February 1, 2009
My physio has banned me from lifting gas bottles so I've made a crane.
All the remain to be done is to saw the pole to the correct length which I will do at the boat. Our design requirement was 33 kgm lift at 40". Generally we will only lift at 28". The crane has an optional extension to 40".
The 40 " requirement dictated a strong pole (to get within 5000psi to 10000psi where the bending moment is at its maximum) which is a bit heavier than we need for the 28" lift but better safe than sorry.
The other design requirement was a single man lift on any one component. This means less than 20kgm.
This is the crane.
The separate components are
The pole at 7.5 kgms
The winch at 3 kgms
The jib at 5 kgms
So we are well within our design spec.
The pole is mounted through the front seat and the wooden clamp is clamped by 2 G clamps to the front deck. It sits in the corner hard against the hull and swings over the gas locker and the towpath.
Here are the hinges in close up.
The winch is strictly speaking a puller and not designed for lifting as it is possible to release both safety catches at the same time! It was easy to fit compared to a proper winch!
Winch in close up.
May be at the boat next weekend to fit it. All depends on the weather.
By the way how many of you guys or gals have a partner that would let you photograph this thing on the lounge carpet?
Cheers Graham