Dont know what boat you went on but the one I got from San An was certainly not a popeye boat and no-one at all was sick over the side!! The boat from San An is handy especially if you fancy seeing Es Vedra whilst you are over, also by being on a boat for 2 hours gets you a cracking tan and you dont feel uncomfortable by burning in the sun cos of the nice sea breeze!!!
Also you must be pretty silly getting the Regular bus and not knowing that its a tourist thing, especially when the leaflet cleraly says that they will show you the sights of Formentera!!!