Never heard of a divit - for the crane, seen one at a water treatment plant, supposedly to make it easier to lift a motor on and off an air mover when being repaired - except that, yes it worked for the motor (250kg), pity they did not account for the impeller attached to the other end which could almost weigh a quarter as much. as previously mention a 600mm pole inserted in the ground and made flush with plug, a tube/shaft that will snuggly be inserted and welded into a 1000mm length of the scaffold pole, this is the vertical shaft/rotating axis, a length of scaffold welded either up at an angle or at 90° to the vertical axis, suitable to reach sufficiently enough over the water, a brace welded to the main vertical and the underside of the beam (to suit the weight of man and boat - as someone will undoutably try to swing on it), a closed eyelet (similar to those used to lift heavy motors) is welded to the underside at the end, a rope and pulley lift is fitted to the end with a suitable weighted hook to retain the tension so that it does not jump the pulleys, the boat is fitted with the handle as originally suggested (kitchen unit style suitably strong enough to lift the boat with all its weight). Then to attach when launching/retreiving, a hook on a pole is used to guide the pully onto the handle in combination with the rope for tension, to swing in and out once the boat is attached and having been pulled up by the rope to miss all obstructions and secured, the operator only has to pull on the brace or top bar to swing left or right until over bank/water. simples or if an old village / re-introduce the old style - witch dunking stool - on wheels - old world charm meets new age use