Dennis Pogson wrote:

How is this any different from the problems of antifouling the same boat?
You simply add supports and wedges adjacent to the existing pads then drop
the main support legs, paint over the pad areas, then wait for the epoxy
to dry and re-attach the main legs, dropping the other two temporary
props. We used to do this every spring on our Hustler 36, (with the mast
still up). The temporary supports need to be fairly sunstantial.

I suspect what he wants to do is spray on umpteen coats, each time
doing the whole underwater hull in one go, and the drying coats would
get damaged by being scrunched by any supports.

Does no-one remember life before the diesel-powered boat hoist?

To be sure. AFAIK life at Port Edgar is still like that. They have
one fixed electric crane at the end of the pier, and they drag boats,
on their cradles, around the site on trolleys pulled by a lawnmower
tractor. The trolley axles have built-in hydraulic lifts, and one
of the axles is removable. The cradles are lowered onto stacks of
diced railway sleepers, and the trolley is then lowered and pulled
away from underneath.

Two advantages are that they can park the boats a lot closer together
than with a travel hoist, and that boats can be manoeuvred into
sheds with limited headroom (especially headroom at the doors).

Disadvantages are that it takes longer, and that use of cradles is
mandatory. They can't deal with boats to be propped up on sticks.