I'm just about to fit a fully battoned main and lazyjacks to my UFO 31. The boom length is about 3m and I've been sold lazyjacks with two 'loops'. Do I attach these at 1/3 and 2/3 distance along the boom.
To get the best result, try temorarily lashing the ties to the boom and dropping the main, the best spacing will depend on how far up the mast the lazy-jacks are attached / hoisted, start with the back one about 3 feet inside the luff and the other midway between the mast and the back one, leave some slack in the lines and make sure the boom (topping lift) is secure. Good luck.
I'm also about to add a home made lazyjack system to my boat (home made because the barton and other systems are too heavy for my needs). My proposed system will have 2 loops each attached at 1/3rds on the boom using sliders on the underneath track - That way I can adjust the postion of the loops on the boom.
Question - on the mast end. Do you attach to the spreaders or to the mast?
Mast is best, especially if the controls are on the mast or led to the cockpit. I've used a system in the past where the controls were on one side of the boom (by the outhaul) and the attachment was to the spreaders. A bit unorthodox, you had to know the layout but it was ok - and easy to install. Incidentally, I found by trial ind error that the loops are better towards the end of the boom - they "contain" more of the roach.