Our boat briefing on the first day of our charter was the most thorough I’ve experienced in more than a dozen charters. It might as well have been a marine survey, which explains why the boat was in impeccable shape despite its years in charter-fleet service. Twice as long, however, was our chart briefing with Horizon’s customer service manager, Bernadette Noel. To get to Tobago Cays Marine Park, the gem of the Grenadines, Horizon has a seven-day itinerary from its True Blue base. On paper, it’s an ambitious plan that requires clearing customs and moving every day — all to get one night on the hook in Tobago Cay. The itinerary is based on a noon departure from the base, with a two-hour sail around the southwestern tip, to anchor off St. George’s. The next day, it’s an “exhilarating day’s sail” to Tyrrel Bay on Carriacou, and from this rustic fishing outpost it’s a few more hours of sailing to the Grenadines’ Union Island to clear customs. Provided you make the office’s calling hours before they go on break, or worse yet, close, you can carry on another hour or so north to Mayreau. If all goes to plan, you wake up in picturesque Saltwhistle Bay and hustle over to Tobago Cays as quickly as possible. With only one night in the anchorage, it’s time to start reversing the route: to Union and then over to the private island of Petit St. Vincent. From there it’s an 8- to 10-hour sail to Prickly Bay on the south coast of Grenada, for one last sleep aboard.