Navigation and Passage Planning. Flashcards
(194 cards)
1
Q
Which IMO convention establishes the principles for maintaining a safe navigational watch?
A
International Convention on Standards of Training, Certification and Watchkeeping (STCW).
2
Q
When may a vessel’s Bridge be manned by only one Officer?
A
- If approved by the Master.
- ‘Sole lookout may be appropriate in daylight.
- Good visibility.
- Appropriate navigational/traffic situation.
- A lookout is immediately available to be summoned to the bridge when the OOW deems it necessary.
3
Q
How might the status of Engine Room manning affect the Bridge?
A
- Many vessels operate with Unmanned Machinery Spaces (UMS) while on passage.
- This may increase the number of alarms that sound on the Bridge, increasing the workload on the OOW
- Use of UMS should take into account when considered the appropriate level of Bridge manning.
4
Q
Who must always be physically on the bridge when the vessel is underway?
A
A suitably-qualifed watchkeeping Officer.
5
Q
How might Bridge manning levels change during a passage?
A
- Poor Weather/visibility,
- Navigational hazards in close proximity.
- High traffic density.
- Time of day (sole lookout).
6
Q
What is the difference between a lookout and a helm?
A
- Lookout focused on maintaining a good lookout.
- Helm focused on steering the vessel.
- One can’t be both unless a small vessel with all-round visibility.
7
Q
What should be included in a handover at anchor?
A
- Detailed breakdown of anchor plan.
- Number of shackles in the water & swing circle.
- Tides, current and prevailing weather conditions.
- Depth of surrounding water.
- Nearby vessels at anchor and navigating near the anchorage.
- Availability and status of engines.
- Potential hazards in the area to monitor.
- VTS channels to be monitored.
- Position monitoring techniques in use.
- Required frequency of position-fixing.
- Status of the crew who are on standby.
- Status of ongoing operations or maintenance.
- Any other relevant information.
8
Q
When should the OOW not commence the handover?
A
- If they are in any doubt that the relieving officer aren’t able to carry out their duties through intoxication or fatigue.
- Shall not commence handover whilst conducting a manoeuvre.
9
Q
What should occur before the handover begins?
A
The reliving officer should be given time to let their eyes adjust and to begin to gain situational awareness. The should also review the Master’s Standing and/or Night orders.
10
Q
What should the handover process at sea end with?
A
A formal and explicit exchange of the conn.
11
Q
When the Master is on the Bridge, who gives helm orders?
A
- It depends on which officer has the conn at that time.
- Master doesn’t relieve the OOW of their responsibility.
12
Q
Which part of the STCW relates to watchkeeping?
A
Chapter 8 Part A/B.
13
Q
What are the three key priorities of a safe navigational watch?
A
The safety of the vessel, its crew and the protection of the marine environment.
14
Q
What must eh OOW do regarding the passage plan in order to maintain a safe navigational watch?
A
- OOW must get the Passage Plan approved by the Master.
- If deviation of the plan is necessary then the Master must be informed.
15
Q
When an why is the Pilot Card used?
A
- Master/Pilot exchange.
- Provides an overview of the vessel’s particulars, current condition and crucial manoeuvring information.
16
Q
How should the bridge be manned while at anchor?
A
- Master is permitted some leeway under STCW Code.
- Best practice, bridge should be manned by a suitably-qualified Officer at all times while at anchor.
17
Q
Which Code gives guidance on the keeping a watch at anchor, in port and during cargo operations?
A
The STCW Code.
18
Q
During a cargo watch, the OOW should ensure that the vessel is loaded in accordance with which plan?
A
The cargo plan.
19
Q
What action should the OOW take on receiving a weather warning?
A
The OOW should immediately inform the Master.
20
Q
How should the OOW monitor the vessel’s position while at anchor?
A
- OOW should continuously monitor the vessel’s position, using a variety of independent means, such as radar ranges and bearings from conspicuous points and/or visual bearings/transits, in addition to GNSS/ECDIS anchor watch functions.
21
Q
When keeping a deck watch in port, what should the OOW monitor regarding the crew?
A
- The OOW should monitor crew are working safely and using appropriate PPE, risk assessment Permits-to-Work and toolbox talks are in place.
- Ensure sufficient crew are onboard at all times to enable the vessel to respond to an emergency.
22
Q
What action should the OOW take when they suspect that the vessel is dragging anchor?
A
- Immediately call the Master.
- OOW should take all actions required for the safety of the vessel, such as mustering the anchor party and veering more chain and/or ordering the Engine Room to start main engines.
23
Q
What is the alcohol limit for seafarers?
A
No greater limit than 0.005% blood alcohol or 0.25 mg/l in the breath.
24
Q
What are the minimum hours of rest?
A
- Min if 10 hours of rest in any 24hour period.
- 77 hours in 7-day period.
- Rest may be divided into no more than two periods, one of which shall be at least 6 hours in length.
- The intervals between consecutive rest periods shall not exceed 14 hours.
25
Which international conventions contain the Hours of Rest requirements?
STCW and then incorporated into the ILO's Maritime Labour Convention.
26
The 2nd Officer arrives on the bridge for a handover looking severely fatigued. What should the off-going OOW do?
- Call the Master.
- Do not commence the handover and continue to maintain a safe navigational watch.
- Once on the Bridge, inform the Master of the situation and await their instructions.
27
How should hours of rest be recorded?
- By each seafarer daily and then shall be submitted to the Master where both parties will sign.
- Seafarer must be given a copy and the records must be kept onboard for at least one year.
28
In the context of hours of rest, what is compensatory rest?
Compensatory rest is when a seafarer who was on call had their rest period disturbed by alarms or call-outs to recoup for lost rest time.
29
When may the Master suspend the hours of rest requirements?
During emergencies or overriding operational conditions. (Safety, Security etc).
30
What is the difference between tiredness and fatigue?
- Tiredness is a temporary state of reduced alertness and performance due to insufficient sleep.
- Fatigue is a more chronic and profound exhaustion that can result from prolonged exertion or inadequate rest over a longer period.
31
What is the acronym for the four stage process of passage planning?
APEM
32
Which IMO Resolution relates to passage planning?
IMO Resolution A.893(21) 'Guidelines For Voyage Planning'.
33
Which chapter of SOLAS relates to passage planning?
- Chapter 5 (Safety of Navigation).
- Regulation 34 (Safe navigation and avoidance of dangerous situations).
- Annex 24 (Voyage Planning).
- Annex 25 (Guidelines for Voyage Planning).
34
Which stage of the APEM process involves gathering together information from all relevant sources?
Appraisal.
35
Which stage of the APEM process commences shortly before departure?
Execution.
36
What charts should we always plan and navigate on?
Largest Scale Chart available.
37
How may the SMS affect the passage plan?
It may outline company requirements for things like minimum under keel clearance, ECDIS contours etc.
38
What does CATZOC stand for and what does it indicate?
Category Zone of Confidence It indicates the accuracy of electronic chart data.
39
How often are Cumulative NtMs published?
Twice a year in January and July.
40
What do Weekly NtMs contain?
Notice to Mariners contain updates for charts and publications so that they can be kept up-to -date.
41
What does 'Ocean Passages for the World (NP 136)' contain?
- Shows common deep-sea voyages on major routes.
- Shows details of weather, current, ice hazards, load line zones and distances between major ports.
- Individual chapters cover each of the world's oceans, with details of weather, climate, winds, currents, swell, seasonal factors and ice hazards.
42
Which volume of ALRS contains information on pilot services, vessel traffic services and port operations?
ALRS - Volume 6.
43
How are Sailing Directions used for passage planning?
- Contain information for passage planning of port approach and coastal navigation, including navigational hazards, buoyage, pilotage, regulations, notes on countries, port facilities, seasonal currents, ice and climactic conditions.
44
When are the Master's preferences likely to be incorporated into the passage planning process?
Master will express their preferences to the OOW at the at the beginning of the APEM process, although there may be additional comments made during the Master's review once the appraisal and planning stages have been completed.
45
Who must give the final approval of a passage plan?
The Master, once a full review has been completed.
46
Where does the Master's review fall into the passage planning process?
At the end of the planning stage but before the Execution stage commences.
47
How are 'no-go areas' highlighted on electronic chart?
Most no-go areas will be highlighted automatically by the safety contour but the OOW may use 'user chart objects' to highlight additional areas of hazard.
48
What will provide guidance on the company's produces relating to passage planning?
The SMS.
49
what is a 'commit point' or 'abort point'?
- Commit point is a point of no return, after which it will be much more difficult to bring the vessel into a safe area. Prior to passing the commit point, the Bridge team must have ensured that key systems are online and tested, and to agree that the vessel is able to continue.
50
Where must the passage plan start and finish?
The passage plan must run from 'berth to berth', so that it covers the entire passage.
51
When does the execution stage of passage planning commence?
Once an accurate ETD and ETA are known or as the departure time nears, if known in advance.
52
With regard to timings, what would be ascertained during the execution stage of APEM?
ETAs and tidal conditions for critical points of the passage plan, as well as a review of manning level at those points.
53
How must the vessel's progress along the passage plan be monitored?
Continuously and closely, using all available means and not relying on one source of position input such as GNSS.
54
When does the monitoring stage of the APEM process start and finish?
the monitoring stage will commence on departure and continue until vessel has arrived at its destination.
55
What process should be followed if the OOW feels it necessary to deviate from the planned passage?
- Inform the Master.
- Draw up an amendment to the passage plan.
- Seek the approval of the Master for the amended plan.
- Implement the amendment.
56
On which chart projection does a line of contestant direction create a straight line?
Mercator.
57
Which chart projection is used more easily plot great circles?
Gnomic.
58
What is 'chart projection'?
The way in which the spherical shape of Earth is projected onto a flat surface.
59
Distances are distorted more at higher latitudes on which type of chart?
Mercator.
60
Which projection is used for most charts found onboard vessels?
Mercator.
61
On which kind of chart can you find mean sea surface pressure for the time of the year?
Routing charts.
62
What's the difference between a Routing Chart and Mariners' Routeing Guide?
- Routing Chart are used to assist with high-level route planning for ocean passages.
- Routeing Guides provide essential routing information for busy and complex shipping routes.
63
What are Maritime Security Charts used for?
They aid passage planning through key areas of the world where there are significant security risks.
64
Why can Port Approach Guides be useful for the Master-Pilot Exchange?
They bring together key information for an entire port entry/exit and present it on one chart.
65
How man types of chart are produced by the UKHO?
- Standard Nautical Charts.
- Port Approach Guides (withdrawn 20th April 2023).
- Maritime Security Charts Mariners' Routing Guides.
- Routeing chart.
66
What information do Routing charts contain?
- Routes and distances between major ports.
- Ocean currents.
- Ice limits.
- Load lines and weather related information such as wind roses.
- Sea/Air temperatures.
- Frequency. intensity of storms.
- Average air pressure.
67
Which electronic chart type is preferable when navigating with an ECDIS unit?
An Electronic Navigational Chart (ENC).
68
Does a small-scale chart represent more or less land/sea area?
More. A small-scale chart uses a smaller scale to represent more land/sea area on a single chart.
69
Which scale is an ENC at scale 6?
Berthing
70
What is an ECDIS called when it is being used to display RNCs?
A Raster Chart Display System (RCDS).
71
Which electronic chart type enables the interrogation of chart data?
ENCs.
72
Which electronic chart type is a database of information which is then represented graphically to the user?
ENCs.
73
Which electronic chart type can make it easier to find information on berth names/numbers?
RNCs, because this information is often harder to find on ENCs and can be laid out less clearly.
74
What is the abbreviation for 'wreck'?
Wk.
75
What chart symbol is an magenta octagon with a white 'X'.
Generic isolated danger symbol - with less depth than user-selected safety contour or where the depth is unknown.
76
Which UKHO publication provides information about the symbols used on paper charts?
NP 5011 - Symbols and abbreviations used on Admiralty Paper Charts.
77
Which UKHO publication provides information about the symbols used on electronic charts?
NP 5012 - Admiralty Gide to ENC Symbols used in ECDIS.
78
Which UKHO publication supports passage planning of port approach and coastal navigation and also contains detailed information on ports?
Admiralty Sailing Directions.
79
Which UKHO publication provides information on the GMDSS system?
ALRS Volume 5 - Global Maritime Distress and Safety System (GMDSS).
80
Which two UKHO publications are used during celestial navigation?
The Nautical Almanac and the Admiralty Sight Reduction Tables for Marine Navigation.
81
Which piece of software has largely replaced the use of Admiralty Tide Tables and Tidal Stream Atlases onboard?
Admiralty Total Tide (ATT).
82
What s an AENP?
Admiralty e-Nautical Publication.
83
Which UKHO publication gives contact details and procedures for ports around the world?
ALRS Volume 6 - Pilot services, Vessel traffic Services and Port Operations.
84
Which volume of IAMSAR is carried by vessels?
IAMSAR Volume III - Mobile Facilities.
85
Which UKHO publication contains information on international standard and daylight saving times and dates?
ALRS Volume 2:
- Radio Aids to Navigation.
- Differential GPS (DGPS).
- Legal Time.
- Radio Time Signals and electronic Position Fixing system.
86
You are on passage and notice that the planned track can be safely shortened. Would you make the change and alter course?
No. The Master is always required to approve any changes to the passage plan.
87
How many reasons to call the Master are given in the STCW Code?
Ten.
88
Which two reasons to call the Master relate to navigation marks?
The OOW should call the Master if they fail sight a navigation mark that they expected to see or if they see a navigation mark that they didn't expect to see.
89
Which two reasons to call the Master relate to the COLREGs?
- Traffic situation or the movements of other vessels are a cause for concern ( inappropriate behaviour).
- If the OOW is in any doubt as to what the correct action is in traffic a situation.
90
How do the OOW's responsibilities change when the Master enters the Bridge?
They don't change at all. OOW is still responsible for the safe navigation of the vessel unless the conn is passed over.
91
In general terms how should the OOW call the Master?
- By whatever means are appropriate.
- Be explicit about the need for the Master to come to the bridge.
- On arrival to the bridge, OOW should brief the Master precisely on the situation.
- Make suggestions to help the Master's decision making process.
92
How long do temporary NtMs typically last for?
3-6 months.
93
What is AIO, in the context of ECDIS?
(Admiralty Information Overlay)
- Contains navigational information, including Ts & Ps.
- Designed to be displayed over an ENC on an ECDIS.
- Provides the OOW with additional during passage planning.
94
How often are cumulative lists of NtMs published and what are they used for?
- Published every 6 months. (January and July).
- This is to aid with the identification of outstanding NtMs and to provide an audit trial for chart and publication corrections.
95
Where and when is the Cumulative Summary of Amendments to Sailing Directions published?
It is published annually (in January), as part of the Annual summary of NtMs.
96
Why are preliminary notices published?
They are issued to warn that important changes affecting navigation will take place soon or when a change affecting navigation has taken place but full information is not yet available.
97
How many sections are there in the weekly NtMs?
8 including;
- Explanatory notes and publication lists. - Updates to Standard Nautical Charts
- Reprints of NAVAREA 1 navigational warnings containing further updates to various publications and the Admiralty Digital Services.
98
Where would you find a summary of the Ts & Ps still in force at the start of the year?
In the Annual Summary of Admiralty Notices to Mariners (NP 247).
99
What are Notices to Mariners?
- Advises seafarers of important changes to charts and publications.
- Contain all of the corrections, alterations and amendments for the UKHO's charts and publications and are published in three different formats, weekly, monthly and cumulatively.
100
How frequently are chart corrections published in NtMs?
Weekly.
101
Complex chart corrections are often promulgated in what format?
As a block or patch which can be cut out and stuck onto the chart using adhesive.
102
What should the OOW do with the NtM index of chart correction?
They should cross-check the NtM index against the vessel's chart folio index and make a list of which charts require correction.
103
Smaller chart corrections are usually printed on what type of paper and why?
- Onto tracing paper.
- They are then overlaid onto the chart features (soundings, contours, Lat/Long) making it easier to position the correction in exactly the right place.
104
Which chart publication contains all symbols and abbreviations used on paper charts?
NP 5011 - Symbols and abbreviations used on Admiralty Paper Charts.
105
Why is magenta ink used for chart corrections?
It stands out clearly as a correction will not disappear under red lighting
106
how often are AVCS DVDs published?
Every week?
107
If more than one update DVD arrives onboard at the same time, what must the OOW do?
The DVDS are cumulative so only the latest ones needs to be loaded.
108
What is the latest edition of the S-52 Presentation Library?
Edition 4.0.
109
What is a cell permit?
Permits control which cells the ECDIS unit will display. They can be purchased for periods from three to twelve months.
110
How can the OOW or Master verify that the latest updates have been applied to the ECDIS?
Although it will vary from manufacturer to manufacturer, each ECDIS should be able to run an 'ENC Update Status Report' which will confirm to which week the cells have been updated.
111
How should chart 1 be used on an ECDIS?
Chart 1 can be used to ensure that the new symbols introduced in Edition 4.0 of the S-52 Presentation Library are displaying correctly.
112
Which section of the weekly NtMs contains corrections for the Sailing Directions?
Section IV
113
What are the two methods of correcting paper nautical publications?
- Pasting the correction directly into the publication over the affected information.
- Crossing out the affected information and storing the affected information and storing the correction in a separate file.
114
What are the two stages of the correction process for the paper nautical publications?
Apply the correction to the publication and record the correction in the correction index inside the front cover.
115
How often are new editions of ALRS published?
They are published annually with the exception of ALRS Volume 4, which is published every 18 months.
116
Which paper nautical publications are corrected using notices to mariners?
- Admiralty Sailing Directions.
- ALLFS.
- ALRS.
- miscellaneous Admiralty Nautical publications, such as the Mariner's Handbook.
117
AENPs meet the carriage requirements of which convention?
SOLAS.
118
What's the difference between Admiralty e- Nautical Publications and Admiralty Digital Publications?
- E-Publications are a way of accessing publications as e-books instead of hard copies.
- Admiralty Digital Publications are standalone software products which allow access to the information in a much more interactive format.
119
How many Admiralty Publications are there?
- Digital List of Lights.
- Digital Radio Signals.
- Total Tide.
120
Will the high tide be highest during spring or neap tides?
Spring tides.
121
What is the primary reference point for heights and depths?
Chart datum.
122
What is a drying height?
They are areas of the seabed (or land) which are higher than chart datum and would therefore be uncovered (dry) by the stated amount if the height of tide was zero.
123
What is the charted vertical clearance and why is this important?
- Height of the lowest point of a bridge or obstruction, normally measured from the Highest Astronomical Tide (HAT).
- OOW should know the charted vertical clearance in order to calculate whether or not the vessel will be able to pass safely underneath.
124
What are MHWN and MLWN
- Mean High Water Neaps.
- Mean Low Water Neaps.
125
Why do neap tides result in smaller tidal ranger than spring tides?
During neap tides the moon and the sun are not aligned resulting in not a combined gravitational force meaning tidal range is at its lowest.
126
What is a secondary port?
Ports for which tidal heights and times have to be determined using a correction from a specified standard port.
127
On a UKHO chart, what does the green area indicate
Drying heights.
128
What does the 'total depth' mean?
The actual depth of water in a position at a certain time, combining charted depth and height of tide.
129
On a UKHO paper chart, what does it mean when a depth sounding has a line underneath the larger number?
It means that it is a negative depth sounding, i.e. a drying height.
130
When does quat typically occur?
- Total depth is less than twice the vessel's draft, typically defines 'shallow water'.
131
What is 'Minimum UKC'?
The lowest that the Master or company are happy for the vessel to have at any time. They will typically document this value in the Master's Standing Orders or the Company's SMS.
132
What is air draft?
The vertical distance form the waterline to the highest point of the ship.
133
What is charted vertical clearance?
The height of the lowest point of a bridge or obstruction, normally measured from the highest astronomical tide.
134
What is the significance of a negative value with calculating clearance under a bridge?
A negative clearance means that the vessel is taller than the bridge and will therefore collide with it.
135
Which two values are summed to calculate the height of a bridge above chart datum?
The highest Astronomical Tide (HAT) and the charted vertical clearance of the bridge.
136
Why are there two columns for rates in the tidal diamond table?
- Because rates vary between spring and neap tides.
- Left side is spring tides.
- Right side is neap tides.
137
What is the symbol for a tidal diamond?
A magenta diamond with a capital letter inside.
138
What piece of information is required before the tidal diamond table can used?
The high water time in the designated Standard Port. This would be obtained form the Admiralty Tide Tables.
139
How many 'hours' are given in a tidal diamond table?
Thirteen. Six before high water, high water and then six after high water.
140
If the arrow on the Tidal Streams Atlas has "(09,21)" written next to it, what is the tidal stream during a neap tide?
0.9 knots.
141
What does the direction of the arrow on a Tidal Stream Atlas indicate?
The direction in which the current is flowing in that position.
142
What does the size of the arrow on a Tidal Stream Atlas indicate?
- Graphical representation of the strength of the current in that position.
- Longer and thicker arrows indicate locations with stronger currents.
143
What will be the effect of a favourable current?
A favourable current will increase the vessel's speed over the ground (SOG).
144
When the water level is falling, what type of tide is it?
An ebb tide.
145
What are tidal curves used for?
To determine tidal height at a specific time or the time of a specified tidal height for periods between high and low water.
146
In the context of a tidal curve, what is a sloping line?
Line connecting high water and low water heights on the left-hand side of the tidal curve diagram
147
Between which two points do you draw the sloping line on the tidal curve?
High Water and Low Water.
148
What does the time axis below the tidal curve use as a reference point?
The time of high water. The scale enables intervals before or after high water to be ascertained.
149
Why is the interpolation factor important when using tidal curves?
Tidal curves have lines for both neap and spring tides. When the range is neither neaps nor springs, the user must calculate the interpolation factor to enable them to decide which point between the two curves.
150
Why might someone wish to calculate the height of tide for a specific time?
- Height of tide to be a limiting factor.
- Minimum tide is required to enter a port where overhead clearance is an issue i.e. bridge.
151
What is a standard port?
A standard port is a port for which tidal predictions are directly given tables.
152
How must seasonal corrections be applied when calculating the height of tide for a secondary port?
The seasonal corrections for the standard port must be removed before the differences are calculated. Seasonal corrections for the secondary port must then be applied to the secondary port once the differences have been applied.
153
what information does the secondary port tide tables provide?
In addition to the number, name a location of the por , they provide differences between the standard port and the secondary port in question for high and low water times and heights.
154
Why do Tidal Stream Atlases have multiple chartlets for each area?
Because each chartlet indicates the expected tidal streams for a different hour before and after high water.
155
What is the Computation of Rates Table used for, with regard to tidal streams?
it is used to permit the OOW to make a more accurate calculation of the Tidal streams given in the Tidal Stream Atlases.
156
Which scale on the chart can we use to measure distances
Latitude scale.
157
Why should we always try to plot using three lines of position?
To ensure accuracy and make it easier to identify if one line of position is erroneous.
158
What is the correct symbology for a position fix obtained using two bearings and one range?
- Bearings should have arrows on the end pointing away form the object.
- Ranges should have an arc pointing outwards.
- Fix should be highlighted by a circle and time should be next to the fix.
159
How should the OOW select points from which to take multiple ranges or bearings.
Conspicuous points that are equally spaced around the horizon ideally 60 degrees apart.
160
In which publication can time zone information be found?
Standard Times Section of the Nautical Almanac.
161
What can GMT also be Called?
UTC (universal time).
162
The motion of the vessel, without consideration for tides or currents, is called what?
The water track.
163
What is 'set and drift'?
- Set is current's direction, expressed in degrees.
- Drift is the current's speed, measured in knots.
164
What is the correct symbology for a ground track?
Two arrows pointing in the direction of travel, positioned half way along the line.
165
What other terms are often used to describe the ground track?
Course Made Good (CMG) or COG.
166
Which symbol is added to a DR position?
DR positions are marked with the time and no other symbology.
167
Out of a DR and an EP, which gives us more a accurate understanding of the vessel's position?
An EP because it takes into account the set and drift experienced by the vessel during the time period.
168
What is the correct symbology for an EP?
A triangle and the time.
169
What is the difference between tidal stream and a current?
- Tidal stream is caused by tidal movement as a result of the gravitational force of the Sun and the Moon.
- Current is non-tidal movement of water mainly due to wind, oceanographic or topographical causes.
170
Why must the OOW not rely on EPs and DRs to monitor the vessel's position?
Although reliable over the short-term, errors with the speed/heading inputs and the effects of wind, tide and current can build up rapidly over time, making the DR/EP positions less and less accurate.
171
How can you plot your vessel's position at anchor without GPS or Radar?
By using a Horizontal Sextant Angles.
172
How many lines of position does a running fix require?
Two, LOP (Line of Position) transferred and crossed by the second LOP, forming a fix.
173
Between a running fix and a fix from 'doubling the angle on the bow', which is more accurate?
A running fix is more accurate because it incorporates set and drift into the final position.
174
Plane and Parallel Sailing produce what kind of course?
A Rhumb Line Course.
175
What kind of course is produced by a Mercator Sailing
A Rhumb Line.
176
What is a Meridional Part?
The length along a meridian on a Mercator chart between the equator and that parallel of Latitude expressed in units of the longitude scale.
177
What are Fist Magnitude Stars?
The Brightest Stars.
178
What is GHA?
(Greenwich's Hour Angle).
Position to an hour circle in the body's position.
179
Where can you find the information required to calculate Sunrise and Sunset for your position?
in the daily pages of the Nautical Almanac.
180
What is an 'increment'?
A correction for the minutes and seconds between the figures given for each hour in the Almanac.
181
When can you take an azimuth?
Any time the body is visible.
182
When can you take an amplitude?
Amplitudes can only be taken when the body is on the corrected horizon. For the sun and moon, this is a semi-diameter above the observed horizon.
183
Which publication contains the ABC tables?
Norrie's Nautical Tables
184
Why is the Graduated Arc 120 degrees but the frame only represents 60 degrees of arc?
Because when a ray of light is reflected twice in the same plane the angle between the first ray and the second ray is twice the angle between the two plane.
185
In what order should the correctable errors be adjusted?
Perpendicular then Side Error then Index Error.
186
What is the remaining, correctable error called once the correction process has been followed?
Index Error.
187
How would you take the Altitude of a celestial body with a sextant?
Bring the body to a position just below the horizon (easterly objects) and wait for it to rise to the horizon before noting the time. For westerly objects, place the body just above and note time once it's dropped sufficiently to brush the horizon.
188
Define Civil Twilight?
The period when the sun is 6 degrees below the true horizon (or 96 degrees from the observer's zenith).
189
When does Meridian Passage occur?
Meridian Passage occurs when
190
Can you use Astronomical Twilight to take a Sun sight?
No. The period where the sun's geometric centre is 12 degrees below the horizon is considered night, and is therefore too dark to discern the horizon.
191
What are the correctable errors of a sextant?
- Perpendicularity.
- Side Error.
- Index Error.
192
What are the non-correctable errors of a sextant?
- Collimation.
- Prismatic.
- Centering.
- Graduation.
- Worm and Rack.
193
What order do you correct the errors on a Sextant?
- Perpendicularity, Side Error, the Index Error.
- Back to Side Error and then Index Error again as many times necessary to get the final Index Error correction as low as possible
194
Which Screws for correcting what sextant error?
- Perpendicularity - Screw on side of the Index Mirror.
- Side Error - Screw on side of Horizon Mirror.
- Index error - screw on top of Horizon Mirror.
