Driving in St John USVI

In Denver, when I go out driving my wife says, "hurry home so you don't kill anybody!" That's why I didn't do any driving in St. John. When you look at these signs you can see I'd probably just get 20 miles to the fender. Although, it's only 12.8 miles across the island. The problem is staying on the left and watching out for boats! Did I read those right?