I called at Onset once just at nightfall headed west through the canal and scared myself sufficiently to never return. We were returning from Maine on Silverheels and planned to anchor overnight in the "gunkhole", as we used to call the Sandwich Marina when boats could anchor there. Anticipating a quiet night and an easy anchor drill, I was "allowed" by the admiral aboard to sip a G & T as the sun was setting on the approach in a flat calm to the eastern end of the canal. I never drink anything alcoholic underway, but this was an exception. So guess what? The gunkhole was full up and we had to transit the canal in favorable current after dark and make for Onset. Making that turn around the rockpile was scary enough, then finding the buoys in with the admiral on the foredeck with the search light. Well, through the grace of God we made it into the anchorage safely, but never returned. Now we do Red Brook which is a bit tricky on the way in but no significant current.