The castle took the form of a motte and bailey design, and a dam was probably constructed to turn the surrounding marshy, low-lying land into an artificial lake, called Skipsea Mere, in turn connected the channel leading to the sea. The complex had its own private harbour, and probably a boat yard and a fresh-water fishery. By the end of the 11th century a church had been built to the east of the castle across the mere, and the village of Skipsea soon grew up alongside the church. Drogo settled 10 knights on lands near the castle in an arrangement known as a castlery or castle-guard system, under which the knights helped to guard the castle in return for their estates, and one of them probably built his own smaller fortification at nearby Aldborough.