But you can use SCHRS to map Cats back into PY.

For example if you have some boats in the US fleet that you trust the PY for; you plug this boat(or boats) into the SCHRS model and get a rating. You then plug the boat you are trying to handicap in PY into the SCHRS model and this ALSO gives a rating. You can then calc the delta between the boats in SCHRS and then apply this delta to the boat you have in PY and this gives a new PY; now this method will assume that both boats (the one you trust in PY and the new boat) have the same crew skills. But it does give you a good (IMO) place to start.

If you have more boats, you can get the deltas to other classes and you might well get a good PY for the new boat.

HOWEVER you must consider that SCHRS does not rate the skills of the crew (and PY does) and so you need to take into account the skills of the sailors. Thus you might choose to make the handicap slightly slower(easier to make time on) than SCHRS suggests when sailing within PY.