I had previously made a pair of dollies to support the boat when it is flipped upside down, but I had not finished them.
They needed vertical supports to support the hull at the bow and stern at a height of 10 1/4" and 17 1/2" respectively.
So this is how the front dolly looked when finished. It's just a block of wood attached to the dolly.
And this is how I completed the rear dolly.
I fixed a vertical post to the dolly to take the compression load, and used a strong plastic bucket securely fixed to the post and the dolly to take any lateral load or twist when moving.
The bucket happened to be exactly the right height!
So the dollies are now ready for the big day.