 |
| 40 | STCW 95 Synopsis. |
| 41 | Electro hydraulic steering gear. |
| 42 | Tugs girding, scouring. |
41.
Standards For
Training & Certification For Watchkeepers
Stcw’ 78 Adopted On 7th July 1978 Which Came Into Force On 28th April 1984, This Convention Had Limited Knowledge And No Skilled Training Programs. Transparency Of The Certification Was Seen Lacking So A New Convention Called Stcw 95 Was Adopted By The Imo On The 1st Feb 1999.
Stcw’ 95
Comprises Of 17 Articles Of 36 Mandatory Regulations Laid Out In 8 Chapters As Compared To Stcw’ 78, Which Comprised Of 17 Articles Of 25 Mandatory Regulations Laid Out In 6 Chapters.
Stcw’
78
|
Stcw’
95
|
| 1.
General Provisions |
|
| 2.
Master Deck Dept |
|
| 3.
Engine Dept |
|
| 4.
Radio Personnel. |
Radio
Comm. & Radio Personnel
|
| 5.
Sp. Req. For Tankers |
Special
Training For Persons On Ships
|
| 6.
Proficiency In Survival Craft |
Emergency
Occupational Safety, Medical Care & Survival Functions. |
| 7.
|
Certificates
For Officers Defining Functions. |
| 8.
|
Contains
2 Regulations
|
Reg. Viii/1 Deals With Fitness Of Duty
Reg. Viii/2 Deals With Watchkeeping Arrangements And Principles To Be Observed.
The Old Certificates Issued Under The ’78 Convention Shall Be Valid Only Until 1st Feb 2002. Thus Before This Day All 78 Convention Certificates Holders Should Renew Their Certificates By Doing A Refresher Course And Updating Training And Assessment As Well As Additional Modular Courses Specified Under The Provisions Of Stcw ’95.
New Certificates Shall Be Valid For 5 Years And In Order To Revalidate The Certificate The Seafarer Will Have To Meet The Standards Of Medical Fitness & Establish Continued Professional Competence As Required By The Imo.
1
All Persons Who Are Assigned Duty As Officer In Charge Of A
Watch Or As Rating Forming Part Of A Watch Shall Be Provided A
Minimum Of 10 Hours Of Rest In Any 24 Hour Period.
2 The Hours Of Rest May Be Divided Into No More Than Two Periods, One Of Which Shall Be Atleast 6 Hours In Length.
3 The Requirements For Rest Periods Laid Down In Paragraphs 1 And 2 Need Not Be Mantained In The Case Of An Emergency Or Drill Or In Other Overriding Operational Conditions.
4 Not Withstanding The Provision Of Paragraphs 1 And 2, The Minimum Period Of 10 Hours May Be Reduced To Not Less Than 6 Consecutive Hours Provided That Any Such Reduction Shall Not Extend Beyond Two Days And Not Less Than 70 Hours Of Rest Are Provided Each Seven Day Period.
5 Administration Shall Require That Watch Schedules Be Posted Where They Are Easily Acessible.
42.
·
This Is Perhaps The Most Popular Type Of Steering Gear. Referring
To The Diagrammatic Lay-Out As Shown In The Figure;
·
It Consists Of A Hydraulic Ram Situated On The Port Side Of The
Tiller And Other Ram On The Starboard Side, Linked At Their Outer
Ends To The Tiller Arm By A Crosshead And Swivel Block.
·
The Other Ends Of The Rams Working Inside Their Own Hydraulic
Cylinders And Pieps Connect These Cylinders To A Hydraulic Pump.
·
Special Mineral Oil Is Used As The Hydraulic Medium And The
Function Of The Pump Is To Draw Oil From One Cylinder And Pump It
At High Pressure Into The Other, Thus Causing One Ram To Move Out
And Push The Tiller Over While The Other Ram Moves Back Into The
Cylinder.
·
The Hydraulic Pump Is A Rotary Displacement Type Driven
Continuously By An Electric Motor.
·
The Pump Is Of A Special Construction And May Be An Hele-Shaw Or
Williams-Janney Design.
·
It Runs Continuously In The Same Direction And The Position Of A
Movable Plate Inside The Pump, Controls The Suction And Discharge
Of The Oil.
·
When The Plate Is In Mid Position, No Oil Is Drawn In Or
Discharged And When The Plate Is Moved In One Direction From Mid
Position Oil Is Drawn From One Cylinder And Discharged Into The
Other.
·
When The Plate Is Moved In The Opposite Direction The Suction And
Discharge Of Oil Are Reversed In Direction.
·
This Plate Is Actuated By A Rod, Which Is Attached At Its Outer
End To The Hunting Lever.
·
If Heavy Seas Strike The Rudder, The Shock Is Transmitted Through
The Tiller To The Rams.
·
This Causes A Suddern Increase In Oil Pressure In One Of The
Cylinders And A Double Spring Loaded Relief Valve Allows The
Tiller To Give Way Slightly By By-Passing A Little Of The Oil
Into The Other Cylinder.
·
|
The Resultant Displacement Of The Rudder, Tiller And Ram
Crosshead Moves The Pump Control Rod Through The Hunting Gear And
The Tiller Is Brought Back To Its Original Position.
·
The Hunting For This Type Of Steering Gear Is A Simple
Arrangement Of Levers And Will Be Readily Understood By Referance
To The Figure.
·
If The Telemotor Link Is Moved To The Right, The Hunting Lever
Will Swivel About ‘A’ As A Fulcrum And The Pump Control
Rod Will Be Pushed Inwards.
·
The Pump Will Then Draw Oil From The Right Cylinder And Discharge
It Into The Left And The Crosshead And The Tiller Will Begin
Moving To The Right.
·
As The Crosshead Moves, ‘B’ Now Acts As The Fulcrum For
The Hunting Lever And The Movement Of ‘A’ To The Right
Will Cause The Other End, Connected To The Control Rod, To Move
Outwards To Bring The Control Plate In The Pump Back To Its Mid
Position.
·
The Pump Will Cease To Deliver Oil And The Gear Will Come To
Rest.
·
A Four Ram Hydraulic Steering Gear May Be Fitted On Large Ships
For Greater Steering Power, Instead Of The Two Ram Type As
Described Above.
·
The Four Ram Unit Is Simply A Double Two Ram Unit, The Tiller
Having A Double Arm So That The Force Of The Two Diagonally
Opposite Rams Can Act On The Tiller To Produce Double The Turning
Effect.
·
The Rotary Vane Type Of Steering Gear System Is A More Recent
Development Of The Hydraulic Steering Gear.
·
It Consists Of A Rotor, Which Is A Taper Fit On The Rudderstock
And Keyed To It, And A Stator Of A Larger Internal Diametre Than
The Outside Diametre Of The Rotor To Form An Annular Space
Between Them.
·
The Stator Being Firmly Fixed To The Ships Structure To Prevent
Its Rotating.
·
The Rotor Has Equidistantly Spaced Outwardly Projecting Radial
Vanes, And The Stator Has Similar Vanes Projecting Inwards, The
Spaces Between The Vanes Form Segmental Pressure Chambers For The
Highpressure Hydraulic Oilsupplied From The Variable Delivery
Pumps.
·
Oil Sealing Between The Ends Of The Vanes And Their Opposite
Working Surface Is Effected By Ruber-Backed Steel Strips In
Grooves In The Vanes.
·
The Pressure Chambers Between The Rotor And The Stator Vanes Are
Divided Into Two Sets So That When The Oil At A High Pressure Is
Supplied To One Set And Drawn Form The Other, The Rotor Will Be
Forced To Rotate In One Direction Turning The Rudder Stock With
It.
·
By Reversing The Oil Flow The Rotor And The Rudderstock Will
Rotate In The Opposite Direction.
·
Allowing For The Thickness Of The Vanes, A Unit Of Three Rotor
Vanes And Three Stator Vanes Will Permit A Rudder Movement Of 35
Degs To Extreme Port Or Stbd From Mid Position.
·
A Total Angle Of 70 Degs. Is Achieved And The Vanes Also Act As
Rudder Stops.
·
Relief Valves And By-Pass Valves Are Incorporated In The Oil
System To Absorb Rudder Shocks.
·
Compared To The Four Ram Steering Gear, The Cost Of The Rotary
Vane Type To Produce The Same Torque On The Rudder Stock Is
Generally Less, It Is Lighter In Weight, Takes Up Less Space And
Is Easier To Maintain.
43.
Girding: Is The Term Used To Describe A Tug Being Towed Sideways By The Vessel She Is Supposed To Tow.
· The Danger Arises When The Vessel Moves Suddenly Ahead Or Astern Without Giving Any Warning To The Master, So That Before The Tug Master Can Swing His Tug In Line With His Tow Line, The Tow Line Leads Abeam.
· This Is A Very Dangerous Situation And The Tug may Even Capsise Often With A Heavy Loss Of Life.
· The Height Of The Towing Hook, The Speed And The Rate Of Swing Of The Towed Vessel Are All Very Important Factors. Ample Warning Must Therefore Be Given To The Tugs If The Vessel Is To Move Ahead Or Astern Or If The Likely hood Presents Itself.
· The Girding Of The Tug May Be Avoided By Using A Gob Line.
· It Is A Small Length Of Rope Which Is Used To Bowse The Tow Line To The Stern Of The Tug To Prevent Girding.
· It Is The Term Given To The Use Of A Stream Of Water From A Tugs Propellers Directed As Far As Possible To Scour Away The Sea Bed Which Is Silting Up The Stranded Hull.
· It Is Often This Silting Which Exerts Pressure Holding The Vessel In Place.
Procedure For Scouring:
· The Area Should Be Roughly Surveyed And The Depth Checked.
· Tug Is Secured To The Ship By A Hawser From The Towing Hook.
· The Manila Hawser Is Lead To Each Quarter For Heaving The Tug Up And Down The Ships Side And The Head Rope For Each Bow For Altering The Tugs Inclination To The Ships Fore And Aft Line.
· The Tugs Should Have Both Her Anchors Out On An Open Moor.
· If Tunneling Beneath The Keel, The Tugs May Make An Angle Of 70 Degs With The Vessel And If The Bilge Area Is To Be Cleared Then The Angle Is 30 Degs.