In order to avoid a collision it has clearly been proved that for most seafarers there exists a set of possible situations known as head-on, crossing and overtaking, while ignoring in a general way the behaviour they should carry out when their vessel is in conditions of restricted visibility. It is obvious that the existence of two different manoeuvre methods in relation to the prevailing visibility confuses the navigator. But there is still more. With the arrival of AIS, the present wording of paragraph d) of Rule 19 leaves the seafarer in a state of total uncertainty when deciding the appropriate manoeuvre, so its amendment must be dealt with as a maximum priority. The following paper tries to find a solution to the dilemma, even though this does not imply a radical change in the general conception that a mariner may have of collision avoidance.