On Tue, 22 Jun 2010 06:24:55 -0400, W1TEF
wrote:

Mechanical advantage would be a good way. If you used two four rove
blocks in series - that works out to something like 35 lbs (I think).
You could hang the blocks off the boom - should be solid enough for 35
lbs.

Wrong. While using a block and tackle will divide the weight among
several bits of line, the total will remain the same and that is what
the boom feels. The entire weight.

Casady