MARK THE PILINGS.
The length of the tracks should accommodate the greatest possible tidal swing, plus 18 inches. Determine which two pilings to use, ensuring that each will line up directly with the stern and spring cleats. (If not, see “Piling Proxy.”) Mark where your boat’s rub rail touches each at the stern and spring cleats at dead low tide, then measure 18 inches below that point and mark it to indicate where the bottom of the track will install. The height of the rub rail in the stern might be lower than the height at the spring cleat, so the marks on each piling might vary.