Howto attach a spinlock xts to an aluminium bowsprit

[rom]

Hi, I believe I have to use 8mm screws. The aluminium tube is 2mm thick, 80mm diameter, 1m long. I need something strong enough for a 90sqm code-0 2to1 halyard...

[slug]

A 2 mm substrate will only accept 2mm fasteners

[Benz]

Get long screws and go all the way through. Use washers and tef-gel.

[rom]

Originally Posted by slug

A 2 mm substrate will only accept 2mm fasteners

Thank you Slug, is it a universal rule or something specific to aluminium ?

[rom]

Originally Posted by Benz

Get long screws and go all the way through. Use washers and tef-gel.

Good idea and rather simple ! but I am afraid I will not be able to tighten the screws enough without bending the tube ... unless someone did it already ?

[sailormed]

use pop rivets?

[slug]

Originally Posted by rom

Thank you Slug, is it a universal rule or something specific to aluminium ?

It’s an engineering rule

A 10 mm diameter bolt will have a 10mm thick nut

The rule can be more precise and only consider thread count

The general shipyards fitters rule is substrate thickness bolt diameter

Your application may require a collar or saddle for mounting the jammer
Everything is doable ...with correct engineering

Ask a pro rigger for ideas

[Training Wheels]

Hmmm.... I’ve got quite a few clutches and cleats on my mast that use machine screws that are threaded onto the mast, all of which are much greater in diameter than the thickness of my mast. Most have been on my mast over 20 years, and they haven’t come off yet!

[slug]

I just worked on a professionally installed mast jammer

A surface mounted aluminum block was welded to the mast wall

The jammer was fastened to the aluminum block

[rom]

Originally Posted by sailormed

use pop rivets?

My initial thought but the rigger here told me the biggest rivets are about 6mm and I really need a 8mm countersunk screws for those xts spinlock. He told me he would find a solution if I bring him the bowsprit but he was not able to give me a price ... I just gave 145 EUR to a mechanic to check/service my honda bf20 carb, now the starter doesn''t work anymore.. I'd rather not say what is my feeling about the pros in this business...


Maybe I can epoxy glue a 4mm aluminium plate (that I have) on the tube. I could make it spinlock long and say 8cm wide. I guess I could give it the round shape of the tube. Now that makes 6mm thickness for the screws ... oh well I could also simply rivet that plate on the tube ?! And that I can do it all myself !

[Jim Cate]

One approach that might be worth considering:

Get a piece of 6 mm alloy plate somewhat wider than the sprit and longer than the jammer. Use a pair of u-bolts around the sprit and up through the plate to secure it, and through bolt the jammer to the plate. This would distribute the loads from the jammer along a decent length of the tubing and provide good attachment for the jammer, all without adding stress riser points in the tube.

Jim

[Benz]

Originally Posted by rom

Good idea and rather simple ! but I am afraid I will not be able to tighten the screws enough without bending the tube ... unless someone did it already ?

Since the screws are in shear, the tube need not get damaged--it's not like they're pulling away from the tube to risk dimpling it. Just tighten them so the jammer can't wiggle, or until the tube just barely begins to visibly squeeze.