the usual practice is to use props to steady a hull sitting on blocks
rather than suspending from rafters. If you suspend with rope its bound to
stretch and shrink with changes in the weather and time of year.
I imagine suspending with chain would be more costly than using props.
Maybe not. You should be able to consult standard sailing texts for the
recommended load for various thicknesses of rope of different materials
and of chain of different thicknesses. I recall seeing this information in
the old copy of "Royce's" I have here.

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