Stan's Previously Owned Vessels, also known as Smilin' Stan's Used Shipyard, was the name of a business operated by the salesman Stan S. Stanman.
It was located on Mêlée Island.
Guybrush Threepwood was able to purchase The Sea Monkey at the docks after much haggling using 5000 Pieces o' Eight credit obtained from the Store Keeper. According to a sign on the sales office door afterward, it was revealed to be Stan's only known sale.
During his battle with the Ghost Pirate LeChuck, it was where Threepwood was able to acquire a bottle of Root Beer which he needed to defeat his opponent.
Interestingly, it is the Scumm Bar Chef who refers to the dockyard by its second name- "Smilin' Stan's Used Shipyard".