How do i attach this to my speader?

[LittleSister]

. . .

I am not happy with the geometry you suggest. If the mast attachment is above the spreaders the lazyjacks are pulling the spreaders aft, putting an unfair load on them.

The aft component of the load on the spreaders, if they are attached there, will be there whether or not the vertical load is taken by the mast.

People can rig them however they like. I am not for a moment suggesting that everyone should suspend them from the mast, just adding a consideration for their, er, consideration.

 

[srm]

The aft component of the load on the spreaders, if they are attached there, will be there whether or not the vertical load is taken by the mast.

Agreed, but as I use a turning block on the spreader with the fall parallel to the mast the angle from the mast of the resultant force is around half that in your system. The loads in my system are higher, but the spreaders have been engineered to take them.
I first fitted lazyjacks this way to a 10ton displacement sloop with heavy wood boom in the mid 80's. I have used the same system on subsequent boats until selling my last boat a couple of weeks ago. None suffered from drooping spreaders as I am well aware of the risk to the rig.

 

[awol]

Just checked - eBay will flog you a rivet gun and rivets for about £7.50. It won't pull 6mm rivets but that's not what you need. Duralac or, in extremis grease or whatever, to resist galvanic action will make the fix last longer.

 

[PetiteFleur]

I moved my lazyjack lines out from the mast by about 6" last spring as one of the small blocks on the side of the mast broke. I tied them to the spreader with 3mm polyester cord, much easier than trying to pop rivet them to the mast with Monel rivets. I'm sure they'll last some time and much easier to replace if one does break.