Reeving two double blocks for mainsheet

[mawm]

My mainsheet is fastened to the boom and is then routed to a double block on the coach roof, to a double block attached to the boom, down and up again, then to a block at the base of the mast and on to a clam cleat in the cockpit. No matter how I configure the lines I am left with either the top or bottom block rotated slightly which is causing the sheet to wear against the side of the block.

I don't think there is enough space to have two fiddle blocks, especially if one has a becket. I do need a 4:1 system.

Any solutions?

 

[prv]

Presumably it's rigged at the moment with the axles of the blocks parallel to each other?

Try un-reeving it all, then rotating the lower block through 90º (twisted shackle or whatever). Then re-reeve it using the upper block to go from forward to aft and vice versa, and the lower block from side to side. Unfortunately that's easier to demonstrate than describe, but hopefully with only two sheaves per block you won't go too far wrong

This approach works fine for my 6:1 mainsheet, no twisting or chafing.

Pete

 

[philip_stevens]

This shows the 4:1 reeving with 90º blocks http://www.harken.com/content.aspx?id=3888

 

[mawm]

Thanks for replies. The problem is the sheet is attached to the boom distal to the top block and goes directly to the bottom block so I can't have it at 90 degrees as shown in the diagram linked to by phillip_stevens. It looks like I will need to buy a new block with a becket. Will this work if there is a lot of rotational movement where the shackles attach to the coach roof and boom?