Complex sentence: Sailors compensate for this by putting their weight as far aft as they can while running downwind, also raking the mast aft of the centreline reduces this motion and can improve the windward sailing ability of the boat.
Split into simpler sentences: Sailors compensate for this by putting their weight as far aft as they can while running downwind. Raking the mast aft of the centreline also reduces this motion and can improve the windward sailing ability of the boat.