My good old boat doesn't have a boom vang, so I'm adding one (not a rigid one (I already have a topping lift, and the fiddle blocks and line have cut in to my beer budget enough already), just an 8:1 cascaded fiddle). There's a bail on the boom for one side to attach to, but nothing on the mast. What is the best way to attach one?
She's 37' LOA. The stick is aluminum; rounded-rectangle in cross-section; 43' from the deck to the masthead (S.A. for the main is 288 sq. ft.); I'm not sure about the wall thickness exactly but it's a pretty heavy section (I can find out the exact thickness if necessary); internal wiring grooves are to either side of the slide track; no slide track below the gooseneck. My sailing is mostly coastal cruising with the occasional offshore passage.
I think that my options are:
- Attach a bracket or a tang to the aft face, probably by drilling and tapping for machine screws. Will this be strong enough? What type of metal for the tang and the screws?
- Drill a hole through the sides of the mast, run a long threaded rod through it, and use that to attach a large bail. This would be stronger and more reliable, but I'm concerned with finding a bail of the right width (though I could probably pad it with washers if it were slightly too wide). What diameter threaded rod should I use?
Any advice on this project would be appreciated.
Drilling and tapping eye straps to the back side of the mast is not going to be strong enough for the pulling loads of the vang.
I am not a big fan of drilling the mast for obviuous reasons, however if the boat is deck stepped you may be able to drill for the trhrough bolted bail because on a deck stepped mast you have compression at the deck level instead of the bending stress that a keel stepped mast will have at the partners. Also on a keel stepped mast you may have some hardware you can attach shackle to or probably just getting a mast plate will help. If that is not the case and you don't want or can't get a mast plate, then go to plan B: install hardware thru-bolted (and watertight) on the deck. Can you drill through the deck next the backside of the mast without damaging a liner ?
If you can install and eye strap or pad eye, right there, then problem solved. Then you just make the call of what to install: the fiddle block directly to the pad eye, the Triangular plate (inset) a soft shackle, etc.
This piece will be of help for the cascade:
Feel free to drop me a note if you have any questions.