Page 43 - CHIRP annual digest 2016.pdf

CHIRPAnnual Digest 2016

OOWs on vessels required to give way should bear in mind Overtaking vessels should offset their course, preferably
that encounters may become more complex. Planning well to pass on the starboard side of vessels they are overtaking
ahead of the anticipated areas of interception should be (leaving the overtaken vessel to port) and should avoid
considered together with the likely behaviour of vessels to following directly astern.
be encountered well before an avoidance manoeuvre is
initiated. VHF and Colregs
Many reports are received at CHIRP that refer to VHF
Masters and OOWs should be aware of the approximate conversations between vessels during manoeuvres to avoid
manoeuvring domain, not only of their own vessel, but for collision. The collision regulations are written to enable
other vessels in an encounter. Such dimensions can only actions to be decided based upon the behaviour of vessels
be an estimate but navigating officers should be urged approaching one another and the ascertainment of a
tlearn the different variations. Opportunities to do this collision risk. There is very little provision for communication
could be during their training when they could serve on a between vessels during these manoeu vres. It is restricted
variety of vessel types or whilst at college, by comparison to sound signals, which most mariners of large powered
with other officers from different service experience. vessels would recognise are of little use in open waters,
especially with noise interference from large fans or funnels
When overtaking the relative overtaking speed between
close to the bridge. Light signals however, are permissible
each vessel directly relates to the time and distance it will in similar form to the sound signals i.e:
take for the overtaking vessel to move from safe position
■ one short or morse “E”- I am turning to starboard;
astern to a safe position ahead. When passing within a TSS two short or morse “I” – I am turning to port; and
lane or any confined waters the timing between starting ■
■ three short or morse “S” – My engines are going
and completing the overtaking manoeuvre MUST be a astern.
carefully considered so that it falls entirely within a straight
and clear section of water and be unencumbered by VHF is not mentioned and neither is AIS. The important
restricted sections or intermediate alterations of course. points to remember are:
Within a TSS a typical section would be between the buoys ■ Identification of vessels may be difficult to match
marking the next leg of the navigational passage. A between the VHF and visual and/or radar targets and
constriction of searoom whilst overtaking must be avoided. mistaken identity is possible;
This especially so as to avoid overtaking and simultaneously ■ AIS provides some measure of identification and also
altering course on a navigational leg at the same. Such heading and destination information that can be
overtaking and altering course around buoys creates a helpful in advance planning but it involves time that
“sandwich” effect where the vessels have to calculate the can be better spent conducting manoeuvres; and
time their commencing of turn for navigational purposes ■ VHF exchanges, if conducted properly, use up con -
and also be restricted by close proximity to another vessel siderable valuable time that close to a manoeuvre
and the risk of collision. Only overtake when you can be would be better invested in the action of manoeu -
past and clear before the next navigational alteration of vring itself.
course on a straight leg. If the relatively low overtaking
It is a fact that accident investigators often use the
speed does not permit this to be achieved then the safe
option is to slow down a little, match the speed of the expression “VHF Assisted Collision” in similar fashion to
“Radar Assisted Collision”. Both expressions, whilst con -
vessel previously being overtaken and to remain on their
quarter all the way up the routing. The little time lost is veying a meaning that is understood by professional
mariners, are inaccurate as it is the action of the operator
not worth the considerably increased risk of prolonged
overtaking and foreseeable constriction of searoom when not the equipment itself that causes the error.
it will be need most to maintain a safe CPA.
Maintaining appropriate Closest Point of Approach
Whilst it is recognised that extreme movements on large (CPA)s
engines can be damaging and therefore are likely to be A minimum 2 miles CPA is best practice for all vessel sizes
discouraged, the Colregs do still include slowing and in open water. Where this is to be achieved in a fine
stopping as alternatives to course alterations. In areas of crossing ahead scenario the minimum safe Bow Crossing
high congestion engines should be in a state of readiness Range (BCR) would be in fact TWICE that… If one vessel
that can respond to slowing and stopping movements. indicates discomfort as to what distance constitutes

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