Mast Tang Attachment

[Rainbow]

I'm attaching new mast tangs to an aluminum mast. Does the compression tube run to the inside of the mast wall and touch the mast wall, or does it run to the outside of the mast wall where it would actually touch the tang itself?

Thanks

[Ian McColgin]

There are variations in design and practice but only rarely are compression tubes a good idea, as it's only rarely that you throughbolt on an aluminum mast. The strain on the tang is pretty much shere and you'll not gain much from throughbolting for that.

Some fittings take a lot of stress out of sheer. The sheet bale under a boom for example is subject to some out-pull on the weather side. Bales often have only one hole on each end to facilitate allowing them to rotate a bit to better allign with the sheet at different angles of trim. For those reasons, a compression fitting and throughbolt make sense.

I could see no practical difference between letting the compression tube land on the inner wall of the spar or go through to the bale. When I've done this, I usually chose the former if it was near enough to the end of the boom that I could reach in there and the latter if not.

You have to trade the modest advantage to having the tube go all the way through and thus protecting the spar from the bolt threads versus the fact of a larger hole in the spar. I doubt there's much difference in any except the most extreemly loaded rigs.

[Rainbow]

Thanks. This was quite helpful.