Complex sentence: Achieving a position to rake a single enemy ship was usually very difficult unless the opponent was unable to manoeuvre due to damage to the sails or rudder; it was easier if a ship was constrained by its position in the line of battle.
Split into simpler sentences: Achieving a position to rake a single enemy ship was usually very difficult unless the opponent was unable to manoeuvre due to damage to the sails or rudder. It was easier if a ship was constrained by its position in the line of battle.