Definitions, Mark-Room
Definitions, Proper Course
Definitions Room
The amount of space that a right-of-way boat obligated to give mark-room to an inside overlapped boat must give at the mark depends on the inside boat’s proper course in the existing conditions.
Question
When a right-of-way boat is obligated to give mark-room to an inside boat that
overlaps her, what is the maximum amount of space that she must give? What is
the minimum amount of space that she must give?
Answer
As the definition Mark-Room states, while the inside boat is at the mark the
outside boat must give her room to sail her proper course. If the overlapped
boats are on the same tack, mark-room includes room to tack. According to its
definition, ‘room’ in this case is the space needed by an inside
boat, which in the existing conditions is handled in a seamanlike way, to sail
her proper course while at the mark.
The inside boat’s proper course is the course she would sail to finish
as soon as possible in the absence of the outside boat. This may entitle the
inside boat to more space than she needs for a seamanlike rounding. For example,
her proper course may be a track that takes her farther from the mark as she
rounds than a seamanlike rounding would so that her speed is not reduced by
the tightness of her turn. Note that, according to the definition Mark-Room,
an inside overlapped boat that is required to keep clear of the outside boat
is not entitled to sail her proper course while sailing to the mark; she is
only entitled to sail her proper course after she is at the mark.
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 relatively little space beyond that required for her
hull and properly trimmed sails. 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 space
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 space so that
the inside boat need not make extraordinary or abnormal manoeuvres to sail her
proper course while at the mark. It also addresses the inside boat. She is not
entitled to complain of insufficient space if she fails to execute with reasonable
efficiency the handling of her helm, sheets and sails while sailing her proper
course.
ISAF 1969/1