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Objectives: To Review.... Controllable ForcesIndirectly Controllable/Semi-Controllable ForcesUncontrollable ForcesShiphandling Evolutions (towing, small boats, tugs)Coaching. . . . . SHIPHANDLING FORCES CONTROLLABLE. PROPELLERRUDDERBOW THRUSTER ANCHORSLINESTUGS. . . . . . . . . PROPELLER F
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1. THE ART OF SHIPHANDLING
2. Objectives: To Review... Controllable Forces
Indirectly Controllable/Semi-Controllable Forces
Uncontrollable Forces
Shiphandling Evolutions (towing, small boats, tugs)
Coaching
3. SHIPHANDLING FORCES CONTROLLABLE PROPELLER
RUDDER
BOW THRUSTER
ANCHORS
LINES
TUGS
4. PROPELLER FORCES
5. PROPELLER SIDE FORCES FOLLOWING WAKE EFFECT
INCLINATION EFFECT
SHALLOW WATER SUBMERGENCE EFFECT
HELICAL DISCHARGE EFFECT
6. FOLLOWING WAKE EFFECT Ship’s hull drags water with it
Upper half of prop works through water with greater velocity than bottom half
Net effect: Stern walks to port when going ahead
7. INCLINATION EFFECT Hull shape causes water to rush in and up under stern
Increases relative velocity of water in front of stern
Right half works through water with greater velocity than left half
Net effect: stern moves to starboard
8. HELICAL DISCHARGE EFFECT Water discharged off the left side of prop
moves up and to starboard
is trapped against the rudder by the hull
Water discharged off right side of prop
moves down and to port
Water flow creates increased relative pitch on the upper half of prop
Net effect: stern moves to starboard
9. SHALLOW WATER SUBMERGENCE EFFECT Top half of prop is closer to surface than lower half
Water is less dense near surface (more air churned into it)
Lower half of prop exerts more force as result of working thru more dense water
Net effect: stern moves to starboard
10. Side Forces on Stern(Going Ahead) Following Wake
Inclination
Shallow Water Sub Effect
Helical Discharge
Total
11. Side Forces on Stern (Going Astern) Following Wake none
Inclination
Shallow Water Sub Effect
Helical Discharge
Total
12. SINGLE PROPELLER VARIABLE PITCH
13. Two Basic Types of Props CONVENTIONAL
blades don’t move
pitch is fixed or variable
shaft changes direction
prop is solid chunk of metal
fewer malfunctions CPP
blades change pitch
pitch creates thrust fore and aft
shaft turns one direction
more complex and more malfunctions
14. TWIN PROPELLERS FIXED BLADE/VARIABLE PITCH (CONVENTIONAL)
15. CONTROLLABLE PITCH PROPELLERS
16. STERN ISSUES PROPELLER FORCES
RUDDER PLACEMENT
COORDINATING RUDDER & ENGINES
IMPLICATIONS OF ALL STOP
PUMP TO THE RUDDER (KICK AHEAD)
17. PIVOT POINT
18. BOW THRUSTERS / PROPS
19. SHIPHANDLING FORCES SEMI-CONTROLLABLE PASSING SHIP EFFECTS
OVERTAKING
MEETING
SHALLOW WATER EFFECTS
SQUAT
BANK SUCTION / CUSHION
INCREASED TACTICAL DIAMETER
MOMENTUM/INERTIA
20. MEETING & OVERTAKING
21. SHALLOW WATER EFFECTS SQUAT PROPORTIONAL TO:
SPEED
DISPLACEMENT
DEPTH & BREADTH OF CHANNEL
CAN CAUSE SHIP TO STRIKE BOTTOM
CAUSES WET WELLS TO INCREASE DEPTH UNEXPECTEDLY AND OUT OF CONTROL
REDUCED RUDDER EFFECTIVENESS
INCREASE IN TORQUE / LESS SPEED
SHIP’S WAKE CAN BE AN INDICATOR
22. SQUAT
23. BANK SUCTION/CUSHION
24. MOMENTUM & INERTIA MOMENTUM: “Generally, we consider momentum as the motion of a ship at the time we no longer want it, especially when we have taken action to obtain the opposite effect. ... Momentum is the quality of motion measured by the product of mass & velocity.”
INERTIA: Inertia is the quality of motion that causes a ship to resist a change in motion. “A force exerted on a ship will result in motion after inertia has been overcome.” Hoover - Behavior and Handling of Ships
25. MOMENTUM MASS X VELOCITY
82’ WPB
76 TONS X 5 KTS = 5 TON MAC TRUCK TRAVELING 76 MPH
378’ WHEC
3100 TONS X 1 KT = 5 TON MAC TRUCK TRAVELING 620 MPH
26. SHIPHANDLING FORCES UNCONTROLLABLE WIND
CURRENT
SEAS
27. SEAMANSHIP EVOLUTIONS
28. ANCHORING
29. ANCHORING SYSTEM SERVES AS: PORTABLE MOORING SYSTEM
EMERGENCY BRAKE
ADDITIONAL CONTROLLABLE FORCE (POOR MAN’S TUG)
30. GROUND TACKLE ANCHOR
SHACKLES
CHAIN/LINE
WILDCAT/WINDLASS
STOPPER
32. RELATIVE HOLDING FACTORS FIRM SAND 1.00
STIFF-DENSE CLAY 1.50 (PLASTIC)
STICKY CLAY 0.66 (MEDIUM DENSITY)
SOFT MUD 0.33
LOOSE COARSE SAND 0.33
GRAVEL 0.33
HARD BOTTOM 0.00 (ROCK, SHALE, BOULDERS)
33. SCOPE OF CHAIN FIVE TO SEVEN TIMES DEPTH OF WATER IS A GOOD RULE OF THUMB
IN HEAVY WEATHER, MORE CHAIN MAY NOT BE THE ANSWER
ALTERNATIVES
STEAMING TO THE ANCHOR
HAMMERLOCK
GET UNDERWAY
36. PRECISION ANCHORING
37. PRECISION ANCHORAGE FINAL APPROACH
MANY TYPES
ADJUST FOR SET AND DRIFT
LET GO WHILE BACKING DOWN
CORPORATE MEMORY WILL PRODUCE THE BEST APPROACH
NAV FIX AS SOON AS ANCHOR IS LET GO
ALWAYS HAVE AN ALTERNATE PLAN
CHECK ANCHORAGE AREA FOR NAV HAZARDS AND OTHER SHIPPING
38. EMERGENCY BRAKE KNOW WHERE YOUR STDBY ANCHORAGES ARE DURING TRANSIT IN RESTRICTED WATERS
IF YOU HAVE TWO ANCHORS MAKE BOTH READY FOR LETTING GO
39. POOR MAN’S TUG
40. LINES AND LINE HANDLING
41. MOORING LINES
42. MOORING LINES
43. LINES WHO GIVES ORDERS TO LINE HANDLERS?
CO
XO
OOD
CONNING OFFICER
REFERENCE - NSTM CH 582
MOORING SYSTEM DESIGNED FOR 50 KNOT BEAM WINDS & 3 KNOT CURRENT
44. STANDARD COMMANDS SLACK
EASE
TAKE TO POWER / CAPSTAN
HEAVE AROUND
SURGE
CHECK
HOLD - WHO GIVES THIS ORDER?
45. DOUBLING LINES FOR HEAVY WEATHER
46. ORGANIZING FOR SUCCESS WHY LINES PART
WET NYLON LOSES 15% STRENGTH
LACK OF CHAFFING GEAR
LINES STORED WET ON REELS
EXCEEDING WORKING LOAD OF LINE
PERSONNEL INJURY
SNAP BACK
UNCONTROLLED SURGE
IMPROPER HANDLING
47. TOWINGA Command Perspective TOWING"...Towing another vessel at seais a maneuver that has been madedifficult by too much planningand discussion..." CRENSHAW
48. TOWINGTHE COMMAND PERSPECTIVE SELECTING THE APPROACH
ABORTING AN APPROACH
SHIPHANDLING CONSIDERATIONS
WEATHER
SAFETY
49. PROVIDE A CATENARYFOR SAFETY'S SAKE CATENARY IS A FUNCTION OF ? SCOPE ? SPEED ? DIRECTION
NORMALLY 2 TO 3 SHOTS OF CHAIN IS ADEQUATE