We did it on a sailboat and had a wonderful time. I was going to add that we sailed for about four days before we ever threw in a tack, just to keep things interesting, but that would be a moot point on a power cat. Departing St. Lucia, you cannot see St. Vincent, so it draws on your navigation skills a little bit and it is an open ocean passage for about 7 hours on a sailboat. No worries, St Vincent is a pretty large target. Boat Boys can be annoying, but play along and expect to pay a little extra for services. It's not bad. There are many more interesting anchorages along the way than in the BVI. Do it, you'll love it!