This paper is concerned with the turning of some destroyer typed ships, which are particular in the point of having twin screws and rudders, comparatively high speed, and large speed reduction during the turning. The authors developed some treatments on the investigation and the calculation about such typed ships, considering the indicated particularities. The brief reviews are given as follows. (1) Some arrangements are given on the velocity increment of water flow around the rudders due to the propeller race in term of thrust coefficient, using momentum theory. (2) Some computations are made about the interaction between two rudders, and it is shown that the effect of the interaction is not negligible. (3) An approximate formula is obtained to estimate the ship speed in steady turning, and is made comparative study of the actual ship data. (4) An expression is developed for the relations between Froude's number and turning radius, and is computed to the successful result. (5) An approximate formula is shown for the computation of angle of roll of ships during turning, and some effects of the steering speed to the heel angle are discussed.