I have this idea I can't shake.
Take the build cradle and just continue it around in the (nearly circular) profile around the boat in 3/4 ply.
Mount some trailer rollers on the ground in a bracket. 2 per frame.
Re-enforce and cut the build frame in a near circle, so now the boat has 2 collars 360 degrees around it.
Spin the boat.
Has this been done?