Ok, you have an Amel 41. That helps. I found an elevation view of an Amel 41 listed for sale
on Yachtworld and see the huge overhangs. That explains how you can get so much weight in 33' lwl. BTW that owner listed his weight at 18,000 lbs.
Travellift scales are notoriously inaccurate and 15 Tonnes (metric, right) equals 33,000 lbs. I can't believe an Amel 41 even loaded for bear weighs that much. My guess would be more like 25,000 lbs.
So if I plug
that into boatdiesel's calculator, I get 19.0 x 14.3. I understand that the max transmission
ratio for your engine is 2.6 and 19" is as big as you can go. If you really weigh 33,000 lbs then the pitch
drops 1". As others have said you can usually repitch a prop up to 2" either way.
The advice about pre-negotiating a free repitch is good, but the haulout (or diver) cost is likely to be yours.
Think harder about the MaxProp. Yes you have to grease them at each haulout, but that is all the maintenance
really needed. Maybe a rebuild
after ten years- about US$1000. You will love the improved thrust in reverse. I could get off most soft groundings by reversing with a MaxProp whereas with a fixed blade prop I probably couldn't.