MEASURING OF SQUAT IN THE FAIRWAY TO THE PORT OF LULEA, NORTH SWEDEN

Carl G. Carlstrom

Abstract


The importance of knowledge of squat and expected underkeel clearance for ships passing a fairway is essential to the navigational safety and the economy of a harbour. In order to check the squat of ships in the fairway to the port of Lulea a photographic measuring method has been evolved and used in measurements on three different ships. Determining of squat is made by levelling the position of vessels in relation to water level at the berth before sailing and en route at measuring points along the fairway. The accuracy of measurements was determined by observations on reference staffs. The order of standard deviation is 1/2 inch, at 2,400 feet distance. Observations indicate squat ranging from 1 foot 5 inches at speeds of 9 knots to 2 inches at 3>7 knots. The measured squat corresponds rather good to tneoretically calculated values according to Woltiger and Shell/Sogreah. The measuring method used has reduced the field work. The greatest advantage is that adequate values of squat will be directly recorded with only a few corrections including irregular factors such as turbulent flow, hull deformations and variable channel sections. A condition is however sheltered water and possioilities of solid foundation for instrument arrangement. 1499

Keywords


squat measurement; Port of Lulea; fairway

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