The plywood frames on the back side were reinforced with 2x4 spacers and shaped to give two stopping points so we could regroup if necessary. The turning frame was belayed  to control the roll with the anchor rode on the back side and jib sheets on the front. (purchased a bit early) I added some bracing to the shed on this side too.  . 

I had designed the shed with two double strength frames to act as hoist points but added temporary columns of 2" steel pipe as reinforcing.   The building cradle was placed on the hull and tied to doubled 2x8" beams run under the hull with plywood frames.  Chain falls were hung above the columns and attached to the cross beams. These would raise the hull to the point that the center of gravity passed over the first pivot point and the hull started to roll on its own.

The turning crew and Captain, the Lab posed under the hull (probably the safest place in the building) as we reached the first balance point. This is also just about the limit of positive stability of the finished boat.  I hope I never find out if John's calculations are correct.

There were two people on the chain falls and two on each of the belaying lines.  In order to maintain clearance under the roof, the hull had to remain in the center of the shed.  Two come-a longs were attached under the hull to the far side of the turning frame so the entire assembly could be dragged over as the turn progressed.

Once we reached the second balance point, it was downhill from there on.  The belaying lines took up the load and we eased off on them as we pulled in on the come-a longs and the boat settled on the building cradles.

It looks big now, no matter which direction you look