The Steamship Authority is the ferry that takes you from New Bedford to Martha's Vineyard and it take an hour and a half. That may seem like a long time, but with a wonderful view of the Mass. shoreline on both sides, you'll savour every minute. You can also pass the time visiting with other travelers. We met a couple from New Mexico who traveled both ways with us.
Schamonchi is the name of the ferry; a large boat with a large crew. However, maybe because it was a Monday, there was only one snack bar open on board. Fortunately, they served hot food so we weren't left without breakfast (hot chocolate to die for). The ferry is a smooth ride, but can be chilly, especially on the front deck, but that's the best place to get a view.
The ferry leaves from Billy Wood's Wharf in New Bedford and docks at Oak Bluffs in MV. The early ride is at 9:15am and the last departure from MV is 7pm, so you definitely get a full day in MV. Cost is, get this, $10 per person, ONE WAY! So, for two people, that's $40, plus the $10 parking fee to park your car in the lot across from the wharf.