This paper assesses the collision probability in different encounter scenarios considering the manoeuvring capabilities of the vessels. The collision risk is analysed by trajectory simulation of the two encounter ships in several scenarios: “blind” navigation, COLREG execution (i.e., correct following of the rules by both vessels), and COLREG-blind (i.e., only one of the vessels follows the rules). The trajectories of the ships involved in collision scenarios are generated probabilistically by Monte Carlo simulation using the first-order Nomoto manoeuvrability model. This paper provides some indications for the relative distance between ships at which a collision avoidance manoeuvre should be executed to reduce the collision probability using the minimum safe distance concept. The generic simulation model based on simple input data and manoeuvring characteristics of the vessels can be later improved for collision avoidance applications.