CASE 21

Rule 18 Preamble
Rule 18.2(a), Rounding and Passing Marks and Obstructions: Giving Room; Keeping Clear: Overlapped – Basic Rule
Definitions Room

The extent of the room that an outside right-of-way boat must give at a mark or obstruction depends on the existing conditions.

Question
What is the maximum amount of room an inside boat without right of way is entitled to take in rounding or passing a mark or obstruction? What is the minimum amount that the outside boat is required to give?

Answer
The possible answers vary widely. To suggest the extremes, they might be:

1. as a minimum, enough room with sails and spars sheeted inboard for the hull to clear by centimetres both the mark and the outside boat;
2. as a maximum, all the room the inside boat takes, setting her course as far abeam of the mark as she wishes.

As the definition Room and the preamble to rule 18 state, the word ‘room’ in rule 18 means the space needed by an inside boat, which in the existing conditions is handled in a seamanlike way, to round or pass promptly between the outside boat and the mark or obstruction, including room to tack or gybe when either is a normal part of the manoeuvre.

The term ‘existing conditions’ deserves some consideration. For example, the inside one of two dinghies approaching a mark on a placid lake in light air will need and can be satisfied with relatively little space beyond that required for her hull and properly trimmed boom. At the other extreme, when two keel boats, on open water with steep seas, are approaching a mark that is being tossed about widely and unpredictably, the inside boat may need a full hull length of room or even more to ensure safety.

The phrase ‘in a seamanlike way’ applies to both boats. First, it addresses the outside boat, saying that she must provide enough room so that the inside boat need not make extraordinary or abnormal manoeuvres to keep clear of her and the mark. It also addresses the inside boat. She is not entitled to complain of insufficient room if she fails to execute with reasonable efficiency the handling of her helm, sheets and sails during a rounding.

ISAF 1969/1