This is not directly related to cruising, but I hope you guys can help
me out on this one...

I rented a Catalina 16.5 today, and being somewhat rusty and in an
unfamiliar boat, decided to sail it with only the main, figuring I'd
have less to worry about. Result: near disaster.

I couldn't tack the thing at all. It would come up into the wind just
fine, and then it would sit there, effectively stopping me. When
sailing even marginally upwind, it had horrible weather helm, trying to
come up into the wind all the time. Luckily the boat had a small
trolling motor on it, so I was able to motor-sail it back to the rental
office and return it without incident. But for the motor, I would have
been stuck on the downwind side of the lake.

Now, I realize that sloops are designed for two sails, but the boats I
learned to sail on (Club 420, if you are interested) handle just fine
under main alone. So why was I having so much trouble? Is it because

a) I haven't sailed over the winter and I'm rusty
b) Catalina 16.5s handle much worse without a jib than an average boat
c) Something else I'm not aware about.

Input appreciated!

Nikita.

PS: For the record, I traded the Catalina for a Hobie Cat, and sailed
just fine in the thing, so I can't be THAT rusty...