The ship, the Eagle Ray, has gotten it name from the rays with the same name, since the shape of its sails resembles them. See the very last (black&white) photographs in the category ‘rays’ of David Doubilet’s amazing portfolio of marine photography.

It’s basically a modified xebec, a type of ship that was popular with the pirates of the Barbary States in the 17th century, and was used also by other fleets in the 18th century. The main reason for my modifications was that I just didn’t have any good references when I started drawing this comic, and had to make things up. But some are also quite conscious: for instance, I didn’t want any oars on the Eagle Ray (four people can’t do anything with that many oars …), and I wanted a proper steering wheel instead of the ‘steering bar’ (I’m worthless with maritime terms in English) of the original chebecks.
Thanks to the wonders of the Internet, I’ve later on found some quite useful references:
Appendix 1 of T.S. Pelican of London
A xebec at modelshipmaster.com
Another chebeck model

Actually, I don’t know if it’s humanly possible for a crew of four people to sail a ship like the Eagle Ray, but hey – it’s all just my imagination anyway …