Determining the optimal ship's safe speed

The purpose and scope of this paper is to outline the best practices when determining the ship’s safe speed and best possible speed for sea voyage legs as per COLREG definition ship’s owner and charterer requirements and 3-D model of ship’s domain. In this paper the author presents the attempt to define the following notions: ‘ship’s safe speed’ ‘critical speed’ ‘limited speed’ ‘reachable speed’ ‘economical speed’ and ‘optimal speed’. The author also depicts methods that can be used for estimating ship’s safe speed in the restricted sea areas by means of three-dimensional model of the ship’s domain.