Downloaded 97 times
Uploaded byLance Grindley
Heavy weather lrg
The document discusses characteristics of waves and heavy weather conditions at sea. It defines key terms like wave height, length, and period. It describes how wind speed affects wave development. It explains dangers like broaching, pooping, hogging and sagging in heavy seas. It provides guidance on ship handling in different sea conditions, including turning, heaving to, and reducing speed. The overall focus is on understanding wave behavior and taking proper precautions to avoid damage to ships in heavy weather.
More Related Content
Heavy weather lrg
- 1. Grunt Productions 2007 Characteristicsof WavesCharacteristics of Waves HEAVY WEATHERHEAVY WEATHER
- 2. Grunt Productions 2007 WAVEWAVE DEVELOPMENTDEVELOPMENTWIND10 KTSWIND 10 KTS WIND 15 KTSWIND 15 KTS WIND 20 KTSWIND 20 KTS WIND 30 KTSWIND 30 KTS Generating Wave MotionGenerating Wave Motion Surface FrictionSurface Friction Particle MovementParticle Movement Well DevelopedWell Developed Large Steep Seas DevelopLarge Steep Seas Develop
- 3. Grunt Productions 2007 1.Wave Height1. Wave Height 2. Wave Length2. Wave Length 3. Period3. Period - The time interval between passage of successive crests relative to a stationary observer. DEFINITIONDEFINITION SS Height Crest Still Water Level CrestCrest Wave Length Trough Trough
- 4. Grunt Productions 2007 SWELL Wavesthat continue through their own inertia after the wind has stopped generating them. FETCH The straight distance a wave has travelled over the surface. PERIOD OF ENCOUNTER The time interval between passage of successive waves relative to a moving observer. Direction of WavesDirection of Waves
- 5. Grunt Productions 2007 HEAVYWEATHERHEAVY WEATHER • CharacteristicsCharacteristics of Wavesof Waves • AvoidanceAvoidance ofof DamageDamage – Knowledge of ship handlingKnowledge of ship handling characteristics.characteristics.
- 6. Grunt Productions 2007 PERIODOF ROLL ANDPERIOD OF ROLL AND PITCHPITCH WL WL ROLL PITCH PIVOT OF BUOYANCY The Time Required From Upright to Right to Left To Upright The Time Required From Level to Down to Up to Level
- 7. Grunt Productions 2007 HEAVYWEATHERHEAVY WEATHER • CharacteristicsCharacteristics of Wavesof Waves • AvoidanceAvoidance ofof DamageDamage – Knowledge of ship handling characteristics.Knowledge of ship handling characteristics. – Careful use of powerCareful use of power – Assessment of speed v possibleAssessment of speed v possible damagedamage
- 8. Grunt Productions 2007 HEAVYWEATHERHEAVY WEATHER • CharacteristicsCharacteristics of Wavesof Waves • AvoidanceAvoidance ofof DamageDamage • PrecautionsPrecautions – Secure for Sea.Secure for Sea. – Stability adjustment:Stability adjustment: • Bilge KeelBilge Keel • Slack TanksSlack Tanks • Cargo ShiftCargo Shift • Anti-rolling tanks - Comp tanks.Anti-rolling tanks - Comp tanks.
- 9. Grunt Productions 2007 HEAVYWEATHERHEAVY WEATHER • CharacteristicsCharacteristics of Wavesof Waves • AvoidanceAvoidance ofof DamageDamage • PrecautionsPrecautions • Consideration for CrewConsideration for Crew – Violent motion reduces efficiency.Violent motion reduces efficiency. – Safety of men on exposed decks.Safety of men on exposed decks. – Keep Ship’s Company informed.Keep Ship’s Company informed. – Consider change in daily routineConsider change in daily routine..
- 10. Grunt Productions 2007 EFFECTSEFFECTS •Broaching.Broaching. • Pooping.Pooping. • Hogging.Hogging. • Sagging.Sagging. • Turning.Turning. • Heaving to.Heaving to.
- 11. Grunt Productions 2007 STAGESIN BROACHINGSTAGES IN BROACHING WIND AND SEA Ship may run on crestShip may run on crest Stern too high - rudder loses effectStern too high - rudder loses effect Bow pitches into trough and buriesBow pitches into trough and buries Stern swings round bringing ship abeam to elementsStern swings round bringing ship abeam to elements Next wave will possibly break over ship and cause severe damageNext wave will possibly break over ship and cause severe damage SOLUTION - reduce to 40% of wave speedSOLUTION - reduce to 40% of wave speed
- 12. Grunt Productions 2007 STAGESIN A VESSEL BEING POOPEDSTAGES IN A VESSEL BEING POOPED WIND AND SEA FACTORSFACTORS 1. Stern lifts at wave speed1. Stern lifts at wave speed 2. Breaking crest travels faster forces down2. Breaking crest travels faster forces down ACTIONACTION Crest sweeps over ship from aftCrest sweeps over ship from aft TO AVOIDTO AVOID Either select a speed equal to 40% below wave speedEither select a speed equal to 40% below wave speed oror heave-toheave-to
- 13. Grunt Productions 2007 HOGGINGAND SAGGINGHOGGING AND SAGGING PROLONGED SAGPROLONGED SAG DIRECTION OF SEADIRECTION OF SEA Particle Movement IsParticle Movement Is Reduced Past RudderReduced Past Rudder Hence Less ControlHence Less Control Better Control AndBetter Control And Even Strain at WaveEven Strain at Wave Speed ± 3 KnotsSpeed ± 3 Knots PARTICLE MOVEMENT PARTICLE MOVEMENT
- 14. Grunt Productions 2007 A.A.Head to sea:Head to sea: a.a. Short bursts of power, wheel hard over, noShort bursts of power, wheel hard over, no headway consider reversing innerheadway consider reversing inner screw to start the turn.screw to start the turn. b.b. ½ way, full power to complete.½ way, full power to complete. B.B. Following sea:Following sea: a.a. Reduce speed, no sternway.Reduce speed, no sternway. b.b. ½ way, plenty of power and wheel then reduce½ way, plenty of power and wheel then reduce when ship answers the helm.when ship answers the helm. TURNING IN HEAVYTURNING IN HEAVY SEA:SEA:
- 15. Grunt Productions 2007 1.1.Sea on the bowSea on the bow a.a. Necessary if there is a lack of sea room to leeward.Necessary if there is a lack of sea room to leeward. b.b. May need 3-5 knots.May need 3-5 knots. c.c. Possible damage:Possible damage: 1.1. Engines driving ship against the sea.Engines driving ship against the sea. 2.2. Greater risk of structural damage with a flared bow.Greater risk of structural damage with a flared bow. d.d. Heavy pitching/pounding likely.Heavy pitching/pounding likely. e.e. Single screw ships keep wind fine on port bow (sidewaysSingle screw ships keep wind fine on port bow (sideways force of propeller).force of propeller). 2.2. Stop engines and driftStop engines and drift a.a. Plenty of searoom to leeward required (surface drift may reach 3kts in forcePlenty of searoom to leeward required (surface drift may reach 3kts in force 8).8). b.b. Best option in a confused sea.Best option in a confused sea. 3. Running before the sea3. Running before the sea a.a. Less satisfactory.Less satisfactory. b.b. Danger of pooping.Danger of pooping. HEAVING TOHEAVING TO
- 16. Grunt Productions 2007 HEAVINGHEAVING TOTO 4.4.Steaming directly into seaSteaming directly into sea Minimum speedMinimum speed 5.5. DoDo a.a. Watch the weather.Watch the weather. b.b. Know ship stability.Know ship stability. c.c. Secure loose gear.Secure loose gear. d.d. Recognise tropical storms.Recognise tropical storms. e.e. Alter course in a beam sea if possible.Alter course in a beam sea if possible. 6.6. Don’tDon’t a.a. Drive too fast into head sea.Drive too fast into head sea. b.b. Be afraid to reduce speed.Be afraid to reduce speed. c.c. Run too fast before a following sea.Run too fast before a following sea.