After all Michael Blackburn managed to sail across the Bass Strait in a Laser (above), which is 117 nm of open waters. It took him 13 hours to cross, at an average of 8 knots.
So the Iceland to Greenland crossing of 150 nm is a bit more but still doable. With the same average speed that would take nearly 19 hours - tough, but a single sailor could do that with a lot of coffee to keep them going.
By linking up a whole series of hops like that I can see no reason why a London to New York voyage couldn't be achieved.
But can guarantee it won't be by me!