I've been through many times with a number of different catamarans. I've always used 'BVI Pirate' as a template .... keeping about 1/3 from Virgin Gorda point (on the right) and 2/3 from Mosquito point (on the left). Immediately passing the two points I head slightly toward the right, in line with Leverick Bay. Leaving North Sound I take the same route, unless headed to Anegada. Yes, it is shallow, although seems to be the route of choice for many charter cats.