Expand your docks and the Merchant Ships will surely come!
1st dock is free and 5 hours to build, 2nd dock for 500 and 6 hours to build, 3rd dock for 3,000 and 12 hours to build, 4th and last dock for 30,000 and 1 day to build. More docks you have more merchants can trade with your island.
When you build and upgrade your docks, you’ll attract merchants looking to buy a wide variety of goods from you. These merchants are ready to trade their Coins, Gems, and other items, but they can only wait around so long. Be sure to help them out as quickly as you can!
As long as you don't tap the merchant ship, it'll be stand on your dock and wait indefinitely. As soon as you tap on and show the trade the timer start. So be careful before tap like having enough room in your storages (to store 10-20 items at high level), all your mills ready to build (no pending items) and personal time to manage the trade.
So don't trade just before go to sleep !
Tap any Merchant icon to view that merchant’s offer.
1) Time remaining on this trade offer.
2) Items and quantity the merchant needs.
3) Rewards for completing this trade.
4) Tap to complete the trade (once goods are ready).