Hydrographic Surveying Practice Exam

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• How many times a year can perigean spring tides occur?
• What does GLORIA stand for and what is its unique feature?
• In relation to tidal gauges, what does TGBM stand for, and what is its main purpose?
• What is the name of the designated marine area in Ireland?
• What year did the Admiralty cease surveying Irish waters?
• What might improve with advancements in GNSS technologies?
• True or False: Airborne lidar can simultaneously scan both land and water in a coastal zone.
• What is the area mapped by the multibeam sonar called?
• Which of the following factors is not typically included in compensation for a multibeam sonar survey?
• What is true about the global network of tide gauges?
• What may produce a less distinct trace of the profile of the seabed?
• A deep water multibeam system typically operates at what frequency to map significant depths?
• Between which two features does the continental slope lie?
• Which term describes the detail level of a multibeam sonar compared to conventional echo sounders?
• When does a full moon occur?
• Which of the following statements about Irish hydrographic surveying is correct?
• What tidal condition occurs when the sun, moon, and Earth are aligned?
• What is the angle at which the sun and moon create neap tides?
• Why is datum control important?
• What frequency range is commonly used in SBES?
• How long does the mid-oceanic ridge extend?
• When does a perigean spring tide typically occur?
• What is a significant concern in modern hydrographic surveying practices in Ireland?
• What does RTK positioning stand for?
• In a bathymetric survey, what are the two lengths that need to be determined to arrive at Z (depth)?
• How can the depth Z be determined using sound instead of physical measures?
• What kind of sonar system is typically employed for mapping waters less than 100 meters deep?
• What characterizes a continental shelf?
• What is the period of the moon's orbit around the Earth?
• What type of pulse does an SBES typically transmit for bathymetry acquisition?
• What is a seamount?
• What must be compensated for when using a single beam sound in hydrographic surveying?
• Hydrography predicts changes over time primarily for which purpose?
• How is frequency of sound wave transmissions measured?
• Airborne LIDAR Hydrography uses which type of laser pulse to capture data from the water surface?
• What is the main purpose of the transducer array in a multibeam echo sounder?
• What type of bathymetry is used to measure water depth in shallow waters?
• Which benefit does hydrographic surveys provide to insurance companies?
• What does the 'yellow stripe' refer to in a multibeam echo sounder?
• What is a characteristic feature of the beam of an echo-sounder?
• Which device is most commonly used to measure fluctuations in water level?
• How is sound speed correction best calculated?
• What does hydrography primarily concern itself with?
• What proportion of inshore charts is derived from surveys of 1:50,000 or smaller?
• What happens when sound waves travel through different temperatures and salinities in water?
• What factors are irrelevant for GNSS surveying that are required for soundings?
• What does bathymetry measure?
• Which configuration involves using an along keel transmit array and an across keel receive array?
• Which German inventor was granted a patent for echo sounding in 1913?
• Which of the following is a key definition of hydrography?
• What is the typical circular aperture range of a transducer in bathymetric data acquisition?
• What issue arises when using an SBES beam sounder on a slope?
• What does TGZ stand for in relation to tidal gauges, and what is its elevation relative to?
• What type of sonar is commonly known as a fathometer?
• What mathematical analysis is commonly used to predict tides?
• What are tide gauges primarily used for?
• What conditions are considered when determining LAT?
• How does knowing seafloor composition aid hydrographers?
• Who conducted the first recorded bathymetric measurement?
• How is data obtained by the sensor of a Side-Scan Sonar scan?
• What satellite technology is used to measure the sea floor features based on gravitational bulges?
• In modern multibeam echo sounders, what is the typical swath width range?
• When do low tides occur in relation to the moon and sun's positioning?
• Are the frequencies used in SBES meant to penetrate seafloor sediments?
• What was the method used before the adoption of LAT as Chart Datum?
• Why is a datum essential when measuring water levels at tide gauges?
• What is the principle function of a motion sensor in hydrographic surveying?
• What are the disadvantages of point-by-point sounding?
• What frequency relationship exists between multibeam and single-beam echo sounders?
• What advantage does airborne lidar have when surveying coastal areas compared to vessel-based scanning?
• What is the equivalent of LAT in US terminology?
• Which factor does not influence the quality of hydrographic charts?
• What causes daily tides?
• What is the typical resolution of the ultra high resolution aerial photography used by Bluesky?
• What does SBES stand for in hydrographic surveying?
• The perpendicular direction to the path of the survey vessel is referred to as what?
• What percentage of the data for Irish charts is post-1980?
• What is the typical distance of the Moon at apogee?
• Is Chart Datum considered fixed across different charts?
• What is the average range of tidal variations?
• What is the timing of spring and neap tides in relation to the Moon?
• Which of the following is NOT a factor complicating tidal predictions?
• What geological activities may cause tidal gauges to move vertically?
• What is a primary focus of Marine Geology in relation to hydrography?
• What are the two main aspects of hydrographic surveying?
• When do spring tides occur?
• What is one limitation of a traditional echo sounder in terms of seafloor mapping?
• What is the general depth range of the ocean floor?
• What is true about the formation of seamounts?
• What scale are the inshore charts of Irish waters published at?
• When were new electronic technologies introduced in hydrography?
• What is the purpose of conducting a sound velocity profile (SVP)?
• When do neap tides occur?
• The ocean bulges outward and inward due to what feature of the ocean floor?
• What is the datum used by mariners related to low tide known as?
• What aspect of Physical Oceanography is essential for hydrographers?
• What kind of activities does hydrography support according to its definition?
• Which term refers to the study of temperature, salinity, and chemical content of water?
• What happens to the Moon’s appearance during a new moon?
• What is one of the main uses of seabed mapping?
• What phenomenon occurs when the Moon is fully illuminated?
• What is the relationship between oceanic trenches and tectonic activity?
• What are the tidal extremes known as during neap tides?
• What sort of data does nautical chart datum largely depend on?
• Who are the main scientific users of hydrographic information?
• What is the main focus of the bathymetric aspect of hydrographic surveys?
• Which physical characteristics of water are included as hydrographic information?
• What plays a crucial role in determining the multibeam sonar's resolution?
• How is water depth defined in a hydrographic survey?
• How often should LAT be reviewed?
• What is the primary importance of tidal theory in navigation?
• What is lunar apogee?
• How many different datasets can Irish hydrographic charts be derived from?
• Which of the following features may pose a hazard to navigation?
• What is the formula to determine depth using sound wave?
• What geological activity is primarily associated with an oceanic trench?
• What is one advantage of using GNSS over traditional soundings for seafloor scanning?
• What is a primary limitation of using point-by-point sounding?
• What is the primary function of the Admiralty Chart Datum (ACD)?
• What maximum beam inclination is used by airborne lidar technology?
• Why are hydrographic surveys beneficial?
• Which of the following is an application of Satellite Radar Altimetry?
• What percentage of the Earth's surface is covered by oceans?
• At what level is Chart Datum set?
• What does the term 'squat' refer to in the context of hydrographic surveying?
• What is recommended good practice for ensuring the accuracy of a TGBM's elevation?
• What does LAT stand for?
• Which term describes the lowest level that can be expected under various conditions?
• How far can the Moon be from Earth at perigee?
• How does a tow-fish side scan differ from a MBES scan?
• How does wire-drag surveys determine the presence of underwater obstructions?
• What does hydrography measure besides the physical features?
• What is necessary to merge historic, current, and future hydrographic data?
• For what duration of observations is LAT officially determined?
• How strong is the gravitational attraction exerted by the sun compared to that of the moon?
• What role does a subsea plant serve in the oil industry?
• Which position fixing method is commonly used in hydrographic surveying to determine underwater locations?
• What is the purpose of using a LAT-WGS84 ellipsoid separation model?
• What type of information is conveyed by a tide gauge?
• What has been observed about global sea level trends over the past century?
• What effect does an apogean spring tide have on tidal ranges?
• Is LAT the same as Chart Datum?
• How is offshore sea level primarily calculated?
• What is the approximate speed of sound in water at 20°C?
• What device is commonly used by UK Hydrographic Office for charting?
• What is lunar perigee?
• According to the International Hydrographic Organization, hydrography primarily supports what?
• What does the y-axis depict in the chart produced by a tidal gauge?
• What datum was in use in the UK, along with the frequency of data collection from 1915 to 1921?
• In a multibeam sonar survey, which factor is NOT typically compensated for?
• What key statistic was obtained during the collection of tide gauge data between 1915 and 1921?
• What would be the maximum tide amount if the Earth was covered only by deep ocean?
• What is the characteristic feature of a continental slope?
• What is typically used to improve the accuracy of long-term sea-level change observations?
• New moons occur when the Moon is positioned between which two celestial bodies?
• An example of bathymetric mapping is typically based on what?
• What is a significant complication when reinitializing RTK positioning systems after a loss of lock?
• Which statement is true regarding the age of data used for current Irish hydrographic charts?
• Which of the following is a principal component of a hydrographic survey?
• What is the size of the designated marine area in Ireland?
• What historical period does the majority of Irish hydrographic data represent?
• What defines the anomalistic month?
• What is the primary function of an echo sounder?
• What is the depth limitation for photo bathymetry in measuring water depth?
• What is the purpose of identifying hazards to navigation in hydrographic surveys?
• How is water depth commonly determined in modern hydrographic surveying?
• According to annual tide gauge records, how much has sea level risen from 1880 to 2000?
• How is tide gauge measurement conducted in modern practice?
• Which principle describes the intersection of transmit and receive footprints in a multibeam system?
• From which stage of the oceanic floor profile may a volcanic island or oceanic ridge arise?
• When did Poseidon conduct the first recorded bathymetric measurement?
• Which element is essential to eliminate for accurate long-term sea level change assessments?
• How do vertical movements affect the measurement of global sea level?
• Hydrography primarily supports activities related to which sector?
• What impact does rough water surface have on echo-sounder beam projection?
• Between 1925 and 1927, which vessel first used SBES for bathymetric profiles in the South Atlantic?
• What is a significant effect of spring tides?
• What is the nadir of a tow-fish side scanner?
• How does Side-Scan Sonar uniquely gather data?
• What shape best describes the Moon's orbit around Earth?
• How has global sea level been measured over the past century?
• Which of the following is NOT a significance of bathymetry?
• How is 52% of the data for Irish hydrographic charts categorized?
• What distinguishes a hydrographic chart from other types of charts?
• What is the primary limitation of photo bathymetry?
• At what depth do abyssal plains generally lie?
• How often do high tides occur during full and new moons?
• What is the purpose of hydrographic charts?
• What does positioning refer to in a hydrographic survey?
• Does GNSS surveying provide accurate Z (vertical) recordings?
• What type of data is primarily used to create a nautical chart?
• What geological process causes the mid-oceanic ridge to form?
• What is the ratio of seabed to land in the designated marine area?
• When comparing airborne lidar to vessel scanning, how many soundings does the airborne lidar capture per second?
• Which term refers to the highest expected water level?
• What technology is used in Airborne LIDAR Hydrography to rapidly measure seabed depths?
• When did the first automatic still-well water gauges come into use in the UK?
• How was sound speed corrected in historical contexts?
• How can shadows from obstructions to the scanner be utilized in seafloor profiling?
• What defines the continental slope in hydrographic terms?
• What is the reference point for the depth of an oceanic floor profile?
• Which of the following are the main charts used in producing a land/sea survey?
• What type of sonar system has narrower beams, single or multibeam?
• What is the benefit of tide gauge zero being equivalent to the Admiralty Chart Datum?
• How is tidal range calculated for unknown locations?
• What does the variable 'c' represent in the sound wave depth formula?
• What is the most commonly used tide gauge measurement system?
• What direction does the moon orbit the Earth?
• What is the percentage of data on current Irish charts that is pre-1900?
• What percentage of charts published of Irish waters is based on data that is more than 100 years old?
• What is one disadvantage of RTK positioning?
• How long were sounding lines used for measuring depths?
• What type of sonar has the ability to map multiple locations on the ocean floor with a single ping?
• What equipment did Poseidon use for the first bathymetric measurement?
• What types of materials are considered in seafloor geology?
• What is the intended outcome of hydrographic studies in terms of marine activities?
• How is the seafloor detected using acoustic pulse?
• At which depth range does the abyssal plain typically lie in relation to the ocean floor?
• What does Sea MARC stand for?
• What is the maximum depth that a continental shelf typically reaches?
• Which of the following are key features of a hydrographic chart?
• What invention was introduced to hydrography in 1904 to improve surveying?
• What is one of the main hazards identified in hydrographic surveys?
• What is backscatter in the context of sonar?
• What is the primary purpose of nautical charting?
• How is bathymetry defined?
• Charts derived from which survey scale are the most common for Irish waters?
• What is the significance of referencing all UK tidal monitoring points to the same datum?
• In what direction does the Earth spin?
• Which meteorological factors are measured by tidal gauges for their impact on sea levels?
• What is datum control in hydrographic surveying?
• What happens to tidal extremes during low tide conditions?
• Who primarily needs tidal tables?
• In a tidal gauge chart, what does the x-axis typically represent?