Skipper. Master of a fishing vessel. Colloquial name for any Master or commanding officer.
Skylight. Glazed opening in deck that allows light to pass to deck below. Glazed covering is usually hinged, to allow air to pass in line weather.
Sky Pilot. Ship's chaplain. Often applied to any clergyman.
Skysail. Square sail set above royal yard.
Skyscraper. Triangular sail set above royal yard.
Slab. That part of a reefed square sail that hangs downwards.
Slabbed Knee. Beam knee made by removing bulb of beam and welding a triangular plate to it.
Slab Hatch Covers. Several hatch covering planks held in a steel frame that can be lifted by a derrick, thus speeding the uncovering and covering of hatches. First introduced by Captain R. E. Thomas, 1909.