In June of 07 I asked if anyone knew of a place that rented beach cats in Cartagena Columbia. No one responded but I can now tell you that after spending 40 bucks on a taxi (believe me $40 takes you a loooong way in Cartagena) and covering every shore line there is, I can tell you I didn't even see a beach cat never mind renting one!!
I asked several of the large hotels but no luck. Someone should set up a Hobie dealer there. 
Beautiful beaches nice even 10 mph breeze all day, looks like a great place to sail. I did find a bunch of cruising cats though.