Ian McColgin
07-28-2009, 02:46 PM
“The Competitive Cat”, Bill Welch’s wonderful primer on how to manage our darlings well, has eight charming drawings by Charles Chapin, three of which illustrate the mechanically correct way to lay out “LazyLifts” - combination topping lifts and lazy jacks.
People have asked about these so I especially commend the pictures on pages one and eighty one. These LazyLifts are on both sides of the sail.
Things I do a little differently:
My outer lift goes back only so far as a bit forward of the gaff tip when the gaff is at rest on the boom and sail. This way, the gaff won’t get snagged on the wrong side of a lift.
I run all but the foremost part under the boom so that the lifts can slide from one side to the other. This allows them to self-adjust, bellying out on the lee side with the sail and being trimmed on the weather side so they won’t flop about. I use cleats on each side of the boom to keep them back in place. The cleats also allow me to secure those moving parts so that on calm days I can use the weather side to pick the boom up a little.
As it happens on Marmalade I have two sets of flying blocks up there, a total of three loops under the boom before the termination. It’s a very heavy nearly thirty foot boom. With the lifts free to work under the boom, pulling from either side gives 8:1 mechanical advantage, absent friction and inefficiency. On the smaller lifts Chapin illustrates you’d have combined 6:1. If the lifts are cleated so the loops can’t slide, you have half that. It’s really more like a net 6:1 on Marmalade because of the friction under the boom and because the lifts don’t have any, much less all, parts out to the end of the boom. And the pull is not straight up. Still, they work well.
I’ll still happily make drawings for any or perhaps one of our computer literate shutter bugs will pay me a visit, photo them in action, and we can post.
G’luck
People have asked about these so I especially commend the pictures on pages one and eighty one. These LazyLifts are on both sides of the sail.
Things I do a little differently:
My outer lift goes back only so far as a bit forward of the gaff tip when the gaff is at rest on the boom and sail. This way, the gaff won’t get snagged on the wrong side of a lift.
I run all but the foremost part under the boom so that the lifts can slide from one side to the other. This allows them to self-adjust, bellying out on the lee side with the sail and being trimmed on the weather side so they won’t flop about. I use cleats on each side of the boom to keep them back in place. The cleats also allow me to secure those moving parts so that on calm days I can use the weather side to pick the boom up a little.
As it happens on Marmalade I have two sets of flying blocks up there, a total of three loops under the boom before the termination. It’s a very heavy nearly thirty foot boom. With the lifts free to work under the boom, pulling from either side gives 8:1 mechanical advantage, absent friction and inefficiency. On the smaller lifts Chapin illustrates you’d have combined 6:1. If the lifts are cleated so the loops can’t slide, you have half that. It’s really more like a net 6:1 on Marmalade because of the friction under the boom and because the lifts don’t have any, much less all, parts out to the end of the boom. And the pull is not straight up. Still, they work well.
I’ll still happily make drawings for any or perhaps one of our computer literate shutter bugs will pay me a visit, photo them in action, and we can post.
G’luck