The DS taxi boats that used to take guests from one end of DS to the other haven't returned (yet). All the resort boats (SSR, OKW, FQ) dock at the Marketplace dock, and you're on your own to walk to your DS destination from there. I'm not sure how to find out the resort boats' schedules - according to the WDW website, their operating hours vary, so you'd have to check at SSR when you're there.