In case of criminal investigation for ship collision, it is important to determine the situations
at the time of the accident such as colliding and collided ship’s courses, speeds, and crossing angle
between both ship’s courses in the accident. Those situations in the accident can be estimated
empirically based on shapes of scratches on a ship damaged in the collision, but, the empirical
method have little scientific basis. So, in this study, shapes of scratches on a ship damaged in ship
collision are discussed scientifically and model test results of those scratches on a ship are
presented. Studied ship is semi-displacement typed high speed ship model. Variables of the model
test are ship speed, crossing angle between both ship’s courses and condition of collided ship (free
or fixed motion). In the future, we would like to clarify the mechanism of ship collision and
contribute to criminal investigations for ship collision.