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Changing course

In a previous piece about rules, we noted that a give-way boat keeps clear of a right-of-way (r-o-w) boat if the r-o-w boat can sail her course with no need to take avoiding action. That is fine when the r-o-w boat is sailing in a straight line and the give-way boat can see where she is heading – but what about when the r-o-w boat changes course in close proximity to the give-way boat?

In that case one of the limitation rules, rule 16.1, applies and says that the r-o-w boat must give the other boat room to keep clear. The definition of room includes both space and time requirements; so the change of course limitation restricts both how fast the course change can be effected and how close to the other boat it can be made.

A give-way boat that is keeping clear is not required to anticipate a change of course by the r-o-w boat and is only required to react when a collision course is established – and rule 16.1 says that she must be given room to respond at that point.

A frequent example of this situation is when a leeward (r-o-w) boat luffs a boat to windward of her. The initial luff must be slow enough that the windward boat has both time and space to respond – and both time and space will be determined by the prevailing conditions as well as by the types of boat involved. Furthermore, if the luff continues after the initial change of course, the change is continuous and so the requirement to give room is also continuous.

There is, in addition, a specialised rule, 16.2, which applies when boats on opposite tacks are sailing towards each other. This rule says that if the port-tack boat is keeping clear by sailing to pass astern of the boat on starboard, the starboard-tack boat must not change course if it would result in the port-tacker having to immediately change her course to continue to keep clear.

The are many situations in which rule 16 applies – so if you are the r-o-w boat do bear in mind that you will have obligations if you change course.

Chris Simon

Regional Rules Advisor