Using a Spyglass in AC4 Black Flag

"Incapacitate a schooner" is the first mission objective in Sequence 3 / Memory 03: Prizes and Plunder


Use your Spyglass to locate a Schooner

Sail to the Schooner

Fire on the Schooner until you damage it enough to cause it to become Incapacitated (you should see fire and smoke coming out of it)