Most of the hazard are well marked. In clear weather you can sail the Maine coast very well with a chartkit chart book. The various passages look a lot worse on the charts than they are in reality. Just remember the tide which averages 10-12 feet. Tidal current isn't normall a probelm once you get past the mid-coast (i.e., from Penobscot bay to the Schoodic penninsula).

Finally, if you get in trouble, just ask a lobsterman to help you out. They are your best resource if you have a problem. Some are a bit grumpy, but most will do what they can for you. Once you get past Boothbay you won't find any commercial towing services