Brass through hulls

[DrWatson 381]

All through-hulls worry me.

 

So, if you don't have any through-hulls, and your keel setup is completely sheathed and sealed in epoxy glass, you have a transom hung rudder and an outboard, is there any need for an anode?

 

It would just seem that fully half the boats that sink at marinas sink through a skin fitting failure, and i guess the rest through a mixture of filling up with rainwater, or general rotting into the sea.

 

Would anyone site a through hull in the transom just above the waterline? You'd have to pump stuff out of it but it could be more reliable than multiple holes under the water line...

[Tim C 23]

All through-hulls worry me.

 

So, if you don't have any through-hulls, and your keel setup is completely sheathed and sealed in epoxy glass, you have a transom hung rudder and an outboard, is there any need for an anode?

 

It would just seem that fully half the boats that sink at marinas sink through a skin fitting failure, and i guess the rest through a mixture of filling up with rainwater, or general rotting into the sea.

 

Would anyone site a through hull in the transom just above the waterline? You'd have to pump stuff out of it but it could be more reliable than multiple holes under the water line...

 

I'm guilty of most of the above. Plastic through hulls for the toilet, but they are in water tight compartments. Outboard and centreboards. No anodes other than those on the outboard, that lifts up of course. I sleep at nights knowing I can't sink. Oh that's right, it is a catamaran, so can't anyway!

[cam 0]

There are some v interesting things in the surveyors report on the home page link, that surprised me anyway. including some installation stuff such as using wooden backing blocks, over tightening etc...

 

Have copied the link below for when it moves off the home page

http://www.michel-christen.com/2T-H.pdf

 

This surprised me...

The difference between brass and bronze thru-hull fittings will be of primary interest to any surveyor or boat owner attending or owning a boat used in seawater. Galvanic corrosion is not as significant a problem for vessels in fresh water, and since there are far more recreational boats in fresh water than seawater, this may be one of the reasons so many brass fittings are available to decorate the underwater areas of a boat.

really? more recreational boats in fresh water, I sure didnt know that. But then of course i expect he is referring the US only (surely), but does explain why there is a market for brass stuff at all.

 

"The amount of Zinc in Brass varies from 5% to 45%, with the 60/40 or 70/30 (copper/zinc) alloys being the most common and causing Brass thru-hull fittings made from 60/40 to be pretty good sacrificial anodes or Melt-Awaynium."

 

Melt-awaynium ... thats a very good way to get sailors attention I reckon.

 

So read on thinking, ok so how do i identify if I have brass fittings that are 15 or less zinc (and could be ok), or 60/40 which are def not ok. Or how do i identify if they are bronze.

Or at least 'is a visual indication of corrosion' a reliable indicator of dezincafication.

 

All NOT possible to do with a high degree of confidence (according to this report)

 

The summary recomendations in that report are worth repeating here for the casual reader.

 

"•Be aware that you have no ready means to determine the quality of a thru-hull fitting after it is installed.

• Do not automatically assume every metal thru-hull fitting is bronze.

• Be aware that catastrophic dezincification of a fitting may not be discoverable by scratch test of the exterior mushroom cap of a fitting. (The sailboat fitting did not show “pink” at the exterior.)

• When specifying new or replacement thru-hull fittings, include UL Listing as a standard of quality.

• Be cognizant that high zinc brass fittings are susceptible to dezincification and stress-corrosion cracking under appropriate conditions such as immersion in stagnant or slowly moving seawater, and head discharge fittings may be particularly vulnerable.

• Become informed about metal alloys and corrosion processes."

[wheels 543]

really? more recreational boats in fresh water, I sure didnt know that. But then of course i expect he is referring the US only (surely), but does explain why there is a market for brass stuff at all.

Both Europe and the US have a lot more boating in fresh water. The US is big time fresh water. In my view, one of the biggest reasons why boats out of the US and Europe are built so "poorly". Most certainly, none are built for NZ coastal conditions and many from those countries are even built with the sea in mind at all.

 

All Bronze fittings should be stamped or cast with the letters DR or DZR on them. DR = de-zincification resistant.

[too_tall 15]

This is interesting and scary.

 

Our boat has some >30 year old through hulls on it - originals. American made ( and proudly too, I might add judging by the size of the "Made proudly in the U.S.A" on every fitting... )

 

All well bonded, and all are still very sound. Still survive a good thump with a heavy rubber maul every time its out of the water. The attached seacocks are in the same state ( these are fully servicable parts, apparently the same as the US Navy were specifying at the time if the engineer who informed me of this is correct ).

 

I would prefer plastic. No argument. But when we looked at changing we were advised against it as what we have is still very sound and "will last forever if you look after them" - I assume meaning keep the seacocks serviced as per required, and keep anodes up to par.

 

What weight are the ones the Euros use to start with? Or are they "out of china" budget stuff which is not made for mission critical use ( which a through hull most certainly is! )

[Guest]

Has anyone questioned what NZ or Aus built boats are also using the same brass through hulls?

It seems to me that if the bulk of the worlds production boat builders are using this spec, then a huge amount of them are probably getting sold here in NZ already......

[too_tall 15]

There are a couple of comments made in their report about the make up of Bronze that are wrong however. Bronze does have zinc. The amount varies as to the manufacturer. But ruffly 15% Zinc. Lead is added for machineability and sometimes Silicon instead for the same.

 

This is incorrect Wheels. True bronze is copper and tin. In amounts from approx 85% copper/15% tin to 90 Copper and 10 tin, although apparently the modern trend is 88%/12%. And only copper and tin ( at least till oxides begin to form ). "Architectural bronze" may well contain zinc, as well may "commercial bronze" but that is actually technically an incorrect term for them as they should be correctly be called Brass. You may well be correct in that the fittings on the european boats are made with the incorrect material, which does indeed contain zinc, but they are technically no longer bronze then, and I am sure should someone challenge the builders on these terms, they would win.

[Guest]

And you have chinese bronze -

50% copper

10% tin

10% zinc

10% Melamine

10% Toyota/Mazda/Mitzi

10% those empty Stinely cans you hiffed in the recycling bin 3 months ago.

 

Chatting around town it appears some of the Euro importers have told their owners about this and fittings are being replaced under manufacturers warranty. But some haven't said much at all to anyone.

 

 

And if those fittings are available there in the EU the chances are high they are also being sold here.

[Guest]

And you have chinese bronze -

50% copper

10% tin

10% zinc

10% Melamine

10% Toyota/Mazda/Mitzi

10% those empty Stinely cans you hiffed in the recycling bin 3 months ago.

 

Chatting around town it appears some of the Euro importers have told their owners about this and fittings are being replaced under manufacturers warranty. But some haven't said much at all to anyone.

 

 

And if those fittings are available there in the EU the chances are high they are also being sold here.

 

Surely the Greenies must love these ones KM....I mean the're 20% recycled.............

[wheels 543]

This is incorrect Wheels. True bronze is copper and tin. In amounts from approx 85% copper/15% tin to 90 Copper and 10 tin, although apparently the modern trend is 88%/12%. And only copper and tin ( at least till oxides begin to form ).

No I am not incorrect. Before you start making comments like that, either spend many years in a metal trade like I have or do some research.

Here's a for instance. Have you ever looked at how many grades of Aluminium there are? Or SST, Or how about just Steel. Lots and lots. Well the same is for Bronze. There are a heap of different mixes for just Bronze alone. There is no actual strickly adhered to recipe for many types of Bronze. It depends on many factors and a smigeon of what the manufacturers think should be added to make their own product. As I said earlier, the most important aspect of making bronze is the process. NOT the amount of zinc in it. Poor process and you will get a bronze that may have all the correct ingredients in the correct ratio, but still end up with a poor product.

[Guest]

And you have chinese bronze -

50% copper

10% tin

10% zinc

10% Melamine

10% Toyota/Mazda/Mitzi

10% those empty Stinely cans you hiffed in the recycling bin 3 months ago.

 

Chatting around town it appears some of the Euro importers have told their owners about this and fittings are being replaced under manufacturers warranty. But some haven't said much at all to anyone.

 

 

And if those fittings are available there in the EU the chances are high they are also being sold here.

 

Surely the Greenies must love these ones KM....I mean the're 20% recycled.............

70% recycled.

The copper was stolen by some Homie G's from the Southsde off the roof of a Church in Manakau.

[tuffyluffy 76]

The melamine comes from recycled kitchen cabinets, so its 80% recycled.

 

Or Fonterra are offloading some they cant get rid of

[Guest]

Don't tell Sue Bradford, next she'll be making all boats use Brass through hulls and paper mache hulls............By the way, has anyway found her a razor yet?

[wheels 543]

By the way, has anyway found her a razor yet?

Something like this??

By the way, has anyway found her a razor yet?

[too_tall 15]

This is incorrect Wheels. True bronze is copper and tin. In amounts from approx 85% copper/15% tin to 90 Copper and 10 tin, although apparently the modern trend is 88%/12%. And only copper and tin ( at least till oxides begin to form ).

No I am not incorrect. Before you start making comments like that, either spend many years in a metal trade like I have or do some research.

Here's a for instance. Have you ever looked at how many grades of Aluminium there are? Or SST, Or how about just Steel. Lots and lots. Well the same is for Bronze. There are a heap of different mixes for just Bronze alone. There is no actual strickly adhered to recipe for many types of Bronze. It depends on many factors and a smigeon of what the manufacturers think should be added to make their own product. As I said earlier, the most important aspect of making bronze is the process. NOT the amount of zinc in it. Poor process and you will get a bronze that may have all the correct ingredients in the correct ratio, but still end up with a poor product.

 

 

Actually TRUE bronze is ONLY copper and tin or copper and arsenic ( its not been made this way for many centuries ). Maybe you need to think about doing research. If it contains zinc, it TECHNICALLY is brass. If it has any other metal in it, then technically it is not bronze. I stand by my statement. Mixing zinc into a Cu/Sn alloy is not bronze any more - although some will incorrectly call it this. It maybe referred to as a bronze alloy ( itself an incorrect term), but being correct, it can only be referred to as a bronze based alloy. If zinc is used as the alloying agent, it is brass.

 

I know people who have spent many years in their respected trades. Occasionally everyone makes a mistake or an incorrect assumption. I do in my profession occasionally. And I am happy to admit it.

[Guest]

By the way, has anyway found her a razor yet?

Something like this??

By the way, has anyway found her a razor yet?

 

Na....more like this

[too_tall 15]

The copper was stolen by some Homie G's from the Southsde off the roof of a Church in Manakau.

 

The problem with that stuff is that they leave bits of the insulation layers attached, makes for a very weak alloy indeed

 

Of course, leave enough of the insulation attached and you no longer need to bond the fitting.

 

Hansen fittings are tough, durable and cheap. Anything I have to replace will promptly get one in it.

[wheels 543]

I see you got that from Wikipedia. Technically is not quite the right term. Traditionaly would be more appropriate. Arsnic was used in Bronze 3000 yrs BC. Metallurgy has come rather a long way since then. But I have said all I need to on this. Moving on.

[too_tall 15]

I see you got that from Wikipedia. Technically is not quite the right term. Traditionaly would be more appropriate. Arsnic was used in Bronze 3000 yrs BC. Metallurgy has come rather a long way since then. But I have said all I need to on this. Moving on.

 

Nah, not Wikipedia. My knowledge dated back to a research project when I was at Uni. Well before wikipedia was in existence.

 

And technically is the correct term. The technical composition of Bronze is Cu and Sn. Simple.

[Guest]

Popcorn anyone?