Wind Generator Mount - Copper or Steel?

[seandepagnier]

Hi,

I have two pipes I can use to mount my Air-X marine wind generator with. One pipe is copper, the other steel.

I thought the copper one would be better because it is lighter, but turns out I'm wrong, both pipes weigh the same. I think the only advantage of copper is it doesn't corrode correct? The advantage to steel is it is stronger, but is copper strong enough?


The manual for the generator says not to use plastic and that steel pipe would work.

[Zanshin]

Is your second pipe stainless steel? What are you going to attach the supports to (more metal or to fiberglass or wood)?

[forsailbyowner]

If I remember correctly the pipe should be able to support 150lbs of horizontal load. You could test the copper by figuring distance from wind gen to first diagonal brace, cantilevering that much off table or something and suspending 150lbs off end. Make sure when you mount it you use rubber isolation mounts so you don't get vibration through the hull. Makes a huge difference. I found a method that costs very little using rubber stock, bimini fittings and a piece of hd engine hose.

[sailorboy1]

use the steel, paint it

copper isn't an acceptable structural support type of material, when I used to structrual I don't even remember even seeing a bending chart for copper pipe, because no one would think to use it for this

[GordMay]

Originally Posted by Don Lucas

use the steel, paint it
Copper isn't an acceptable structural support type of material, when I used to structrual I don't even remember even seeing a bending chart for copper pipe, because no one would think to use it for this

I agree.

[witzgall]

How about Schedule 80 1.5" aluminum pipe? Easy to cut, don't need to paint. It is slightly smaller than 2" at 1.9 (I think, look it up) but you could shim it with inner tube, which might also serve as an isolator as well.

Chris

[David M]

I would consider aluminum or stainless. The other downside to copper is that it is heavy for its strength. If you go with either of the former metals make sure you get a grade that is suitable for the marine environment.

[seandepagnier]

Originally Posted by forsailbyowner

If I remember correctly the pipe should be able to support 150lbs of horizontal load. You could test the copper by figuring distance from wind gen to first diagonal brace, cantilevering that much off table or something and suspending 150lbs off end. Make sure when you mount it you use rubber isolation mounts so you don't get vibration through the hull. Makes a huge difference. I found a method that costs very little using rubber stock, bimini fittings and a piece of hd engine hose.

The copper pipe can easily support this, but it will flex more than the steel. Steel is about 4x stronger than copper, but the same weight. Aluminum is half as strong as steel, but 1/4th the weight roughly (correct me if I'm wrong) In either case, I think the copper may be strong enough.

How about Schedule 80 1.5" aluminum pipe? Easy to cut, don't need to paint. It is slightly smaller than 2" at 1.9 (I think, look it up) but you could shim it with inner tube, which might also serve as an isolator as well.

I would love to use aluminum, but I'm working with the junkyard here, and that is not available. As for painting steel, I need a metal primer first right? Am I going to have to keep repainting it every few years?

[forsailbyowner]

If the copper can support the 150 lbs it conforms to southwest windpower's requirements for a tower. I built mine out of available material also, luckily someone offered me a 20 ft stainless pole for $20. To make the Isolation mounts I took a 6" piece and cut 3/4" notches in the end and bent them inward so it closes the end except for a hole in the middle. On one end I drilled holes for bolting to the deck.then I did the same to one end of the long piece. I used some of the heavy duty wire-in wet exhaust hose to join them with rubber between the two butt ends so they don't touch. I used an old shorepower cord for the cabling. Double clamped the hose and made a canvas cover to protect hose from UV. For the diagonals I bolted stainless bimini deck hinges through rubber to deck. Been through many gales and squalls never had tower issues. My ammeter from SW windpower melted down on an upwind sail. If you want one with a shunt(much safer) they have them at MPJA.com for under $10. Part #17679ME. Great price considering they want over twice that for one without shunt.

[Martinini]

Check this place out for Brass and Stainless steel tubing and fittings. In most cases 1/2 the price of most suppliers and as good or in most cases better than other suppliers.MARKSTAAR - Tubing, Rails and Fittings - Category Details

[clausont]

One other thing to keep in mind about copper is that it is more susceptible to vibration fatigue than steel or aluminum.

[barnakiel]

Alu or 316.