This and the other ship achievements can easily be obtained on Grand Bahama. On the south side of the map, there will be a race event, right next to a checkpoint. Go do the race event and repeat till you farm enough gold for the ship.
Select "The Wanderer" as your ship (hopefully you have maxed out speed).Equip the "Full Speed" and "Boost" perk in the sails category and "speed up" ability for the figurehead category. Just use the boost and speed up abilities every time they pop up.You only have to worry about the mines and a few ships, which are easy to avoid once you've memorised them. There is also no gust/wind in this event. It will take you about 30-40 secs to net 6000 gold per race. It can get a bit tedious, but as there is a checkpoint right next to it, feel free to capture it and come back to it, if you wish to do other things.