It is a very simple cradle just two planks aligned with the seat fronts, some blocks added so that the base will align with the floor of the garage and the planks should follow the shape of the bottom.
This is the whole thing, the idea is that the weight of the boat will shape the planks to follow the bottom.
Perhaps another picture will make it more clear....
The weight of the boat is simulated by sand buckets and lead pigs, you can see that the longitudinal planks bend and fit with the bottom (actually the weight I put on was not enough to get the correct bend)
So the transverse planks are aligned with each other and will rest on the floor, the longitudinal planks will support the bottom. I will also put supports under the stem and the transom. Make sense??
I am of to bed now, have an early flight to Prague tomorrow, back to the garage on Thursday.
Time today: 2h