nes 109 stability standards for surface ships

Ministry of Defence Defence Standard 02-109 (NES 109)

Issue 1 Publication Date 01 April 2000

Incorporating NES 109 Category 1

Issue 4 Publication Date February 2000

Stability Standards For Surface Ships

Part 1Conventional Ships

DStanDStan is now the publishing authority for all Maritime Standards (formerly NESs). Any reference to any other publishing authority throughout this standard should be ignored.Any queries regarding this or any other Defence Standard should be referred to the DStan Helpdesk as detailed at the back of this document.

AMENDMENT RECORD

Amd No Date Text Affected Signature and Date

REVISION NOTE

This standard is raised to Issue 1 to update its content.

HISTORICAL RECORD

This standard supersedes the following:

Naval Engineering Standard (NES) 109 Part 1 Issue 4 dated February 2000

Ministry of Defence

Naval Engineering Standard

CATEGORY 1

NES 109 Part 1 Issue 4 February 2000

STABILITY STANDARDS FOR SURFACE SHIPS

PART 1

CONVENTIONAL SHIPS

E CROWN COPYRIGHT 2000

This NES Supersedes

NES 109 Issue 2 June 1986NES 109 Issue 3 August 1989

Record of Amendments

AMDT INSERTED BY DATE

1

2

3

4

5

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NAVAL ENGINEERING STANDARD 109

STABILITY STANDARDS FOR SURFACE SHIPS

PART 1 ISSUE 4 FEBRUARY 2000

CONVENTIONAL SHIPS

This Naval Engineering Standard is

authorized for use in MOD contracts by the

Defence Procurement Agency and the

Defence Logistics Organization

Published by:

Sea Technology Group,Defence Procurement AgencySTGSAAsh 0, #95MOD Abbey WoodBristol BS34 8JH

NES 109 Part 1Issue 4February 2000

(ii)

NES 109 Part 1Issue 4

February 2000

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SCOPE

1. This NES sets out the minimum acceptable standards of stability for conventional andunconventional surface vessels for which theMOD is responsible. Distinction ismade betweenthe minimum standards for vessels with and without a military role.

2. This NES is issued in two parts. Part 1 specifies minimum acceptable standards for surfacevessels of a conventional monohull form. Part 2 specifies minimum standards for surfacevessels meeting the NES 109 definition of surface vessels having an unconventional form.

3. For the stability of any vessel not clearly covered under NES 109Part 1 or Part 2, advice shouldbe sought from the Sea Technology Group, Defence Procurement Agency.


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NES 109Part 1Issue 4

February 2000

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FOREWORD

Sponsorship

1. This Naval Engineering Standard (NES) is sponsored by the Defence Procurement Agency,Ministry of Defence (MOD).

2. The complete NES 109 comprises:

Part 1: Conventional Ships

Part 2: Unconvential Ships (to be published later)

3. Any user of this NES either within MOD or in industry may propose an amendment to it.Proposals for amendments that are not directly applicable to a particular contract are to bemade to the publishing authority identified on Page (i), and those directly applicable to aparticular contract are to be dealt with using contract procedures.

4. If it is found to be unsuitable for any particular requirement MOD is to be informed inwritingof the circumstances.

5. No alteration is to be made to this NES except by the issue of an authorized amendment.

6. Unless otherwise stated, reference in this NES to approval, approved, authorized and similarterms, means by the MOD in writing.

7. Any significant amendments that may be made to this NES at a later date will be indicatedby a vertical sideline. Deletions will be indicated by 000 appearing at the end of the lineinterval.

8. This NES has been reissued to correct errors found in NES 109 Issue 3, and to allow for thepublication of Part 2. Part 2 will be published in due course to address unconventional vessels.In the meantime the requirements for stability standards for such vessels should be referredto Sea Technology Group, Section STGSS1.

Conditions of Release

General

9. This Naval Engineering Standard (NES) has been devised solely for the use of the MOD, andits contractors in the execution of contracts for the MOD. To the extent permitted by law, theMOD hereby excludes all liability whatsoever and howsoever arising (including but withoutlimitation, liability resulting from negligence) for any loss or damage however caused whenthe NES is used for any other purpose.

10. This document is Crown Copyright and the information herein may be subject to Crown orthird party rights. It is not to be released, reproduced or publishedwithout written permissionof the MOD

11. The Crown reserves the right to amend or modify the contents of thisNES without consultingor informing any holder.

MOD Tender or Contract Process

12. This NES is the property of the Crown. Unless otherwise authorized in writing by the MODmust be returned on completion of the contract, or submission of the tender, in connectionwith which it is issued.

13. When thisNES is used in connection with aMOD tender or contract, the user is to ensure thathe is in possession of the appropriate version of each document, including related documents,relevant to each particular tender or contract. Enquiries in this connection may be made tothe authority named in the tender or contract.

14. When NES are incorporated into MOD contracts, users are responsible for their correctapplication and for complying with contractual and other statutory requirements.Compliance with an NES does not of itself confer immunity from legal obligations.


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Categories of NES15. The Category of this NES has been determined using the following criteria:

a. Category 1. If not applied may have a Critical affect on the following:

Safety of the vessel, its complement or third parties.

Operational performance of the vessel, its systems or equipment.

b. Category 2. If not applied may have a Significant affect on the following:

Safety of the vessel, its complement or third parties.

Operational performance of the vessel, its systems or equipment.

Through life costs and support.

c. Category 3. If not applied may have a Minor affect on the following:

MOD best practice and fleet commonality.

Corporate experience and knowledge.

Current support practice.

Related Documents16. In the tender and procurement processes the related documents listed in each section and

Annex A can be obtained as follows:

a. British Standards British Standards Institution,389 Chiswick High Road,London, W4 4AL

b. Defence Standards Directorate of Standardization, Stan BM&D,Kentigern House, 65 Brown Street,Glasgow, G2 8EX.

c. Naval Engineering Standards DSDC(L) Llangennech, Llanelli, Dyfed,SA14 8YP.

d. Other documents Tender or Contract Sponsor to advise.

17. All applications to the MOD for related documents are to quote the relevant MOD Invitationto Tender or Contract number and date, together with the sponsoring Directorate and theTender or Contract Sponsor.

18. The Form Facsimiles shown in this NES are not to be copied since they are only replicas forinformation purposes and will be subject to change by the form Sponsor to reflect currentMOD policy.

19. Prime Contractors are responsible for supplying their subcontractors with relevantdocumentation, including specifications, standards and drawings.

Health and Safety

Warning

20. This NES may call for the use of processes, substances and/or procedures that are injuriousto health if adequate precautions are not taken. It refers only to technical suitability and inno way absolves either the supplier or the user from statutory obligations relating to healthand safety at any stage of manufacture or use. Where attention is drawn to hazards, thosequoted may not necessarily be exhaustive.

21. This NES has been written and is to be used taking into account the policy stipulated in JSP430: MOD Ship Safety Management System Handbook.

Additional Information22. (There is no relevant information included.)


February 2000

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CONTENTSPage No

TITLE PAGE (i). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SCOPE (iii). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FOREWORD (v). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sponsorship (v). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conditions of Release (v). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Categories of NES (vi). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Related Documents (vi). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Health and Safety (vi). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Additional Information (vi). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CONTENTS (vii). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 1. PERFORMANCE SPECIFICATION 1.1. . . . . . . . . . .1.1 General 1.1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2 Intact Stability Criteria for Vessels Designed to

MOD Standards with a Military Role 1.2. . . . . . . . . . .1.2.1 General 1.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 1.1 Examples of Minimum Acceptable GZ Curves 1.3. . . .Table 1.1 Shape Criteria for GZ Curve 1.3. . . . . . . . . . . . . . . . . .Figure 1.2 Range and GZ Maximum Limitations 1.4. . . . . . . . . . .1.2.2 Stability in Beam Winds 1.4. . . . . . . . . . . . . . . . . . . . . .Table 1.2 Nominal Wind Speed 1.4. . . . . . . . . . . . . . . . . . . . . . . . .Figure 1.3 Beam Winds Combined with Rolling 1.5. . . . . . . . . . . .1.2.3 Stability Under Icing 1.5. . . . . . . . . . . . . . . . . . . . . . . . .Table 1.3 Shape Criteria for GZ Curve with Ice 1.6. . . . . . . . . . .1.2.4 Heeling Caused by High Speed Turning 1.6. . . . . . . . .Figure 1.4 High Speed Turning 1.6. . . . . . . . . . . . . . . . . . . . . . . . . .1.2.5 Lifting of Heavy Weights 1.7. . . . . . . . . . . . . . . . . . . . . .Figure 1.5 Lifting of Heavy Weights over the Side 1.7. . . . . . . . . .1.2.6 Crowding of Passengers on One Side 1.7. . . . . . . . . . . .Figure 1.6 Crowding of Passengers to One Side 1.8. . . . . . . . . . . .1.2.7 Water on Deck 1.8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2.8 Stability in Harbour 1.9. . . . . . . . . . . . . . . . . . . . . . . . . .1.2.9 Stability during Docking 1.9. . . . . . . . . . . . . . . . . . . . . .1.2.10 Firefighting 1.9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.3 Damage Stability Criteria for Vessels Designed to

MOD standards with a Military Role 1.9. . . . . . . . . . .1.3.1 General 1.9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.3.2 Extent of Damage 1.9. . . . . . . . . . . . . . . . . . . . . . . . . . . .1.3.3 Permeability 1.10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Table 1.4 Permeability Factors 1.10. . . . . . . . . . . . . . . . . . . . . . . . .1.3.4 Wind Speed 1.10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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1.3.5 Damage Stability Criteria 1.11. . . . . . . . . . . . . . . . . . . . .Figure 1.7 Damaged Stability 1.12. . . . . . . . . . . . . . . . . . . . . . . . . . .1.4 Intact Stability Standards for VesselsDesigned to

MOD Standards with no Military Role and VesselsDesigned to Legislation with a Military Role 1.12. . . . .

1.4.1 General 1.12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.4.2 Stability of Vessels Making Bow or Body Lifts 1.12. . . .Figure 1.8 Beam Wind Criteria 1.13. . . . . . . . . . . . . . . . . . . . . . . . . .Figure 1.9 Breaking Wire Criteria Initial Impulse 1.14. . . . . . . . . .Figure 1.10 Breaking Wire Criteria Steady State 1.14. . . . . . . . . . . .1.4.3 Stability of Vessels Performing a Bollard Pull 1.14. . . .Figure 1.11 Criteria for Vessels Performing a Bollard Pull 1.15. . . .1.5 Damaged Stability Standards for VesselsDesigned

to MOD Standards with no Military Role andVessels Designed to Legislation with a Military Role 1.15

1.5.1 General 1.15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5.2 Extent of Damage 1.15. . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5.3 Damaged Stability Criteria 1.16. . . . . . . . . . . . . . . . . . . .

SECTION 2. NATIONAL/INTERNATIONAL REGULATIONS 2.1

SECTION 3. MILITARY STANDARDS/REQUIREMENTS. 3.1. . .3.1 Stability Related Military Design Requirements 3.1. .3.1.1 Watertight Subdivision And Integrity 3.1. . . . . . . . . . .3.1.2 Calculation of the Red Risk Line 3.1. . . . . . . . . . . . . . .3.1.3 Calculation of the VLines 3.1. . . . . . . . . . . . . . . . . . . .Figure 3.1 Minimum Extent of Watertight Subdivision and

Integrity 3.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Figure 3.2 Envelope of Damaged Waterlines 3.2. . . . . . . . . . . . . . .Figure 3.3 Angle of Heel Used to Derive Red Risk Zone

and VLines 3.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 4. DESIGN REQUIREMENTS/GUIDANCE 4.1. . . . . . .4.1 Stability Related Design Requirements 4.1. . . . . . . . . .4.1.1 Provision of Freeing Ports for Ships with Bulwarks 4.1

SECTION 5. CORPORATE EXPERIENCE & KNOWLEDGE 5.1

ANNEX A RELATED DOCUMENTS A.1. . . . . . . . . . . . . . . . . . . .

ANNEX B ABBREVIATIONS B.1. . . . . . . . . . . . . . . . . . . . . . . . . . .Table B1 Loading Conditions for Vessels Designed to

MOD Standards B.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Table B2 Loading Conditions for Vessels designed

to Legislation B.3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Table B3 Definition of Tank States B.4. . . . . . . . . . . . . . . . . . . . . .Table B4 Definition of Variable Load States B.5. . . . . . . . . . . . . .

ANNEX C PROCUREMENT CHECK LIST C.1. . . . . . . . . . . . . . .


February 2000

1.1

1. PERFORMANCE SPECIFICATION1.

Related Documents: SSP 24; SSP 78; see also Annex A.

1.1 General

a. This NES is to be read in conjunction with SSP 24 (which gives details of theprocedures to be used to obtain and analyse stability information) and SSP 78,(which details the procedures relating to the audit of stability information andsubsequent issue of a Certificate of Safety Stability (CSS)).

b. Any unusual vessel geometry or unusual threats to stability must beinvestigated separately, assuming the most unfavourable circumstances, andthe Sea Technology Groupmust be consulted on the criteria for acceptance. Theissue of NES 109 does not remove the responsibility from the Integrated ProjectTeam Team Leader (or equivalent) for ensuring that new designs haveadequate stability. It is emphasised that the checks and criteria included hereinare the minimum acceptable. All users must continue to exercise theirprofessional judgement to the full when applying them to specific vessels. Inparticular, it is essential to take proper account of any special characteristics ofthe vessel or its intended role and apply whatever additional checks may beappropriate. Should users wish to depart from the stability criteria, they mustformally consult with the Sea Technology Group and a record of all agreeddepartures maintained.

c. NES 109 is applicable to the following types of vessel:

(1) Vessels designed to MOD standards with a military role (Warships), forexample a Frigate.

(2) Vessels designed toMOD standards without amilitary role, for example aRoyal Navy manned Navigation Training ship.

(3) Vessels designed to legislation with a military role, for example a RoyalFleet Auxiliary manned Roll on Roll off landing ship.

d. A military role is considered as any role of the vessel that is outwith the scopeof legislation, for example any role that exposes the vessel to danger due toenemy action or a peacetime exercise simulating that role. Vessels without amilitary role and not designed to military standards are not subject to NES 109and should meet the appropriate legislation. If there is any doubt as to whethera vessel is to be considered as having a military role, the Sea Technology Groupshould be consulted.

e. NES 109 Part 1 provides basic stability requirements for surface vessels with aconventional monohull form.

f. NES 109 Part 2 provides stability criteria for surface vessels of unconventionalform. Definitions of unconventional and conventional forms are detailed inAnnex B. If there is any doubt as to whether a vessel is to be considered asconventional or unconventional, the Sea Technology Group should beconsulted.


1.2

g. In all cases the criteria, both intact and damaged, must be met including amargin for unattributable weight and KG growth that may occur before thenext stability assessment. Such growth may consist of unofficial anduncontrollable condition alterations and also official (but undocumented)alterations. In the absence of evidence of the magnitude of this weight and KGgrowth the following margins are to be applied to the Basic Ship (or Lightship,as applicable to ship type) condition at the LCG of that condition. Conditionsare detailed in Annex B.

(1) Warships, 0.65 % p.a. increase in Basic Ship displacement and 0.45 % p.a.increase in Basic Ship KG.

(2) RFAs, 0.65%p.a. increase inBasic Ship displacement, 0.40%p.a. increasein Basic Ship KG.

(3) Other auxiliary vessels which operate in coastal waters, 0.73 % p.a.increase in Basic Ship displacement and 0.66 %p.a. increase in Basic ShipKG.

h. Where the application of such growth is considered likely to affect vesselperformance and / or operability to an unacceptable degree, project and the SeaTechnology Group should formally agree a stability plan, with revised growthrates. Further guidance is provided in SSP 78 and SSP 24.

i. In all cases it is essential for the warship project manager to ensure themaintenance of adequate stability, in accordance with NES 109, throughout avessels service life. Thismay be achieved byvariousmethods, such as increasedgrowth allowances, removal of growth, additions and alterations, at differentpoints in time. However all such proposed measures should be formallydocumented in a stability plan.

j. For new designs, the stability criteria must be achieved at completion of buildand for a subsequent period of at least ten years without operational limitationssuch as liquid loading restrictions.

k. For inservice vessels, the stability criteria should be achieved without therequirement for liquid loading restrictions or ballasting, where possible, for theduration of the proposed CSS. Compensating savings in payload or othermeasures that limit operational effectiveness may be found to be necessary inorder to achieve the stability criteria.

l. Given current uncertainty as to the effectiveness of crossflooding it isrecommended that the adoption of crossflooding to meet the criteria afterdamage is avoided. Where crossflooding is deemed necessary, procedures forassessing the effectiveness of crossflooding should be employed (as detailed inSSP 24) to the satisfaction of the Sea Technology Group.

m. All computer based calculations are to be performed using models maintainedand validated in accordance with SSP 24.

1.2 Intact Stability Criteria for Vessels Designed to MOD Standards with a MilitaryRole

1.2.1 General

a. Section 1.2 specifies intact stability standards appropriate to all vesselsdesigned to military standards and with a military role (see Clause 1.1.c.).Vessels designed to military standards without a military role and vesselsdesigned to legislation with a military role, should meet the intact stabilitycriteria detailed in Clause 1.4.


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1.3

b. Figure 1.1 shows minimum acceptable GZ curves providing intact stabilityagainst which compliance with criteria must be demonstrated. These criteriaare enumerated in this section. Table 1.1 gives figures relating to the GZ curveterminated at the angle of downflooding through large openings. An effectiverange of 70 degrees is to be the minimum design aim.

Figure 1.1 Examples of Minimum Acceptable GZ Curves

Area under GZ Curve up to 300 Not less than 0.080 m radArea under GZ Curve up to 400 Not less than 0.133 m radArea under GZ Curve between 300 and 400 Not less than 0.048 m radMaximum GZ Not less than 0.3 mAngle of Maximum GZ Not less than 300

GM Fluid Not less than 0.3 mAngle of Vanishing Stability (Range) To be as large as possible

limited by the angle of un-restricted flooding. SeeClause 1.2.1b.

Table 1.1 Shape Criteria for GZ Curve

c. The angle of downflooding is that which causes unrestricted flooding of thevessel through openings in the structure. Small openings [as defined by SSP 24]such as tank ventsmay be disregarded as long as they do not immerse before theangle of maximum GZ. When the result of downflooding is contained within awatertight compartment this may be taken as not prompting GZ terminationprovided the resulting asymmetric moment and added weight are takenaccount of in the stability assessment. The point of downflooding shall be abovethe Vlines at that longitudinal location.

d. Where the stability curves have double peaks or the downflooding angle isexcessively large, the curves can be as shown in Figure 1.2. The following rulesare to be followed:

(1) The value of maximum GZ is to be taken at the first peak or at 500,whichever angle is less.


1.4

(2) The effective range is to be the angle at which unrestricted downfloodingoccurs or 700 whichever is less.

Figure 1.2 Range and GZ Maximum Limitations

1.2.2 Stability in Beam Winds

a. The effects of beam winds and rolling in rough seas are to be consideredsimultaneously. Wind heeling levers are to be obtained using procedures givenin SSP 24.

b. A rollback angle of 250 is applicable to vessels of conventional monohull form.Table 1.2 gives applicable nominal wind speeds.

Type of Vessel Wind Speed

(a) Ocean going vessels which may be expected to weath-er conditions encountered. This includes all vesselswhich move with the operational fleet.

90 knots

(b) Ocean going or coastal vessels whichmay be expectedto avoid extreme conditions.

70 knots

(c) Coastal vessels which will be recalled to protected an-chorages if winds over Force 8 are expected, and har-bour vessels.

50 knots

Table 1.2 Nominal Wind Speed


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1.5

c. Criteria (refer to Figure 1.3)

(1) Angle of heel due to beam winds in Table 1.2 must not exceed 300.

(2) GZ at point C must not exceed 60% of the maximum GZ.

(3) Area A1 is not to be less than 1.4 A2.

Figure 1.3 Beam Winds Combined with Rolling

1.2.3 Stability Under Icing

a. Stability under icing shall be proven in all cases, unless otherwise agreed withthe Sea Technology Group in advance. Where stability under icing is not proventhe CSS and all related mandatory operator guidance documents must statethat stability under icing has not been assessed and that the vessel is not toenter geographic areas where icing is considered possible.

b. It is assumed that high winds and icing will occur simultaneously. Theprocedure for accounting for this is as follows:

(1) l50 mm of ice to be assumed distributed on all exposed horizontal decks,platforms and roofs. Density of ice is assumed to be 950 kg/m3.

(2) The weight and centre of gravity of the ice is to be taken into account inthe computation of the GZ curve.

(3) Wind heeling levers are to be calculated ignoring the effect on the profilearea of the ice thickness, but allowing for the weight of the ice on thevessels displacement.

c. Criteria: (refer to Figure 1.3):

(1) Wind heeling lever is to be based upon a wind speed of 70% of the windspeed given in Table 1.2.

(2) Angle of heel caused by the above is not to exceed 300.

(3) GZ at point C must not exceed 60% of maximum GZ.

(4) Area A1 > 1.4A2.


1.6

(5) Area under the GZ curve, the GM and the maximum GZ are to be inaccordance with Table 1.3.

(6) These stability requirements and wind speeds are not acceptable if therole of the vessel requires frequent operation in icing conditions. For suchvessels Clauses 1.2.1b. and 1.2.2 will apply.

Area under GZ curve up to 300 Not less than 0.051 m rad

Area under GZ curve up to 400 Not less than 0.085 m rad

Area under GZ curve between 300 and 400 Not less than 0.03 m rad

Maximum GZ Not less than 0.24 m

Angle of Maximum GZ Not less than 300

GM Fluid Not less than 0.15 m

Table 1.3 Shape Criteria for GZ Curve with Ice

1.2.4 Heeling Caused by High Speed Turning

a. To calculate the heeling lever generated during a high speed turn:

Heeling lever (m) = V2 h cos !Rg

where:V = Speed on the turn (65% of approach speed) (m/s)

h = Vertical separation of KG and mean draughtpoint (vessel upright) (m)

R = Radius of steady turn with rudder hard over (m)

g = Acceleration of gravity (m/s2)

! = Angle of Heel (degrees)

In the absence of any information on the radius of steady turn, a value of 2.5times the LBP for warships and 3.5 times the LBP of auxiliaries is to be used.Note: 1 m/s = 0.514 knots.

b. Criteria (refer to Figure 1.4)

(1) Steady angle of heel < 200.

(2) GZ at point C < 60% maximum GZ.

(3) Area A > 40% total area under GZ curve.

Figure 1.4 High Speed Turning


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1.7

1.2.5 Lifting of Heavy Weights

a. When assessing the effects of lifting heavy weights, the following points are tobe observed:

(1) Theweight is initially assumed to be on theupper deck at the centre line ofthe vessel.

(2) Heeling lever = w (a cos ! + d sin !"#

where:w = Weight being lifted (Tonnes)

a = Offset of point of suspension (m)(top of lifting boom) from ships middle line

d = Height of point of suspension (m)above the deck

! = Angle of heel (degrees)

# = Displacement (including w) (Tonnes)

(3) All possible positions of jib or boom are to be considered.

b. Criteria (refer to Figure 1.5):

(1) Angle of heel


1.8

1.2.6 Crowding of Passengers on One Side

a. The effects of crowding of passengers can be calculated as follows (refer toFigure 1.6). The term Passengers is defined in Annex B2.b.

(1) Curves of righting levers are to be calculated assuming all passengersstanding on the upper deck, with crew at their stations.

(2) Heeling lever = w a cos !#

where:w = Weight of passengers (80 kg eachmoreif carrying equipment) (Tonnes).

a = Distance of CG of men from centre line (m).Assume all move as far as possible and eachoccupies 0.2m2.

# = Displacement (Tonnes).

! = Angle of inclination.

(3) If the number of passengers is not defined, assume 2.5 per square metre ofavailable deck space.

(4) Where applicable the launching of fully loaded davitlaunched survivalcraft should be considered as an additional heeling moment.

b. Criteria (refer to Figure 1.6)

(1) Angle of heel < 100.

(2) GZ at point C < 60% of max. GZ.

(3) Area A > 40% of total area under GZ curve.

Figure 1.6 Crowding of Passengers to One Side


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1.9

1.2.7 Water on Deck

a. Water on deck is to be considered as trapped when substantial bulwarks arepresent.

b. Where bulwarks are fitted with freeing ports in accordance with 4.1.1 the effectof water trapped on deck shall not be assessed. Proof of compliance with 4.1.1shall be provided.

c. Where freeing ports are fitted but are not in accordance with Section 4.1.1, theeffect of trapped water on stability shall be assessed. A suitable method ofassessment shall be agreed with the Sea Technology Group.

1.2.8 Stability in Harbour

a. The criteria to be applied to vessels in harbour are as follows:

(1) The GM fluid is not to be less than 150 mm.

(2) The heel under a 30 knot wind is not to exceed 70.

1.2.9 Stability during Docking

a. The GM of the vessel must remain greater than 150 mm during the entiredocking process.

b. The critical condition is just before the vessel takes the blocks when the sueingload is highest. A trim of 0.3m by the stern is to be assumed or a higher value ifthe vessel cannot achieve this.

c. It should be noted that extreme trimmay lead to a substantial load on the dockblocks. Additional structural calculations may be necessary and arerecommended.

1.2.10 Firefighting

a. The effect of 10 minutes of both firefighting and boundary cooling water inlarge compartments and those high in the vessel is to be investigated. Anyresultant loll is not to exceed 20 degrees.

1.3 Damage Stability Criteria for Vessels Designed to MOD standardswith a Military Role

1.3.1 General

a. The loading condition of the vessel, prior to sustaining damage, that results inthe least stability after damage is to be assessed. This is most likely to be alightly loaded condition, but should be confirmed by assessment of otherloading conditions.

b. In all cases, the transverse and vertical extent of flooding is to be taken as thatwhich causes worst stability. This should include feasible incidents ofgrounding, raking and collision. Guidance is given in SSP 24.

c. Nonwatertight compartments which would flood slowly are to be assumedwatertight if this degrades stability. For example, where water is initiallypresent above a non watertight deck and, in reality, would slowly drain, theworst case distribution of water (water remaining above the deck and notdraining down) should be assessed.

d. Intermediate levels of flooding are to be checked as well as the final water levelto establish the worst case. The Lost Buoyancy approach is to be used.


1.10

1.3.2 Extent of Damage

a. The following degrees of damage are to be assumed:

(1) Vessels of waterline length less than 30m.Any single main compartment.

(2) Vessels of waterline length between 30m and 92m.Any two adjacent main compartments. A main compartment is to have aminimum length of 6m.

(3) Vessels of waterline length greater than 92m.Damage anywhere along its length, extending 15% of the waterlinelength, or 21m whichever is greater.

1.3.3 Permeability

a. Permeability is the term for the floodable space within a compartment,expressed as a percentage volume.

b. Definitions of floodable space should exclude all solid material within acompartment such as structure, air pockets, outfit, stores and systems. It isimportant to note that the permeability of cargo holds and stores may varywithloading condition.

c. For damage stability calculations, the permeability factors given in Table 1.4are to be used. For watertight, void compartments and tanks, validated valuesshould be used where validation has been established bymeans of calibration atbuild.

Space Permeability (%)Watertight VoidCompartments and Tanks

97 (warships)95 (auxiliary vessels)

Workshops, Offices, Operational and Accommodationspaces etc.

95

Vehicle Decks 90

Machinery Compartments 85

Store rooms, cargo holds, etc. 60

Table 1.4 Permeability Factors

1.3.4 Wind Speed

a. Wind heeling levers are to be calculated using nominal wind speeds as detailedin (1), (2) or (3).

(1) Nominal Wind Speeds for vessels of displacement less than or equal to1000 tonnes.

VWind $ %20 0 005. #


February 2000

1.11

(2) Nominal Wind Speeds for vessels of displacement greater than 1000tonnes and less than or equal to 5000 tonnes.

VWind $ &506 10. ln( )#

(3) Nominal Wind Speeds for vessels of displacement greater than 5000tonnes.

VWind $ %225 015. . #

where VWind = Wind Velocity (knots)

# = Displacement (deep) (tonnes)

1.3.5 Damage Stability Criteria

a. Referring to Figure 1.7:

(1) Angle of list or loll 0.

b. Where a vessel is subject to 1.3.2.a.(1) or 1.5.2.b(1), it shall be proven, inaddition, that the vessel is not lost after two compartment damage bydemonstration that :

(1) Following a damage of extent detailed in 1.3.2.a.(2), the Metacentricheight in the damaged condition shall be greater than 0.15m.

NOTE GZ max. is the maximum within the range to downflooding or to 450,whichever angle is less.


1.12

Figure 1.7 Damaged Stability

1.4 Intact Stability Standards for VesselsDesigned to MOD Standards with noMilitary Role and Vessels Designed to Legislation with a Military Role.

1.4.1 General

a. The intact criteria detailed in Section 1.2. are to be applied. Wind speeds for thecriteria are to be selected from Table 1.2.

b. Although through the Orders in Council there is no legal requirement to do so,all registered vessels subject to Section 1.4 must comply with the statutoryintact stability requirements of the Merchant Shipping Acts unless there is asound military or operational reason not to do so.

c. Some vessels have limited areas of operation inwhich case the icing criteriamaybe omitted or reduced to statutory standards after consultation with the SeaTechnology Group.

1.4.2 Stability of Vessels Making Bow or Body Lifts

a. The GZ curve is to be drawn to include the load which acts at the suspensionpoint of the supporting wires.

b. Criteria (refer to Figure 1.8, Figure 1.9 and 1.10) under a 30 knot beam windand 150 of roll.

(1) Angle of heel


February 2000

1.13

c. The effect of one wire breaking only needs to be investigated if it results in aneccentric load, with the load W supported on the remaining wires.

Heeling Lever = W a cos !#

where W = Load (Tonnes)

# = Displacement including load (Tonnes)

a = Transverse offset of centroid ofremaining reactions (m)

Initial Impulse Criteria

(1) !2 < 300 at A3 = 1.25A4

'(" !2 < !DF (the angle of downflooding)

')" !D < 150

(4) GZ at point D < 0.5 GZ maximum

Steady State Criteria

(1) A5>A6

Figure 1.8 Beam Wind Criteria


1.14

15 DEGREES

Figure 1.9 Breaking Wire Criteria Initial Impulse

Figure 1.10 Breaking Wire Criteria Steady State

1.4.3 Stability of Vessels Performing a Bollard Pull

a. Vessels performing a bollard pull must have sufficient stability towithstand themaximum possible bollard pull acting athwartships. The heeling lever is givenby the formula below (see Figure 1.11).

T AB Cos( ) 2!#

b. The criteria are (refer to Figure 1.11):

(1) The angle of heel < 150.

(2) GZ at point C < 60% of GZ max.

(3) Area A1 >40% total area under GZ curve.


February 2000

1.15

Figure 1.11 Criteria for Vessels Performing a Bollard Pull

1.5 Damaged Stability Standards for VesselsDesigned to MOD Standards with noMilitary Role and Vessels Designed to Legislation with a Military Role

1.5.1 General

a. Damaged stability is to be assessed on the same basis as Clause 1.3.1, exceptthat theworst case is likely to bewhen the initial condition before damage is thefully loaded condition. This is to be confirmed by investigating other initialconditions.

1.5.2 Extent of Damage

a. Onlymain transverse watertight bulkheads which are spaced at least (3.00m+0.03L) or 10.65m apart, whichever is less, are to be considered as effectivewatertight boundaries.

b. The following damage is to be assumed unless a smaller extent results in worsestability:

(1) All vessels less than 75m waterline length.

Any single compartment anywhere along the vessel.

(2) Vessels between 75m and 200m in waterline length.

Any three adjacent main compartments (excluding large machineryspaces). Where compliance with a three adjacent compartment standardin way of large machinery spaces is clearly demonstrated to the SeaTechnology Group as impractical, damage to any two adjacent maincompartments in way of main machinery may be accepted.


1.16

(3) Vessels over 200m in waterline length.

A damage length of 12.5% of waterline length anywhere along the vessel.

1.5.3 Damaged Stability Criteria

a. The criteria for damaged stability given in Clause 1.3.5. must be achieved.Although through the Orders in Council there is no legal requirement to do so,all registered vessels subject to Clause 1.5 must comply with the statutorydamage stability requirements of the Merchant Shipping Acts for thedesignated Class of Ship unless there is a sound military or operational reasonnot to do so.

b. In the case of passengercarrying vessels, the passengers are to be taken to beon the highest decks and on the low side.


February 2000

2.1

2. NATIONAL/INTERNATIONAL REGULATIONS2.Related Documents SSP 24, see also Annex A.

a. Chapter 3 of SSP 24 outlines the requirements for national and internationalmonohull stability regulations.


2.2


February 2000

3.1

3. MILITARY STANDARDS/REQUIREMENTS3.

3.1 Stability Related Military Design Requirements

3.1.1 Watertight Subdivision And Integrity

a. The extent and standard of watertight subdivision and integrity has a majorimpact upon vessel safety and resistance to damage caused by grounding,collision, enemy action or arising from any other incident.

b. Section 3.1 details issues to be considered during the design of a vessel to MODstandards with respect to watertight subdivision, integrity and other aspects ofship structure with an influence on stability. Definitions are provided in AnnexB.2.3. SSP 24 provides further guidance.

c. This section is aimed at vessels with a military role but many of the principlesare also applicable to vessels with no military role.

d. Assessment of the location of a ship designs V lines and Red Risk Line shall beundertaken in the following manner. The deepest centreline immersion of abulkhead when it forms the boundary of a damaged length in accordance withthe stability standards that apply are to be drawn on a profile to determine anenvelope of damagedwaterlines. Theywill be based upon, firstly the anticipatedDeep Displacement at end of life, and secondly, the maximum extent of floodingpossible within the limits specified. This envelope of damaged water lines, asillustrated in Figure 3.2 forms the basis for calculating both the Red Risk Lineand the VLines.

3.1.2 Calculation of the Red Risk Line

a. The Red Risk Line delineates the zone withinwhich all watertight closures, notalready closed by virtue of the ordered NBCD condition, need to be closedrapidly in the event of damage or imminent damage. For each section, theheight of the Red Risk Line at the middle line is defined by the height of theenvelope of damaged water lines at that section. The Red Risk Line is drawnfrom this point with a semiangle of 15* in addition to any static heel angle dueto the damage stability calculations. The 15* addition is a dynamic allowancefor transient heel angles and rolling in waves. This is illustrated in Figure 3.3.

3.1.3 Calculation of the VLines

a. The VLines define the level up to which watertight structure is required. Foreach section, the height of the VLines at the centre line is defined by theheight of the envelope of damaged water lines at that section plus an allowanceof 1.5metres to allow for vessel motion relative to thewaves. The angle of heel tobe assumed is 35degrees based on the criteria for angle of heel following damageof 20 degrees plus the 15 degree dynamic allowance for transient heel angles androlling in waves. This is illustrated in Figure 3.3. For small vessels withspecified maximum acceptable operating conditions, where 1.5 m relativemotion and 15 degree transient heel allowances are not practicable, SeaTechnology Group shall be consulted as to a suitable allowance. The suitableallowance shall consider the maximum sea state given the vessel operatinglimitations. This limiting sea state shall be specified on all relevant operatorguidance documentation.

b. When assessing damage stability, the range of the GZ curve is truncated at 45*or at the lowest angle at which progressive flooding is possible, for examplethrough nonwatertight bulkhead penetrations.


3.2

Damage Control Deck

Red Risk Line

V Line

Static Damage Waterline

WeathertightWatertightWatertight Access and SystemPenetrations PermittedNo Openings inMain Watertight Bulkheads

Key :

Figure 3.1 Minimum Extent of Watertight Subdivision and Integrity

Key :Locus of Damaged WaterlinesDamage Control DeckDamage Waterlines

Figure 3.2 Envelope of Damaged Waterlines

1.5m

damagedraught ( t )

Red Risk Line ('+ + 15 deg)

V Line (20 + 15 deg)

Static DamageWaterline'+ deg)

CL

Figure 3.3 Angle of Heel Used to Derive Red Risk Zone and VLines


February 2000

4.1

4. DESIGN REQUIREMENTS/GUIDANCE4.

4.1 Stability Related Design Requirements

a. Stability related design requirements are detailed in SSP 24. Section 4.1.1specifies mandatory design requirements for ships with bulwarks.

4.1.1 Provision of Freeing Ports for Ships with Bulwarks

a. Freeing ports are recommended for ships where bulwarks are considered toaffect the removal of water from exposed decks.

b. The minimum recommended freeing area on each side of the ship, for each wellon the weatherdeck, or other deck with bulwarks, shall meet the followingrequirements:

(1) Where the length of the bulwark (L) is 20 m or less the freeing port area(A) shall be greater than the formula given below:

A = 0.7 + 0.035 L m2.

(2) Where the length of the bulwark (L) is greater than 20 m, the freeing portarea (A) shall be greater than the formula given below:

A = 0.07 L m2.

c. Where the average height of the bulwark exceeds 1.2 m the area of the freeingport shall be increased by 0.004m2 per metre of length of well for each 0.1 mincrease in height.

d. Where the average height of the bulwark is less than 0.9 m, the area of thefreeing port may be decreased by 0.004 m2 per metre of length of well for each0.1 m decrease in height.


4.2


February 2000

5.1

5. CORPORATE EXPERIENCE & KNOWLEDGE5.Related Documents SSP 78, see also Annex A.

a. Corporate Experience and knowledge form the basis for much of the criteriapresented in section 1 and SSP78.


5.2


February 2000

A.1

ANNEX A.A.

RELATED DOCUMENTS

A1. The following documents and publications are referred to in this NES:

SSP 24 Stability of Surface Ships

SSP 78 Procedures for the Issue of a Certificate of Safety Stability


A.2


February 2000

B.1

ANNEX B.B.

ABBREVIATIONS

B1. For the purpose of this NES the following abbreviations apply:

NES Naval Engineering StandardMOD Ministry of DefenceSSP Surface Ship PublicationCSS Certificate of Safety StabilityRFA Royal Fleet AuxiliaryKG Vertical Centre of Gravity (from keel)LCG Longitudinal Centre of GravityLBP Length Between PerpendicularsGZ Righting LeverGM Metacentric Height

B2. For the purposes of this NES, the following definitions apply:

a. Classification of Vessel Type.

(1). Conventional: Monohull vessels, of all rigid construction, meeting the followingdefinition:

V Lwl4where: V = Maximum Velocity (knots)

Lwl = Length (waterline) (m)

Such vessels include the following vessel types:

Aircraft Carriers, Assault Landing Ships, Frigates andDestroyers, Fleet Auxiliaryvessels, Port Auxiliary vessels, including tugs and fleet tenders.

(2). Unconventional: Vessels of any of the following groups:

(a). Monohull vessels of allrigid construction, meeting the following definition:

V Lwl>4

where: V = Maximum Velocity (knots)

Lwl = Length (waterline) (m)

(b). Monohull vessels having all or part of their primary hull constructioncomprising inflated or resilient material.

(c). Multihull vessels of all forms.

(d). Vessels having a significant proportion of their mass supported byaerostatic pressure, or hydrodynamic lift generated on either hull(s) orunderwater foils.

Such vessels include the following vessel types:

Planing and Semiplaning craft, Inflatable and Rigid Inflatable craft,Catamarans, Trimarans, SWATH Vessels, all Air Cushion Vehicles whetheramphibious or Surface Effect Ships, Hydrofoil craft, hybrids of above.


B.2

b. Definition of Vessel Loading Conditions

(1). Vessels Designed to MOD Standards

(a). Standard loading conditions for vessels designed to MOD standards aredefined below. SSP 24 provides further definition of loading conditions.

Basic Condition The condition of a vessel when complete and readyfor sea, including header tanks and system fluids, butwithout any stores, fluids in storage tanks, provi-sions, crew or ammunition.

Deep Condition The vessel is in all respects complete; fully comple-mented, ammunitioned, fuelled, stored and provi-sioned.

Light Condition The lightest condition of a vessel at sea; fullyequipped and crewed but with little fuel, fresh wateror provisions.

Light SeagoingCondition

This is a modified Light Condition with a revised setof liquid loading restrictions to meet the minimumstability criteria for vessels in service at sea.

Light HarbourCondition

This is the Light Condition with additional liquidloading restrictions necessary to meet the stabilitystandards for a vessel in service in harbour.

Table B1 Loading Conditions for Vessels Designed to MOD Standards

(b). See Table B.3 for tank states appropriate to each condition and Table B.4 forthe relevant stores conditions.

(c). A passenger can be considered as a person on board the vessel who is not amember of the normal operating complement.

(d). A Liquid Loading Restriction is considered as an operationally undesirableimposition of a restriction on the amount of a specific fluid that can beconsumed during operations, to maintain an acceptable level of stability.Where the ships operational regime by necessity requires ballast water to bepresent this shall not be considered as a liquid loading restriction. Forexample, maintenance of a specific draught for survey operations by ballastwater is not a liquid loading restriction. Maintenance of a minimum fuellevel to maintain a minimum level of stability is to be considered a liquidloading restriction.


February 2000

B.3

(2). Loading Conditions for Vessels designed to Legislation

(a). The relevant loading conditions for vessels designed to legislation are:

LightshipCondition

The vessel ready for sea, complete with permanentballast, outfit and spare gear, machinery andsystems, but with no fuel, fresh or feed water, luboil, provisions, consumable stores, crew and effectsor cargo on board.

DepartureCondition

Lightship plus all the deadweight items (fuel,fresh and feed water, lub oil, provisions, consumablestores, crew and effects and cargo) on board.

Arrival Condition Departure Condition less 90% of all consumables inthe deadweight. Water ballast may be necessary tomeet stability requirements.

Least StableCondition

The condition between the Departure and ArrivalConditions which results in least stability. Thecondition must still satisfy the stability criteria.There may be different Least Stable Conditions forintact stability and stability following damage.

Table B2 Loading Conditions for Vessels designed to Legislation

(3). Definition Of Variable Load States

Tank DeepCondition

BasicCondition

LightCondition

LightSeagoingCondition

LightHarbourCondition

Dieso BunkerTanks

95% Empty Empty AR AR

Water Dis-placed FuelTanks

100% Fuel Empty Empty 100%* Fuel AR

Service andRU FuelTanks

Workinglevel

Workinglevel

Workinglevel

Workinglevel

Workinglevel

Cargo FuelTanks


Feed Water:MainAuxiliaryReserveOverflow

95%95%95%95%

95%95%EmptyEmpty

95%95%EmptyEmpty

95%95%ARAR

95%95%ARAR

AVCAT Tanks 95% Empty Empty AR AR

Luboil StorageTanks

95% Empty 95% 95% 95%

Luboil DrainTanks

95% Empty 95% 95% 95%

Fresh WaterTanks



B.4

MiscellaneousDrainTanks

Empty Empty Empty Empty Empty

Ballast Tanks AD Empty AD AR AR

Sewage Tanksand Systems,Black/GreyWater Tanks

WorkingLevel

Empty WorkingLevel

WorkingLevel

WorkingLevel

Fresh WaterSystems

Full Full Full Full Full

Salt WaterSystems

Full Full Full Full Full

MiscellaneousSystemsand Tanks

Workinglevel

WorkingLevel

Workinglevel

Workinglevel

Workinglevel

*Notes:

Tank contents are to be of a practical nature. It is not intended that all tanks are to containslack fluid to give the least stable condition possible unless this is a likely operationalcondition.

Unless operator guidance specifically states that fuel in the water displaced tanks is to beused before fuel from the noncompensated tanks, special care must be taken to identifythe tank state with the lowest stability.

AR = As required by liquid loading instructions to achieve minimum stability criteria.

AD = As designed to meet specific operational requirements.

Table B3 Definition of Tank States

Item BasicCondition

DeepCondition

Light, LightSeagoing,

Light HarbourConditions

Equipment Storese.g. Naval Stores, NBCD Stores,Boatswains Stores.

Victualling Storese.g. Dry Provision and Refriger-ated Stores, NAAFI Compart-ments

Others

0

0

100

100

50

10

AircraftCommando GroupCommando VehiclesCommando AmmunitionAmmunitionOfficers, crew and effects

000000

100100100100100100

Least favourableLeast favourableLeast favourableLeast favourableLeast favourable

100

Note:

SSP 24 provides further definitions of vessel loading conditions.

Table B4 Definition of Variable Load States


February 2000

B.5

c. Watertight Subdivision and Integrity Definitions

(1). This annex contains definitions useful in the development of a watertightsubdivision policy and design details, for a vessel designed to MOD standards.

(a). Damage Control Deck: The lowest deck on which continuous foreandaftaccess, generally via watertight doors, is provided. The Damage ControlDeck should be above the lower apex, both longitudinally and transversely, ofthe Red Risk Line.

(b). Design Draught: The Design Draught is measured from the mouldedbaseline at amidships. It is to be determined when the vessel is in the DeepCondition (or Departure Condition if appropriate for vessel) with allspecified margins. In special circumstances, the operation of the vessel orthe specification may require that a higher waterline be used, such as thatderived from the draught following damage.

(c). Downflooding: Downflooding causes termination of a GZ curve when theeffect of the floodwater on the GZ curve at that angle is not accuratelymodelled. Therefore downflooding to an already flooded space need notcause termination of a GZ curve. Downflooding to an empty space cannot beadequately modelled and hence causes termination of the GZ curve.

(d). Red Risk Zone: The part of the ship, delineated by the Red Risk Line, is atimmediate risk of flooding following damage. Therefore all watertightclosures within the Red Risk Zone not closed by virtue of the ordered NBCDcondition need to be closed rapidly following damage and are markedaccordingly. The Red Risk Zone also provides a criterion for selecting theDamage Control Deck. The Red Risk Zone is determined from the highestextent of flooding following damage for the period of certification based onthe damage extents prescribed in the stability standards.

(e). VLines: VLines bound that part of the ship which is at some (notnecessarily immediate) risk of flooding following the worst extent of damagewhich the ship is required to survive provided that the watertightsubdivision is effective. Hence it is of paramount importance that themaintransverse bulkheads are of watertight construction up to the Vlines andthat all penetrations are fitted with glands and closures as appropriate.VLines are determined from the highest extent of flooding at a boundingbulkhead following damage at the end of life of the vessel based on thedamage extents prescribed in the stability standards that are applied at thestart of life and an allowance for the motion of the vessel due to the action ofwaves. Vlines are solely for the designers guidance and have no directsignificance to the operator.

(f). Weather Deck: The Weather Deck is the lowest deck or decks exposed to seaand weather loads, and is not to be taken lower than the watertight envelopefor the determination of the requirements for closing appliances.

(g). Waterline Length: The Waterline Length, Lwl, is the distance in metresmeasured at the Design Draught from the foreside of the stem to the afterside of the stern or transom.


B.6

(h). Watertight: Watertight boundaries must be continuous and of sufficientstrength to withstand water and/or air tests in accordance with ownersstructural requirements. A closing appliance is considered watertight if it iscapable of preventing the passage of water in either direction under a head ofwater for which the surrounding structure is designed. All openings belowthe watertight envelope in the outer shell envelope (and in main bulkheads)are to be fitted with a permanent means of watertight closure. Self closingdevices are not considered watertight.

(i). Weathertight: A closing appliance is considered weathertight if it is designedto prevent the passage of water into the ship in any sea condition. Allopenings above the watertight envelope and in enclosed superstructures areto be provided with weathertight closing appliances.


February 2000

C.1

ANNEX C.C.

PROCUREMENT CHECK LISTThis NES contains no Procurement Check List information.


C.2


February 2000

INDEX.1

ALPHABETICAL INDEXThis NES contains no Alphabetical Index


INDEX.2

Inside Rear Cover

Crown Copyright 2000

Copying Only as Agreed with DStan

Defence Standards are Published by and Obtainable from:

Defence Procurement AgencyAn Executive Agency of The Ministry of Defence

Directorate of StandardizationKentigern House65 Brown Street

GLASGOW G2 8EX

DStan Helpdesk

Tel 0141 224 2531/2 Fax 0141 224 2503

Internet e-mail [email protected]

File Reference

The DStan file reference relating to work on this standard is D/DStan/69/02/109.

Contract Requirements

When Defence Standards are incorporated into contracts users are responsible for their correctapplication and for complying with contractual and statutory requirements. Compliance witha Defence Standard does not in itself confer immunity from legal obligations.

Revision of Defence Standards

Defence Standards are revised as necessary by up issue or amendment. It is important thatusers of Defence Standards should ascertain that they are in possession of the latest issue oramendment. Information on all Defence Standards is contained in Def Stan 00-00 Standardsfor Defence Part 3 , Index of Standards for Defence Procurement Section 4 Index of DefenceStandards and Defence Specifications published annually and supplemented regularly byStandards in Defence News (SID News). Any person who, when making use of a DefenceStandard encounters an inaccuracy or ambiguity is requested to notify the Directorate ofStandardization (DStan) without delay in order that the matter may be investigated andappropriate action taken.

CONTENTSTITLE PAGESCOPECONTENTSFOREWORDSponsorshipConditions of ReleaseCategories of NESRelated DocumentsHealth and SafetyAdditional Information

1. PERFORMANCE SPECIFICATION1.1.1 General1.2 Intact Stability Criteria for Vessels Designed to MOD Standards with a Military1.2.1 GeneralFigure 1.1 -Examples of Minimum Acceptable GZ CurvesTable 1.1 -Shape Criteria for GZ CurveFigure 1.2 -Range and GZ Maximum Limitations1.2.2 Stability in Beam WindsTable 1.2 -Nominal Wind SpeedFigure 1.3 -Beam Winds Combined with Rolling1.2.3 Stability Under IcingTable 1.3 -Shape Criteria for GZ Curve with Ice1.2.4 Heeling Caused by High Speed TurningFigure 1.4 -High Speed Turning1.2.5 Lifting of Heavy WeightsFigure 1.5 -Lifting of Heavy Weights over the Side1.2.6 Crowding of Passengers on One SideFigure 1.6 -Crowding of Passengers to One Side1.2.7 Water on Deck1.2.8 Stability in Harbour1.2.9 Stability during Docking1.2.10 Firefighting

1.3 Damage Stability Criteria for Vessels Designed to MOD standards1.3.1 General1.3.2 Extent of Damage1.3.3 PermeabilityTable 1.4 -Permeability Factors1.3.4 Wind Speed1.3.5 Damage Stability CriteriaFigure 1.7 -Damaged Stability

1.4 Intact Stability Standards for Vessels Designed to MOD Standards with no1.4.1 General1.4.2 Stability of Vessels Making Bow or Body LiftsFigure 1.8 -Beam Wind CriteriaFigure 1.9 -Breaking Wire Criteria Initial ImpulseFigure 1.10 -Breaking Wire Criteria Steady State1.4.3 Stability of Vessels Performing a Bollard PullFigure 1.11 -Criteria for Vessels Performing a Bollard Pull

1.5 Damaged Stability Standards for Vessels Designed to MOD Standards with no1.5.1 General1.5.2 Extent of Damage1.5.3 Damaged Stability Criteria

2. NATIONAL/INTERNATIONAL REGULATIONS2.3. MILITARY STANDARDS/REQUIREMENTS3.3.1 Stability Related Military Design Requirements3.1.1 Watertight Subdivision And Integrity3.1.2 Calculation of the Red Risk Line3.1.3 Calculation of the V LinesFigure 3.1 -Minimum Extent of Watertight Subdivision and IntegrityFigure 3.2 -Envelope of Damaged WaterlinesFigure 3.3 -Angle of Heel Used to Derive Red Risk Zone and V Lines

4. DESIGN REQUIREMENTS/GUIDANCE4.4.1 Stability Related Design Requirements4.1.1 Provision of Freeing Ports for Ships with Bulwarks

5. CORPORATE EXPERIENCE & KNOWLEDGE5.ANNEX A. RELATED DOCUMENTSANNEX B. ABBREVIATIONSTable B1 -Loading Conditions for Vessels Designed to MOD StandardsTable B2 -Loading Conditions for Vessels designed to LegislationTable B3 -Definition of Tank StatesTable B4 -Definition of Variable Load States

ANNEX C. PROCUREMENT CHECK LISTALPHABETICAL INDEX

nes 109 stability standards for surface ships

Documents

naval engineering standard

nes supersedesnes

complete nes

stability standards

ministry of defence

conventional shipspart

surface shipspart

maritime standards