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Alaska Pilots > Tug Use in Port > Flashcards

Tug Use in Port Flashcards

1
Q

Tug Use in Port - Four categories of Ports

A

1 - Conventional is majority
2 - Ports with mainly terminals
3 - Ports with mainly jetties - tugs can assist on both sides of ship
4 - Mooring facilities at remote locations

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2
Q

Tug Use in Port - tugs around world

A
  • single screw tugs
  • twin screw tugs
  • tractor type tugs
  • tugs with azimuth propellers aft
  • Rotor tugs
  • Combi tugs (with one propulsion unit forward and one aft)
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3
Q

Tug Use in Port - main types of tug assistance

A
  • tugs towing on a line, usually 1.5x length of tug
  • tugs operating at the ship’s side made fast with 1, 2, or 3 lines
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4
Q

Tug Use in Port - two basic tug types

A
  • tugs with propulsion aft and towing point near midships (conventional)
  • tugs with towing point aft and propulsion forward of midships (tractor tugs with Voith or azimuth drives)
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5
Q

Tug Use in Port - tug subcategories

A
  • conventional
  • tractor tugs with azimuth or voith propulsion
  • ASD - tugs
  • reverse-tractor tugs
  • combi-tugs - older tug modified with 360º bow thruster have towing point on bow and stern
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6
Q

Tug Use in Port - other related tug types

A
  • Rotortug - has 3 azimuth thrusters
  • Z-tech and RSD tug - have 2 azimuth thrusters under one of the tug ends
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7
Q

Tug Use in Port - performance

A
  • response time
  • bollard pull
  • underwater shape
  • small maneuvering space
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8
Q

Tug Use in Port - wheelhouse visibility

A
  • good visibility from wheelhouse, 360º if possible
  • essential info comes from towline, assisted ship, and combined ship/tug direction of movement
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9
Q

Tug Use in Port - wheelhouse / propulsion construction

A
  • superstructure should be well inboard of decks edge and propulsion units should be designed to not hit the ship’s hull
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10
Q

Tug Use in Port - fendering resistance

A
  • to polluted water, ozone, UV radiation, and high /low temps
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11
Q

Tug Use in Port - fendering considerations

A
  • size of contact area
  • engine HP for horizontal load and kinetic energy
  • type of vessel to be assisted / handled
  • environmental conditions
  • tug’s bow and stern construction
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12
Q

Tug Use in Port - additional fendering

A
  • for vessels handling subs and aircraft carriers
  • underwater fendering and top of wheelhouse
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13
Q

Tug Use in Port - fendering materials

A
  • weldable with steel backing
  • foam filled
  • pneumatic
    (non-marking for type for navy ships)
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14
Q

Tug Use in Port - bow fenders

A
  • should have large contact area and radius to reduce pressure on ship’s hull
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15
Q

Tug Use in Port - fendering friction

A
  • large coefficient of friction on bow/stern to so not to slide
  • side fendering should be low friction
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16
Q

Tug Use in Port - Conventional tug TP

A
  • 0.45 LWL aft
  • not common in US, but if used normally more forward
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17
Q

Tug Use in Port - direct-reversible

A
  • oldest and not very common
  • engine started ahead and started astern
  • only so many starts limited by air reserves
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18
Q

Tug Use in Port - diesel electric system

A
  • engines drive generators which drive electric motors driving propellers
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19
Q

Tug Use in Port - diesel electric characteristics

A
  • easily controlled from wheelhouse
  • deliver any shaft speed ahead/astern without delay
  • higher power available
  • cheap to work on
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20
Q

Tug Use in Port - controllable pitch propeller - astern power

A
  • 40-45% of ahead power astern
  • standard right-handed propellers = 60%
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21
Q

Tug Use in Port - CPP astern blade configuration

A

when blades pitched for astern thrust the lower parts have smaller pitch than the tops which causes the less efficiency

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22
Q

Tug Use in Port - Kort nozzles

A
  • Ludwig Kort designed 1927, in service 1932
  • 15-25% increase in towing/pushing thrust
  • high prop load at low speed best efficiency
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23
Q

Tug Use in Port - type 19A nozzle

A
  • very common since cost effective
  • Hannan type gives 70% of ahead thrust astern with fixed pitch prop and special blades
  • 60-65% with ordinary blades
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24
Q

Tug Use in Port - type 37 nozzle

A
  • used to increase backing (typically conventional tugs) but has a little less efficiency ahead
  • CPP with type 37 gives 45% astern of ahead thrust
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25
Q

Tug Use in Port - azimuth thruster nozzles astern

A
  • astern propulsion achieved by turning drive = astern performance not relevant
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26
Q

Tug Use in Port - azimuth thruster nozzle - Nautican

A
  • increase ahead efficiency 8-12% in bollard pull conditions
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27
Q

Tug Use in Port - azimuth thruster nozzle - Optima

A
  • commonly used
  • similar ahead as 19A and astern as 37
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28
Q

Tug Use in Port - azimuth thruster nozzle - Schottel’s VarioDuct SD45

A

-latest nozzle type
- compact size
- greater bollard pull
- greater efficiency in medium to high speed ranges

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29
Q

Tug Use in Port - nozzles and steering

A
  • increase propeller efficiency, but reduce steering capabilities
  • often paired with specialty rudder systems or steerable nozzles
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30
Q

Tug Use in Port - steerable nozzles

A
  • NOT ASD - those are steerable props
  • at angles no more than 25-30º due to side thrust
  • superior to normal rudder arrangement
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31
Q

Tug Use in Port - common rudder types

A
  • balanced, semi-balanced, spade
  • these have the leading edge of rudder extend forward of rudder shaft
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32
Q

Tug Use in Port - balanced rudder

A
  • most tugs have balanced rudders
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33
Q

Tug Use in Port - spade rudders

A
  • hang free, are not attached at heel
  • decrease propeller efficiency due to flow separation at leading edge
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34
Q

Tug Use in Port - moveable flap rudder angles

A
  • max lift at 30º rudder angle, increased by 60-70% than conventional
  • flap is 20-30% total main rudder area
  • max helm rudder angle 45-65º (depending on type)
  • flap increases rudder angle 45º, up to max angle 90-110º
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35
Q

Tug Use in Port - Becker flap rudder claim

A
  • 95-97% of of propeller thrust covered and used for maneuvering
  • other books say 70%
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36
Q

Tug Use in Port - fishtail rudder

A
  • max lift at 40º rudder angle, increased 30-40% more than conventional
  • better astern steering
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37
Q

Tug Use in Port - Schilling VecTwin rudders

A
  • max outboard angle 105º, inboard 40º
  • max side thrust 70% of ahead
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38
Q

Tug Use in Port - bow thruster effectiveness

A
  • low effectiveness with speed ahead
  • even at 2 kts, bow thruster loses 50% effectiveness
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39
Q

Tug Use in Port - Voith Schneider history

A

vertical axis propeller invented in early 1920s at UW

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40
Q

Tug Use in Port - Voith recommended pitch settings

A
  • max pushing about 9
  • max pulling about 8
  • max running free about 10
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41
Q

Tug Use in Port - Voith thrust control

A
  • units can be controlled independently to longitudinal thrust
  • units must be controlled together for transverse thrust
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42
Q

Tug Use in Port - Voith assist towing/pushing switch

A

can switch from towing on line to pushing, forward or aft, at ship speed of 2 kts or less

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43
Q

Tug Use in Port - Voith assist braking forces

A
  • special braking maneuver for light pull on line astern
  • should stay in line with ship
  • pitch levers should be adjusted according to ship speed to avoid overheating
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44
Q

Tug Use in Port - Voith assist ship approach

A

ship speed 5 kts or less when approaching the bow or stern

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45
Q

Tug Use in Port - AST propulsion location

A

propulsion usually fitted 0.30 - 0.35 LWL from forward

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46
Q

Tug Use in Port - AST / Voith tractor assist

A
  • Voith better at stern indirect towing at higher speeds
  • ASD better as forward tug and at stern direct towing at speed (100% thrust any direction)
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47
Q

Tug Use in Port - CPP AST

A

when need full power astern, thrusters should be turned around on ahead

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48
Q

Tug Use in Port - reverse tractors design

A
  • propulsion 0.01 LWL from aft
  • work better from bow winch
  • not good stern towing, less than conventional
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49
Q

Tug Use in Port - reverse tractor astern power

A

5-10% less bollard pull astern than ahead power

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50
Q

Tug Use in Port - general tractor assist orientation rule

A

tractor tugs always operate with towing point towards assisted ship and propulsion units away

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51
Q

Tug Use in Port - reverse tractor assist

A
  • not effective as forward steering tug with headway
  • very suitable for stern steering and speed control for ships at speed
  • great direct mode, slightly less effective as VS in indirect mode
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52
Q

Tug Use in Port - Japanese tractor

A
  • bulbous bow for fast dry deck vessel
  • up to 15 kts
  • dangerous indirect mode
  • stern transom below waterline
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53
Q

Tug Use in Port - ASD tug design

A
  • combined advantages of conventional and reverse-tractor tugs
  • can stern tow and do bow work
  • winch on each end
  • propulsion 0.35 - 0.40 LWL from from stern
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54
Q

Tug Use in Port - Rotortugs design

A
  • three azimuth thrusters in triangle pattern
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55
Q

Tug Use in Port - Rotortug assist

A
  • are effective up to 10 kts in direct mode
  • good braking and steering up to 10 kts
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56
Q

Tug Use in Port - ASD tugs assist

A

are very effective and suitable for all types of ship handling

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57
Q

Tug Use in Port - Z tech tug design

A
  • ASD drive with a skeg to limit heeling
  • runs towline over bow
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58
Q

Tug Use in Port - reverse stern drive tug (RSD) design

A
  • like Z tech but has two stern drives below house on forward end with 2 skegs
  • has two bows, can run like tractor and reverse-tractor
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59
Q

Tug Use in Port - Carrousel tug design

A

conventional tug with big skegs and movable tow point

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60
Q

Tug Use in Port - carrousel tug use

A
  • ship speed helps tug use hydrodynamic forces
  • slow speed not very useful
  • good for channel work, long trips up
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61
Q

Tug Use in Port - dynamic oval towing (DOT) tug design

A
  • conventional tug with moveable tow point along heavy rail
    -very rare and small
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62
Q

Tug Use in Port - ship docking modules (SDM) design

A
  • skegs on each end and an azimuth thruster on each end offset a little
  • beamy with large working deck aft
  • one hole in each skeg to reduce pressure
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63
Q

Tug Use in Port - ship docking module (SDM) characteristics

A
  • decent bollard pull
  • good stability
  • 12.5 kts free sailing speed
  • 6.5 kts side-stepping speed
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64
Q

Tug Use in Port - Eddy (Efficient Double-ended Dynamic) tug design

A
  • two diesel electric driven thrusters in line operated at each end
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65
Q

Tug Use in Port - EDDY (Efficient Double-ended Dynamic) tug characteristics

A
  • very good fuel economy
  • well suited for tight quarters maneuvering
  • dual winch - two towlines, one winch
66
Q

Tug Use in Port - carrousel Rave tug (CRT) design

A
  • two Voith units in line
  • 360º movable tow point around house with alarms and cameras
67
Q

Tug Use in Port - Giano tug design

A
  • like an EDDY with two escort winches fore and aft with high fairleads
  • two skegs with fendering create a tunnel
  • high stability - max escort heeling angle 8º
68
Q

Tug Use in Port - IMO escort heeling regs

A

requires tugs engaged in escort operations with the max heeling lever in an equilibrium situation, heeling angle 15º or less

69
Q

Tug Use in Port - hazardous area classifications - Zone 0

A
  • highest
  • explosive gas atmosphere present for long periods of time (>1000 hrs/yr)
70
Q

Tug Use in Port - hazardous area classifications - Zone 1

A
  • explosive gas atmosphere likely in normal ops (10-1000 hrs/yr)
71
Q

Tug Use in Port - hazardous area classification - Zone 2

A
  • explosive gas atmosphere likely in normal ops but for short time (<10 hrs/yr)
  • still need controls over ignition sources
72
Q

Tug Use in Port - IMO emission standards

A
  • Tier I-III
  • through Annex VI of MARPOL
73
Q

Tug Use in Port - mechanical propulsion

A
  • normal tug setup
  • better fuel economy at design speed 80-100% top speed
  • below 70%, poor efficiency and high emissions
  • tugs only use 20% max power for towing during transit
74
Q

Tug Use in Port - electric propulsion

A
  • mainly fixed pitch
  • diesel generator
  • poor fuel and high emissions
75
Q

Tug Use in Port - hybrid propulsion

A
  • good for tugs that operate mostly at low speeds
  • mechanical efficient for high speeds
  • electric for low speeds
  • NO emissions
76
Q

Tug Use in Port - electric propulsion with hybrid power

A
  • electric generator for high speeds
  • reserved energy for low
77
Q

Tug Use in Port - Hybrid propulsion with hybrid power

A
  • mechanical power plus reserved energy plus reserved fuel supply
  • reliability and safety risks
78
Q

Tug Use in Port - electric propulsion with DC power

A
  • all electric
  • battery studies ongoing
79
Q

Tug Use in Port - diesel electric tugs propulsion solution

A
  • better fit with diesel generator propulsion system
  • engine changes cause too much interference for mechanical propulsion
80
Q

Tug Use in Port - tugs preferred for Ice

A
  • ASD tugs with CPP
  • open wheel system as opposed to nozzles (less blockages)
81
Q

Tug Use in Port - brake horsepower (bhp) measured

A

at the flywheel

82
Q

Tug Use in Port - shaft horsepower (shp) measured

A
  • at the propeller shaft
    shp = about 0.97 x bhp
83
Q

Tug Use in Port - positive flow condition

A
  • tug’s prop wash with direction of water flow
84
Q

Tug Use in Port - negative flow conditions

A
  • tug’s prop wash against direction of water flow
  • fluctuating torque loads on prop and engine
85
Q

Tug Use in Port - line pull relationship to bollard pull

A
  • if prop RPMs double, then line force will increase by a factor of 4 and required engine power will increase by a factor of 8
  • applies to most tug ops
86
Q

Tug Use in Port - bollard pull depth and line length

A
  • water 6x prop immersion depth
  • line 50x length of prop diameter
87
Q

Tug Use in Port - tons / bhp per propulsion type

A
  • Voith = 1.1tons per 100bhp
  • ASD = 1.4tons per 100bhp
  • Conventional w/nozzle = 1.5tons per 100bhp
88
Q

Tug Use in Port - lateral center of pressure

A
  • non-stationary
  • depends on hull form/rudder/prop/skeg
  • where incoming water flow exerts force on tug
89
Q

Tug Use in Port - tow point / center of pressure

A
  • tow point should be close to or aft of center of pressure
  • risk of tripping if not
90
Q

Tug Use in Port - pushing / propulsion point

A

when pushing, the farther propulsion pt is from towing pt the more efficient tug is right angles

91
Q

Tug Use in Port - ASD / skeg / indirect mode

A
  • addition of skeg helps with indirect mode by moving center of lateral pressure farther forward
  • decreases directional stability going ahead
  • increases directional stability going astern
92
Q

Tug Use in Port - beamier tugs

A
  • more being built
  • about 2.8:1 L/W ratio
  • increases righting moments
  • decreases directional stability
93
Q

Tug Use in Port - sponsons

A

some tugs have sponsons added to increase flaring for buoyancy

94
Q

Tug Use in Port - underwater resistance

A

more underwater resistance on a tug contradictory to work performance

95
Q

Tug Use in Port - tow point / center of lateral resistance

A

towing point should be as low as possible to reduce heel and be above center of lateral resistance

96
Q

Tug Use in Port - Bureau Veritas

A
  • group studies tug stability
  • helped IMO set standards and regs
  • 2008 IS code for 24m in length or more for international voyages
97
Q

Tug Use in Port - quick release reg

A

IMO states tug tow winch shall have a quick release

98
Q

Tug Use in Port - conventional tug / steering assistance at stern

A
  • ship speed over 3kts - only give steering assistance on one side
  • ship speed below 2kts - both sides working astern
  • both sides on bow at very low speeds
99
Q

Tug Use in Port - combi at speed assist position

A

works well on the stern, especially with aft towing point

100
Q

Tug Use in Port - reverse-tractor and tractor at speed assist position

A
  • work well on stern
  • at bow - not quite as good as conventional
101
Q

Tug Use in Port - ASD at speed assist postition

A
  • great for bow tug when ran like a conventional tug, line from astern
102
Q

Tug Use in Port - max wave height restriction

A
  • conventional = 1.5 - 1.8 meters
  • tractors and ASD = 2.0 meters
103
Q

Tug Use in Port - 5 factors for required bollard pull

A
  • port particulars
  • berth construction
  • the ship
  • environmental conditions
  • method of tug assistance
104
Q

Tug Use in Port - Beam wind bollard pull formula

A

Fw= 0.08 x V² AL kgf
- AL = longitudinal wind in M²
- V = wind velocity in m/sec
- used for wind up to 30º off beam
- 20% safety factor included

105
Q

Tug Use in Port - required bollard pull programs

A
  • now ship programs that calculate required bollard pull
  • one by Marin called Tug Assist
106
Q

Tug Use in Port - cross current bollard pull formula

A

Fc = 40 V² Lbp T kgf
- T = draft
- Lbp = length between perpendiculars
- current velocity in m/sec
- only for deep water 6x the draft
- UKC 1.5x draft use 110 V²
- UKC <20% draft use 150 V²
- UKC <10% draft use 185 V²
- 20% safety factor included

107
Q

Tug Use in Port - approximate wave bollard pull formula

A
  • Fwave =112x LxHs² kgf
  • L = length between perpendiculars
  • Hs wave height
108
Q

Tug Use in Port - towline length

A
  • should be as long as possible
  • tugs lose 40-60% on short towline
  • in heavy wave conditions could lose up to 90%
109
Q

Tug Use in Port - displacement bollard pull formula

A

(displacement/100,000) x 60 + 40 = BP in metric tons

110
Q

Tug Use in Port - stopping ship by tugs alone formula

A

S = (Displ x V²) / 74,13 x BP
- V = speed in kts
- S = stopping distance in meters
- BP = bollard pull in metric tons

111
Q

Tug Use in Port - shallow water bank effects

A
  • shallow water bank effects increase proportionately by the square of the ships’s speed
  • ship speed 4kts = bank effects 4x what they are at 2kts
112
Q

Tug Use in Port - ‘added mass’

A

attempting to stop a ship after passing through a narrow channel in shallow water, only to have the ship be pushed ahead and sideways by the following water

113
Q

Tug Use in Port - tug approaching a ship from astern

A
  • will notice an increase in speed as well as suction force
114
Q

Tug Use in Port - ASD bow lines speed

A
  • make up bow lines at 6kts max ship speed
  • some say 3-4kts
115
Q

Tug Use in Port - gob rope

A
  • conventional tugs use to shift tow point
  • allows for more maneuverability
  • high forces have been seen on gob rope
116
Q

Tug Use in Port - radial towing hook

A
  • conventional tugs use to shift towing point
  • circular
  • class society requires to be released manually from bridge and winch
117
Q

Tug Use in Port - winch brakes

A
  • top layer of winch brake will slip at 50% rated tonnage
  • brakes should hold 2-3x BP of tug
118
Q

Tug Use in Port - winch standards

A
  • have release activated in 3 sec
  • able to be clutched
  • diameter of drum not less than 14x rope diameter (Slesinger says 6-8x)
  • 3 dead turns must remain on drum
  • drums shall have disc sheaves
  • if multi drums used, each must be capable of individual operation
  • inboard end of winch line weak link
  • after emergency release, winch must be able for regular use
  • emergency release must be capable with no power and in all control areas
119
Q

Tug Use in Port - wire specs

A
  • 6x36 means six strands with 36 individual strands
  • tow wire should have middles to withstand crushing forces and is 7-8% stronger
  • wire with more strands is more flexible
120
Q

Tug Use in Port - Aramid specs

A
  • does NOT float
  • decomposes at 500ºC
  • not good UV protection
120
Q

Tug Use in Port - UHMPE

A

Ultra High Modulus Polyethylene

120
Q

Tug Use in Port - HMPE (Spectra, Dyneema) specs

A
  • floats
  • melts at 143º-155ºC
  • good UV resistance
  • max work temp 70º
  • low friction coefficient
  • can be 20% stronger than advertised on first use
121
Q

Tug Use in Port - polyester specs

A
  • does NOT float
  • heavy
  • most durable
122
Q

Tug Use in Port - Nylon specs

A
  • does NOT float
  • very high stretch
123
Q

Tug Use in Port - polypropylene specs

A
  • light
  • floats
  • bad in hot weather
124
Q

Tug Use in Port - retire lines

A
  • when under 75% of original breaking strength
125
Q

Tug Use in Port - tow line length doubles…

A
  • it creates approximately double the the time for reaction
126
Q

Tug Use in Port - steep tow angle / wear on line

A
  • steeper tow angles create more force on tow line and cause more wear on the line at the staple
127
Q

Tug Use in Port - wire strength required

A
  • wire breaking strength should be 4x the tug’s BP
128
Q

Tug Use in Port - tug assist line strength

A
  • should be 4-6x tug’s BP rating
129
Q

Tug Use in Port - Ship mooring lines strength

A
  • Ship mooring lines should not be used for tug low line
  • 50,000 dwt = 50 ton rating
  • 200,000 dwt = 70 ton rating
  • mooring lines have much less strength ratings required than tug tow lines
130
Q

Tug Use in Port - Ships after 2007 must mark…

A
  • SWL on bitts for towing
  • if not marked for towing, use lower SWL for mooring
131
Q

Tug Use in Port - bitt strength

A
  • now commonly the weak link in towing Ops
  • all bitts should be 1.25 the SWL
  • all lines should not be taken over 4/5 above the tube height
132
Q

Tug Use in Port - emergency tow points on tankers

A
  • should be on each end of every tanker 20,000 dwt or more
133
Q

Tug Use in Port - emergency towing arrangement required for tankers

A
  • one pre-rigged arrangement able to deploy in harbor conditions in 15min
  • able to pick up gear by one person
  • non-pre-rigged ready in 1hr
134
Q

Tug Use in Port - emergency towing all ships

A
  • all ships should have emergency towing procedures
135
Q

Tug Use in Port - manned models

A
  • 5x faster for everything, even winds and current
136
Q

Tug Use in Port - Escort history

A
  • 1975 WA escorting by Foss
  • 1977 Prince William Sound started escorting
  • 1999 Oil Pollution Act enabled USCG to set guidelines
137
Q

Tug Use in Port - accident history / tankers

A
  • USCG studies found only 20% of all accidents were from tankers
138
Q

Tug Use in Port - 1992 Marpol requirement for escorting vessels

A
  • amended to 5000 dwt
139
Q

Tug Use in Port - escorting long distance VS port areas

A
  • port areas = regular assist tugs
  • long distance = specifically designed tugs
140
Q

Tug Use in Port - towing alongside forward arrangement

A
  • a tug on each side should be used or at least a rudder tug
141
Q

Tug Use in Port - waves affect on assisting

A
  • extremely limit assisting power
142
Q

Tug Use in Port - Conventional tug steering forces

A
  • over 3-4 kts cannot apply steering forces
  • can push, but pushing increases speed
143
Q

Tug Use in Port - securing tug at bow ship speeds

A
  • keep speed less than 6kts
144
Q

Tug Use in Port - stern tug VS bow tug steering forces

A
  • stern tug able to apply better steering forces
  • oppose sheer better too
145
Q

Tug Use in Port - conventional fwd and Omni aft escort speeds

A
  • around 4-5kts but limited to fwd tug
146
Q

Tug Use in Port - conventional fwd braking forces

A
  • cannot apply braking forces
147
Q

Tug Use in Port - opposing sheer tug positions

A
  • rudder tug and tugs on quarters are better
148
Q

Tug Use in Port - escort steering/braking fwd tugs

A
  • fwd tugs good for steering, but not braking
149
Q

Tug Use in Port - escort steering stern tugs

A
  • omni, carousel, or combi are good
  • conventional are VERY limited by ships speed
150
Q

Tug Use in Port - direct pull speeds

A
  • tug is pulling with Ship speed 3kts or less is best
  • less than 5kts is recommended
151
Q

Tug Use in Port - indirect mode ship speeds

A
  • good for 6-10kts Ship speeds for making high steering forces
152
Q

Tug Use in Port - powered indirect mode ship speeds

A
  • 3-7kts
  • tug is 90º to Ship’s centerline using indirect mode for very high steering forces
153
Q

Tug Use in Port - center of pressure relation to tow point and heel

A
  • the smaller the distance from center of pressure vertically to the towing point will reduce heel
154
Q

Tug Use in Port - propulsion point relation to tow point and heel

A
  • longer distance from propulsion point vertically to tow point will counteract heel
155
Q

Tug Use in Port - ASD VS Voith escort brake / steering forces

A
  • ASD tugs brake better
  • Voith tugs steer better
156
Q

Tug Use in Port - escort tug free sailing speed

A
  • most 12.5-15kts
157
Q

Tug Use in Port - minimum tug GM height

A
  • minimum recommended metacentric height is 3m
158
Q

Tug Use in Port - max heeling angle placard

A
  • for max angle at 10kts will be the same no matter the speed
  • if posted, an inclinometer must also be posted
159
Q

Tug Use in Port - Risk assessment steps

A
  • Identify
  • Analyze
  • Evaluate
160
Q

Tug Use in Port - ISM (international safety management) Code - SMS

A
  • requires shipping companies to have SMS in place

Alaska Pilots (36 decks)

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