Page 140 - Collision Avoidance Rules Guide

Vessels constrained by their draught
Any vessel, except a vessel not under command or restricted in her
ability to manmvre, must avoid impeding the safe passage of a vessel
constrained by her draught and exhibiting the signals mentioned in
Rule 28. The words ‘if the circumstances of the case admit’ are
included in Rule 18(d) to take account of the fact that some vessels,
particularly vessels engaged in fishing, may be unable to take effective
avoiding action in sufficient time.
Rule 8(f) must be taken into account by a vessel complying with
Rule 18(d)(i). A vessel required to avoid impeding the safe passage
of a vessel constrained by her draught must, if the circumstances of
the case admit, take early action to allow sufficient sea room for the
safe passage of the other vessel (see pages 58-60).
Early action can only be taken if the circumstances of the case
admit. It may not be possible to recognise the lights or shape exhibit-
ed by a vessel constrained by her draught at sufficient range to enable
action to be taken before risk of collision develops. However, as
stated in Rule 8(f)(ii), the vessel which is required not to impede is
not relieved of this obligation when there is risk of collision but when
taking action must have full regard to the action which may be
required by the Steering and Sailing Rules.
In a crossing situation in which a power-driven vessel has a vessel
constrained by her draught on her own port side the power-driven
vessel must, if the circumstances of the case admit, take early action
to allow the safe passage of the other vessel. If the signals are not
recognised at long range so that risk of collision develops the vessel
constrained by her draught will become the give-way vessel, but the
power-driven vessel should, if necessary, take action in accordance
with Rules 8(f)(ii) and 17(a)(ii). She should avoid altering course to
port in accordance with Rule 17(c).
Rule 18(d)(ii) requires a vessel constrained by her draught to navi-
gate with particular caution having full regard to her special condi-
tion. According to the Rule 3(h) definition such a vessel is severely
restricted in her ability to deviate from the course she is following.
It is also probable that a vessel constrained by her draught will be
severely limited in her ability to change her speed. Among the factors
to be taken into account in determining a safe speed are the manceu-
vrability of the vessel with special reference to stopping distance and
turning ability in the prevailing conditions and the draught in relation
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