Product Description
Original genuine Portland Speed Time Distance Calculator by BH Navigation.
NATO PATTERN : 0655.37
INSTRUCTIONS FOR USE .
1. WHEN THE SPEED IS KNOWN, TO FIND THE TIME REQUIRED TO RUN A GIVEN DISTANCE OR THE DISTANCE RUN IN A GIVEN TIME. SET SPEED IN KNOTS ON UPPER MILES SCALE AGAINST 60 MINUTES (THIS ALSO SETS SPEED ON LOWER MILES SCALE AGAINST 1 HOUR) AND RED OFF TIME OPPOSITE DISTANCE OR VICE VERSA.
2. TO FIND THE SPEED MADE GOOD FROM THE TIME TAKEN TO RUN A KNOWN DISTANCE. SET DISTANCE (MILES) AGAINST TIME AND READ OFF SPEED IN KNOTS ON MILE SCALES OPPOSITE THE ARROWS. UPPER SCALES ARE FOR PERIODS BETWEEN 15 SECONDS AND 2 HOURS AT ANY SPEED UP TO 40 KNOTS. LOWER SCALES ARE FOR PERIOD BETWEEN 1 HOUR AND 4 DAYS. (FOR SPEEDS BELOW 5 KNOTS USE UPPER SCALE TO SET SPEED ON SLIDE AND READ OFF AS REQUIRED FROM LOWER SCALES).
IMPORTANT : SHOULD THIS INSTRUMENT REQUIRE CLEANING , TOILET SOAP AND WARM WATER ARE RECOMMENDED. DO NOT USE STRONG DETERGENTS , SOLVENTS OR ABRASIVE POWDERS.