MEASURING SPEED

A precise kilometer was measured on the north and south Pamlico River banks in 1996 and first used for record runs in 1997. Russ Dodge, the chief surveyor for the American Power Boat Association, and his wife, Carol, traveled from Seattle in February to conduct timing for the speed-record attempts. Setting up on the south bank, they located the survey irons under the sod and those 4,000 feet away across the river, which are marked with a bright stake. A small cable is laid between the kilo irons and connected to a set of stopwatches that are triggered as the boat passes the start and finish of each kilo run. That electronic trigger is built into a pair of World War II-vintage M6A1 elbow telescopes that swivel on a tripod placed directly over each survey rod. Russ and Carol set the electronic switches to trigger the stopwatches as the telescope pivots in alignment with the mark across the river. As the boat approaches the start line, the telescope is aimed at the bow and follows as it passes by, triggering the watches. The same procedure stops the watches at the end of the kilo. It’s a method that predates digital stopwatches and has not been replaced because of the challenge of measuring a speeding boat, according to Russ. Civilian GPS updates too slowly to be accurate over this short distance, it’s not possible to set up magnetic triggers on the river bottom, and optical devices can be triggered by flying birds and are confused by boat spray.