When you clear out of Carriacou you will state your destination in the clearance papers ("Zarpe") as Canouan, St. Vincent and the Grenadines. Then, just like in Monopoly when you get a "go to jail" card, you just sail directly there and don't stop anywhere on the way. If you arrive out of hours, then anchor and stay aboard until the next day when the captain clears in. I cross check with Noonsite for St. Vincent and the Grenadines before traveling. That site states that you can even stop for 24hours underway, perhaps because of the geographical size of the country, but the official SVG Clearance page makes no mention of that.