Maintaining Dripless Shaft Seals
Story and photography by Capt. Vincent Daniello
If the cooling water that’s injected into either lip- or face-seal housings stops, the housing may fail entirely, leaving only the stern tube, a torn or melted rubber bellows, and a rush of seawater. After a boatyard launch or any engine-related raw-water work, remove the hose from your seal housing to ensure water is flowing in from outside the boat. Then, with the engine idling, the same hose (while disconnected) should fill a gallon jug in about a minute. Also, crossover hoses between two shaft seals provide good backup, but can also mask a stoppage from one engine—until flow from the other engine stops too! So check crossovers—in both directions.