Boom sheaves puzzle

[zoidberg]

I have a spare boom, and the arrangement of sheaves and mast-end jammers has me puzzled as to the makers' intentions.

At the mast/forward end, there are 3 sheave blocks with jammer handles, clearly to lock off three outboard-end reefing pendants.... if three were brought forward internally.

At the aft-end of the boom, there are two sheaves oriented vertically - and two sheaves oriented horizontally.

Also, there is a cast 'bail' for the mainsheet attachment, and another one presumably for a topping lift and/or a fixed outhaul.


How does the team reckon I could use these to facilitate 3 reef pendants?

 

[JumbleDuck]

I have almost exactly the same Proctor boom. I think the theory is that three lines from the jammers give either three reefs (as I have) using the two side sheaves and one on top, or two reefs and an outhaul using one side sheave and both the top ones. There does not, annoyingly, seem to be any way to use all four sheaves at once to have three reefs and an outhaul.

My mainsheet is attached to a sliding loop in the track under the boom and - for the moment - both my topping lift and outhaul go the the cast thingy on top.

 

[vyv_cox]

Not a good idea to.use the casting for the mainsheet block. Quite a few have done so and found high wear rates and even fracture. The loop in the track below is the better way.

 

[Spirit (of Glenans)]

Assuming you could have two reefs and an outhaul occupying three of the sheaves, is there any sheave at the forward end, to correspond to the fourth sheave at the after end, even though there is no fourth jammer?

 

[JumbleDuck]

Assuming you could have two reefs and an outhaul occupying three of the sheaves, is there any sheave at the forward end, to correspond to the fourth sheave at the after end, even though there is no fourth jammer?

Nope. I'm thinking of having a slot machined in my boom so I can bring an outhaul out of the side to a tackle alongside the boom.