"Steve B" wrote in message
...
I'm building a lift, probably 1,000 $ max, but mostly 500 or less. Is
there a chart that gives different structural configurations and their
relative efficiencies?

i.e. .............. a bar joist design
a pyramid with lifting point at the apex
two poles with a right angle peak point of attachment
and one horizontal purlin
a plain truss shaped span, pitched to the roofing,
with diagonal bracing ............

16' wide span, verticals 8', then up with the framework. I actually need
two so I can lift my boat entirely with straps. Weight of boat, about
1500#.

I have been googling, but no luck yet.

Material would be 3 x 3 x .120" tubing MIG welded together, and gusseted
mostly wherever possible, and lateral bracing to help side loading.

TIA

Steve

Flickr of ideas ....................

http://www.flickr.com/photos/deserttraveler/