Vessels of 12 feet (3.7 m.) or less draft.-Vessels of this draft at low water and about 18-foot (5.5 m.) draft at high water, bound along the coast of Maine, generally use the thorofares and passages inside and between the islands. The most frequently used route leads southward of Cross and Libby Islands, through Moosabec Reach and Tabbott Narrows, southward of Petit Manan lighthouse and Schoodic Island, across Bass Harbor Bar, through Casco Passage, Deer Island Thorofare or Merchant Row, Fox Islands Thorofare, Muscle Ridge Channel, Davis Straits, Fisherman Island Passage (near Boothbay Harbor), and between Seguin and Pond Island. Vessels of this draft can then pass southward of the islands in Casco Bay or can find a more protected route inside the islands as described in the directions following; the most frequently used route in good weather is southward of the islands in Casco Bay.

This inside route is very narrow in places and leads close to many dangers, but the principal dangers for vessels of 12-foot (3.7 m.) draft are marked, and it can be used by vessels of that draft in the daytime and with clear weather, by a close attention to the charts and the following directions: A 13-foot (4 m.) shoal on the course between Hardwood Island and Fessenden Ledge at the west end of Moosabec Reach has been reported recently. Most of the route is used by local vessels up to 18-foot (5.5 m.) draft, but strangers in vessels of over 12-foot (3.7 m.) draft seldom use it. There are anchorages at frequent intervals, as mentioned under the descriptions of the bays and thorofares, and vessels caught in a fog anchor until the weather clears. Pilots for the route can be obtained at most of the cities and towns along it, and strangers often take pilots.

Vessels using this track and bound in the reverse direction—that is, from Portland toward West Quoddy Head-will find courses tabulated for that direction on page 47.