Mixing Metals...

[Bob Aberton]

My little 12' daysailer is almost ready to float...hull's all together, seams fiberglassed, siliconed, bondoed, and otherwise sealed. Now its time for the finishing touches...

She's put together with epoxy and galvanized screws. My question is this: I plan to fasten a copper stempiece and a copper grounding shoe on the stem and keel, and plan to fasten the copper with copper tacks.

I know that this will eventually cause the galvanized screws to deteriorate, but as others have pointed out, the screws are kinda redundant, given the liberal amounts of goop gluing the boat together.

So, is it a really, really dumb idea? Or not? And how many years can I expect out of the screws, given the presence of the copper?

[Bob Aberton]

Back to the top.

Or is my question really so dumb nobody can even bothered to answer? tongue.gif

[Frank Wentzel]

Bob

I assume that this boat will be dry-sailed, that is spend most of its time on a trailer. In that case there is no problem. Even for a boat that will spend most of its time in the water, if it is thoroughly sealed in epoxy you will have no problem since your fasteners will not be wet. No electrolyte - no electrolytic corrosion.

/// Frank ///

[ishmael]

What Frank said.

Galvanic corrosion is a problem in traditionally constructed boats that sit in salt water. Yours will be fine.

[Bruce Hooke]

I agree with Frank, I really don't think that a small amount of copper in a stem band and grounding shoe will have any significant impact on the galvanized screws embedded in epoxy. If water gets at the galvanized screws they will, of course, deteriorate on their own much more quickly than bronze screws would have, but as long as the epoxy coating keeps the water out they should last a good long time. If the boat will spend most of it's time out of the water and under cover then you just about anything will work.

I am rather surprised that you are thinking of using copper for the stem band and grounding strip. Straight copper is pretty soft stuff. Brass or stainless steel is more common in this application...

[Bob Aberton]

Thanks for answering my concerns, everyone.

I'm using copper because it's the cheapest and most easily worked. Plus it looks better than aluminum. I'm not really interested in expending the effort putting in something more rigid, like stainless or brass.

Thanks again, people...