Davis Whale Tail XL Stabilizer The Davis Whale Tail XL is an aluminum stabilizer and ski boat fin. With this stabilizer, you can improve the performance in any IO or outboard motor. The Whale Tail XL extends out behind the propeller to utilize prop wash energy which is normally lost. Whale Tail transforms this energy into lift for immediate response when the throttle is applied. The Whale Tail XL also flattens the wake for water skiing, creating positive, skin-free turns. Use the Whale Tail XL y