Intro: Propeller-shaft stuffing boxes—often the only holes below the waterline without a valve—can quickly deteriorate from a slow drip to pouring water. Repacking your own isn’t hard when the boat is out of the water, and once you’ve done it, emergency in-water repairs aren’t hard either.
Step 1: Two parts of a stuffing box squeeze rings of packing around the shaft to form a seal. It’s tightened until it leaks a tiny bit of water to cool packing heated by a spinning propeller shaft. Too much heat hardens packing and makes it leak, and regular over-tightening wears shafts. A longer or shorter hose moves the packing to a new area of shaft, but check with a prop shop on how deeply the shaft can be worn, as this varies by horsepower, prop size, and transmission reduction. “Over 90 percent of the calls I get are because a stuffing box is too hot, either from over-tightening or using oversized packing,” says Steve Gaston, executive vice president of stuffing-box manufacturer Buck Algonquin (www.buckalgonquin.com). Unfortunately, packing sizes aren’t standard among manufacturers.