View Full Version : Sustituting For Bronze…

A. Mason
01-17-2003, 11:21 AM
In the spirit begun by Dave & Bob, I decided to post the following.

I was just doing a little research on Ennals Ives and Transpacific Marine. They had marketing arrangements with Al for a number of years.
Ives built quite a few wood boats to Al's designs before Transpac switched to fiberglass. When they were first getting established in Taiwan, Ives wrote [1964] to Al saying:

"We have a problem here regarding bronze fastenings. Brass, copper, stainless steel, and galvanized iron are readily available but bronze
will have to be imported. The plank to frame fastenings will be copper rivets and we have a small supply of bronze screws sufficient to use on
the hood ends of the planking. We would like to know however, if there is an acceptable substitute for the bronze nails required to edge nail
the planks and for the bronze bolts required at the frame to floor timber and backbone to floor situations."

Al's answer to Ives question:

"Fastenings— Copper nails would be equally suitable for edge nailing providing they are of ample wire gauge to extend thru 2-1/2 strakes of planking. Copper nails riveted over roves or burks [don't ask, I don't know what he means] would be suitable for planking to frames.

We would NOT recommend brass for any fastenings except interior joiner work.

Bolts should be of stainless steel with galvanized iron as our second choice."

Ives responded:

"Your advice regarding fastenings was appreciated. We will use copper rivets with burrs for plank to frame and copper nails for edge nailing. All keel bolts are stainless steel and frame to floor fastenings will be of galvanized iron. This has solved our fastening problem so far!"

Here's another tidbit:

Ives: " what electrolytic problems would we create by using a stainless steel prop shaft and rudder stock in connection with bronze stern bearing carriers and rudder fittings? Stainless steel shafting is more easily obtained here than Tobin bronze shafting and, since stainless steel is also less expensive, we would prefer its use to bronze if no other problems would arise."

Al's response: "As for using stainless steel prop shaft, we see no problem if using rubber bearings but there might be trouble with the bronze propeller depending on the type of stainless steel. However, if no direct electric or metallic contact, there will be no electrolytic problem! Remember that unless two dissimilar metals in a glass of salt water are in metallic contact, no action will result! Hence if the rudder prot was a welded fitting fabricated from tubing & plt. your
problem would be solved!"

"Certain stainless steels such as 18-8 Type 304 (passive) and 18-8-3 Type 316 (passive) are comparable to Monel and compatible with Silicon
Bronze but the active state of these same stainless steel are more suitable with Manganeze Bronze. However, unless a stainless steel propeller is available, we would recommend the Tobin Bronze or Monel specified."

Feel free to take this anywhere you want to go with it. I have nothing further to add.


Bob Cleek
01-17-2003, 02:47 PM
Solid advice and if my 40 year old boat is any indication, it works fine. However, as I recall, there were problems with stainless in Asian built boats back then because there are many stainless alloys and some are not suitable for underwater use. Stainless forms a patina that prevents further corrosion. When underwater, there is no air to permit the formation of the patina and it does corrode in some alloys. The other problem, which I have learned I have to live with, is that the Asian builders, Cheoy Lee in my case, sometimes would slap a hand forged iron bolt somewhere in the topsides. The result, in my otherwise all copper riveted topsides, are a couple of persistent bleeders. (Arrrrgh!)

Ken Liden
01-18-2003, 01:23 AM
Actually the patina to which Bob refers does form under water by utilizing the oxygen in the water. This requires that the water be circulated somewhat to keep the oxygen supply fresh. However when the oxygen is depleted the corrision begins. This is often evident in areas of low circulation such as in the stuffing box or cutlass bearings when the boat is idle for long periods.