Mercury - Quicksilver Replacement Skeg Lower Unit Component Cast Aluminum 15985A02. Overview. If you've clipped a rock, snagged a stump, or worn your skeg down over time, you already know how much it affects steering and stability. The Mercury Marine 15985A02 Quicksilver Replacement Skeg restores that solid, steady feel your boat had when it was new. Designed for Mercury, Mariner, and Force outboards between 50 and 125 horsepower, it matches the factory dimensions perfectly. Tough, durable, and