ukc policy shell

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Shell Shipping

Shipping PolicyUnder Keel

Clearance Policy andApplication to Group Shipping

Activities

SP1

01 Mar ch 2012

UNRESTRI CTED


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Version Control Table

Version Date Valid Amended by Comment

1 1 March 2012 D. George Original Issue

2 1 March 2014 C.Hurford Version 1.1

Applicability

This document applies to all vessels managed or chartered by Shell.

The copyr i ght of t hi s document i s vest ed i n Shel l I nter nat i onal Tr adi ng and Shi ppi ng Company Li mi t ed,London. Al l r i ght s r eser ved. Nei t her t he whol e nor any par t of t hi s document or sof t ware may be

r epr oduced, st ored i n any ret r i eval syst emor t r ansmi t t ed i n any f orm or by any means ( el ect r oni c,mechani cal , r epr ogr aphi c, r ecor di ng or other wi se) wi t hout t he pr i or wr i t t en consent of t he copyri ght

owner .

SHELL I NTERNATI ONAL TRADI NG AND SHI PPI NG COMPANY LI MI TED, LONDON: Mar ch 2012


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Contents

1. Purpose and Applicability ................................... 4

2. Under Keel Clearance Policy (UKC) ........................... 4

3. Exceptions .................................................. 5

4. Authorisation ............................................... 5

Appendi x 1 Ter mi nol ogy....................................................................................................... 7

Appendi x 2 Dynami c Component s t o be consi dered i n cal cul at i ng UKC..... 9


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1.Purpose and Applicability

This Under Keel Clearance Policy (UKC Policy) provides a common approach to themanagement of under keel clearance on all vessels managed or chartered by Shell1. The objectiveis to ensure that all vessels remain afloat with a safety margin appropriate to the specific

circumstances. Governmental, State and Local Regulatory requirements must be complied within all circumstances. Where such requirements require greater UKC than prescribed by thispolicy, then the larger UKC shall always be adopted.

In the case of a non-Shell Group owned or managed vessel, where the UKC policy documentedin the vessels Safety Management System dictates a greater UKC than prescribed by this policy,then the greater UKC shall always be adopted.

2. Under Keel Clearance Policy (UKC)

All vessels managed or chartered by Shell shall comply with the following minimum UKCrequirements.

Open Sea

Where the UKC exceeds 50% of the vessels current maximum static draft, further UKCcalculations are not required. Masters shall plan their voyages to avoid, wherever practical,transiting areas where the UKC is less than 50% of the vessels maximum static draft.

Confined Waters2(Excluding Channels, Fairways and alongside a terminal)

Where the UKC is less than 50% of the vessels current maximum static draft the vessel shallmaintain a minimum UKC of 10% of the current maximum static draft, after taking into accountapplicable dynamic factors.3

Channels, Fairways4and alongside a Terminal

Whilst Underway the minimum UKC required is 1.5% of the moulded breadth of the vessel,but not less than 0.6m, after taking into account applicable dynamic factors.

Whilst alongside a berth, the minimum required UKC is 1.5% of the moulded breadth of thevessel, but not less than 0.3m.

Where a Port Authority or terminal requires a greater under keel clearance than prescribedwithin this policy, the larger UKC shall be adopted.

Safe Draft Declarations5

In port areas where the relevant Authority manages channel navigation and terminal limitationsbased upon a declared safe draft, rather than indicating depth and required UKC, the

Authority declared safe draft may be followed where there is clear precedent of similar sized

1Shell means Shell Group companies and Joint Ventures under operational control2 Confined waters shall mean areas other than open sea, generally closer than 20 miles to the grounding line3 Dynamic factors include squat, motion due to wind, wave and swell, heel experienced in a turn etc4 Channels and fairways shall mean those areas that are generally within the jurisdiction of a port authority, and actively managed, includingdredging.5 The Authorised Subject Matter Expert in Maritime Safety will confirm which locations comply with this clause.


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vessels safely navigating the channel in numerous transits under similar conditions, and that thepassage is conducted under Authority Pilotage.

Loading to a Specific Draft

If a vessel is advised to load to given draft and the disport is named the Master shall confirm thatthe vessel can maintain the UKC required, including allowances due to swell, squat, increase indraft due to list...etc, based on, but not limited to, the depth information on charts, sailingdirections, relevant publications and advice from local agents, Port Authorities, TerminalOperators, Suppliers and Receivers as appropriate.

If a vessel is advised to load to a specific draft but the disport is unknown the Master shallcalculate the minimum depth of water required to maintain the required UKC at all times andadvise the charterer and managing office prior to loading.

If a vessel is advised a 'safe draft' to load to, or in the event that no 'safe draft' is advised, thenthe Master shall use all available means to determine the actual depth of water, or maximumallowable draft, such that the necessary UKC calculation may be made to ensure full compliance

with the UKC policy.

3.Exceptions

Inland Water or Riverine dedicated vessels

Vessels dedicated to trading on inland waters or Riverine systems shall maintain a UKCfollowing the principles of this Policy. However, following evaluation of local considerations,minimum UKC shall be agreed with Authorised Subject Matter Experts in Maritime Safety.

Taking the bottom

In a small number of ports, the practice of taking the bottom whilst alongside for cargooperations, is normal practice due to excessive rise and fall of tide. This exception shall bemanaged considering contractual, structural and bathymetric aspects and shall be agreed with theSME.

Project Based Evaluation of UKC

A project, during the assess to execute development cycle, may require a more detailedevaluation of the factors impacting the UKC calculation. In these cases STS/3 Shipping

Technology shall be engaged to manage the evaluation following a project based methodology.

Support Vessels

Support vessels shall maintain a UKC following the principles of this Policy. However,recognising differences in size and form, minimum UKC shall be agreed with Authorised SubjectMatter Experts in Maritime Safety.

4.Authorisation

This policy is owned by the STASCo GM Maritime Standards STS/4.

Exceptions and deviations from this policy will be approved by: Shell managed vessels: STASCo GM Ship Management STS/2


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Third party vessels: STASCo GM Maritime Standards STS/4 and Principal TechnicalExpert (PTE).

Inland Water and Riverine dedicated vessels, support vessels and taking the bottom.Authorised Subject Matter Experts in Maritime Safety and the Regional General ManagerShipping.


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Appendix 1 Terminology

Under Keel Clearance (UKC)

A

B

C

D

SEA BED

Ships

Salt

Water

Draft*

Water Line

SHIP

Fresh Water Allowance

Allowance for Dynamic Factors

Net UKC allowance = 10% of A + B

* The Static draft is the draft when the vessel is not making way or subject to dynamic factors,i.e. the draft the vessel has loaded to. This may include an allowance due to water density.

Dynamic factors include Squat determined from ships data curves or calculation, motion causedby sea waves, swell, or heel due to turning etc.

Depth of water to provide required UKC = A+B+C+D

Net UKC is 10% Static Draft (including FWA as applicable)

Gross UKC is Net UKC + Allowance for dynamic factors.

Example: Whilst in restricted waters, a vessel is loaded to 12.0m even keel. The squat at the 8knots transit speed is calculated as 0.8m. There is no sea, swell, or appreciable heel, and norequirement for density allowance (FWA), so the draft including dynamic factors is 12.8m. Theminimum UKC as per the UKC policy is 0.6m, so the vessel requires a minimum depth (ChartDatum + tide) of 12.8 + 0.6 = 13.4m.

When calculating the minimum UKC the following factors shall be taken into consideration:


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The effects of Squat (guidance contained in Appendix 2)

Tidal conditions, particularly the range and direction of the tidal stream.

State of the sea and swell due to prevailing weather conditions.

The accuracy of the soundings, tidal information and predictions.

The accuracy of the ships draft - both observed and calculated, including provision forhogging and sagging.

Increase of draft due to heel/list.

Possible changes in the water density.

Nature of the seabed and its subsequent stability e.g. sand waves, potential for depths ofrivers to be effected by sitting.


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Appendix 2 Dynamic Components to be considered in

calculating UKC

Squat

Squat is the reduction in under keel clearance (UKC) between a vessel at rest and underway dueto the increased relative flow velocity of water underneath the hull when the vessel is in motion.

The reduction in UKC has the potential for a vessel grounding when the waterway is shallow,and requires to be calculated and taken into consideration when assessing minimum under keelclearance in the Navigation Passage Plan. Squat is influenced by the ships hull particulars such asblock coefficient, breadth, water plane area, speed of transit and by the particulars of the

waterway, such as water depth, breadth, bottom soil conditions.

The increase in draft due to squat is largely dependent on speed. Loss of under keel clearancedue to squat can be reduced by reducing transit speed, subject to the manoeuvring limitations of

the ship involved. A reduction in UKC may also be indicated by:

Increased helm requirements to maintain steerage

Increased or excessive vibration.

A sudden reduction in speed over the ground for the same RPM.

The formation of heavy bow and stern waves

The calculation of squat is a complex process and many industry published formulae exist. ShellShipping Technology has documented a study of widely used Industry formulae in Marine

Management Guideline (MMG) 22, Calculation of Ship Squat, and recommended the optimumprocess for calculation of squat for Shell managed fleet vessels. This is contained within theIntegrated Management System and shall be followed for all Shell managed vessels. Charteredships shall follow the instructions of their respective Operators.

In calculating the effects of squat for the passage plan, consideration should be given todetermining the maximum speed permissible that will avoid contravening the minimum UKCrequired, rather than simply determining the UKC for a proposed transit speed.

Increase in Draft due to Heel/List

Increase in draft due to heel and/or list can be substantial on wide bodied vessels. Heel should

be considered, taking into account the environmental loads e.g. wind on the vessel, mooring lineloads whilst alongside and the heel of the vessel caused by large course alterations whenunderway. .

Dynamic motion due to waves and swell

Additional consideration should be given for any further potential reduction in UKC resultingfrom the vessel pitching due to possible swell and wave action. Similar to squat, pitching resultsin changes of trim and the position of the centre of buoyancy with corresponding resultantchanges in draught.


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Document Authorisation & Validation Record

Document

Ti t l e ( and Ver si onNo) Under Keel Cl ear ance Pol i cy and Appl i cat i on t oGr oup Shi ppi ng Act i vi t i es

Document No SP1

Cat egor y No EXP 1 001

Author ( s) Davi d Geor ge, STASCO STS/ 4,

Document Cust odi an Cl i ve Hurf ord STS/ 44

Authorisation & Validation Process

Pr ocess Or i gi nat or Davi d Geor ge, STASCO STS/ 4

St ar t Date 11 March 2014Comment Cl ose Dat e 31s Mar ch 2014

Reviewers (Authors should not review their own work)

Cont entRevi ewer( s)

Format Revi ewer ( s)

Authors Concurrence on Final Document

Author(s) Name Ref

Indicator

Status (sign master copy)

Cl i ve Hur f or d STS/ 44


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Authorisation

Authorised By*

Ref

Ind Name

Status (sign

master copy) Date

GeneralManager

STS/ 4 J ohn Bar t on

Manager Oi l &Gas Pr oj ect s

Manager Port s& Ter mi nal s

Document

OwnerDi sci pl i neLead

Techni calRevi ewCommi t t eeChai r

Shi p Operator

* X = Required for this Document

Distribution:

Copy available from: Cl i ve Hur f or d STS/ 44

Queries and Suggestions for

Changes to:

Same as above


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