opinion. The strength is simply all on the thru hull. Seacocks to us, are things bolted to the hull. Supported ball valves, plastic, reinforced plastic...put them in your boat if you want, but that is not our opinion.
We built a vessel over 30 years ago with real solid bronze Apollo seacocks and they all still work perfectly. We love bronze. A good solid backing plate or additional hull layup and an all bronze real seacock...perfect.
The OP asked for a professional opinion. He can check our qualifications and make his own decision. So let’s see who you have worked for, how long and what you have built with your own two hands.
I don’t quote others...period. Let people decide about the advice given without comments on the advice of others.

Captain Mark

It looks like it hit a nerve, and I assume this has been directed at me... That was not my intention, like everyone else, I was stating my opinion, just like you were expressing your opinion as mentioned in your post, and the OP did not indicate he was asking for professional advice.
This is what this great forum is for, we provide opinions that lead to an educated decision. And yes, I have built boats too.
Cheers

[goboatingnow]

Captain marks’ opinion is fine and represents the best possible solution. However many “ good” solutions exist. DNZ brass will provide a long service life especially if not bonded together and with the bonding not connected to shore power, in my view ABYC recommendations are why there is an issue in North America . One does not see habitual replacement of dnz brass in the med for example. Many fittings are well over 15 years and still strong . The PO of my Bavaria got bad advice and had all the original fittings replaced they then tested the originals , which turned out to be fine!

Hence what is a perfect solution and what is an acceptable solution can be quite different

[Sorcery61]

Brass fittings are always a poor choice if sailing in salt water. Warmer oceans accelerate the degradation which is typically the loss of the zinc from the alloy
Poor electrical designs and in adequate corrosion protection design and maintenance are also significant issues.

One if the very high performing alloys is Tungum alloy(1) (UNS C69100) iThis is an aluminum-nickel-silicon brass (chemical composition: 81-84% Cu, 0.70-1.20 Al, 0.8-1.40 Ni, 0.80-1.30 Si, with the remainder Zn) and is reported to have good corrosion performance in marine environments (fully wetted, splash zone and atmospheric conditions) from many years' service
Used in thin wall tubing for saturation diving system oxygen plumbing among other uses.

Be very careful if adopting the through bolted seasick concept. In greater than 50% of sea cocks that my team have inspected the bolts were dissimilar metals and had set up their own corrosion loops with loss of section of the bolts being the typical issue

Consult a recognized marine architect or certificated survey for specific advice on your vessel and a wholistic view of the integrated systems

[goboatingnow]

Use good quality DNZ Brass , don't bond , will last 30 years in the med , currently the saltist and hottest sea in the world , not my opinion , merely what's around me