There are special rules dealing with obstructions because, as mentioned last month, there are safety matters involved. There are two such rules: rule 19 being the general rule about giving room at an obstruction (dealt with below); and rule 20 dealing with the situation when a boat needs to tack to avoid an obstruction (to be dealt with next month).
It is important to remember that all the other ‘when boats meet’ rules (numbers 10 to 17) continue to apply when the obstruction rules are in force.
The general rule, 19, states that a boat that is ‘outside’ (i.e. further from the obstruction) must give room to the inside boat to avoid the obstruction. Clearly, for boats to have an inside/outside relationship they must be overlapped. The rule does not require any hail from the inside boat (although hailing is usually a good thing to do), so the outside boat must be alert to her obligation and give room where necessary. If the inside boat hails for room and the outside boat thinks that room is not necessary at that place/time, she must, nevertheless, give room and protest if she thought that the hail was too early (i.e. too far from the obstruction) or room was not necessary at all.
When two overlapped boats are approaching an obstruction it is the right-of-way boat that decides on which side she wishes to pass the obstruction (assuming that there is a choice). For instance, if two boats are approaching a large moored boat the right-of-way boat (usually the leeward one of the pair) can decide:
a) to pass it to windward, in which case the windward boat will be outside and must give room to the leeward boat; or b) to pass it to leeward, in which case she (the leeward boat) must give room for the windward boat to pass on the same side.
An obstruction does not have to be visible. Shallow water or a submerged object are obstructions if a boat would run aground on them. The decision as to whether such areas are obstructions is made by the boat nearer the area and if she asks for room it must be given even if the outside boat thinks it is not necessary – in which case the outside boat must protest.
The obstruction rules are ‘safety’ rules and, as such, will over-ride other rules that may provide conflicting rights. In RYA Case 2017/1 there was insufficient room for all the overlapped boats to pass between a mark and the adjacent riverbank. The obstruction rule took precedence so that the boats nearer the bank were given room and boats nearer the mark were not entitled to mark-room.
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