Boom Vang

[SouthBrooklyn]

Hello,

I want to install a boom vang and I need to figure out where to attach it. Right now the only place on the boom is a bail somewhere in the middle, looks too far aft (and flimsy too). On the mast there are two holes with bad threads. I would have to re-thread them but I would rather not make new holes, if I don't have to. What kind of loads are we talking about?

Are bails good enough or I need to use different hardware?

At what angle should the vang be set?

Does the image from Harken look like a good solution?

Thank you.

[sailingdog]

It would help if you said what kind of boat you have. The two holes on the mast are probably not sufficient to support the base plate of a boom vang on anything but a very small boat. The loads are proportional to the size of the boat, and without knowing what boat you have, not much can be said.

As for how far along the boom the vang should be attached, that really depends on how heavy a spar you have. The heavier the spar, the further forward a boom vang can attach. The vang should be 45-60˚ from vertical or so. Any more than 60˚ and it won't be very effective, anything less than 45˚ requires more leverage than you'll likely want to use.

[SouthBrooklyn]

Thanks Sailingdog, it's a Seafarer 29'. This is a picture of the boom vang I have.

4:1, SWL: 1750 lb (795kg)
Includes 40 ft of 3/8" line

[sailingdog]

That should work just fine.

You'll probably want to have the mast attachment point of the boom vang through-bolted through the mast with a compression sleeve to prevent you from damaging the spar by over-tightening it.

A bail would work nicely for the boom attachment point, but again, you'll probably want it through-bolted with a compression sleeve.

[SouthBrooklyn]

Sorry, I'm not very familiar with compression sleeves.

[AllThumbs]

A vang undergoes tremendous forces, so whatever you do, you want it well secured. Most of the ones I have seen use bails on the mast and boom with SS rivets holding them in place, but I only have experience with smaller boats than yours. A through bolt with a compression sleeve is a good idea but would likely require taking the mast down. A through bolt without the compression sleeve would be fine for now, just don't over tighten the nut and definitely use a nylock nut. That existing bail on your boom does not look like it will do the job.

Eric

[AllThumbs]

Originally Posted by SouthBrooklyn

Sorry, I'm not very familiar with compression sleeves.

It's just a bit of tubing inside your mast that the bolt goes through to keep the mast from being crushed or deformed by the bolt when tightening it.

[Faster]

Allthumbs' solution makes sense.. through bolt with nylock nuts and don't dimple the spar.. you could do this at both ends.

Agree, too, that the present bail is too weak and too far aft, the vang angle should be approx 45-55 deg.