To examine the hydrodynamic characteristics of the saucer-shaped otter boards made of plastic, their camber is varied from 0 to 25 percent at intervals of 5 percent. The lift force and drag force of the otter boards are measured by three components load cell in the flume tank. The lift coefficient, drag coefficient and lift-drag ratio are calculated for attack angles between 0 and 60 degrees. The maximal lift coefficients of the otter boards for camber from 0 to 25 percent are obtained at attack angle from 30 to 35 degrees. The drag coefficient gets greater when attack angle is gradually increased from 0 to 60 degrees. From the points of view of the mean value of lift-drag ratio in some fixed range of attack angle where the maximal lift-drag ratio was obtained and width of attack angle in 75 percent of maximal lift-drag ratio, it is most efficient for the saucer-shaped otter boards cambered in 5 percent that we have experimented.