When rule 18 begins to apply
The old rule 18 began to apply when boats were “about to round or pass” That was sometimes at a different moment and place then at the moment when the lock-in/ lock-out provision of rule 18.2(b) and (c) began to apply. (when the closest boat reached the zone)
You could be outside the two length zone and were already busy with your spinnaker, still not sure if you were going to round the mark as inside boat or that the overlap would be broken before the zone was reached and you would need to keep clear, as clear astern boat.
That has been changed in the new rule 18. The moment you enter the zone rule 18 begins to apply and also the lock-in/lock-out provisions of the new rules 18.2(b) and (c) begin to apply.
The “about to round” provision in the old rule had one advantage. It could be argued that the rule began to apply further from the mark with for instance fast boats, strong wind or strong favourable current. You had protection within the context of that rule when you had already an inside overlap outside he zone. That is no longer the case. Rule 18 never ‘switches’ on outside the zone.
However, the obligation of an outside boat under the new rules 18.2(b) begins to apply at the moment one of the boats enters the zone. If before that, the boats had been overlapped for some time, the outside boat had better sail a course that will be in compliance with 18.2(b) the moment she reaches the zone. If after that, the inside boat is not able to sail to the mark in a seamanlike way, the outside boat risks breaking rule 18.2(b).
So, you do need to anticipate what rule 18 will say before you reach the zone. You can’t wait until you are in the zone and then begin to start complying. With he exact moment the rule takes effect now written in the rule, comes the responsibility to comply with that rule at that very moment.
When rule 18 ceases to apply
There is no longer a sentence in the rule which states when rule 18 ceases to apply. That was in the old rule when boats ‘have passed’ the mark. The principal obligation in the new rule is to give mark room until it is no longer needed.
Rule 18.2(c) does give two specific conditions under which rule 18.2(b) ceases to apply:
- if either boat passes head to wind or
- if the boat entitled to mark room leaves the zone.
Both conditions can happen before the need for mark room has ended.