Connections to mast, screws or rivets?

[er9]

what about bronze or titanium machine screws into aluminum? both are affordable and easy to get now a days.

[roland stockham]

Chances of being able to remove screws in a few years time is, in my view, slim and rivets are way easier to drill out than screws when the heads break off!

[Hesti]

Monel rivets ...

[CarinaPDX]

I built my mast, from a kit, back in 1980. I drilled and tapped, and used SS machine screws for everything except the trysail track for (which I used monel rivets). Twenty years later I stripped the mast for repainting and EVERY screw came out clean (I used NeverSeize on them originally, but I have used Tefgel and Duralac on other boats as well). Use SS screws only a little longer than the needed grip length and with coarse threads, drill and tap with a sharp tap and steady hand (and cutting paste), then assemble with anti-seize. It may take a little longer than rivets but it is utterly maintainable.

Greg

[Reefmagnet]

I don't understand the love for monel rivets into aluminium. While monel itself is very much corrosion resistant, it's anodic index against aluminium is about 1/3rd more than stainless steel. I could be wrong, but that means it's going to cause more problems with aluminium in regards to corrosion, not less.


https://www.engineersedge.com/galvanic_capatability.htm


Having pulled and replaced every stainless steel screw and rivet on a couple of old masts in the past, it is true that stainless machine screws can corrode out the threads (seizing isn't that big of an issue on thin base materials). Using a barrier paste during original assembly reduces this dramatically. When threads are stripped, this is easily fixed on reassembly with a stainless helicoil installed with loctite to seal it's thread into the aluminium.

[thinwater]

Originally Posted by er9

what about bronze or titanium machine screws into aluminum? both are affordable and easy to get now a days.

Bad combinations. See below. Note that SS depends on whether active or passive.

[wingssail]

Pretty much don't have many attachments on my mast except a few like the steaming/deck light fitting and the B&G 20/20's. They are held on with monel rivets, and I will replace them with the same when needed, Drilling out is easy. These fittings are light duty.

Otherwise there are some very heavy duty fixtures which are held on with stainless machine screws. I've removed them in the past and reattached them and used plenty of never-seize products.

Most of the hardware on my mast is welded or otherwise has no fasteners.

[Elie]

Originally Posted by RaymondR

I'm a rivet favourer myself.

When an SS screw "grows" into aluminium they are buggers of things to drill out. Aluminium blind rivets self pilot the hole, are easy to drill and tend to drill clean without enlarging the hole. Unfortunately, if what you are riveting to the mast or boom is made of SS the heads will tend to sacrificially corrode off the alloy rivets so in that case monel rivets are better.

Also the advantage of not sticking through so far or being as mean to ropes and wires.

Rivets are in my experience much better than screws. To remove them you simply drill them out, while screws can loosen, or wurst become welded by the galvanic action after a time, and become impossible to remove.

[Patrigo]

Rivnuts--easy to fit.
Rivnuts--easy to remove whatever is fitted.
Rivnuts--stronger than any other method.
Rivnuts--why use anything else?

[MikkiDuda]

I apologize if I steal the thread to some extent. I am about to install some DIY steps on my mast.

Steps are galvanized steel band 3 cm wide.
Mast is steel as well.

What would be the best way to attach the steps to the mast? I was thinking SS rivets covered in Tefgel or similar. I was under the impression that bolts could undo themselves when exposed to vibrations.
Thank you.

[Ron Bailey]

I always used monel rivets on mast fittings much stronger the aluminium, had no problems with this over many years!

[Ron Bailey]

I always used monel open rivets, blind rivets leave foreign metal in the rivet

[IanTrail]

Nothing to add on screws v rivets but here's a snippet on Duralac v TefGel. I used Duralac on the boat successfully for years. One year I needed to ship some spares and consumables out to the boat overseas. I discovered that Duralac is marked 'Flammable' which causes problems with international couriers. (Personally, it seems about as flammable as cold custard!). However, TefGel is not flammable so easier to ship. Seems to work just as well.

[pendragon]

Stainless screws seize up in aluminum and are very hard to drill out, while monel rivets don't seize up. To replace, grind flush and punch them out.

[Manateeman]

Hi. Why can’t you TIG whatever you are installing.
Rivets...monel or 316 .I won’t live long enough to figure out which is better.
Mylar or some plastic.
Tef-Gel. No equal in my experience.
Rivnuts. Hard to get out if the spin loose but pretty reliable.
Happy trails to you.
Manatee