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In this research study, effects of the draught and sheet height in pontoon floating sheet-breakwaters on the transmission and reflection coefficients against irregular sea waves was investigated. The project has been carried out using an experimental method within a wave flume of Soil Conservation and Watershed Research Institute. The incident waves were irregular and the wave spectrum was JONSWAP. The range of wave heights varied between 2 and 12cm and their mean periods were set to be between 0.63 and 1.26 seconds. To investigate the effect of draught in pontoon breakwaters, three experimental model with similar breadth and different draughts of 8, 10 and 12 cm were tested. Also, in order to investigate effect of sheet height in pontoon sheet breakwaters, sheet heights with 8, 16 and 24 cm were examined and compared without sheet case. The water depth was set to be 60 cm. The number of waves for each test was 250.