The
hull is supported on the center - typically for a fixed keel
boat. But a light flat
power boat or a light sail
racer may be supported only by the 3 or 4 supports.
The first time you do it, you let the keel touch the platform, then while she is still held by the crane or the
lift, you adjust the supports accordingly. Mind the supports are there to just keep the boat in vertical. So do not - over-tighten these.
Make sure the platform and its support layout match the boat - so that when you maneuver the platform the boat cannot slip out of the 'craddle'.
I have seen a big yacht, a Cape Georde heavy keeler, slip off the platform while being towed in NZ. Avoid this kind of adventures at all cost.
Cheers,
b.