Rivets: Aluminum or Stainless?

[billknny]

I have the opportunity to install conduit in my mast and finally silence the banging of the wires. After careful consideration of many options, my plan is to rivet plastic conduit to the mast from the outside.

Question: Should I use aluminum rivets for their galvanic compatability with the spar? Or go with stainless rivets suitably gooped to isolate them from the mast? My first thought is to use Al, but in a previous thread Brion mentioned using stainless rivets, and that got me to wondering if I had forgotten something!

Bill Kinney
S/V Moorea
Sausalito, CA
http://www.geocities.com/bill_knny

[Brion Toss]

Hi Bill,
Yeah, we ordinarily prefer to use stainless rivets for anything heavier than a winch handle pocket. But your conduit is in that range, so aluminum is fine. Goop the rivets anyway, as they are of a different alloy than the mast, so can still make your paint bubble. And do you know the two-holes-and-a-hook technique for attaching the conduit?
Fair leads,
Brion Toss

[billknny]

Thanks Brion.

That 2 holes and a hook approach is exactly the one that I had intended on using. In fact on the mizzen mast I'll be using the same holes that the cable clamps for the external wires were attached to.

Speaking of holes...

There are a number of places on my 30 year old spars where PO's (Previous Owners) had installed hardware without appropriate "goop" on the stainless threads. Some of this hardware has been removed, leaving (surprise!) broken off stubs of stainless bolts embedded in the spar. Should I just cuss the stupidity of the PO and leave them there? Drill them out and fill the holes? Fill the holes with what? The mast is unpainted, so appearance isn't the issue.

[Bob Pingel]

OK. I'll bite, what is the two holes and a hook method?

Bob

[billknny]

Bob,

I don't know where I learned this, so I can't give credit where it is due. Here it is in my own version. certainly not as clear as if written by Brion, but clear enough to follow, I hope.

1.) Cut the conduit to length.

2.) Draw a straight line down the length of the conduit (this will help keep things straight as they go together)

3.) Draw a straight line down the length of the outside of the mast along the path the conduit will take.

4.) Exactly how to get started will depend on the exact individual situation, but hopefully you have access to either the top or the bottom of the mast so you can hold the conduit in place as you drill the first hole through the line on the mast and then through the line on the conduit.

5.) About 18 inches along the line on the mast, drill a hole ONLY IN THE MAST.

6.) Use a wire hook in the previous hole, align the conduit with the second hole so you can drill right into the line you marked on the conduit. Hitting the line is important, if things start twisting you will get in trouble is short order as the conduit tries to spiral inside the mast!

7.) Putting your hook in the second hole, align the FIRST holes in mast and conduit and secure with a pop rivet.

Repeat steps 5 through 7 until you reach the end of the mast.

Best results may be had using a brad point wood working bit to drill into the conduit; things tend to skate around less. In any event, be sure the drill bit used for this step is sharp; you can't push on it and keep things aligned.

[Brion Toss]

Hi again,
And wow, I never saw it done that way. The method we use is to drill two sets of parallel holes in the mast, one set for a bent piece of steel, to hold the conduit in place, the other for the rivet hole for the conduit. It's twice as many holes, but might be net faster, and less fussy than the one-line method. After the conduit is done, you fill the hook holes with rivets. Take a look at almost any mast, and you will see the two rows of rivets where the conduit goes.
Fair leads,
Brion Toss