If you are going to Grand Turk Island when you dock (Carnival I take it) you will walk down the long dock and then Jacks is off to the leff about a 15 min walk.
http://www.jacksshack.com/what-is-jacks-shack.php
http://www.jacksshack.tc/
https://www.facebook.com/pages/Jacks-Shack-Grand-Turk/197858410231582
http://www.theshroyers.com/nieuwamsterdam/grandturk.html