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This NATO Time, Speed & Distance Calculator by Blundell Harling is a simple, reliable slide rule for quick navigation calculations at sea. Ideal as a primary or backup tool when electronic systems are unavailable.
Easy-to-use slide rule: Calculates the third variable from time, speed, and distance inputs
Clear, legible scales: Enables fast readings for course planning and ETA checks
High-impact plastic sleeve: Provides durability in demanding marine environments
Compact navigation aid: Fits neatly on the chart table or in a navigation kit
A trusted, manual solution for accurate TSD calculations during coastal and offshore passages.
