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Navigation B — Instruments question bank — Mashit 30

All 193 questions of the paper, arranged by topic, with the correct answer. For searching, browsing and revising before the exam.

Jump to a topic

  • Radar — 17 questions. Range, discrimination, controls and detecting risk of collision
  • Radio communications — 50 questions. VHF, channels, antennas, DSC and calling procedures
  • NAVTEX — 11 questions. Reception, frequencies, the transmitter network and message types
  • Distress and rescue — 30 questions. MAYDAY, PAN-PAN, EPIRB, SART and GMDSS
  • Compasses — 18 questions. Magnetic, gyro, fluxgate, deviation and variation
  • GPS — 11 questions. Initialising, controls, accuracy and speed over ground
  • Echo sounder — 14 questions. The transducer, its care and comparing the sounding with the chart
  • Time and time zones — 10 questions. UTC, zone time, local time and the date line
  • Stars and sky — 13 questions. The Pole Star, constellations and the sun's motion
  • The earth and charts — 14 questions. Latitude and longitude, the nautical mile and distances

1. The earth, coordinates and charts

  1. Why is the earth's surface divided by meridians of longitude and parallels of latitude? To define positions where they intersect.
  2. Where should distances be measured on a Mercator chart? In units of latitude, on the scale at the left or right side of the chart, level with the area you are sailing in.
  3. A nautical mile is equal in length to: One minute of arc on a great circle.
  4. What is the length of one nautical mile? 1852.5 metres.
  5. On the geographic grid, how many whole degrees are there from the equator to each of the poles? 90° to the North Pole and 90° to the South Pole.
  6. The Greenwich meridian is: All of the above.
  7. Parallels of latitude on the earth are: Apart from the equator, small circles at right angles to the earth's axis of rotation, whose diameter decreases towards the poles.
  8. Meridians (lines of longitude) are: Great circles at right angles to the equator, passing through the poles.
  9. What is a rhumb line? Answers b and c are correct.
  10. What is the shortest route between the Strait of Gibraltar and New York City? An arc of the great circle that passes through the two places.
  11. What is the distance, in nautical miles, between two adjacent parallels of latitude on the earth's surface? 60 miles.
  12. Is the distance between two adjacent meridians on the earth's surface constant? No.
  13. Where does the parallel of latitude 20°N end? It does not end.
  14. Which meridian joins the meridian of 40°E to make a complete circle? 140°W.

2. Sun, moon and stars

  1. Why do you see the sun rise in the east and set in the west? The earth rotates on its axis from west to east.
  2. What can a vessel conclude if every evening she measures the same altitude of the Pole Star (Polaris) above the horizon? Answers a and b are correct.
  3. In which of the following star groups is the Pole Star (Polaris) found? option b (a picture)
  4. Choose the drawing that shows the star group called the Plough (Big Dipper): option d (a picture)
  5. If the altitude of the Pole Star (Polaris) is 45° above the horizon, the observer can be assumed to be at about: Latitude 45° north.
  6. The sun rises in the east and sets in the west because: The earth rotates on its axis from west to east.
  7. What causes the seasons? The plane of the earth's equator is tilted 23½° to the plane of its orbit around the sun.
  8. What is affected by the position of the moon relative to the earth and the sun? Answers a and c are correct.
  9. What will the altitude of the Pole Star (Polaris) above the horizon be for a vessel sailing between Haifa and Cyprus, at a latitude of about 36°N? The Pole Star will be about 36° above the horizon.
  10. You are sailing east along latitude 30°S. On what bearing can you see the Pole Star (Polaris)? The star is not visible.
  11. Where is the Pole Star (Polaris) in relation to the earth? On the imaginary extension of the northern end of the earth's axis of rotation.
  12. Where does the Pole Star (Polaris) lie among the stars? At the end of the handle of the Little Dipper.
  13. Why do the stars look small? Because they are far away from us.

3. Time and time zones

  1. How is local time worked out? From the vessel's present longitude east or west of Greenwich.
  2. What does 'zone time' mean? The uniform time kept across a band of 15°, 7½° east and 7½° west of a central meridian.
  3. On 31 December you are on longitude 179°31'E and the time is 23:59. What are the time and date on longitude 179°31'W? 23:59 on 30 December.
  4. What does it mean when the zone time is said to be UTC+3? All of the above.
  5. The date on board is 24.06.11, the zone time is 10:42 and the observer's longitude is 154°39'E. What will the time and date be at Greenwich? The time will be 00:42 on 24.06.11.
  6. You are on the yacht MARNI, MMSI 428666099, lying at anchor off Haifa port in position 32°42'N 034°58'E. At midnight local time an unidentified vessel collides with your yacht. She is now lying over on her side and is in danger of sinking. There are 3 passengers and 3 crew on board. Your vessel is equipped to GMDSS requirements for sea area A1. Choose the correct statement: Send a distress call to all stations; send a DSC distress alert with the nature of distress COLLISION, and state on VHF that there are 6 people on board.
  7. Your position is 32°17'N 157°42'E and the time is 17:53 UTC. The zone time is therefore: 04:53
  8. Zone time (ZT) is defined as: The time in an area, set by its time zone.
  9. UTC is defined as: Coordinated Universal Time, equal to Greenwich Mean Time.
  10. What is local mean time? The time in an area according to the observer's meridian (longitude).

4.1 Compasses and directions

  1. How will equipment containing loudspeakers, headphones, microphones and batteries affect the vessel's compass? It will disturb the magnetic compass.
  2. What is compass deviation? An error caused by masses of metal and electrical equipment on board.
  3. What is magnetic course? The angle between the vessel's fore-and-aft line and magnetic north.
  4. Which compasses does variation affect equally? A magnetic compass and a fluxgate compass.
  5. What is needed to make a deviation table for a magnetic compass? Answers a and b are correct.
  6. What are the main drawbacks of the mechanical gyrocompass? It needs a continuous power supply and depends on it, and it does not settle immediately when switched on.
  7. Regarding the fluxgate compass, choose the correct answer: Answers a and b are correct.
  8. A compass is an angle-measuring instrument that shows the angle between: Compass north and a given object on the horizon.
  9. A fluxgate compass has the following advantages. Mark the one that does NOT apply: Deviation and variation errors are easy to correct in it.
  10. The most accurate bearing of an object on shore is obtained with: A pelorus.
  11. What can equipment containing loudspeakers, headphones, microphones and batteries affect? It will affect a magnetic compass and throw it off.
  12. Variation affects equally: A magnetic compass and a fluxgate compass.
  13. How does a fluxgate compass work? Answers a and b are correct.
  14. What are the main drawbacks of the mechanical gyrocompass? It needs a continuous power supply and depends on it, it does not settle immediately when switched on, and it develops an error that depends on the latitude and on the course and speed of the vessel it is fitted in.
  15. Which of the following instruments shows the vessel's true course relative to true north? GPS.
  16. Your vessel is going astern, moving towards the east. What course will the magnetic compass show, and what course will the GPS show? Magnetic compass – W; GPS – E.
  17. A stationary vessel heading 150° is turned 30° to port. What course will the magnetic compass show, and what course will the GPS show? Magnetic compass – 120°; GPS – will not respond.
  18. The lubber line of a marine compass is on north. If we turn the compass 90° to the left, where will the lubber line point? West.

4.2 Autopilot and wind-vane self-steering

  1. What is a drawback of an electric autopilot? It uses a lot of electricity, especially in rough seas.
  2. What course does wind-vane self-steering hold? A course at a constant angle between the vessel's fore-and-aft line and the apparent (relative) wind.
  3. What is the main advantage of an autopilot? It makes watchkeeping at sea easier and lets you concentrate on the lookout and on urgent jobs in hard conditions.
  4. What does the accuracy with which an electric autopilot holds the set course depend on? Answers b and c are correct.
  5. What are the main drawbacks of an electric autopilot? All of the above.
  6. About wind-vane self-steering, choose the most correct statement: All of the above.
  7. What is the effect of changing the autopilot's response sensitivity? It reduces or increases how quickly the autopilot responds to changes in course.

5.1 Echo sounder

  1. What is an echo sounder used for? Safety at sea, navigation, route planning and anchoring.
  2. Where is the echo-sounder transducer fitted? The depth at which it is fitted does not matter, because the display can be adjusted to show depths from the deepest point of the draught; but the beam must not be disturbed by bubbles or nearby objects.
  3. How should you look after the echo-sounder transducer? Gently remove weed and marine growth from it (not with a metal tool).
  4. How should you look after the echo-sounder transducer? Paint it with a paint that contains no metal.
  5. When would you use the echo sounder? For safety at sea, navigation and anchoring.
  6. While underway, the echo sounder shows a depth of 12 metres, while the chart shows 10 metres at the same place. The vessel's draught is 1.2 metres. What causes the difference? The chart gives depths at the lowest low water, and at the time of the sounding the height of tide is 3.2 metres.
  7. Which of these does not affect the accuracy of an echo sounder? The electric field created by the friction of the rudder against the surface layer of the water.
  8. The echo sounder shows a depth of 10 metres, your vessel's draught is 2 metres and the height of tide is 1 metre. What depth should the chart show? 11 metres.
  9. While underway, the echo sounder shows a depth of 12 metres, while the chart shows 10.8 metres at the same place. The vessel's draught is 1.2 metres. The difference arises because: The chart gives depths at the lowest low water, and at the time of the sounding the height of tide is 2.4 metres.
  10. If there is no echo sounder, or it is not working, how else can you estimate the depth? Choose the most practical answer: For small depths, use a line with a weight on it; for greater depths, read and work out the depth from the chart's figures and symbols, allowing for high and low water.
  11. When you increase the depth range on an echo sounder: Fewer pulses are transmitted per unit of time.
  12. What is the function of the transducer in an echo sounder? To convert the electrical (radio-frequency) pulses into sound waves when transmitting, and to convert the returning echo back into an electrical signal when receiving.
  13. How should you look after the echo-sounder transducer? If it is an oil-filled ceramic type, check the oil level and top it up if needed.
  14. Assume the echo sounder shows the depth below the deepest point of the hull. A vessel with a draught of 1.5 metres measures a depth of 1 metre, while the chart shows 2 metres. What is the reason for the difference? The chart depth is given for the lowest low water, but at the time of measurement the tide is 0.5 metres above the charted level.

5.2 Speed, distance and wind

  1. Which wind does the wind instrument show when the vessel is not moving? True wind.
  2. A partly submerged floating object is thrown from the bow of a 15-metre vessel. It takes 5 seconds to reach the stern. What is the vessel's speed in knots? About 6 knots.
  3. A line with knots tied in it at equal intervals of 5 metres is paid out from the stern of a moving vessel. If five knots (not counting the end) run out in ten seconds, what is the vessel's speed? All of the above.
  4. What is the distance to the horizon for an observer with a height of eye of 9 metres? About 6.3 miles.
  5. What does the vessel's wind instrument show when she is underway? Apparent (relative) wind.
  6. When a vessel lies at anchor where there is a current: The GPS receiver will show zero, and the log (speed through the water) will show the speed of the current.
  7. A power-driven vessel is heading 270° in a westerly wind of 10 knots, with a current of 2 knots setting west. Her mechanical log shows 8 knots and her GPS receiver shows 10 knots. What is the reason for the difference? The log measures speed through the water and does not allow for the current and the wind, while the GPS receiver shows the true speed over the ground.
  8. A GPS-based speed indicator shows 8 knots, in an area with a 2-knot current against you. What is your vessel's speed over the ground? 8 knots.
  9. In which instruments or systems is the Doppler effect used? The Cospas-Sarsat satellite system.

5.3 GPS

  1. How does a GPS receiver work out its position? It receives the identification code and range of 3 or more satellites, and converts the point where the ranges meet into the intersection of a meridian and a parallel on a chart or other display.
  2. What do the initials GPS stand for? Global Positioning System.
  3. The difference between SET UP and INITIALISATION is: All of the above.
  4. What is the difference between the MOB key and the MARK key? MOB marks the present position as an 'active waypoint' and shows the bearing and range to it continuously, while MARK only marks the present position.
  5. To get a position from GPS (Global Positioning System) you need: Simultaneous reception of at least 3 satellites.
  6. Where is it recommended to fit the GPS antenna on board? As low as possible (to reduce its movement), while keeping a clear view of the sky all round.
  7. The loss of position accuracy caused by receiving satellites that are close together is indicated by: Position dilution of precision (PDOP).
  8. Various systems can improve GPS accuracy to a fraction of a metre. How will you know whether they are available to you, or at least how accurate your receiver is? With the vessel moored alongside, compare a fix from 3 crossed bearings with the position the GPS gives, and check that the GPS shows zero speed.
  9. What is the difference between the MOB key and the MARK key? MOB marks the present position as an 'active waypoint' and shows the bearing and range to it continuously, while MARK only marks the present position.
  10. On a GPS receiver, what do the following mean, in order: 1 – ROUTE, 2 – TRACK, 3 – Course To Steer? 1 – several legs on different courses, each between two adjacent, consecutive points, linked into one route and stored in memory under a chosen name; 2 – the path the vessel is meant to follow between the point of departure and the destination; 3 – the course, corrected by the receiver, that must be steered to reach the selected waypoint.
  11. Can a GPS measure speed? Yes.

6. Radar

  1. What do you need to check whether there is a risk of collision with a vessel nearby? A hand-bearing compass, a watch, at least 3 bearings of the vessel being checked, and the ability to judge the range.
  2. What is radar used for? All of the above.
  3. Can aircraft and rain clouds be detected by radar? Yes, but only at heights within the vertical beamwidth of the radar.
  4. What does the detection range of a radar depend on? The antenna height, the transmitter power, and weather and atmospheric conditions.
  5. What is the GAIN control on a radar used for? To reduce or increase receiver sensitivity.
  6. In heavy rain, can small vessels and a marina entrance be detected on radar, and which control on the control panel should you use? Yes, but it depends on the size and material of the objects and on how heavy the rain is; the right control is Anti-Clutter Rain or FTC.
  7. The quality and detection range of an object on radar depend on: All of the above.
  8. What do you need to detect a risk of collision on radar? All of the above.
  9. STAND-BY mode on a marine radar: The radar neither transmits nor receives, but the screen is "warm" and ready for immediate use.
  10. What is the difference between a RADAR REFLECTOR (the first) and a SART (the second)? All of the above.
  11. On the radar, 2 targets that are physically close to each other lie on the same bearing. When will they be better distinguished? When the transmitted pulse length is shorter.
  12. What is the effect of the bending of radar waves? Answers b and c are correct.
  13. What is radar used for? Collision avoidance, navigation, route planning, and search and rescue.
  14. In heavy rain, can small vessels and a marina entrance be detected on radar, and which control on the control panel should you use? Yes, but it depends on the size and material of the objects and on how heavy the rain is; the right control is Anti-Clutter Rain or FTC.
  15. Choose the statement about marine radar that is most correct: On short range scales we select a short pulse to separate close objects well, and we also get better bearing accuracy; on long range scales we prefer a longer pulse for good echoes from small objects, but bearing accuracy is poorer.
  16. What do the quality and detection range of an object on radar depend on? All of the above.
  17. When can you tell from the radar that your vessel is at risk of collision? When the target's bearing stays steady and the range decreases.

7.1 The VHF radio, channels and frequencies

  1. Why do you need the appropriate class of radio operator's certificate to use radio equipment for international communications? Because not knowing the procedures and what the controls do could stop you getting help in distress, or could interfere with other vessels' rescue communications.
  2. What does the DUAL WATCH (DW) control on a VHF radio do? You listen and transmit on the selected channel, but reception switches to channel 16 whenever there is traffic on it.
  3. What do the squelch on a VHF radio, the anti-clutter controls on a radar, hand steering and correct sail trim have in common? All of the above.
  4. What mainly affects communication range on VHF? A clear path between the antennas, transmitter power, the height of the antennas and radio propagation conditions.
  5. Which transmissions are made on low power? All of the above.
  6. Can two Israeli yachts talk to each other on channel 26? No, channel 26 is a duplex channel for public correspondence.
  7. What is VHF channel 6 used for? Communication between vessels.
  8. What is required of a VHF radio's antenna? Its length must suit the radio's transmitting and receiving frequency band.
  9. What is the main factor that determines transmission range on VHF? Line of sight between the antennas.
  10. When vessels are required to carry a VHF radio, this means a radio that receives and transmits between 156 and 174 MHz. Why? Because this is the band allocated to the maritime mobile service by the international telecommunications organisation.
  11. For which purposes have no channels been allocated in the marine VHF band? Monitoring vessels at anchor, an automatic alarm when the radar detects a close approach, automatic dialling through a satellite relay.
  12. Switching to which channels, and for what reason, will cause voice contact between two vessels to be lost? Choose the answer that is not correct. Channel 13, because it is meant for "bridge-to-bridge" contact between large ships, whose antennas are higher than those of smaller vessels.
  13. What does the physical size of an antenna depend on? The higher the frequency, the smaller the antenna can be.
  14. In FM modulation: The frequency of the carrier wave is varied according to the information transmitted.
  15. What is the DUAL WATCH button on a VHF radio used for? The radio listens on channel 16 and one other selected channel.
  16. Can two yachts talk to each other on VHF channel 25? No – it is a duplex channel.
  17. When will you choose to transmit in simplex, and when in duplex, on a marine VHF radio? We cannot choose; the radio switches between them automatically when the channel is changed.
  18. Why is it sometimes necessary to change the transmitting frequency at night when setting up HF communication? Because the height of the ionosphere changes.
  19. What is the frequency range of a marine VHF radio? Between 156 MHz and 174 MHz.
  20. A (portable) VHF transmitter can reduce its transmitting power down to: 1 W.
  21. What mainly affects communication range on VHF? A clear path between the antennas (antenna height), transmitter power, antenna gain and matching, and a number of radio-wave propagation conditions.

7.2 Identification, DSC and AIS

  1. What is a vessel's MMSI? All of the above.
  2. What is the electronic unit known as DSC? A unit built into radios that encodes and decodes messages in digital communication.
  3. What is meant by "Digital Selective Calling"? The device or system whose purpose is to identify others and itself, and to decode and process messages for digital communication = Digital Selective Calling.
  4. The identification of a vessel's radio station in international communication: Answers b and c are correct.
  5. Which of the following identifies a ship? 232000432
  6. What is the purpose of AIS? To improve safety of navigation and prevent collisions between vessels.
  7. What does the code MA33 indicate? The identification code of a NAVTEX message.
  8. What is the number 428000500? Answers a and b are correct.
  9. Which DSC data is sent automatically with every transmission? MMSI.
  10. What is the electronic unit known as DSC? A unit built into radios that encodes and decodes messages in digital communication, designed so that it does not depend on the operator's skills.

7.3 NAVTEX

  1. How often is a NAVTEX broadcast received from a given coast station? Every 4 hours.
  2. What should you set up on the NAVTEX receiver before sailing? The "stations" and the types of message you want.
  3. Distress messages that appear in the output of a NAVTEX receiver: Come from coast stations and the regional administration of the NAVTEX transmitter, to increase the number of vessels that can give help.
  4. VITAL, IMPORTANT and ROUTINE are: The grades that classify NAVTEX messages by priority and content.
  5. On which frequency band does a NAVTEX receiver receive? MF.
  6. What do VITAL, IMPORTANT and ROUTINE messages refer to, and what do they mean? The grades that classify NAVTEX messages by priority and content.
  7. How many times, and for how long each time, does a NAVTEX station transmit in one day? Every 4 hours, for at most 10 minutes each time.
  8. Which messages can be transmitted from the vessel on a NAVTEX set? None of the above.
  9. How are messages delivered in the NAVTEX system? Through a worldwide network of administrations and transmitters that broadcast safety information to shipping; vessels receive the information in printed form on dedicated receivers called NAVTEX receivers.
  10. How is the chain of NAVTEX transmitters that broadcast safety information laid out? So that within each transmitter's designed range (about 400 miles) there is no interfering overlap with the transmitter covering the neighbouring area (about 800 miles), while neighbouring administrations coordinate power and broadcasts.
  11. How do distress messages appear in the output of a NAVTEX receiver? They come from coast stations and the regional administration of the NAVTEX transmitter, to increase the number of vessels that can give help.

7.4 Radio procedures and tests

  1. You are handling distress traffic on channel 16 and, because of constant interference, you want to move to a 'clear' channel. Which group of channels is suitable? 06, 08, 13.
  2. When a distress incident is over and channel 16 is to be released for normal calls, how does the station controlling the distress traffic announce it? SEELONCE FEENEE.
  3. You have called a coast station and there is no answer. What do you do? I wait at least two minutes and call it again on its calling channel or its working channel, after making sure the channel is clear.
  4. A station controlling distress traffic wants to stop interference on channel 16 from stations that are unaware of the situation. It will tell them: SEELONCE MAYDAY.
  5. A station that is not controlling the distress traffic, but is in the area of a distress incident, wants to stop interference on channel 16 from stations unaware of the situation. What will it say? SEELONCE DISTRESS.
  6. When a distress incident is nearly over and channel 16 is no longer needed continuously (a "careful ending"), the station controlling the traffic will announce: PRUDONCE.
  7. Which checks of a vessel's radio equipment must be carried out and recorded in the ship's log? Answers a and b (if such a log exists) are correct.
  8. Which checks must be carried out on a vessel's radio equipment? Answers a and b (if such a log exists) are correct.

8.1 Distress, urgency and safety procedures

  1. When is the distress procedure used from a vessel's radio station? When there is grave and imminent danger to one person, to the whole crew or to the vessel, and the person actually in command decides that immediate assistance is needed.
  2. In which cases should the urgency (PAN-PAN) procedure be used? All of the above.
  3. What does the radio call PAN-PAN, repeated 3 times, mean? A call that comes before an urgency message, which has second priority on the radio.
  4. For which kinds of event is the "urgency" level used? None of the above.
  5. A DISTRESS CALL is: All of the above.
  6. A person has fallen overboard from a vessel and has been lost from sight: The distress procedure is followed, and the message must state the position and time the person was last seen.
  7. A message preceded by the word MEDICO: Has urgency priority and must include the patient's sex and age, body temperature, pulse, a description of the symptoms and any treatment given. After the call on channel 16 you may change to another channel.
  8. Messages preceded by SÉCURITÉ, said 3 times: All of the above.
  9. The following call was heard on VHF channel 16: MAYDAY MAYDAY MAYDAY THIS IS SONDRA SONDRA SONDRA MMSI 356004420 MAYDAY SONDRA THREE FIVE DEGREES FOUR FOUR MINUTES EAST THREE TWO DEGREES FIVE NINE MINUTES NORTH IN ROUGH SEA AND IN DANGER OF SINKING. REQUIRE IMMEDIATE ASSISTANCE 8 PERSONS ON BOARD OVER The wording of this distress call may contain some errors. Choose the correct answer: When giving the vessel's position, the latitude must be stated first.
  10. When a distress incident is over and channel 16 is to be "released" for routine calls, what will the station controlling the traffic announce? SEELONCE FEENEE.
  11. In which cases should the safety (SÉCURITÉ) procedure be used? None of the above.
  12. What is a DISTRESS CALL? All of the above.
  13. Who should respond immediately to a MAYDAY call? Anyone who hears the call.

8.2 Beacons, transponders and survival equipment

  1. What is meant by the 'FLOAT FREE' feature? A technical arrangement that lets distress beacons release themselves and float.
  2. Which of the following can tell you that another vessel is in distress? NAVTEX.
  3. Where should the EPIRB be placed, in relation to the liferaft, so that its transmission is received best? In the water, next to the liferaft.
  4. Until when will DSC equipment keep transmitting a distress alert? Until a coast station or another vessel acknowledges receipt of the alert by DSC.
  5. How is a SART "woken up" into action? Only when an X-band radar triggers it.
  6. An EPIRB that belongs to the Cospas-Sarsat system: Operates on 406 MHz.
  7. What is a search and rescue radar transponder? All of the above.
  8. What are the features of a SART? Buoyancy, a battery for 96 hours of receiving or 8 hours of transmitting, a light and an audible signal.
  9. A vessel's radar screen shows the following marks: ●●●●●●●●●●●●, then after a while ) ) ) ) ) ), and after a further while ◎. What is being received? SART transmissions at about 8 miles, about 5 miles and less than 1 mile respectively, in the order the marks appeared.
  10. On which equipment can SART transmissions be received? On marine radars working in the X-band.
  11. On which equipment on board can a distress message be received? NAVTEX.
  12. Under the GMDSS requirements, which emergency equipment must a vessel carry in sea area A1? DSC, SART, EPIRB, portable VHF, VHF, NAVTEX.
  13. What can be worked out from detecting a SART on the radar screen? The approximate range and bearing of the target.
  14. In which sea areas can an EPIRB that works through satellites orbiting the earth from pole to pole be used? All of the above.
  15. Choose the correct statement about a Cospas-Sarsat beacon: It transmits on 406 MHz to a satellite system, but it is allowed as part of a vessel's equipment as an alternative to a beacon on VHF channel 70.
  16. What is meant by the 'FLOAT FREE' feature? A technical arrangement that lets distress beacons release themselves and float.
  17. What are the features of a SART? Buoyancy, a battery for 96 hours of receiving or 8 hours of transmitting, a light and an audible signal.