Mast Boom Track Fixing

[Guest]

The track which the boom gooseneck attaches on our mast has come loose. At present the fixing arrangment are tapped holes M6 say directly into the mast, which has been threaded. The mast must only be 3mm thick, so not a lot of threads. We are thinking about trying to put locking nuts on the back inside the mast. any other ideas?

 

[Col]

A local fabricator should be able to fit "rivnuts" to your mast for you,they are a bit like giant pop rivets,but with threads in them.Available in various sizes including M6.This will make fixings as good as new.

 

[AndrewB]

I've done this with mast/boom fittings.

Rivets MAY be strong enough for your purpose - they are stronger than they look, and have great advantages: easily applied from the outside, easily removed by drilling out, little electrolytic corrosion with the aluminium mast. Home DIY pop rivets are not adequate, ask your boat yard if you can borrow their rivetter, and buy a few large Monel rivets off them, to fit the existing holes.

Bolting on with stainless bolts is stronger. Getting the nuts on half way up inside the mast is tricky. I poked up an old-fashioned sweep's broom, with the spanner strapped on in place of the brush, the nut sellotaped in the jaws. Use a Nylock nut (the type with a blue nylon insert) which helps with final tightening as well as locking the nut in place.

Once done up firmly, a countersunk bolt is there to stay, getting it out is all but impossible. For that reason I prefer to use hex-headed bolts since the head can be hacked off to release. I've also put some bolts on the wrong way around, i.e. with the nut on the outside. That way the nut can be tightened/loosened from the outside by gripping the end of the bolt. Not very tidy though.

Some patent bolts are sold as being one-side only, i.e. you do not need access from the inside. Mostly these are mild (rusty) steel, and require an outsize hole to be made, so I wouldn't use them. But in a thread a little while back, someone did claim to have used a stainless version with success on his mast.

 

[charles_reed]

I'd definitely go along with using rivets - monel ones not the useless little aluminium ones - for the od of rivet you are talking of you'll need a long-handle or lazy-tong rivet-gun.

Talk to any rigger, stainless fixings and anodised ally masts are a no-no.

 

[Guest]

Thanks for the help,
I think we will try the Monel Rivets.

Thanks again