IntroIntro

Only training and « hands-on » experience take the mysteryOnly training and « hands-on » experience take the mystery out of shiphandlingout of shiphandling

IntroIntro

Manoeuvring characteristics of ships:Manoeuvring characteristics of ships:

– « Course keeping ability » and « Dynamic stability »« Course keeping ability » and « Dynamic stability »• Dynamically stable ship after small disturbance move along a Dynamically stable ship after small disturbance move along a

new straight course without using ruddernew straight course without using rudder• Dynamically unstable ship performs turning circle with rudder Dynamically unstable ship performs turning circle with rudder

amidshipsamidships• Dynamically unstable ships are more difficult to handleDynamically unstable ships are more difficult to handle

– « Turning ability »« Turning ability »• Measure of ability to turn the ship with hard-over rudderMeasure of ability to turn the ship with hard-over rudder• Obtained by performing a « turning circle » manœuvreObtained by performing a « turning circle » manœuvre• « Initial turning ability » is defined by the amount of heading « Initial turning ability » is defined by the amount of heading

deviation per unit of distance travelleddeviation per unit of distance travelled

Intro / Dynamic stabilityIntro / Dynamic stability

Intro/ Dynamic stabilityIntro/ Dynamic stability

• Dynamically stable- Fine line ships (cargoships, containerships,

passengerships) tend to be directionally stable- directionally stable ship will move on a straight course if

rudder is kept amidships- When during a turn, rudder is put amidships: rate of turn

reduce to zero and vessel continues on straight course

• Directionally unstable - ship deviates with the smallest disturbing cause- If rudder put amidships during turn: reduction of rate of turn

but vessel keeps turning on a track with larger diameter

TurningTurningAbilityAbility

Intro / Inertia - MomentumIntro / Inertia - Momentum

Intro / Inertia - MomentumIntro / Inertia - Momentum

Intro / Inertia - MomentumIntro / Inertia - Momentum

Intro / Inertia - MomentumIntro / Inertia - Momentum

Intro / Qualities of a good shiphandlerIntro / Qualities of a good shiphandler

• PatiencePatience• Anticipation: be « proactive » Anticipation: be « proactive » • instead of « reactive »instead of « reactive »• QuietnessQuietness• ExperienceExperience• SteadfastnessSteadfastness• ConcentrationConcentration• Knowledge / Know-howKnowledge / Know-how• The « Art » of shiphandlingThe « Art » of shiphandling

You will see:You will see:

Fast captains,Fast captains,

You will see:You will see:

Old captains,Old captains,

Very seldom willVery seldom willYou see:You see:

Old and fast CaptainsOld and fast Captains

Chapter OneChapter One

Various factors Various factors

influencing the manoeuvring of the shipinfluencing the manoeuvring of the ship

Ch1. Effect of Fixed Factors on shiphandlingCh1. Effect of Fixed Factors on shiphandling

Fixed factors of the shipFixed factors of the ship

– Design and Design and dimensions of the dimensions of the shipship

– Propulsion unitPropulsion unit

– PropellersPropellers

– RuddersRudders

Ch1. Effect of Variable Factors on shiphandlingCh1. Effect of Variable Factors on shiphandling

Variable factors inherent Variable factors inherent to the shipto the ship

- Draft- Draft- TrimTrim- DisplacementDisplacement- FoulingFouling

Variable factors outside ship Variable factors outside ship - Wind, Sea, Swell Wind, Sea, Swell - CurrentCurrent- Interaction: Depth of water / Shallow watersInteraction: Depth of water / Shallow waters- Interaction: Proximity of other shipsInteraction: Proximity of other ships

Ch1. Factors influencing the shiphandling

Size of the ship

• Ships are designed to make speed , not to stop• Engine power does not increase in proportion to

ship’s size• Large ships:

– Difficult to judge speed from the bridge– When swinging in port: large swinging room required– Estimation of distances to berth difficult– Bridge is isolated from forecastle or poop– Large ship causes more damage when colliding with berth

Ch1. Factors influencing the shiphandling

What is a large ship?

• In 1952 biggest tanker in the world was 45000DWT• Lenght is a more relevant criterion than tonnage:

- Below 100m : small ship- Longer than 200m: large ship- Between: medium size

Size of ship versus available space gives degree of difficulty:- For small ports 5000DWT ship is big- A 5000 DWT ship does not present same problems of

dimensions, mass, inertia and momentum as a 50.000DWT.

Ch1. Design of ship / Bridge amidships

Bridge amidships:Bridge amidships:AdvantagesAdvantages

Shiphandler near the pivoting point when swingingShiphandler near the pivoting point when swingingBest position in a small shipBest position in a small shipClose to forecastle and poop / visual communication Close to forecastle and poop / visual communication Good indication of rate of swingGood indication of rate of swing

DisadvantagesDisadvantagesOn large vessels: each end far from the bridgeOn large vessels: each end far from the bridge

Ch1. Design of the ship / Bridge forward

Bridge forwardBridge forward

AdvantagesAdvantagesShiphandler has excellent view of berth on arrivalShiphandler has excellent view of berth on arrivalClose to anchor when anchoring / easy communication with Close to anchor when anchoring / easy communication with anchor partyanchor partyClose to entrance of locks + good visual communication with Close to entrance of locks + good visual communication with the shore the shore

DisadvantagesDisadvantagesDifficult to assess the ship’s heading without looking aftDifficult to assess the ship’s heading without looking aftFrom the wings: objects on one bow may appear onFrom the wings: objects on one bow may appear on the other

Ch1. Design of the ship / Bridge after

Bridge after

AdvantagesEasy to judge rate of swing / start and end of swingAll ship is seen when looking ahead / ship’s heading visualizedIf bridge is near stern: astern clearance easy to assess

DisadvantagesShiphandler far from forecastle : visual communication impossible when mooring, anchoring, approaching lock or berthDifficult to select precise spot for anchoringVessel passing ahead from bridge may still collide with foredeckWith restricted visibility

Ch1. Design of the ship

• Ratio Lenght/Breadth (L/B)– Big L/B : bad turning / good course keeping (dynamically

stable ship) / good speed

• Ratio Lenght/Draft (L/D)– Big L/D: bad dynamical stability (example: bulkcarrier or

tanker in ballast)

• Ratio Block coefficient (Cb = V/LBT)– Big Cb: bad dynamical stability, easy turning

Ch1. Effect of ship parameters on manoeuvring perf.

Good turning Bad

Bad course keeping ability Good

Ch1. Effect of the bulb on performance

Reduce the water resistance:Increase of speed: one knot / depending on draft/trim Consumption reduced Better course keeping ability Worse turning ability

Ch1. Vorm achtersteven / Forme de la poupe

Design of the stern influences the flow of the water striking the propeller and the rudder

Ch1. Design of the Hull

New hulls are designed to improve the quantity of waterpassing through the propeller/rudder area.

Ch1. Design of the Hull

Ch1. Propulsion of the Ship / Diesel motor

• Manoeuvrability is function of type of propulsion

• Most common: diesel engine + fixed pitch propeller Ship is called m/s (for motorship) or m/v (for motor vessel)

• advantages - Can be instantly stopped- Can be quickly reverted- During a stop manœuvre: engines can be stopped at the

moment that the ship is stopped / propulsion ceases immediately.

- Can be quickly accelerated for emergency or kick ahead

Disadvantages- Compressed air : quantity limited / N°of cons.starts.- Big engines cannot run slowly / deadslow = 9 or 10knots- Difficult to start astern when speed ahead to high

Ch1. Propulsion of the Ship / Propulsion of the Ship / Diesel motorDiesel motor

Ch1. Propulsion of the Ship / Ch1. Propulsion of the Ship / Steam turbineSteam turbine

• Second most common: Steam turbine. Ship is called s/s for steamship.

• Disadvantages:

– Stern power only 40 to 50% of ahead power (smaller turbine used for astern)

– Problems to stop the vessel ; mostly in emergency

– Turbines can keep turning slowly ahead when supposed stopped.

Ch1. Propulsion of the Ship / Ch1. Propulsion of the Ship / Steam turbineSteam turbine

Ch1. PropellersCh1. Propellers

• Fixed right handed propellerFixed right handed propeller

• Variable pitch propellersVariable pitch propellers

•Twin propellersTwin propellers• OutturningOutturning• InturningInturning

• Kort NozzleKort Nozzle

• Azimuth stern drive (ASD)Azimuth stern drive (ASD)

• Voith Schneider Voith Schneider

Ch1. Variable Pitch propellerCh1. Variable Pitch propeller

Ch1. Kort Nozzle / Tuyère KortCh1. Kort Nozzle / Tuyère Kort

Ch1. Propulsion « Voith SchneiderCh1. Propulsion « Voith Schneider »

Ch1. RuddersCh1. Rudders

Ch1. Effect of Variable Factors on shiphandlingCh1. Effect of Variable Factors on shiphandling

Variable factors inherent to the shipVariable factors inherent to the ship

- Draft- Draft

- TrimTrim

- DisplacementDisplacement

- FoulingFouling

Ch1. Effect of Draft / Fully loaded ULCCCh1. Effect of Draft / Fully loaded ULCC

Difficult to stop and to bring in a turnDifficult to stop and to bring in a turn

Ch1. Effect of draft / Ship in ballastCh1. Effect of draft / Ship in ballast

Ship heavily affected by wind

Ch1. Effect of Trim Ch1. Effect of Trim

Trim by the head:Trim by the head:- will turn into the windwill turn into the wind- difficult to steerdifficult to steer- rudder and propeller come out of the rudder and propeller come out of the water when ship is pitchingwater when ship is pitching

Trim by the stern: vessel tends to fall off with side wind

Ch1. Fouling / Salissure de coqueCh1. Fouling / Salissure de coque

Ch1. Effect of Fixed Factors on shiphandlingCh1. Effect of Fixed Factors on shiphandling

• Variable factors outside ship Variable factors outside ship

– Wind, Sea, Swell Wind, Sea, Swell

– CurrentCurrent

– Interaction: Depth of water / Shallow watersInteraction: Depth of water / Shallow waters

– Interaction: Proximity of other shipsInteraction: Proximity of other ships

Ch1. Effect of the wind

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Ch1. Effect of waves on the shipCh1. Effect of waves on the ship

The stability of the ship is affected by stern wavesThe stability of the ship is affected by stern waves

Ch1. Effect of currentCh1. Effect of current

Ch1. Effect of currentCh1. Effect of current

Ch1. Interaction between ship and shoreCh1. Interaction between ship and shore

Closeness of obstacles like shore, berth, etc… willCloseness of obstacles like shore, berth, etc… will modify the pressure fields around the ship andmodify the pressure fields around the ship and provoke changes of heading, uncontrollable swings,provoke changes of heading, uncontrollable swings, due to suction and repulsion forces.due to suction and repulsion forces.

Ch1. Interaction between shipsCh1. Interaction between ships

Close quartersClose quarters

Ch1. Interaction between shipsCh1. Interaction between ships

Overtaking shipsOvertaking ships

Ch1. Interaction between ship and assisting tugboatCh1. Interaction between ship and assisting tugboat

The tug is affected by the closeness of the ship The tug is affected by the closeness of the ship Dangerous position when close to the bowDangerous position when close to the bow

Ch1. Comparison between ratios mass/powerCh1. Comparison between ratios mass/power

• Airplane : 4 to 6 kg/PkAirplane : 4 to 6 kg/Pk

• Car: 25 kg/PkCar: 25 kg/Pk

• Coaster: 50 kg/PkCoaster: 50 kg/Pk

• Sea ship: 2000 to 3000 kg/Pk Sea ship: 2000 to 3000 kg/Pk