Installing Boom bails

Moderator: GreenLake

Installing Boom bails

Postby TRWXXA » Sat Feb 13, 2021 9:10 pm

Putting bails on a boom for attaching mainsheet blocks (mid-boom sheeting). The bails attach with 1/4" bolts. Would it be beneficial to drill oversized holes and insert bronze flange bushings? All I can imagine is the threads on the bolts slowly sawing into the aluminum over time. The bushings would be sort of "sacrificial" in that regard, and they'd apply the force pulling on the holes over a larger area. Thoughts? Experiences?

Thanks!
Chris S.
DSII #10220 -- "Uisge Beatha"
TRWXXA
 
Posts: 25
Joined: Wed Jan 27, 2021 1:02 pm
Location: Indianapolis, IN

Re: Installing Boom bails

Postby Fly4rfun » Sat Feb 13, 2021 11:35 pm

my boom has a bail on it, looking thru photos I have archived for reference quite a few have bails or a rail. you could rivet them on with pop rivets
"Sail Aweigh" 1966 DS1 #2675
Fly4rfun
 
Posts: 287
Joined: Tue Oct 13, 2020 5:10 pm
Location: Salem, WV

Re: Installing Boom bails

Postby GreenLake » Wed Feb 17, 2021 2:59 am

Not necessary.

Bronze would add dissimilar metal. Nice corrosion promoter unless you electrically insulate. So there's that, too.

I have a bail for my vang I riveted to the boom. Works fine with simple pop rivets - except: I made the mistake and didn't align it perfectly with the direction of the pull. Now the bail is bent (!) but the rivets still hold. Held for several seasons, and that points to the fact that loading rivets on shear is where they are strongest.
~ green ~ lake ~ ~
GreenLake
 
Posts: 7135
Joined: Mon Jun 18, 2007 3:54 am

Re: Installing Boom bails

Postby TRWXXA » Wed Feb 17, 2021 2:07 pm

The bails are meant for 1/4" bolts. I was hoping to prevent the bolt threads from working against the aluminum, and increase the area on which the force is applied to the boom.
Chris S.
DSII #10220 -- "Uisge Beatha"
TRWXXA
 
Posts: 25
Joined: Wed Jan 27, 2021 1:02 pm
Location: Indianapolis, IN

Re: Installing Boom bails

Postby GreenLake » Wed Feb 17, 2021 7:51 pm

You need to get a bolt that has no threads for the width of the boom?

The 1/4" isn't a problem, I think.

I'm sure you can look it up at what loads you should expect it to pull out. For a vang, people tend to dimension them for working loads of around 800lbs. If you can find some links that show that this is more than a 1/4" bolt can hold on shear in aluminum, I'm sure we'd all love to see them. I'm not an engineer, so I don't have anything like that bookmarked.

There's not a lot of rotation under load, so even if the bolt is forced to turn with the bail, I don't think it will do much grinding.
~ green ~ lake ~ ~
GreenLake
 
Posts: 7135
Joined: Mon Jun 18, 2007 3:54 am


Return to Rigging

Who is online

Users browsing this forum: No registered users and 20 guests