Ablative paint is nasty foul stuff - get white suits and tape cuffs, legs, and collars shut. Dust masks and goggles. wear shoes you can toss.
Don't know about a 40ftr, but removing 2 coats of ablative paint from a J/24 took 5 people busting their backs for 2 days for 6 straight hours - and all we did was smooth the ablative paint down, we didn't remove it entirely. Removing 100% might have taken another 2 days.
All done using hand sanding - no power tools.
Your 40 ftr might have 4 times the surface area of a J/24.