Self-Trimmer. Vessel with large hatches and clear holds that allow coal, grain and similar cargoes to be teemed into any part of a hold.
Selvagee. Rope made by spunyarn being laid in parallel lengths, and bound together with marline-hitched spunyarn passed around all parts. Has great flexibility and grip.
Selvagee Strop. Strop made by laying spunyarn in coils and binding it with marline-hitched spunyarn.
Selvedge. Normal edge of woven material, such as canvas. 2. An alternative form of 'Selvagee'.
Semaphore. Method, or apparatus, for signalling alphabetical letters, numbers or code signs, by visible movements and changes of position. In nautical signalling, hand flags, or apparatus having movable arms, is used.
Semi-Diameter. Half diameter of disc of Sun or Moon. As this is the distance of the centre from the limb it is of great importance when measuring sextant altitudes.