Coupling wiring to aluminum spars

[pdqaltair]

Both my last boat and my new boat have grounds to aluminum spars to power lighting, and over 20 years I have had a few ground issues. The base of the mast is at the back of the trampoline and is a very wet area, but ther have been issues a the spreaders and masthead too (the factory wiring set a poor example in many areas). Clearly we are creating a galvanic couple, going from copper to tin to aluminum (going straight from copper to aluminum would be worse from a galvanic standpoint). Some years ago, after a few failures, I went to cleaning the surfaces well and coating them with a very heavy grease/cosmoleen type product (just a tiny dab). No problems in > 5 years. No-alox would be another choice, more prone to wash-out, but better in other ways. Other, better, products?

[sailingdog]

Why not install a proper ground wire and not use the spar to connect the lights to ground??? It would solve the problem.

[Northbeach]

Interesting observation! Being neither a marine surveyor nor an electrician it will be interesting to read their input when and if they join the discussion. An owner can do just about what they want to their own boat - even if it is a bad idea. I thought I had read somewhere that in marine instillations the practice of using the structure as the return path for ground was not permitted, as it is in the automobile industry. Therefore a two wire system (DC) was required. I tried to find my “reference” for that but was unsuccessful this morning. I would think that hooking up wires to structural metal(s) is a recipe for future headaches. I would very much like to hear from a marine electrician and those more experienced on this.

Is there in fact a “requirement” for a U.S. recreational boat manufacturer to use a 2 wire system in a recreational DC marine system? I’m talking the vanilla bland off the shelf recreation production boat, not the heavy duty offshore marine industry, governmental or military (can you imagine the complexity of the numerous electrical systems on a current generation nuke-sub cruising underwater-mind boggling). If so who/what is the regulatory enforcement agency.

[sailingdog]

there are no "requirements" for us-built boats with respect to that, but i do believe the abyc frowns upon such wiring.

[pdqaltair]

Originally Posted by sailingdog

Why not install a proper ground wire and not use the spar to connect the lights to ground??? It would solve the problem.

The question resulted from a recent dockside conversation with a fellow who was doing just that. However, depending on how the wires are installed in the mast, it is a bit of an undertaking for just a few conections. I believe the practice used to be common.

Don't get me started on facory wiring or the thread will take a life of its own. But there are a few interesting things on the same boat....
* the positive wire in the mast and running lights were 20 ga
* the battery cables were actually secured to the bottom of the bilge
* none of the 12 v sub-pannels ever had covers: ground strips or possitive strips
* no charging means was provided, other than the outboard alternator
* they must not have sold heat-shrink in the mnfg's state

I replaced everything but the mast wiring when I bought the boat.

That was some years ago.

However, let's stay with the question; how to maintain a good conection.

[sailingdog]

Replacing the mast with a proper ground wire is the easiest way to maintain a good connection, since it elminates the need to connect it to the aluminum mast.

[pdqaltair]

Originally Posted by sailingdog

Replacing the mast with a proper ground wire is the easiest way to maintain a good connection, since it elminates the need to connect it to the aluminum mast.

or the easiest solution.

Industrially it is not unusual to bond aluminum conductors to copper, and some of the settings in chemical plants are not much more pleasant. There are conectors made for this purpose that use anti-corrosion conpounds, effective seals, and in many cases tin as an intermideiate, much as we would use tinned wire, a tinned crimp, No-alox (or contact grease or equivalent), and a seal.

I was curious to see if we as a group had marine experience. It seems we have not found it. As I said in my first post, contact grease and tinned connectors solved the problem for me in a real water-hose spot (mast base of a Stiletto), and that is a real-world torture test.

[Omatako]

Correct. running a new dual wire is not the only or the easiest solution.

But it is the best.

[pdqaltair]

Originally Posted by Omatako

Correct. running a new dual wire is not the only or the easiest solution.

But it is the best.

But if I were an in-shore racer considering, for example, replacing cap shrouds and halyards with high-tech line to shave ounces, would I run 3 extra lighting (anchor, steaming, deck) wires? No way. I'm a racer an I don't believe in the easy way, the simple way, or the safe way.

My new boat has twin wires and wieghs >7500 pounds. My Stiletto weighed <1300 pounds and hit 20 knots on a few occations, no surfing. I wouldn't call the boat "seaworthy" in the off-shore sense() but it sure was fun. Every pound saved mattered. An example of how one-size does not fit all.

[nmccubbin]

We use a stainless steel bolt with no direct contct between copper and Al.
Also, use TefGel, ALWAYS in alumonum threading/bolting etc.
it is good stuff.
We buy direct from TEF-GEL - Ultra safety systems - Home page
The chandlers do not seem to like stocking the stuff.