CUNiFer Alloy materials for marine constructons

[mik lenoir]

Hello ,
CuNiFer Alloys (copper/nickel) have many advantages as material for building hulls, rudders and any other wetted part of seawater exposed of boat.
I have found little mentioning in this and some other forum.
It may not be number 1 choice for boatbuilding because of material cost but saves( supposedly) in the long run.
I would love to hear comments and experiences on pro or con's.
I myself thinking of making extractable keel insert(lead filled) for fixed shallow shoal keel.
Please comment
mik lenoir

[jehardiman]

CuNiFe = 86/66-10/30-x-x coppernickel (mostly tubing) or Nickle Aluminum Bronze or Manganeze Bronze. This is important as they are very different alloys.

Hard to weld, fluxs can attack it, needs to be furnace or TIG welded.

Hard to machine, sensitive to hot or cold working, needs to be normalized.

Expensive, nickel is not cheap.

Better as a casting or tubing, but there are cheaper materials, especially if you can control flow velocities.

I like Inconel 718, but it is not worth the cost. If you want to pay for it, go ahead and use it.

Look it up on www.copper.org

[gonzo]

There have been some boats built with it. The initial cost is higher, but has several advantages. For example, the plating can be thinner because there will be no corrosion. Also, it doesn't need paint or antifouling coatings.

[jehardiman]

Gonzo; could you point me to those boats. I know of several wood-NiAlBz composite hulls built in the teen's and twenties, and in the 70's-80's there were some trials with CuNi (90-10 if I recall, not CuNiFe) sheet welded over a steel hull. But for the life of me, I can't recall any hulls built with totaly CuNi or CuNiFe plating, it would be almost impossible to weld without major distortion (much like Al but worse).

[yokebutt]

What ever happened with Monel? If there are any metallurgists here, I'm wondering how Monel would do in contact with carbon. The only material that doesn't corrode in contact with carbon seems to be titanium, but I'd really like to have a chewier, less brittle alternative.

Yoke.

[mik lenoir]

Thanks for comments so far,
here is something I dug out,pretty recent article too:

The oldest copper-nickel boat in existence.
"The Asperida, a Copper-Nickel Sailboat after More than Thirty Years in Seawater,"
by Harold T. Michels and Kenneth P. Geremia, paper No. ...
www.nickelinstitute.org/index.cfm/ci_id/13943.htm

Initial cost was high ,but lower maintenace cost was offsetting those; as reported.
I still wonder about the thickness 4mm/ aprox 3/16" when hitting object compered to regular steel hull 5/16/ to 3/8".
cheers mik

[jehardiman]

OK, now I know where to start looking.

This report..
http://www.copper.org/applications/cuni/pdf/nace_05238.pdf
gives a much better overview of ASPERIDA and construction/maintainence problems, as well as pointing to two other CuNiXXXX hulls. Also pictures of hull fairness.

Yokebutt, carbon or Ti will eat Monel right up unless it is heavily zinc'd, especially at the welds. This happens to a be a serious problem with deep submergence vehicles. Best to paint everything so there is minimal cathode or anode and zinc it as well.