EA10 Approaches to Lowestoft - United Kingdom Hydrographic Office

THE UNITED KINGDOM
HYDROGRAPHIC OFFICE
EAST ANGLIA
APPROACHES TO LOWESTOFT
ASSESSMENT ON THE ANALYSIS OF ROUTINE RESURVEY AREA EA10
FROM THE 2005 SURVEY
FEBRUARY 2006

THE UNITED KINGDOM
HYDROGRAPHIC OFFICE
EAST ANGLIA
APPROACHES TO LOWESTOFT
Assessment EA10/2005
An assessment of the 2005 hydrographic survey of the area: to monitor recent seabed
movement; to identify any implications for shipping; and to make recommendations for
future surveys.
The Admiralty Chart extracts, other graphics and tables in this Report are included for illustrative purposes
only and are NOT TO BE USED FOR NAVIGATION.
This material is protected by Crown Copyright. It may be downloaded from the UK Hydrographic Office's (UKHO) web site and printed in
full for personal or non-commercial internal business use. Extracts may also be reproduced for personal or non-commercial internal
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parties) can be made interactively on the UKHO's web site (www.ukho.gov.uk), by e-mail to intellectualproperty@ukho.gov.uk or in
writing to Intellectual Property, UK Hydrographic Office, Admiralty Way, Taunton, Somerset, TA1 2DN.
Assessment EA10/2005 – Original Page 1 of 20

CONTENTS
1. EXECUTIVE SUMMARY 3
2. INTRODUCTION 4
3. HISTORY 4
4. DESCRIPTION OF THE AREA 5
5. SHIPPING IN THE AREA 5
6. 2004 SURVEY DETAILS 6
7. 2005 SURVEY DETAILS 7
8. DESCRIPTION OF RECENT BATHYMETRIC CHANGE 7
9. IMPLICATIONS FOR SHIPPING 8
10. RECOMMENDATIONS FOR FUTURE SURVEYS 8
11. REFERENCES 9
ANNEXES
A. Area Specifications (Including Survey History) 10
B. Location Plot and Diagrammatic Representation of Ships' Tracks from COAST v6.1 11
C. 2005 Survey Data Overlaid on Chart 1536 12
D. Three Dimensional View Generated from the 2005 Survey Data 13
E. Sun Illuminated View of the 2005 Survey and Location of Cross Sections Shown 14
At Annex F
F. Cross Sections from the 2005 Survey 15
G. Colour Banded Depth Plot from the 2004 Survey showing Selected Depths 16
H. Colour Banded Depth Plot from the 2005 Survey showing Selected Depths 17
I. Variability Plot showing Bathymetric Changes between the 2004 and 2005 18
Survey Data and Charted Contours from the 2005 Survey
J. Composite Diagram of the 5 metre Contour from the 2004 and 2005 Surveys 19
K. Composite Diagram of the 10 metre Contour from the 2004 and 2005 Surveys 20
Assessment EA10/2005 – Original Page 2 of 20

APPROACHES TO LOWESTOFT, 2005
1. EXECUTIVE SUMMARY
The Area and Recent Changes
1.1 A focused area within EA10 is surveyed on an annual cycle and includes Stanford Channel,
which provides the main approach to Lowestoft Harbour from the south. The full area,
which includes the adjacent banks, is surveyed on a 3 year cycle. The 2005 survey was
the second routine resurvey of the area using a multibeam echosounder.
1.2 Depths in the final approach to Lowestoft, including the area of The Ridge, and across the
seaward entrance to Stanford Channel, where there is an area of sandwaves, are
potentially limiting to shipping. Vessels with draughts of up to 7 metres are understood to
use Stanford Channel, with vessels up to 6 metres commonly berthing in Lowestoft Inner
Harbour.
1.3 The minimum depth in the entrance to Stanford Channel has increased from 6.0 metres to
6.3 metres when compared against the 2004 survey and sandwaves have migrated
southwards by approximately 75 metres.
1.4 A sandwave previously lying close north of Southwest Holm buoy has a similar minimum
depth, but now lies immediately southeast of the buoy.
1.5 The 5 metre contour delimiting Holm Sand has extended southwards slightly, but remains
outside the buoyed channel.
1.6 Depths throughout the rest of the area remain broadly similar. A shoal depth of 1.9
metres exists on the edge of the survey area, to the southeast of the entrance to
Lowestoft Harbour. This reflects a shoaling to a ridge which extends into the area, a
charted depth of 1.3 metres exists over this ridge outside the focused survey area.
Reasons for Continuing to Resurvey the Area
1.7 Stanford Channel provides a buoyed approach to the port of Lowestoft. The following
areas require frequent resurveying due to changes occurring -
• the shoal ridge and sandwaves at the entrance to Stanford Channel are of most
concern and required annual surveying;
• the remainder of the approach appears more stable and contains fewer mobile
features, as such the requirement for annual surveying needs further
consideration;
• the adjacent banks of Newcome Sand and Holm Sand are mobile, but outside the
buoyed channel and require less frequent surveying.
Recommendations
1.8 Much of Stanford Channel is generally stable and, away from the area of sandwaves at the
entrance to the channel, there is potential for reducing the requirement for annual
resurveying. Although 2 multibeam surveys of the focused area are available and have
been examined in this report, with previous reports also consulted, it is considered that a
more extensive examination of historical data is undertaken when the 2006 survey,
covering the full area, is assessed. Inclusion of a third multibeam data set will also
provide a better indication of trends occurring in the area.
Assessment EA10/2005 – Original Page 3 of 20

1.9 The limits and frequency should remain unchanged at present.
2.
INTRODUCTION
2.1 This Assessment is produced by the United Kingdom Hydrographic Office (UKHO) for the
Maritime and Coastguard Agency (MCA).
2.2 Analysis of the Routine Resurvey Areas forms part of the Civil Hydrography Programme
and the reports are distributed to members of the Committee On Shipping Hydrography
(COSH). When approved by the annual COSH meeting and endorsed by the Civil
Hydrographic Review Committee (CHRC), the recommendations are incorporated into the
Routine Resurvey Programme. The report is governed by a Memorandum of
Understanding between the DfT (including the MCA) and the MOD (including the UKHO).
3.
HISTORY
3.1 EA10 is one of the routine resurvey areas of the East Anglian Routine Resurvey
Programme, which covers the approaches to the East Anglian ports of Great Yarmouth and
Lowestoft.
3.2 Prior to 1980 the area that includes EA10 was designated as areas A and B. These
covered an area extending from Holm Sand in the north via Pakefield Road to Barnard in
the south.
3.3 In 1980 areas A and B were reorganised with changed limits and given the identifiers C1
and C3. These had an annual and 3 year survey interval respectively.
3.4 The 1994 report on C1 and C3 radically altered the limits, removing C3 from the
programme, although parts of C3 were subsumed within other areas. In 1997 C1 was
given the identifier EA10, with unchanged limits and survey interval.
3.5 Following assessment of the 2001 survey, the area limits were revised to better focus on
areas of concern to shipping. The southwest part of the area was transferred to EA12, and
the southern limit was extended to take account of sediment transport along Newcome
Sand.
3.6 At a Working Group meeting convened after the 2002 Committee on Shipping
Hydrography (COSH) meeting, it was agreed that for the 2003 survey EA10 would be fully
surveyed to IHO Order 1 Standard between the 5 metre and 15 metre contours. Over the
banks, survey lines were to be opened up to 150 metre line spacing and sounding-only
lines run to monitor the stability/movement of these banks.
3.7 Subsequent to conducting the 2004 survey, new limits and survey regime for EA10 were
proposed. This consisted of a survey of the full area on a 3-year cycle, but with reduced
limits, and a focused survey, restricting surveying to the channels on the intervening
years. The 2004 survey was conducted as a focused survey of the main channel, covering
the approach to Lowestoft.
3.8 This is the tenth Assessment on the area. A Report covering multiple surveys was
published in 1994.
3.9 Trinity House Lighthouse Service (THLS) also conducts surveys of Stanford Channel.
These are understood to generally conducted at about 6 monthly intervals; the frequency
of these surveys has been extended, initially from quarterly to every 4 months (1997) and
then to every 6 months (1998). However, the latest surveys held by the UKHO were
Assessment EA10/2005 – Original Page 4 of 20

conducted in May 2003 (whole of Stanford Channel surveyed) and December 2004
(entrance to Stanford Channel).
4. DESCRIPTION OF THE AREA
4.1 EA10 covers Stanford Channel and final approach to Lowestoft, and the focused area
surveyed in 2005 covered 1.69 SQ NM (5.8 SQ KM).
4.2 Stanford Channel, which is buoyed, effectively bisects EA10 and separates the shoal areas
of Holm Sand and Newcome Sand. Stanford Channel provides the main approach route to
Lowestoft Harbour from the south. The channel was buoyed and opened up to shipping in
1994, at which time the controlling depth across the entrance was 4.6 metres. At the
same time, buoys marking Pakefield Road and Lowestoft South Road were discontinued.
Depths of 6.3 metres and greater were found across the entrance to the channel in the
2005 survey.
4.3 The potentially limiting depths in the area are those on the final approach to Lowestoft,
including those over The Ridge, lying to the northeast of Lowestoft Harbour entrance and
those across the seaward entrance to Stanford Channel. A channel dredged to 4.7 metres
lies inside the harbour entrance.
4.4 The seabed sediments comprise of mud, fine sand, sand, pebbles and broken shell.
Southward migrating sandwaves lie within the flood dominant Stanford Channel,
predominantly at the entrance to the channel and along the western side of Holm Sand.
The final approach to Lowestoft Harbour is made up of extensive small sand ripples, with
ripples of up to 0.3 metres on the southern side of the channel. A small area of
sandwaves up to 1.5 metres in height lies at the entrance to the channel.
4.5 Area specifications, including the survey history, are at Annex A and limits are shown at
Annex B.
5. SHIPPING IN THE AREA
5.1 During recent surveys a moderate flow of commercial shipping has been observed to
transit EA10. These were North Sea oil and gas installation support vessels and medium
sized coasters. Additionally a small number of fishing vessels operate within EA10 and
recreational sailing vessels are seen, particularly at the weekend.
5.2 Vessels up to 6 metres draught can normally berth in Lowestoft Inner Harbour, although
vessels up to 6.5 metres are accommodated subject to available tide and suitable weather
conditions. Vessels with draughts of up to about 7 metres are understood to anchor
outside the harbour, usually to shelter from inclement weather.
5.3 The main approach to Lowestoft Harbour is through Stanford Channel. Lowestoft South
Road and Pakefield Road to the west of the area provide inshore access from the south for
fishing vessels and are used by the occasional small coaster of less than 1,000 tonnes and
drawing no more than 2 metres en route through the area. Lowestoft North Road is very
rarely used as a passage for shipping, with only a small number of standby vessels, with
drafts below 3 metres, regularly using Lowestoft North Road and Corton Road further
north.
5.4 A search of the COAST database v6.1, based on a 1.7 nautical mile radius centred on
52° 27’.4N 1° 46’.5E (see Annex B), shows an estimate of 678 vessels per annum
transiting the search area. The statistics use a common destination point off Great
Yarmouth for the ports of Great Yarmouth and Lowestoft. As such, the data is of little use
in determining actual shipping patterns within the area.
Assessment EA10/2005 – Original Page 5 of 20

Type DWT Total
< 1,500 112
Merchant 1,500 – 5,000 422
>5,000 24
Tankers
< 5,000 92
> 5,000 0
< 1,500 20
RORO >1,500 0
Container
< 1,500 0
1,500 - 5,000 8
Total: 678
5.5 The following figures provided by the Port of Lowestoft detail arrivals at the port in 2003
and 2004.
Vessel Type 2003 2004
Container 52 12
Tankers 7 3
Cargo 130 115
Standby 182 148
Research/Barges 341 388
Tugs 176 180
Deep Sea Fishing 89 47
Inshore Fishing 2,012 1,810
Total: 2,989 2,703
6. 2004 SURVEY DETAILS
6.1 The survey was conducted from 25 May to 09 June. Weather in the area remained good
while on survey task with the exception of three days where the weather picked up forcing
the vessel to return alongside Lowestoft.
6.2 This survey was conducted using a dual head Kongsberg Maritime EM3000D multibeam
echosounder. The system forms 127 beams from each sonar head, giving a total of 254
beams, but with an overlap in swaths in the nadir region. Survey lines were run at 50
metre intervals, with object detection criteria met with the multibeam echosounder. Cross
lines were run in accordance with survey instructions. The survey achieved IHO S44
Order 1 standard.
6.3 Positioning was by DGPS and the survey referred to the International Terrestrial Reference
Framework 2000 (ITRF2000) Datum. The survey achieved a horizontal accuracy of ±1.7
metres (2σ).
6.4 The data was processed using Kongsberg Neptune v4.1 and shoalest depths from 2 metre
cells were extracted, retaining the observed depths in their true positions.
6.5 The accuracy of depth measurements at nadir was assessed as 0.17 metres with the error
increasing to 0.5 metres at the outer beams. Details are as follows:
Assessment EA10/2005 – Original Page 6 of 20

Depth in metres
5 10 15
Combined Total Error at Nadir (2σ) 0.17 0.17 0.17
Requirement (2σ) 0.50 0.52 0.54
7. 2005 SURVEY DETAILS
7.1 The survey was conducted from 24 to 26 May. Weather in the area remained good during
the period. Shoal areas were surveyed during periods of high tide and slight seas so that
lift was kept to a minimum.
7.2 This survey was conducted using a dual head Kongsberg Maritime EM3000D multibeam
echosounder. The survey achieved IHO S44 Order 1 standard.
7.3 Positioning was by DGPS and the survey referred to the International Terrestrial Reference
Framework 2000 (ITRF2000) Datum. The survey achieved a horizontal accuracy of ±0.9
metres (2σ).
7.4 The data was processed using Caris HIPS v5.4 and shoalest depths from 2 metre cells
were extracted, retaining the observed depths in their true positions.
7.5 The assessed accuracy of depth measurements at nadir met the required standard.
Details are as follows:
Depth in metres
5 10 15
Combined Total Error at Nadir (2σ) 0.13 0.14 0.15
Requirement (2σ) 0.50 0.52 0.54
7.6 The survey data draped over chart 1536 is shown at Annex C and a three-dimensional
view is also shown at Annex D, showing the main features of EA10. A sun illuminated
view of the 2005 survey, showing the location of cross sections is at Annex E and the
cross sections are shown at Annex F.
8. DESCRIPTION OF RECENT BATHYMETRIC CHANGE
8.1 Colour banded depth plots of the 2004 and 2005 surveys are at Annexes G and H. A
variability plot showing depth differences between the 2004 and 2005 surveys is at Annex
I.
8.2 Comparison plots of the 5 and 10 metre contours are at Annexes J and K respectively.
8.3 The minimum depth within the buoyed entrance to Stanford Channel has increased from
6.0 metres in 2004 to 6.3 metres in 2005. This follows a reduction in depth from 6.6
metres to 6.0 metres between the 2003 and 2004 surveys. This depth lies on one of the
sandwaves which lie across the entrance to the channel. These sandwaves are migrating
southwards through the flood dominant channel. This will result in changes to both the
height and position of the shallowest depth as the sandwaves move across the ridge at
the channel entrance. Between the 2004 and 2005 surveys these sandwaves have
migrated south by approximately 75 metres.
8.4 The sandwave previously lying close north of Southwest Holm buoy has a similar
minimum depth to that surveyed in 2004 (increasing from 5.7 metres to 5.8 metres), but
now lies immediately southeast of the charted position of the buoy.
Assessment EA10/2005 – Original Page 7 of 20

8.5 The 5 metre contour delimiting Holm Sand has extended southwards slightly, but remains
outside the buoyed channel.
8.6 Depths throughout the rest of the area remain broadly similar. Depths over the shoal
patch to the east of North Newcome buoy are shoaler by around 0.1 metres, but the
differences are well within survey tolerances. Six hundred metres the southwest of this
shoal area there is a new shoal depth of 1.9 metres. This reflects a shoaling to a ridge
which extends into the area, a charted depth of 1.3 metres exists over this ridge outside
the focused survey area.
8.7 A provisional Notice to Marines was issued (3757(P)/05) advising of changes to depths on
Chart 1536.
9.
IMPLICATIONS FOR SHIPPING
9.1 Changes that have occurred within the area are not of immediate concern to shipping
using the buoyed channel and approach to Lowestoft.
9.2 Ongoing migration of sandwaves and changes in their minimum depths at the entrance to
Stanford Channel are of potential concern to shipping, in particular the sandwave close to
South Holm buoy.
9.3 Much of the northern area is devoid of mobile bedforms and the need to resurvey the area
annually requires careful consideration.
10.
RECOMMENDATIONS FOR FUTURE SURVEYS
10.1 Much of Stanford Channel is generally stable and, away from the area of sandwaves at the
entrance to the channel, there is potential for reducing the requirement for annual
resurveying with 100% multibeam cover. Although 2 multibeam surveys have been
examined in this report and previous reports consulted, it is considered that a more
extensive examination of historical data is undertaken when the 2006 survey of the full
area is assessed. Inclusion of a third multibeam data set will also provide a better
indication of trends occurring in the area.
10.2 The survey limits and frequency should remain unchanged at present.
Assessment EA10/2005 – Original Page 8 of 20

11. REFERENCES
11.1 Safetec Nordic AS, 2005: COAST Database v6.1.
11.2 HR Wallingford, 2002: Southern North Sea Sediment Transport Study, Phase 2.
11.3 United Kingdom Hydrographic Office, 2004: Report of Survey, Approaches to Lowestoft
(M4158).
11.4 United Kingdom Hydrographic Office, 2005: Report of Survey, Approaches to Lowestoft
(M4268).
11.5 United Kingdom Hydrographic Office, 2005: Approaches to Lowestoft, Assessment of
Routine Resurvey Area EA10 from the 2004 Survey.
11.6 United Kingdom Hydrographic Office, 2003: NP54 North Sea (West) Pilot, Sixth Edition.
Assessment EA10/2005 – Original Page 9 of 20

ANNEX A
AREA SPECIFICATIONS
(Including Survey History)
REGION: East Anglia NAME: Approaches to Lowestoft AREA: EA10
LIMITS:
Area co-ordinates are
referred to WGS84 Datum
1yr interval
A 52°29’.00N 1°45’.72E
B 52°29’.00N 1°47’.10E
C 52°28’.00N 1°47’.10E
D 52°26’.78N 1°47’.50E
E 52°26’.10N 1°47’.10E
F 52°26’.10N 1°46’.80E
G 52°28.15N 1°46’.30E
H 52°28.15N 1°45’.10E
to (A) via the 2m contour
3yr interval
A 52°29’.00N 1°45’.72E
B 52°29’.00N 1°48’.80E
C 52°26’.60N 1°47’.60E
D 52°26’.60N 1°46’.40E
E 52°28’.00N 1°45’.80E
F 52°28’.00N 1°45’.00E
to (A) via the 2m contour
AREA SIZE:
1.69 SQ NM (5.8 SQ KM) Approx. – 1yr survey interval
3.64 SQ NM (12.51 SQ KM) Approx. – 3yr survey interval
SURVEY INTERVAL: 1/3 yr
SURVEYS: (conducted at 1:25,000 scale (not applicable to multibeam surveys))
Year Survey File Ref Data Year Survey File Ref Data
1994 M2261 HH090/624/01 s.d. 2000 M3349 HH090/884/01 s.d.
1995 M2481 HH090/663/01 s.d. 2001 M3542 HH090/941/01 s.d.
1996 M2613 HH090/688/01 s.d. 2002 M3722 HH090/999/01 s.d.
1997 M2814 HH090/735/01 s.d. 2003 M3913 HH090/021/01 s.t.d.
1998 M3007 HH090/767/01 s.d. 2004 M4158 HH091/076/01 m.
1999 M3212 HH090/849/01 s.d. 2005 M4268 HH091/112/01 m.
KEY: s = sonar sweep, t = seabed texture tracing, d = digital data, m = multibeam digital data
REPORTS: 1994 Latest survey included M2261 (HA145/02/03/04)
ASSESSMENTS: 1995 M2481 (HA145/02/003/05) 2001 M3542 (HA145/010/065/01)
1996 M2613 (HA145/010/004/01) 2003 M3722 (HA145/010/077/01)
1997 M2814 (HA145/010/004/01) 2004 M3913 (HA145/010/089/01)
1998 M3007 (HA145/010/004/01) 2005 M4158
1999 M3212 (HA145/010/033/01) 2005 M4268
2000 M3349 (HA145/010/033/01)
REMARKS:
1979 Report on old areas A and B (H1964/77)
1980 Area C1 established (H3912/80)
1993 Change of limits to include Newcome Sand up to the 10m line. Inshore of the 2m contour
only to be surveyed every 3/6 years. Dept of Transport accepted recommendations on 15
Oct 93 (HA145/02/03/04)
1994 Report amends limits. Dept of Transport accepted recommendations Jul 95
(HA145/02/03/04).
1997 Limits amended. Identifier changed to EA10
2004 Introduction of focused annual surveys
LARGEST SCALE CHART: 1536 (1:20,000 & 1:40,000)
Assessment EA10/2005 – Original Page 10 of 20

ANNEX B
LOCATION PLOT
AND
DIAGRAMMATIC REPRESENTATION
OF SHIPS’ TRACKS FROM COAST V6.1
Search Radius 1.7 NM: Centre 52º 27’.4N 1º 46’.5E
EA9
EA8
Lowestoft/Gt Yarm-Willebroek
EA10
EA12
Key
_____ Limits of Focused Area EA10 (2005 survey)
_____
Adjacent Routine Resurvey Areas
_____ Search Area
_____
Ships’ Tracks
Assessment EA10/2005 – Original Page 11 of 20

2005 SURVEY DATA OVERLAID ON CHART 1536
ANNEX C
Assessment EA10/2005 – Original Page 12 of 20

ANNEX D
THREE DIMENSIONAL VIEW GENERATED
FROM THE
2005 SURVEY DATA
Viewed from the South
Vertical Exaggeration x12
Assessment EA10/2005 – Original Page 13 of 20

ANNEX E
SUN ILLUMINATED VIEW OF THE 2005 SURVEY
AND
LOCATON OF CROSS SECTIONS SHOWN AT ANNEX F
A
B
C
D
E
Direction of sandwave
Sediment migration transport based on sandwave based
on asymmetry sandwave asymmetry
F
Assessment EA10/2005 – Original Page 14 of 20

ANNEX F
CROSS SECTIONS FROM THE 2005 SURVEY
(see Annex E for locations)
A Profile AB B
C Profile CD D
E Profile EF F
Assessment EA10/2005 – Original Page 15 of 20

ANNEX G
COLOUR BANDED DEPTH PLOT
FROM THE 2004 SURVEY
SHOWING SELECTED DEPTHS
SCALE 1:40,000
Depths in Metres
0.0 to 3.0
3.1 to 5.0
5.1 to 7.0
7.1 to 9.0
9.1 to 11.0 Selected shoal depths
11.1 to 16.0
Assessment EA10/2005 – Original Page 16 of 20

ANNEX H
COLOUR BANDED DEPTH PLOT
FROM THE 2005 SURVEY
SHOWING SELECTED DEPTHS
SCALE 1:40,000
Depths in Metres
0.0 to 3.0
3.1 to 5.0
5.1 to 7.0
7.1 to 9.0
9.1 to 11.0 Selected shoal depths
11.1 to 16.0
Assessment EA10/2005 – Original Page 17 of 20

ANNEX I
VARIABILITY PLOT SHOWING
BATHYMETRIC CHANGES BETWEEN THE 2004 AND 2005 SURVEY DATA
AND CHARTED CONTOURS FROM THE 2005 SURVEY
SCALE 1:40,000
Values in Metres
Shoaling
Deepening
4.0 to 3.0
3.0 to 2.0
2.0 to 0.0
0.0 to 1.0
1.0 to 2.0
2.0 to 3.0
Assessment EA10/2005 – Original Page 18 of 20

ANNEX J
COMPOSITE DIAGRAM OF THE
5 METRE CONTOUR FROM THE 2004 AND 2005 SURVEYS
SCALE 1:40,000
Year of Survey
_____ 2005
_____ 2004
Assessment EA10/2005 – Original Page 19 of 20

ANNEX K
COMPOSITE DIAGRAM OF THE
10 METRE CONTOUR FROM THE 2004 AND 2005 SURVEYS
SCALE 1:40,000
Year of Survey
_____ 2005
_____ 2004
Assessment EA10/2005 – Original Page 20 of 20