Nautical Slide Rules

Speed-time-distance calculators and nautical slide rules for navigation planning. The Blundell Harling Speed-Time-Distance Calculator handles the basic velocity triangle; the NATO version adds knot conversion useful in mixed-fleet work. The Weems & Plath Nautical Slide Rule covers speed, time, distance and fuel calculations, and the Vectormaster adds wind and current vector solutions for more complex passages.

All are analogue tools that require no battery and work regardless of screen glare. A useful backup to chart plotter calculations and required on some RYA and MCA practical navigation courses.