|
PREVIOUS | TOC
| NEXT
APPENDIX 2
Channel, Maneuvring and Anchorage Guidelines
1 CHANNELS
1.1 The cross-sectional geometry and alignment of a ship channel are
site-specific matters. Moreover, in those instances where tidal stream or
current directions are not invariably axial to the direction of the ship
channel, the design ship’s dimensions must be of primary consideration.
This is particularly so where the ship channel changes directions.
1.2 Channel width should be established in accordance with good engineering
practice. In determining the width of one-way channels consideration should
be given to allowances for the beam and maneuverability of the largest
design ship, accuracy of position-fixing equipment, bank suction, tidal
stream, current, wind, shallow water, operating speeds, hardness of banks,
length of the channel and whether overtaking will occur. In addition to the
above, the width of two-way channels should include a separation zone
between the inbound and outbound lanes. Where bends occur in a channel, the
radii of the curvature must be compatible with the design ship’s maneuvering
characteristics, taking into account the depth of water
available in the bend. Channels should be widened in bends, and adequate
transition zones provided between sections of channel having different
widths, according to good engineering practice. Similarly, good channel
design practice dictates avoidance of "S" curves, provision of
adequate straight sections before, after and between bends, consideration of
the navigator’s sight distance in a bend, and avoidance of sudden large
changes in water depth in channels. Adverse conditions of visibility, wind,
current, wave dynamics or large turns may necessitate speed restrictions or
tug escort / assistance.
1.3 Anchorages and emergency containment areas should be located as close as
is practicable to the channels they serve. The bottom in anchorage areas
should provide a good holding ground. The area should provide the maximum
practicable protection.
1.4 In one-way channels where the design ship’s maximum breadth is not a
primary consideration, the minimum channel width should be at least four
times the design ship’s breadth allowing for the draught of the design
vessel. In two-way channels where the design ship’s maximum breadth is not
a primary consideration, the minimum channel width should be increased to at
least seven times the design ship’s breadth, again allowing for the
draught of the design vessel.
1.5 For a distance of at least five times the length of the design ship from
the marine terminal berth, the channel bank on the terminal side should be
maintained at an angle not exceeding ten degrees (10°
) from the direction of the alignment of the bank face. Where this
requirement cannot be met, as in the case of finger piers, tug assistance
will be required to bring the design ship in line with the berth face before
the final approach.
2 CLEARANCES
2.1 Except where appropriate calculations have been made, every ship when maneuvering
should have an underkeel clearance not less than fifteen percent
(15%) of the deepest draught at that time (see section 3.6 of the TERMPOL
Studies and Surveys).
2.2 Special consideration should be given to identifying any physical
limitations along the route, especially power transmission lines and the
effect of ice in further reducing the air height of those lines.
3 MINIMUM DISTANCE BETWEEN THE BERTH AND THE CENTRE OF
THE CHANNEL
3.1 In those instances where the proposed marine terminal’s ship berth is in
close proximity to a frequently used ship channel, careful consideration
should be given to the minimum distance requirement between the berth and
the centerline of the ship channel. This is a site specific consideration
and should exceed six times (6X) the design ship’s beam.
4 TURNING BASIN
4.1 There should be at least one area in the vicinity of the terminal where
the design ship in any displacement condition, aided by bow and stern tugs,
may be brought to a stop and maneuvered so as to obtain the required
heading. The minimum depth in the turning basin, or in at least one turning
basin where more than one is provided, should be equal to the maximum
draught of the ship plus 10% to 15% of such draught or as required to be
computed in accordance with the Special Underkeel Clearance Survey (see
section 3.6 of the TERMPOL Surveys and Studies). The permissible area of the
turning basin should be such as to completely contain a turning circle clear
of structures with a diameter equal to two and a half times (2.5X) the
overall length of the design ship. If local conditions are favourable and
subject to the proposed docking and undocking procedures being acceptable,
the turning circle described may be reduced to a minimum of two times (2X)
the overall length of the design ship.
5 ANCHORAGES
5.1 Anchorages and emergency containment areas should be located as close as
is practicable to the channels they serve and relate to site-specific
conditions. The bottom in anchorage areas should provide a good holding
ground. The depth should be not less than the maximum draught of the design
ship plus 15% and not more than 100 meters. The radius of each anchorage
berth should be not less than one half nautical mile.
PREVIOUS | TOC
| NEXT
|
