Baidak was a wooden sailing ship, similar to a cog. It had a flush-laid flat bottom approximately 3–4 metres wide, which narrowed to tapered ends, and one 5 metre mast. Measuring approximately 15–20 (or 36–60) metres in length, a baidak could carry a load of approximately 200 tons. It could be operated by oars or sail.
Baidaky were in use from the 16th - 19th centuries in the territory of present-day Ukraine, primarily for cargo delivery on the Dnipro and Don rivers,however they were also frequently used by the Zaporizhian Cossacks for their military campaigns to the Black Sea.