FYI: it’s the same for nearly every catamaran
You must catch the main structural bulkhead the mast
is supported on and the aft box beam.
That’s it. Holds true in 95% or more cases.
When blocking, it’s the same idea, but you want to try to spread the load out a bit so you don’t squish the core
. But the main supports should be at the same spots as the lift
, but hopefully spread out to avoid concentrating all the weight into 2 square inches of support