latinoamericano 20151027 dukc
DESCRIPTION
CANCÚN-MÉXICO 2015VIII Foro Latinoamericano de Prácticos26 al 30 de octubre del 2015TRANSCRIPT
Slide 1
ENHANCING SAFETY
UNDERSTANDING
UNDERKEEL CLEARANCE
Captain Jonathon PearceBusiness Development Manager
VIII Foro Latino Americano de Practicos
Cancun, 2015
Slide 2
The GuidelinesThe Design and Use
Component
Slide 3
PIANC WG 49Harbour Approach Channels
Design Guidelines
Slide 4 Channel Depth factors
2.1
Slide 5 Manoeuvrability Margin (MM)
“Therefore, only motions which affect the lowest average position of the
bottom of the ship need be taken into consideration in the calculation of
MM (= depth – draught – squat – heel). For this reason, it is an
independent check which should always apply in channel design (and
operation)”
“this check of MM is separate from calculations of Gross UKC that
includes the wave response allowance”
Ship factors include … (f) Net UKC. Separately, a manoeuvrability margin is
checked such that a minimum clearance under the ship (between the
seabed level and the lowest average position of the ship) is provided
The limiting value of MM depends on ship type, channel dimensions and
alignment, and ship traffic (including whether one-way or two-way).
A minimum value of 5% of draught or 0.6 m, whichever is greater, has
been found to provide adequate MM for most ship sizes, types, and
channels.
Slide 6 Muddy Channel - Nautical Bottom
Approach
(PIANC WG30) defined the nautical bottom as “the level where
physical characteristics of the bottom reach a critical limit beyond
which contact with a ship’s keel causes either damage or
unacceptable effects on controllability and manoeuvrability.”
This guideline is
implemented
through full
analysis and
complemented
by pilot
experience of
actual ship
handling.
Slide 7
The PortThe Workplace
Component
Slide 8 Bathymetry
High Density Bathymetry
Slide 9 Bathy Nodes
DUKC®
Bathymetry
Nodes
Dividing the channel
into sections for
accurate analysis
Slide 10 Channel Segment
14.8m BC
Declared Depth
15.7m Max
Channel Section
300m to channel boundary
100m segment
MM 15.0m for 300m x 100m section
Channel Boundary
Scale exaggerated by 25x for emphasis
Slide 11 Overlays – PPU Chart
Overlays
High resolution sounded
depths
Minimum
depth
10m x 10m
overlay grid
DUKC®
Bathymetry
Nodes
Compare DUKC® minimum
keel elevation to overlay grid
cell depth
Methodology High-resolution bathymetry of
transit area
Create 2D Grid overlay (10m x 10m)
Compute DUKC® predictions of
minimum keel elevations
In each grid cell compare the
(nearest adjacent) predicted keel
elevation with the depth at this
location
Mark each grid cell as “pass” or
“fail” (go/no go)
Produce real-time overlay (Web)
Promulgate overlay to users
ECDIS/PPU
Slide 12 Hydrodynamic model
Slide 13 Tidal Datums
Slide 14 Complex Tidal Regimes
12:00 18:00 00:00 06:00 12:00-1.5
-1
-0.5
0
0.5
1
1.5
Wate
r level relative to A
HD [m]
Recorded water level across Prince of Wales Channel 15/16 May 2007
booby
goods
hammond
nardana
ince
Slide 15
Turning Points
Residuals Lags
Predictions
Measurements
Tidal Residuals
Slide 16 Predicted UKCM Tidal Plane
Slide 17
VesselsThe Economic
Component
Slide 18 Ship Size
Slide 19 Theory – Stability
Slide 20 Ship Motions Unique to each Vessel
Slide 21 Calculating Ship Motions
Slide 22 Vessel Spectra
Slide 23
Wave TheoryThe Enviroment
Component
Slide 24
Waves
Slide 25 Idealised wave spectrum
Slide 26 The AWAC
Acoustic Wave and Current bottom-mounted
measurement device
Wave Measurement
AWAC is designed to measure wind/swell
waves
0.5-30 second period
Slide 27 WaMoS radar images
Slide 28 Wave theory – Wave period and height
• Wave period relates to wave length.
• Commonly used wave periods:– Tp: Peak period
– Tz: Zero-crossing period
– Tm: Mean period (=average)
• Significant Wave Height Hs
• Stands for significant wave height.
• Corresponds well to visual estimate of wave heights.
• Average of largest one third of waves over a certain period of time.
• Also known as H1/3
Slide 29 Wave Spectra
• A statistical representation of a stationary sea
state
0.0
2.0
4.0
6.0
8.0
1 0.0
1 2.0
0.0 0 0.0 5 0.1 0 0.1 5 0.2 0 0.2 5 0.3 0
F requency [Hz]
Wa
ve
en
erg
y [m
2/H
z]
20 s 10 s 5 s 4 s6.7 s 3.3 s
peak
TP
FFT rapidly converts a time series
signal to a representation in the
frequency domain, a spectra
Units are m2/hz v hz, convert
spectral density to m by integrating
hence related to area under the
curve
Parameters\ specifically
Spectral density can be interpreted
as the total variation or variance of
sea-surface elevations over
frequencies
Also equals 4 x SD: standard
deviation of sea surface elevations
Hmo is typically 5-10% larger than
Hs by Longuet-Higgins 1980
Sea swell split often picked at
around 8s when deriving wave
paramters from spectra, strictly
speaking..