I won't go into the ugly details, but after a stolen mast and finding a replacement, I'm stuck realizing that I never actually looked at how many rivets and what size were used to mount the Harken-392 4:1 double downhaul block set to the mast. (The replacement doesn't have.) I assume you would use monel rivets for an aluminum mast, but how many and what size? I'm thinking four and the biggest that will fit in through the holes?
![[Linked Image]](http://store.catsailor.com/pc/catalog/01-4523.jpg)
I would use the largest diameter (3/16) monel or SS given that it is probably the highest loaded control line on the boat- maybe aside from maybe the forestay/mainsheet when sheeted in maximum. Even better to use backing plates on the rivets if you can get them up in there after taking off the foot of the mast.
most of that hardware is setup for 3/16" rivets.
I would also suggest 5/32, i have found a lot of fittings use that size as well,
Take the fitting with you to be sure. they should be around 1/2 inch long
Hope this helps Richard
Looks like an 8:1 setup...3/16
stainless is fine. The plate itself is stainless, so why bother tracking down/pay for the hard to find/high priced Monel (I've paid ~$7/pop for a 1/4
monel from Murray's) when the stainless plate will also be in contact with your mast?
Just put on a coat of Duralac or TefGel to reduce electrolysis and it'll last 10-15 years.
Thanks all!!!
I never use monel because the stuff is so much of a pain to drill. I use alli and have never been let down by it. You are talking sheer strength here and anything more than alli is over engineering and if you do need to remove or replace causes monel problems.