Rule 18.1

Section C: At marks and obstructions

Section C rules do not apply at a starting mark surrounded by navigable water or at its anchor line from the time boats are approaching them to start until they have passed them. When rule 20 applies, rules 18 and 19 do not.

18 Mark room

18.1 When Rule 18 Applies

Rule 18 applies between boats when they are required to leave a mark on the same side and at least one of them is in the zone. However, it does not apply

(a) between boats on opposite tacks on a beat to windward,

(b) between boats on opposite tacks when the proper course at the mark for one but not both of them is to tack,

(c) between a boat approaching a mark and one leaving it, or

(d) if the mark is a continuing obstruction, in which case rule 19 applies.

See also: mark-room thumb|300px|left|Rule 18 Mark Rounding

Rule 18.1 illustrated

	File:Rule18.1b applies.gif	File:Rule18.1b na.gif
File:Rule18.1c na.png	File:Rule18.1 barging at start.png	File:Rule18.1d na rule19 applies.png
	static and animated images wanted

The VSK auto-umpire can be especially quick to judge when a boat first begins to be leaving a mark.

Barging at the start

A boat is said to be barging at the start when it is sailing below close hauled and to windward of the outside layline to either starting mark. (In practice this appears most often for starboard tack boats at the committee boat or right-hand end of a start line however it is also applicable to the symmetrical situation for the port tack layline to the left hand end of the start line.)

• The barging boat has no right to "mark room" because the entire set of Section C rules expressly do not apply a starting mark.
  FYI: this exclusion used to be expressed as Rule 18.1(a) in the 2005-2008 RRS.
• Any boat sailing close-hauled and to leeward of the barging boat may push the barging boat to windward and the barging boat must keep clear (per Rule 11) even if this means missing her start altogether.
• The barging boat may use intimidation to trick an inexperienced skipper into allowing them to round the start mark. Do not let yourself be intimidated. It is better to politely teach the barging skipper the correct rules of sailing.