You must master new Discoveries in order to access new types of Buildings and Units . Construct theObservatory to begin researching new Discoveries. The more you upgrade the Observatory , the faster you can complete new research. Researching each Discovery costs Gold, Lumber and Rum . The more advanced the Discovery, the more expensive it will be. The cost of upgrading a given Discovery also becomes progressively more expensive with each higher level. After a certain point you will find that you need to acquire a set number ofSketches to unlock research on a specific new Discovery. You will get a new Sketch from your Tinker every day, but you must have all the Discovery-specific Sketches for a given Discovery before you can initiate Research. (For example, if you have 3/6 Sketches for Shipbuilding and 5/8 for Armor Plating...you still can't research either one. You can trade with other players for specific Sketches you need...so in this case Trade 3 of your Armor Plating Sketches for 3 more Armor Plating Sketches, then you can begin researching Armor Plating.)
As your Discoveries become more advanced, you will start to be required to collect a set number of Sketches before you can unlock them. You will get a new Sketch from your Tinker each day to put toward completing a set for a given Discovery, after which you can initiate Research. Sometimes you won't get the Sketch you're waiting for, or the right one in the series. Use the Trading feature to get the ones you need. (For example: If you have 3/6 Sketches for Shipbuilding and 5/8 for Armor Plating, you still can't research either one. But if you Trade 3 of your Armor Plating Sketches for 3 of your missing Shipbuilding Sketches, then you can begin to research Shipbuilding.) You can also gift your friends Sketches they need instead of Trading. Go to your Friend's Haven, click "Actions" and choose "Send Sketch" to send them a Sketch. You can also go to the Map, find your Friend's Haven, and choose "Send Sketch" from the drop-down menu. Once you research a Discovery, exchange a Sketch, or gift it to friends - it's gone. You do not retain a copy. Seawater does not agree with printing presses, and McCallan doesn't believe in making backup doodles.
LevelsDiscoveries used to unlock new Units have 20 upgrade levels. The higher the upgrade level of the Discovery, the more effective its related units or buildings. (e.g. to increase your Marauders’ stats upgrade Swordplay Discovery.) View the current upgrade level at the top part of each Discovery's window.