Weights and Arrangements Impact: Active fin stabilizers require port and starboard equipment spaces directly inboard of the fin location on the hull. This complicates the arrangement of other propulsion and auxiliary equipment and tankage arrangements. If the fins are retractable, additional equipment and associated area and volume are needed. The through-hull penetration of the fin stock well below the waterline requires watertight compartmentation around the stabilizer equipment room to prevent flooding from seal failure or other fin damage. All of this contributes to additional lightship weight and required area and volume.