Expert System - Sailing Ships by McGoo Software

Based on the responses you have made:

The vessel is probably a Schooner

Conclusion Notes:

This vessel has 2 masts with no square sails. The aft mast is taller than the fore mast.

Expert System Rule:

IF the number of masts on the vessel is 2 only
AND there are square sails on no masts
AND the taller of the 2 masts is the the aft mast
THEN the vessel is probably a Schooner.

Calculated Certainty Factor: 0.48 = probably