1.1 This note has, as its primary aim, the provision
of advice to mariners on what to expect and how to handle a high-speed
craft in severe following and stern-quartering seas. The guidance
offered here is based, not only on the recent research, but also on
the accumulated experience of practising mariners.
1.2 The principal hazards likely to be experienced
by a high-speed craft in severe following or stern-quartering seas
are surfing, bow-diving and broaching.
1.3 The master will be in a better position to
avoid dynamic problems if he has instruments that inform of the behaviour
of his vessel and information on the sea states he is likely to encounter
on the voyage. These parameters include vessel speed, heading, vertical
acceleration, longitudinal acceleration, wave forecasts and current
sea state.
1.4 Following seas refer to seas which are dead
astern while stern-quartering seas refer to wave directions between
dead astern and 45° from dead astern.
1.5 Bar crossings may involve behaviours similar
to a number of those outlined in this appendix. As this guidance is
of a general nature, it does not include specific information on bar
crossing for which the hazards and behaviours are highly variable
according to the individual circumstances. Specific information in
this regard in relation to the craft and its route should be provided
in the Route Operational Manual.
1.6 It should be noted that the advice given in
this note is for guidance only and should augment and not replace
the skill and judgement of the mariner, or the tenets of good seamanship.