The Nautical Slide Rule offers a foolproof, immediate solution to all common speed/time/distance problems and is convertible to statute or nautical miles. It also allows the user to compute distance in yards if the speed is factored in knots. The Nautical Slide Rule is sometimes referred to as a Time Speed Distance Calculator.- Immediate solution to all speed-time-distance problems- Equally applicable for nautical or statute miles- Speed in knots or mph; time in hours, minutes or seconds; distance in nautical or statute miles, or yards if speed is in knots- Easy-to-read & accurate