BALANCED RUDDER

Description

Before the balanced rudder, all ships employed a rudder that was a simple flat piece of wood or metal, situated at the after end of the hull and hinged at the forward end, which could be angled to one side or the other to deflect the water passing it and hence provide an impulse to turn the ship. This required the exertion of significant force, as the passage of the water past the rudder tended to force it into a straight line in conformity with the flow.

The concept of a balanced rudder involved the shifting of the centre of rotation of the rudder to point approximately 1/2 of the way from the forward end to the after end. This meant that when the rudder was turned, the flow of water past the ship actively worked on the forward third to increase the angle of deflection, whereas the same flow acted on the after 1/2 to reduce the angle.

The mechanics of fluid dynamics produced a solution in which the turning force applied in one direction on the rudder by the passing fluid was balanced by the turning force applied in the other direction, allowing the rudder to be moved with only limited mechanical resistance.

The balanced rudder was soon adopted by the fledgling aircraft industry in the early 20th century, which often made use of the horn balance, in which a section of the rudder, usually at the top of the vertical stabiliser, projected into the airstream. Two illustrations of aircraft rudders published by Flight Magazine in 1920,^[1] illustrate both the conventional balanced rudder (at lower left on the Short Swallow) and with a large 'horn' (at left centre, in this case in the form of a semicircle, on the 'Short Sporting Type').

Different types of balanced rudder shown: 3 balanced, 4 semi-balanced, 5 non-balanced (hinged about axis 'A')

How Is Water In Double Bottom Tanks & Bilge Spaces Handled?

Introduction

We have learnt about the pipline arrangement on ships and also tips on how to identify pipeline systems used for different purposes such as lubricating oil, sea water and so forth. In this article we will study the general piping arrangement on a ship relating to bilge pipes as well as DB tank pipe fitting arrangement. Basically these types of piping systems are used for ballasting/deballasting operations, flood water removal and bilge water handling.

Piping Arrangement

Regarding the bilge pipes, you can see figure 1 below. As you will notice, there is an elaborate system of pipes which run through the bilges in all areas of the ship. The symbols for the various objects shown in the diagram are as follows

• Inverted triangle – mud boxes
• Circles – non return bilge valves
• Circles with a line diametrically across it – flap valves non return
• Thick dots – sounding pipes

The bilge injection valve can be seen towards the bottom of the image somewhere towards the left hand side of the centre portion. The various pumps shown in the picture consist of

• Bilge pump
• General Service pump
• Sanitary pump
• Ballast pump

The various areas of the ship have means for suction through some pump or the other and most of the pumps and pipes are interconnected and can be used appropriately as the situation demands either in routine operations or emergency situations.

Similarly the diagram in figure 2 shows the piping arrangement for the deep tanks of the ship, which are also known as double bottom or db tanks. These are mainly used for ballasting procedures. If you are wondering why are these pipelines not in common which will save cost and equipment; I must tell you that this is mandatory as per IMO regulations that the bilge pipes cannot pass through the DB tanks and they have to be a part of a separate system. In case there is a common pump it should have appropriate isolating arrangement in terms of non return valves or one way cocks.

One such is shown in the diagram and you can notice that it has two pipe connections to it, one for suction and the other for discharge of the sea water. Similarly the ballast pumps can either take water from the sea for delivery to the deep tanks or vice versa depending on whether the ballasting or deballasting operation is required to be performed.

Important

An important rule which always needs to be followed in laying down the ballast piping arrangement is that there should not be any possibility of the ballast water to gain access to areas which carry dry cargo. Similarly regulations also state that there should be ample provision to ensure that the water ballast and the fuel of the ship are always isolated from one another.

Last but not least, I must say that since there are so many types of ships which are used for different purposes, it is not easy to generalize the piping systems in all of them. The above described features fit most aptly on cargo vessels though other type of ships are not much different at least in principle if not in the actual layout of the pipelines.

Read more: http://www.brighthub.com/engineering/marine/articles/48582.aspx#ixzz1C9gnI5Ko

Double hull

A double hull is a ship hull design and construction method where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some distance inboard, typically by a few feet, which forms a redundant barrier to seawater in case the outer hull is damaged and leaks.

The space between the two hulls is often used for storage of fuel or ballast water.

Double hulls are a more extensive safety measure than double bottoms, which have two hull layers only in the bottom of the ship but not the sides.

In low-energy casualties, double hulls can prevent flooding beyond the penetrated compartment. In high-energy casualties, however, the distance to the inner hull is not sufficient and the inner compartment is penetrated as well.

Double hulls or double bottoms have been required in all passenger ships for decades as part of theSafety Of Life At Sea or SOLAS Convention.^{[citation needed]}

One of the disadvantages of a double hull is that the stability of a ship can be less than that of a single hull. Because the double hull raises the centre of gravity, the metacentric height is reduced.

Under water survey

GUIDE FOR THE CLASS NOTATION

UNDERWATER INSPECTION IN LIEU OF

DRYDOCKING (UWILD)

APRIL 2007

American Bureau of Shipping

Incorporated by Act of Legislature of

the State of New York 1862

Copyright

American Bureau of Shipping

ABS Plaza

16855 Northchase Drive

Houston, TX 77060 USA

© 2007

ABS

GUIDE FOR THE CLASS NOTATION UNDERWATER INSPECTION IN LIEU OF DRYDOCKING (UWILD) . 2007 ii

Foreword

Foreword

This Guide aims to consolidate the classification requirements, currently specified in Appendix 7-A-1

of the ABS

response to the industry and market demands.

This consolidated

(UWILD)

as specified in Appendix 7-A-1 of the ABS

improve the usefulness as a Guide, some reorganization of the text and additional information are

provided.

Rules for Survey After Construction (Part 7) for the optional class notation (UWILD) inGuide for the Class Notation Underwater Inspection In Lieu of Drydocking Surveyis prepared for the user’s convenience, but intends to change the current applicable requirementsRules for Survey After Construction (Part 7). In order to

ABS

GUIDE FOR THE CLASS NOTATION UNDERWATER INSPECTION IN LIEU OF DRYDOCKING (UWILD) . 2007 iii

Table of Contents

GUIDE FOR THE CLASS NOTATION

UNDERWATER INSPECTION IN LIEU OF

DRYDOCKING (UWILD)

CONTENTS

SECTION 1 Introduction ............................................................................1

1 Scope and Application........................................................... 1

3 Approval Procedure............................................................... 1

5 Governmental Regulations.................................................... 1

FIGURE 1 Approval Procedures for UWILD Class Notation ........ 1

SECTION 2 Conditions and Procedures .................................................. 2

1 General.................................................................................. 2

3 Conditions.............................................................................. 2

3.1 Limitations .........................................................................2

3.3 Existing Outstanding Recommendations...........................2

3.5 Thickness Measurements and Nondestructive Testing .....3

3.7 Tailshaft Surveys...............................................................3

3.9 Plans and Data..................................................................3

3.11 Underwater Conditions......................................................3

5 Physical Features.................................................................. 3

5.1 Stern Bearing ....................................................................4

5.3 Rudder Bearings ...............................................................4

5.5 Sea Suctions .....................................................................4

5.7 Sea Valves ........................................................................4

7 Procedures ............................................................................ 4

7.1 Exposed Areas..................................................................4

7.3 Underwater Areas .............................................................4

7.5 Damage Areas ..................................................................5

7.7 Planning ............................................................................5

9 Alternatives............................................................................ 5

11 Maintenance of UWILD Class Notation................................. 5

ABS

GUIDE FOR THE CLASS NOTATION UNDERWATER INSPECTION IN LIEU OF DRYDOCKING (UWILD) . 2007 1

Section 1: Introduction

S E C T I O N

 

1 Scope and Application

A request for Underwater Inspection may be accepted as an alternative to Drydocking Inspection

provided that all arrangements and equipment meet the requirements specified in this Guide.

For vessels 15 years of age or over and subject to the Enhanced Survey Program (ESP), Underwater

Inspections in Lieu of Drydocking (UWILD) are not permitted as an alternate Drydocking Surveys.

3 Approval Procedure

An ABS optional notation,

to a vessel in full compliance with the requirements as specified in this Guide. The entire procedure

for assignment of the

UWILD, for Underwater Inspection in Lieu of Drydocking, is to be assignedUWILD notation is shown in Section 1, Figure 1.

5 Governmental Regulations

The requirements specified in this Guide are for classification only. Flag Administrations may have

specific regulations for Underwater Surveys in Lieu of Drydocking, including requirements for enrollment,

hull markings, extent of visibility and procedures for older vessels.

FIGURE 1

Approval Procedures for UWILD Class Notation

UWILD

1.Request for

(by Owner/Operator)

2.Preparation and submission of plans as

required by 2/3.9, 2/5

3.Initial survey of underwater hull markings

and other means of orienting the diver

during new construction

OR

An out-of-water drydocking (Existing Vessel)

4.Issue certification of compliance

with

UWILD NotationUWILD requirements

ABS

GUIDE FOR THE CLASS NOTATION UNDERWATER INSPECTION IN LIEU OF DRYDOCKING (UWILD) . 2007 2

Section 2: Conditions and Procedures

S E C T I O N

2 Conditions and Procedures

1 General

At the request of the Owner, the Bureau may consider Underwater Inspection in Lieu of Drydocking

Survey provided all arrangements and conditions meet the requirements of the Guide.

All requests for Underwater Inspection in Lieu of Drydocking Survey are to be forwarded to the

applicable ABS Divisional Assistant Chief Surveyor’s Office for review and authorization.

Underwater inspection is to be carried out by a qualified diver under the surveillance of the attending

Surveyor. The diver is to be employed by a firm approved by the Bureau as a service supplier.

The Surveyor is to be satisfied with the method of pictorial representation, and a good two-way

communication between the Surveyor and divers is to be provided.

If the Underwater Inspection reveals damage or deterioration that requires further attention, the Surveyor

may require that the vessel be drydocked in order to undertake a detailed survey and necessary repairs.

The extent of the underwater inspection is to be sufficient to include all items which would normally

be examined if the vessel was on drydock, some of which are listed in 2/7.3.

The following Subsections describe the conditions and procedures under which a properly conducted

underwater inspection may be credited as an alternative of Drydocking Survey.

3 Conditions

3.1 Limitations

i) Non-ESP

subject to special consideration based on the following review and examination before being

permitted to have underwater inspection:

vessels 15 years of age or over applying to maintain their UWILD notation are

•

Review of vessel’s records to ensure that no unusual repairs have been required/made

•

Internal examination of representative tanks and cargo holds

ii)

where there is record or indication of abnormal deterioration, existing recommendation, or

damage to underwater body, rudder, or propeller.

Underwater Inspection In Lieu of Drydocking Survey (UWILD) may be restricted or limited

3.3 Existing Outstanding Recommendations

UWILD may not be applicable if there are outstanding recommendations for repairs to propeller, rudder,

stern frame, underwater structure, or sea valves. It may also be inapplicable if damage affecting the

fitness of the vessel is found during the course of the survey.

 

3.5 Thickness Measurements and Nondestructive Testing

Underwater or internal thickness measurements of suspect areas may be required in conjunction with

the underwater inspection. Means for underwater nondestructive testing may also be required for fracture

detection.

Note

drydock in conjunction with visual inspection of the bottom plating by the Surveyor.

Thickness measurements of the hull underwater body, as required for Special Periodical Survey, are to be taken at

3.7 Tailshaft Surveys

Tailshaft Surveys are not covered by this Guide and are to be dealt with in accordance with Chapter 5

of the ABS

Rules for Survey After Construction (Part 7) and other applicable Rules.

3.9 Plans and Data

Plans showing the following items are to be submitted to the attending Surveyor, together with the

proposed inspection procedures for review, well in advance of the inspection.

i)

bottom plugs, appendages and all underwater openings.

Location of bottom shell seams and butts (Shell Expansion), including any doublers, straps,

ii)

specific areas of plating, (e.g., locations of bulkheads or tanks) sea suction and discharge

openings, propeller blades and rudder surfaces. Such preparations may include a weld bead

grid system on the hull, a contrasting color coating system, a movable grid, an acoustic locating

system, or any other arrangement that is satisfactory to the Surveyor.

Hull markings or other means to orient the diver and identifying photographs, which entail

iii)

means of access to sea chests to inspect the external side of hull connections and sea values,

to rudder bearings to determine clearances of rudder bearings or to propeller shaft strut and

stern bearings.

Reference data and instructions to the diver for any necessary underwater operations such as

vi)

scantlings for the underwater body.

Most recent gaugings and gauging report from last Special Periodical Survey and the as-built

3.11 Underwater Conditions

i)

permit meaningful examination and photography by the diver. “Sufficiently clean” is taken to

mean that sections of the underwater body, including flat keel plating forward, amidships and

aft, are cleaned to the extent that the Surveyor can determine the condition of the plating, the

welding and the coating. Additional cleaning may be necessary. Overall or spot cleaning may

be required at the discretion of the attending Surveyor.

The vessel’s underwater body is to be sufficiently clean and the sea water is clear enough to

ii)

with weak tidal streams and currents and with the vessel at light draft.

Where possible, the underwater examination should be carried out in protected waters, preferably

5 Physical Features

The following physical features are to be incorporated into the vessel’s design in order to facilitate the

underwater inspection. When verified, they are to be noted in the vessel’s records for reference at

subsequent surveys.

Section 2 Conditions and Requirements

ABS

GUIDE FOR THE CLASS NOTATION UNDERWATER INSPECTION IN LIEU OF DRYDOCKING (UWILD) . 2007 4

5.1 Stern Bearing

i)

bearings and to verify that the clearance or weardown is within limits on the stern bearing

Means are to be provided to ascertain that the seal assembly remains intact on oil-lubricated

ii)

including accurate oil-loss records and a check of the oil for contamination by sea water or

white metal and/or oil sample reports (considerations are to be included in the proposals for

UWILD). For wood or rubber bearings, an opening in the top of the rope guard and a suitable

gauge or wedge is sufficient for checking the clearance.

For oil-lubricated bearings, this may require the review of operating history and onboard testing

iii)

checked by external measurements or by the vessel’s wear-down gauge, where the gauge wells

are located outboard of the seals or the vessel can be tipped. For use of the wear-down gauges,

up-to-date records of the base depths are to be maintained onboard the vessel. Whenever the

stainless steel seal sleeve is renewed or machined, the base readings for the wear-down gauge

are to be re-established and noted in the vessel’s records and in the survey report.

Any doubt on wear-down of oil-lubricated metal stern bearings from above is to be further

5.3 Rudder Bearings

Means and access are to be provided to determine the condition and clearance of the rudder bearings,

and verify that all parts of the pintle and gudgeon assemblies are intact and secure. This may require

bolted access plates and a measuring arrangement.

Where it is deemed impractical, clearance verification on the rudder pintle may be dispensed with if

the attending Surveyor is satisfied with the physical condition and securing arrangements of the pintle,

the operating history and the onboard testing. These considerations are to be included in the proposals

for UWILD.

5.5 Sea Suctions

Means are to be provided to enable the diver to confirm that the sea suction openings are clear. Hinged

sea suction grids may be used to facilitate this operation.

5.7 Sea Valves

Sea valves and their attachment to sea chests are to be examined externally, including expansion pieces

in sea water cooling and circulating systems.

7 Procedures

7.1 Exposed Areas

An examination of the outside of the shell plating above the waterline and exposed portions of appendages

(such as propeller, rudder and rudder bearings) is to be carried out by the attending Surveyor. Means

are to be provided to enable the Surveyor to accomplish this visual inspection.

7.3 Underwater Areas

An examination of the entire vessel below the waterline is to be carried out by an ABS-approved diver

using closed-circuit television with two-way communication. The progress of the dive is to be

monitored by the onboard Surveyor as required, or is to be photographically documented, or both,

depending on the age and type of vessel. Items that must be recorded on the tape/photograph include

but are not limited to:

i)

Time at which dive commences

ii)

iii)

Time viewed

iv)

Conditions of hull markings

v)

Random areas of plating

vi)

All sea chests

vii)

All inlets and discharges

viii)

Rudder

ix)

Pintles

x)

Propeller

xi)

The above examination is to be supplemented by the diver’s report describing and attesting to the

conditions found. A copy of this report and pertinent photographs are to be submitted to the attending

Surveyor. Copies are also to be retained onboard.

Time and point of completion of the dive;

7.5 Damage Areas

Damage and corrosion areas are to be taped/photographed. Internal examination or thickness gauging

of such locations may be necessary, as determined by the attending Surveyor. Means are to be provided

for orienting and identifying underwater surfaces in photographs, as noted in 2/3.9ii).

7.7 Planning

The equipment and procedure for observing and reporting the survey are to be discussed with the

parties involved prior to the UWILD, and suitable time is to be allowed to permit the diving company

to test all equipment beforehand.

9 Alternatives

The Bureau is prepared to consider alternatives to the above guidelines.

11 Maintenance of UWILD Class Notation

For maintenance of the UWILD notation, a vessel’s markings and equipment installed for UWILD are to be satisfactorily verified by the attending Surveyor at each Drydocking.

ABS GUIDE FOR THE CLASS NOTATION UNDERWATER INSPECTION IN LIEU OF DRYDOCKING (UWILD) . 2007 5Point of commencement

1 Introduction

GUIDELINES FOR PRE-PLANNING OF SURVEYS IN DRY DOCK

INTERNATIONAL MARITIME ORGANIZATION

4 ALBERT EMBANKMENT

LONDON SE1 7SR

Telephone: 020 7735 7611

Fax: 020 7587 3210

IMO

E

Ref. T4/8.01 MSC.1/Circ.1223

11 December 2006

GUIDELINES FOR PRE-PLANNING OF SURVEYS IN DRY DOCK

OF SHIPS WHICH ARE NOT SUBJECT TO THE ENHANCED

PROGRAMME OF INSPECTIONS

1 The Maritime Safety Committee, at its eightieth session (18 to 27 May 2005) recognized

that pre-planning is essential in order to ensure that major necessary repairs and maintenance

works were effectively carried out during dry docking and that it was the duty of shipowners to

prepare the dry dock survey.

2 The Committee further recognized that resolution A.948(23) did not provide for

pre-planning of surveys carried out in the dry dock whereas resolution A.744(18) did impose a

planning for the intermediate and renewal surveys, which are to include a survey in dry dock

depending on the vessel’s age, conducted under the enhanced programme of inspection and

therefore tasked the Flag State Implementation Sub-Committee, at its fourteenth session, to

develop a draft circular for the pre-planning of surveys in dry dock of ships which are not subject

to the enhanced programme of inspections.

3 The Committee, at its eighty-second session (29 November to 8 December 2006),

approved the Guidelines for pre-planning of surveys in dry dock of ships which are not subject to

the enhanced programme of inspections, as set out in the annex.

4 Member Governments are invited to bring the annexed Guidelines to all the parties

concerned for their application for pre-planning of surveys in dry dock of ships which are not

subject to the enhanced programme of inspections.

***

MSC.1/Circ.1223

I:\CIRC\MSC\01\1223.doc

ANNEX

GUIDELINES FOR PRE-PLANNING OF SURVEYS IN DRY DOCK

OF SHIPS WHICH ARE NOT SUBJECT TO THE ENHANCED

PROGRAMME OF INSPECTIONS

Scope

1 These Guidelines apply to ships which are not subject to the enhanced programme of

inspections (resolution A.744(18), as amended).

2 Discretion may be exercised in the application of these Guidelines for smaller sized ships

(e.g., cargo ships of less than 100 m in length

the surveyor can occur during, rather than in advance of, the survey in dry dock as dry docks for

these smaller ships are much more available and the dry docking of these ships occurs more

promptly and with much less advanced notice than it does for larger ships.

∗) where the meeting held between the owner and

Objective

3 To assure that a survey in dry dock will be effectively and safely carried out in

accordance with the relevant rules and regulations applicable to the ship and that major necessary

repairs and maintenance will be effectively undertaken, the owner, the attending surveyor and

other interested parties (e.g., a representative of the thickness measurement company), should

co-operate and meet in advance of the dry-docking survey.

Pre-planning meeting

4 A pre-planning meeting should occur in advance to co-ordinate the work to be undertaken

during the survey which should include, as a minimum, a review of the following information:

.1 survey status and basic ship information;

.2 survey records from the previous bottom survey;

.3 details of any outstanding recommendations or known damaged areas (due to

grounding, lightering, etc) that affect or may affect the dry-docking survey;

.4 details of any known structural damage previously suffered by the ship;

.5 reports of known structural repairs that will be carried out during the dry-docking

survey; and

.6 details of any additional items to be surveyed, thickness measurements to be taken

and known maintenance work that will be carried out during the dry-docking

survey.

Dry Docking

Preparation of Dry Docking

Dry Dock Periods

A docking survey should be carried out twice within a 5 year period. The intermediate survey must be completed within 3 years. One of the two docking surveys within the 5 year period should coincide with a special survey. A Docking Survey is considered to coincide with the Special Survey when held within the 15 months prior to the due date of the Special Survey. An in water survey may be accepted in lieu of the intermediate survey For vessels operating in fresh water special consideration may be given.

In-water Surveys

An In-water Survey may be accepted in lieu of the intermediate docking between Special Surveys, an *IWS notation is assigned. This requires suitable underwater protection for the hull in part taking the form of high resistance paint. This survey is to provide information normally obtained from a docking survey.

The In-water Survey is to be carried out at agreed geographical locations under the surveillance of a Surveyor to LR, with the ship at a suitable draught in sheltered waters; the in-water visibility is to be good and the hull below the waterline is to be clean. The Surveyor is to be satisfied that the method of pictorial presentation is satisfactory. There is to be good two-way communication between the Surveyor and the appropriately qualified diver.

Should damage be found a dry dock may be required for better inspection

Dry Dock file

Preparation for dry dock begins after the ship sails from its previous one. A dry-dock list of new items is created with specification sheets describing individual jobs. These sheets are compiled into a dry dock file which some time before the due date of the docking is submitted to several dry docks for pricing.

The jobs are priced individually and as a whole. This allows the ship managers to streamline the jobs to provide maximum value for money.

Preparation

The vessel must be prepared before entering the dry dock. Structural loading must be taken into account as the vessel is to be point supported on blocks. A docking plan of the ships which shows such things as drain plugs, sea boxes, underwater attachments etc is sent to the dry dock. Added to this are indications where hull repairs are required. This allows the drydock ship managers to place the blocks on which the vessel will sit.

The vessel must be trimmed so as to be equal draught with zero list. Special attention should be made when planning this for any tanks whose contents may be varied due to repair or housekeeping requirements.

In dock

The safety and fire fighting responsibilities of the vessel are handed over to the dry dock safety department for the duration of the dry and wet dock period. All hot work, tank entry or jobs requiring special safety measures carried out by ships crew must be first agreed with the dry dock safety department. A daily meeting is held to discuss forth coming jobs and any special requirements. This also allows the vessels staff and company representatives to monitor the progress of the dock.

Inspections & Measurements

Where a ship is in dry-dock or on a slipway it is to be placed on blocks of sufficient height, and proper staging is to be erected as may be necessary, for the examination of the shell including bottom and bow plating, keel, stern, sternframe and rudder. The rudder is to be lifted for examination of the pintles if considered necessary by the Surveyor.

Attention is to be given to parts of the structure particularly liable to excessive corrosion or to deterioration from causes, such as chafing and lying on the ground, and to any undue unfairness of the plating of the bottom.

The clearances in the rudder bearings are to be measured.

The sea connections and overboard discharge valves and their attachments to the hull are to be examined.

The propeller, sternbush and sea connection fastenings and the gratings at the sea inlets are to be examined.

The clearance in the sternbush or the efficiency of the oil glands is to be ascertained.

When chain cables are ranged, the anchors and cables are to be examined by the Surveyor.