Zeevaartkunde (3)

3de Bach NW Samenvatting Zeevaartkundep. 1/18

Great circle sailingGreat circle sailing

Definition

Great circle is circle on surface of Earth, plane passes through Earth’s centre Shortest distance between any 2 points on surface of Earth Adjust ship’s course continuously to sail great circle track Curve on Mercator Charts Dividing into smaller segments to change courses less often Potential problem: closer to poles

Distance

Conform zenithal distance formulae in astronavigation Cos Mo = sin la * sin lb + cos la * cos lb * cos g Mo expressed in degrees & minutes => converted to minutes Gain of distance: M = Mo – M

Course at start and end of voyage

Neper

oo Tg (A + B) / 2 = (cos (NB – NA) / 2) / (cos (NB + NA) / 2 ) * cotg N/2o Tg (A – B) / 2 = (sin (NB – NA) / 2) / (sin (NB + NA) / 2 ) * cotg N/2o Tg (A + B) / 2 = cos l/2 * cosec lm * cotg g/2o Tg (A – B) / 2 = sin l/2 * sec lm * cotg g/2o A & B obtained by adding & subtracting the results => lead to courses

Calculation possible using ABC-tables


Vertex and equatorial intersections

Vertex is highest latitude of great circle defined by 2 positions Great circle has two vertex with same latitude but different sing & symmetrical Equatorial intersections are points where great circle intersects the equator Latitude 0° & symmetrical Difference in longitude between vertex & equatorial intersection is 90° At vertex course is 90° / 270° => use rectangular spherical triangle Cos lv = sin A * cos la

Cos lv = sin B * cos lb

Cos gav = cotg ( 90° - colv ) * cotg cola = cotg lv * tg la

Cos Moav = sin la * cosec lv

Cos Mobv = sin lb * cosec lv

Moav + Mobv = Mo Course in equatorial intersection = latitude of vertex

Waypoints

Chosen by following meanso Same latitude intervalo Same longitude intervalo Same distance intervalo Same course interval

Most common = same latitude interval Start calculations from vertex => simplified rectangular spherical triangles Determine latitude, longitude & distances => each time new triangle Waypoints on other side of vertex = symmetrical What to calculate

o Latitude waypointo Distance waypoint to vertexo Course at each waypoint

Tg lwp = cos g * tg lv

Cos Mowpv = sin lwp * cosec lv

Sin Awp = cos lv * sec lwp


Composite sail

Placing two vertexes on limiting latitude => 2 great circle paths Three sections Limiting latitude chosen taking into account

o Latitude original great circle vertexo Weather conditions in higher latitudeso Obstacles such as land masses

Total distance less than rhumbline, more than great circle Great circle path: formulae see above Rhumbline distance: M = e = g * cos lmax

Traverse distance to an obstacle

Calculate orthodromic start course of original track Calculate orthodromic course of track from departure to obstacle Make difference between both angles Calculate distance from departure to obstacle Determine traverse distance Calculate distance from departure to position of traverse distance (cosinus formulae)

Errors and accuracy in astronavigationErrors and accuracy in astronavigation

Introduction

Error is difference between specific value & correct or standard value Mistake is blunder as incorrect reading, taking wrong value … Mistakes & errors combined => incorrect LOP’s => incorrect fix Current mistakes

o Incorrect reading of instrumento Incorrect reading of timeo Plotting of reciprocal bearingo Incorrect reading of pre-computed tables and almanaco Incorrect input in computer programso Incorrect computing

Current errorso Altitude errorso Time erroro Ambiguity

Difference between systematic & random erroro Systematic error more or less eliminated by careful calibrationo Random error is unpredictable in sign or magnitude, not rectifiable


Altitude error

Observed altitudes always contain random errors Standard deviation approximately 1’ under fair working conditions Lines of position better considered as bands of position Counter measures

o Azimuth roughly symmetrically distributedo Optimum range of altitude between 20° & 70°

Time error

Direct effect because inaccurate GHA & obtained Direct impact on obtained longitude

Course and distance error

Related to drift due to current & wind Subdivided in 2 parts

o Transfer as per Rv & not course made goodo Distance or drift speed

Combined effect => large errors Counter measures

o Never rely on 2 observations onlyo Take additional observations with opposite bearing

Ambiguity

Poor geometry => decrease accuracy / result in entirely wrong fix

Reduced methods in astronavigationReduced methods in astronavigation

HO 249

3 volumeso Volume 1: selected starso Volume 2: all celestial bodies, latitude 00° - 40°o Volume 3: all celestial bodies, latitude 40° - 89°

Edited for air navigation but can be used for marine navigation Special edition for marine navigation (HO 299) 6 volumes without one for selected

stars


Principle of tables

Enter with LHA, declination & latitude in full degrees Insert LOP

o Plot assumed latitude & longitudeo Set out azimuth & intercept from this position

Volume 1

Contains selected stars Use

o Convert hi to hvo Find GHAo Convert GHA to LHA in whole degreeso On page assumed latitude => read hc & Zn in accordance with LHA o hv – hc = intercepto Follow procedure each observationo Plot LOP’s => fixo Adjust fix for precession & nutation

Volume 2 and 3

Used unlimited in time Pre-computed tables divided into declination & latitude same name & declination &

latitude contrary name Stars with declination higher than 29° can not be used Enter assumed latitude whole degrees & LHA celestial body whole degrees &

declination whole degrees => hc hc corrected for minutes of declination => “Correction to Tabulated Altitude for

Minutes of Declination” Azimuth obtained by instruction on top & bottom of table Plotting LOP’s identical to Volume 1 No correction necessary for precession & nutation

Sight reduction table Nautical Almanac

Reduced method to obtain intercept & bearing Full text in Nautical Almanac


Identification of an unknown celestial bodyIdentification of an unknown celestial body

Star charts

Grid of declination & right ascension Find LHA of moment of observation Introduce position as zenith on chart

o Latitude on declination scaleo Longitude with LHA on right ascension scale

Bearing to each star obtained by angle between direction from zenith to star & meridian

Altitude (by divider)o Read declination of star on star charto Mean latitude between your latitude & declination of staro Distance between zenith & staro To “Scale of altitude”

One end on mid latitude scale at spot corresponding with calculated mid latitude

Other end in horizontal plane Follow curve till altitude scale & read altitude

Star finder

Portrays altitude & azimuth of 57 numbered stars Additional celestial bodies may be plotted Provides best way to identify isolated stars & planets in view Predicts locations of bodies not yet in view Helps navigator to predict & plan best star-planet-moon combination Unit consists of

o Dual star baseo Nine altitude azimuth templateso Meridian angle diagramo Instruction sheet

Basic template indicates celestial equator (N / S same as latitude)

Plotting other celestial bodies on the basic template

Plot planets for certain moment of day Need RA & RA = 360° - SHA planet Other template same name as latitude on basic template Red arrow point to RA => introduce planet as per declination


Determination of altitude and bearing

Calculate LHA Blue coloured template most approximate latitude to your latitude & place on basic

template Blue arrow in line with LHA on border => all stars & planets within blue grid

visible, others invisible

HO 249

Volume 1 identify selected stars for certain moment at certain latitude Calculate LHA On page corresponding to latitude of observer, insert LHA => height Hc & bearing

By calculation

Observation => altitude & bearing Calculate & SHA Formulae see previous year

Navigation dutiesNavigation duties

Coastal voyages

Start leaving berth till moment vessel reaches area of open waters Subdivided

o Berthing / unberthing Regular watch system stops Special duties

Assistance during manoeuvring Deck duties to moor & unmoor Preparing bridge to make fully operational / stop navigational

aids Starting ISPS implementation / completion Documentary evidence Communication

End / start voyage => logbook “finished with engines” / “standby” Starts when vessel fit for sailing, ands when manoeuvring capacity

unavailable Stress factor rises Attentiveness at highest level Most cases pilot assistance


o Calling / leaving port Extra tasks

Preparing hatches & loading / discharging gear Clearing / securing anchors, deck gear, hatches Preparing / storing pilot ladder Make vessel ready for tug assistance Preparing gangway for launching Preparing vessel for ISPS Preparing vessel for berthing / unberthing VTS, port control & pilot station communication Readiness of internal communication Briefing of crew Anti-pollution arrangements Start / end sea voyage Wheelman / look-out

Attentiveness focussed on many tasks Delegation / supervision necessary Clear briefings!! Navigational duties

Fixes at small intervals Use all navaids & proper interpretation Use of communication Appropriate cooperation with pilot Observing meteorological conditions & anticipate accordingly Hand steering by wheelman where appropriate

o Restricted area Non-navigational zones, traffic separation lines, traffic by other vessels,

ice … Fixes at regular intervals with all means

High sea voyages

Vessel at sea speed Fixes only by GPS, LORAN-C & astronavigation Water depth doesn’t limit manoeuvrability Endangers attentiveness of OOW


WatchkeepingWatchkeeping

Introduction

More & more stringent rules Mandatory passage planning New factor: over-confidence in automation Introduction procedures & checklists => avoid mistakes & raise level of attentiveness See “Bridge Procedures Guide” See “Mariner’s Handbook” Chapter 8 See “Annual Summary of Admiralty Notices to Mariners” Human factor remains pre-dominant (casestudy p. 74 – 77) Gains in safety & pollution prevention = substantial due to changing ships More than 80% shipping casualties result of human error Other factors: automation, operating ships is skilled job Important steps: ISM code + revision STCW Human factor

o Unmanned / badly manned ship is sub-standardo Ship with serious manning deficiencies = unseaworthyo Manning is increasingly factor in regulation of shippingo Manning & management have clear significance in assessing ship’s overall

quality Main causes & main types major P&I claims

o Fatigueo Moraleo Motivationo Loyaltyo Trainingo Standards of certificationo Experienceo Conditions of serviceo Environmento Languageo Management policies


Causes of investigationo Collisions

Conclusion Human error: 90% Under way: 82% Between 0300 & 0700: 1/3

o Run aground Main origin

General over-confidence Neglect of use of echo sounder Errors in position fixing Approaching rather than leaving a port One man bridge in general Poor planning Short sea-trades Little evidence of work patterns of watch systems Poor visibility NOT significant

Conclusion Poor organisation Poor communication Over-confidence

Important elementso Awarenesso Watchkeepingo Fatigue element (casestudy see p. 83 – 87)

Watchkeeping duties subdivided intoo Watchkeeping at seao Watchkeeping at anchoro Watchkeeping in port

Basic principles good watchkeepingo Theoretical knowledgeo Experienceo Communicationo Use of standard procedureso Knowledge & understanding of limits & errors in automation


SOP = standard operating procedureo Why?

Same working pattern for all Psychological effect in emergencies & distress

o What? Routine items Deviation patterns Emergency Operations Safety ISPS Marine environment Management

o How?

Steps to create a SOP

o SOP necessary?o Note key pointso Make flowcharto Identify critical stepso Make logogramo Write procedure in simple wordso Control procedure in try-out at small scaleo Modify where necessaryo Implement SOP on large scaleo Introduce corrective actionso Keep in mind

Not too much information (clear & simple) Not assume but rely on reality Complete & executable


Watchkeeping at sea

Watch arrangements

Composition of watch at all times adequate & appropriate to prevailing circumstances & conditions & take into account need for maintaining proper lookout

Following factors taken into accounto No time bridge unattendedo Weather condition, visibility & whether daylight / darknesso Proximity navigational hazardso Use & operational condition of navigational aidso Whether ship fitted with automatic steering gearo Unusual demands may arise as result of special operational circumstances

Navigation

Intended voyage planned in advance, any course laid down => checked before voyage commences

During watch: course steered, position & speed checked at sufficiently frequent intervals

Officer of watch full knowledge of location & operation all safety & navigational equipment

Not assigned or undertake any duties which would interfere with safe navigation of ship

Navigational duties & responsibilities

Officer of the watcho Keep watch on the bridge which he shall not leave until properly relievedo Continue to be responsible for safe navigation, despite presence of master,

until master informs specifically that he has responsibilityo Notify master when in any doubto Not hand over watch to relieving officer if he has reason to believe latter

obviously not capable of carrying out duties effectively + notify master Taking over watch, relieving officer satisfy himself ship’s estimated / true position &

confirm intended track, course & speed & note any dangers to be expected Proper record kept of movements & activities during watch relating to navigation of

ship


Lookout

Purposeo Appraising situation & risk of collisiono Strandingo Other dangers to navigationo Detection ships / aircraft in distress, shipwrecked people, wrecks & debris

Following observedo Able to give full attention to keeping proper look out, no other duties

undertaken or assignedo Duties of look out & helmsman separate except on small ships where

unobstructed all-round view provided at steering positiono Officer of watch may be sole look-out in daylight provided that

Situation carefully assessed Full account taken of all relevant factors

State of weather Visibility Traffic density Proximity of danger

Assistance immediately available

Navigational equipment

Most effectively use of all navigational equipment Using radar, necessity to comply with provisions on use of radar Not hesitate to use helm, engines & sound signalling apparatus

Taking over the navigational watch

Relieving officer of watch ensure that members of watch fully capable of performing their duties (night vision)

Relieving officer not take over watch until vision fully adjusted & personally satisfied regarding

o Standing orders & other special instructionso Position, course, speed & draught of shipo Prevailing & predicted tides, currents, weather, visibility & effect of factors

upon course & speedo Navigational situation, including

Operational condition all navigational & safety equipment Errors of gyro & magnetic compasses Presence & movement of ships in sight or known to be in vicinity Conditions & hazards likely to be encountered Possible effects of heel, trim, water density & squat

At time officer of watch is to be relieved, manoeuvre or other action taking place, relief of officer deferred until action completed


Periodic checks of navigational equipment

Operational tests carried out as frequently as practicable & as circumstances permit Regular checks

o Helmsman / automatic pilot steering correct courseo Standard compass error determined once a watch & after major alteration of

course; standard & gyrocompasses frequently compared & repeaters synchronized

o Automatic pilot tested manually once a watcho Navigation & signal lights functioning properly

Automatic pilot

Necessity to comply with requirements of Steering Appliances and Equipment Regulations

Station helmsman & put to manual steering in good time to deal with potentially hazardous situation in safe manner

Change-over from automatic to manual steering & vice-versa made by or under supervision of responsible officer

Electronic navigational aids

Officer of watch thoroughly familiar with use of electronic navigational aids including capabilities & limitations

Echo sounder valuable navigational aid & used whenever appropriate

RADAR

Use radar when appropriate & whenever restricted visibility encountered / expected & in congested waters

Appropriate scale, observe carefully & plot effectively Range scales changed & sufficiently frequent intervals => echoes detected early Small / poor echoes may escape detection Plotting / systematic analysis commenced early Clear weather, whenever possible => radar practice

Navigation in coastal waters

Largest scale chart on board suitable for area & corrected used, fixed at frequent intervals, by more than one method

Positively identify all navigation marks

Clear water

Frequent & accurate compass bearings of approaching ships (early detection of risk of collision)

Early & positive action regarding compliance applicable regulations for preventing collisions at sea

Restricted visibility


Comply relevant rules for regulations for preventing collisions at seao Sounding fog signalso Proceeding at safe speedo Engines ready for immediate manoeuvres

In additiono Inform mastero Post proper look-out & helmsman, in congested waters => hand steeringo Exhibit navigational lightso Operate & use radar

Know handling characteristics & stopping distance

Calling the master

Restricted visibility encountered / expected Traffic conditions or movements of other ships causing concern Difficulty experienced in maintaining course Failure to sight land, navigation mark / obtain soundings by expected time Unexpectedly land / navigation mark sighted / change in soundings occur Breakdown of engines, steering gear & any essential equipment Heavy weather if in doubt about possibility of weather damage Ship meets any hazard to navigation Any other emergency / doubtful situation Not hesitate to take immediate action where circumstances require

Navigation with pilot embarked

Any doubt to pilot’s actions => seek clarification Doubt still exists => notify master & take action necessary before master arrives

Watchkeeping personnel

Appropriate instructions & information to ensure keeping of safe watch

One man bridge operated ships

Bridge configuration, arrangements of consoles, equipment location enable officer to perform navigational duties & other functions as well as maintain proper lookout from convenient position on bridge, referred to as workstation

Efficient operation by one person under normal operating conditions, all relevant instrumentation & controls easily visible, audible & accessible

Field of vision to enable observation all objects which may affect safe conning of ship, vision in accordance with guidelines on navigation bridge visibility, other functions, other workstations may be arranged

Enable ship to be navigated & manoeuvred safely by two navigators in cooperation External sound signals from ships & fog signals audible on open deck, also be audible

inside wheelhouse

Bridge safety system


Vigilance system provided to indicate that alert officer of watch present on bridge System used for verification of officer of watch’s alertness, not cause interference with

performance of bridge functions System so designed & arranged could not be operated in unauthorized manner

Watchkeeping at anchor

If master considers necessary => continuous navigational watch maintained at anchoro Determine & plot ship’s position on appropriate chart as soon as practicable,

check at sufficiently frequent intervals whether ship remaining securely anchored by taking bearings

o Efficient lookout maintainedo Inspection rounds made periodicallyo Observe meteorological & tidal conditions & state of seao Notify master & undertake necessary measures if anchor dragso State of readiness of main engines & other machinery in accordance with

master’s instructiono Visibility deteriorates => notify master & comply with COLREGo Appropriate lights, shapes & sound signalso Protect environment from pollution

Watchkeeping in port

Introduction

Applies to ship safely moored under normal circumstances in port Following principles & operational guidance taken into account by masters &

watchkeeping officers

Watch arrangements

Arrangements shouldo Ensure safety of life, ship, cargo & porto Observe international, national & local ruleso Maintain order & normal routine of shipo Act corresponding to ISPS code

Master decide composition & duration of watch depending on conditions of mooring, type of ship & character of duties

Qualified deck officer in charge of watch, except ships under 500 gross tons not carrying dangerous cargo

Necessary equipment arranged to provide efficient watchkeeping


Taking over the watch

Not hand over watch to relieving officer if he has reason to believe latter obviously not capable of carrying out duties effectively + notify master

Relieving officer informed of followingo Depth of water at berth, ship’s draught, level & time of high & low waters,

fastening of moorings, arrangement of anchors, slip of chain & other features of mooring, state of main engines & availability for emergency use

o All work to be performed on board; nature, amount & disposition of cargo loaded / remaining / any residue on board after unloading

o Level of water in bilges & ballast tankso Signals or lights being exhibitedo Number of crew members required to be on board & presence of any other

persons on boardo State of fire-fighting applianceso Any special port regulationso Master’s standing & special orderso Lines of communication available between ship & dock staff / port authorities

in event of emergency arising / assistance being requiredo Other circumstances of importance

Relieving officer satisfy himself thato Fastening of moorings / anchor chain adequateo Appropriate signals / lights properly hoisted & exhibitedo Safety measures & fire protection regulations maintainedo Aware of nature of any hazardous / dangerous cargo being loaded / discharged

& appropriate action in event of spillage / fireo No external conditions or circumstances imperil ship & own ship doesn’t

imperil others Moment of handing over watch, important operation performed, concluded by officer

being relieved except ordered otherwise by master


Keeping a watch

Make rounds to inspect ship at appropriate intervals Pay particular attention to

o Condition & fastening of gangway, anchor chain / moorings, especially at turn of tide or in berths with large rise & fall & take measures to ensure they are in normal working condition

o Draught, under keel clearance, state of ship to avoid dangerous listing or trim during cargo handling or ballasting

o State of weather & seao Observance of all regulations concerning safety precautions & fire protectiono Water level in bilges & tankso All persons on board & their location, especially those in remote / enclosed

spaceso Exhibition of any signals or lights

In bad weather or receiving storm warning, take necessary measures to protect ship, personnel & cargo

Take precautions to prevent pollution In emergency threatening safety of ship => raise alarm, inform master, take all

possible measures, request assistance from shore authorities / neighbouring ships Be aware of state of stability so in event of fire, shore fire-fighting authority advised

of approximate quantity of water can be pumped on board Offer assistance to ships / people in distress Take necessary precautions to prevent accidents / damage propellers to be turned Enter in appropriate logbook all important events

Mandatory minimum requirements for a watch in port on ships carrying hazardous cargo

Master every ship carrying hazardous cargo in bulk => ensure safe deck watch & safe engineering watch maintained, even when safely moored / at anchor

Master every ship carrying hazardous cargo not in bulk => organise safe watchkeeping arrangements

Zeevaartkunde (3)

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