Pop rivetting to alloy boom

[rex_seadog]

I need to pop-rivet a small fitting (a simple 'U' thingy that supports the outhhaul after it exits the jamming cleat) to our boom. The original rivets seem to have corroded the boom so does that mean that there was some electrolytic action? To refit do I use ordinary pop rivets that came with the gun or do I need a special grade (hence expensive!) for this application?

 

[Gin]

monel rivets

 

[PuffTheMagicDragon]

When pop-rivetting stainless steel steps to my alloy mast I used Monel (for the strength) with a generous application of a yellow insulating paste called Ducolay (not sure about the spelling).

For a less critical application - the cheek blocks for my slab reefing - I used ordinary aluminium pop rivets. Same metal as the boom, therefore no corrosion. However, since the bit of the 'nail' that remains in the rivet is plain steel, I simply filled in the hole of the rivet head with a smear of silicone sealer that was handy to seal against the ingress of moisture. Has been there for some ten years now.

 

[Skyva_2]

As you say Monel metal rivet is best and the paste is 'Duralac', I would use it no matter what the rivet material, and also apply it under the eye you are rivetting.

 

[PuffTheMagicDragon]

That's the one! For some reason, 'Duralac' is one trade name that I can never recall. /forums/images/graemlins/smile.gif

I agree with your suggestion to smear it on the mating surfaces, regardless of the materials. It helps to ensure that there are no spaces where moisture can accummulate.

 

[Rivers & creeks]

If you use Monel rivets you'll need a pair of lazy tongs - I borrowed some but they are dead cheap from screwfix. An ordinary pop riveter was no way strong enough - or I have weak hands???

 

[PuffTheMagicDragon]

[ QUOTE ]
If you use Monel rivets you'll need a pair of lazy tongs - I borrowed some but they are dead cheap from screwfix. An ordinary pop riveter was no way strong enough - or I have weak hands???

[/ QUOTE ]

Not only do you need good lazy tongs, when fitting 5mm monel rivets I have to put all my body weight on the thing to get them to pop! Arms alone won't do it.

 

[Gaz22]

Where can you buy monel rivets??? as per rex_seadog l have a couple of rivets to replace on my mast, was going to use ordinary rivets but after reading this will use monel instead!!

 

[Rivers & creeks]

Most chandlers sell them in those little plastic packs. Jimmy Green Marine do them but you pay postage. I called in on a rigger and bought some.

 

[Chrissie]

The salt water with the differing metals will act like a battery and cause galvanic erosion, its very important to use duralac as a barrier.
I lost my kicker bracket during the RTI because of it.

 

[rex_seadog]

Many thanks for all the advice. However, since the boom is aluminium and there is negligible load on the fitting so strength is not an issue can I not use ordinary pop-rivets which if I understand correctly (ref Puff the Magic dragon) are made of aluminium?

 

[PeterGibbs]

Rivet stubs - punch them back through, then fill void with sealant. Always use monel on rigging gear, plus anti-corrosion paste. All this is worth the extra couple of bob it costs.

Tongue riveter - £29.90 in Screwfix. Will last a lifetime, and is a must for this job.

PWG

 

[Chrissie]

The fitting might be a different metal, so would need to be completly backed with duralac.
Plastic is okay.
Ive seen duralac (or similar)still on a fitting 40 years later, new masts and booms are lacquered behind the fittings instead, I wonder how they will fare over the years.

Ordinary pop rivets may not be adonised, the mast or boom will be. Unprotected aluminium will get the white powdery corrosion, but can be conditioned with mineral oil, monal is easier and not much dearer.

 

[PuffTheMagicDragon]

[ QUOTE ]
monal is easier and not much dearer.

[/ QUOTE ]

No question about that. However, you do need a 'proper' tool to pull them, something like this:

Not like this:

 

[maxi77]

To be quite honest i find the standard squeeze type |OK for the smaller sizes even up to 4.8 if it is only one or two, but for doing a lot the lazy tongs are essential.