How to secure steaming light to mast with halyards inside mast.

[Eihli]

I ran into a problem while rewiring the mast on my S2 8.0b. The halyards run inside the mast. I have to replace the steaming light. I had planned on drilling some holes and tapping out some threads and screw the light to the mast, but I thought that would leave the screws protruding into the inside of the mast and would cause abrasion to the halyards running through there.

The original steaming light was riveted on. I looked up how to rivet on youtube and everything I see points toward you having to have access to both sides of whatever you are riveting. That would mean I'd have to stick an extension 15' down the mast to insert the rivet. Does anyone have any ideas how they riveted on the original?

Thanks for any tips/advice.

[sailingdog]

Pop rivets are the way to go. You don't need access to both sides, the rivets use a mandrel to tighten the rivet.

[scottyt]

if you are set on screws you could drill and tap, then measure the thickness of the mast. then just cut the screw so it is flush on the inside before you screw it in

[sailingdog]

There are some problems with screws. First, many masts are too thin to take screws well. Second, with the screws cut to be flush with the inside of the mast, there isn't enough of a safety factor. Third, screws are far more prone to corrosion problems than are aluminum, stainless steel or monel pop rivets.

[zz4gta]

sailing dog, if I were to attach a stainless bit to an aluminum mast, should I use a stainless rivet or an aluminum rivet?

[nickmerc]

I would use a Monel rivit and place s thin piece of plastic (or something else that is nonconductive) between the stainless bit and the aluminum mast. This will minimize the corrosion. I used to sail Hobies and had to deal with mixing stainless and aluminum quite a bit.

[sailingdog]

It depends on whether you need the strength of stainless steel or not. Stainless steel rivets are considerably stronger than aluminum ones... using TefGel, LanoCote or something similar can reduce the corrosion problems. I'm not a big fan of putting compressible washers between the two since they can trap water and cause crevice corrosion issues on the stainless steel.

A thin sheet of mylar, which is basically too thin to compress to any noticeable degree works as a galvanic isolation washer if you have to separate large stainless steel hardware from the mast. BTW, this is generally only necessary with larger pieces of hardware, since the relative size of anode to cathode in part determines the degree of galvanic corrosion.

Originally Posted by zz4gta

sailing dog, if I were to attach a stainless bit to an aluminum mast, should I use a stainless rivet or an aluminum rivet?

[tommays]

My mast is 28 years old and when i refinished it the 3/16 dia SS rivets ALL came out perfect

The down side is you need the BIG TOOL to set 3/16 and 1/4 SS because they are so strong