649
1 INTRODUCTION
The territorial sea is an integral part of the Polish
territory. It extends as a belt with a width of 12
nauticalmilesfromtheso‐called„baseline”.This line
was defined in Art. 5 Paragraph 2 of the Act
concerning the maritime areas of the Republic of
Poland and the ma
ritime administration [Act, 1991]
as:„alow‐waterlinealong the coast or theouter limit of
internal waters”. The amendment of the cited Act of
2015 [Act, 2015] introduces a redefinition of the
concept of the TSB as: „a line joining the appropriate
points d
efining the lowest water level along the coast or
other points designated in accordance with the principles
setoutintheUnitedNationsConventionontheLawofthe
Sea, signed in Montego Bay on 10 December 1982”
[UNCLOS,1982].
InPoland,theproblemofdeterminingthecourse
oftheTSBwasalsotheproblemofcompetence.Only
the Act [Act
, 2015] solved the division of tasks
between: maritime administration authorities, the
HydrographicOfficeofthePolishNavy(HOPN)and
the Head Office of Geodesy and Cartography
(GUGiK).Inaddition,Art.5Paragraph2ofthatAct
states that the Council of Ministers shall define, by
wayofaregulation,thedet
ailedcourseoftheTSBin
theformoftextandgraphics inaccordancewiththe
nationalspatialreferencesystem,takingintoaccount
theprinciplessetoutintheUNConvention.
The need to introduce legislative changes arises
due to, am
ong others, the obligation to implement
intothePolishlegalorder,by18September2016,the
provisions of Directive 2014/89/EU of the European
Parliament and of the Council of 23 July 2014
establishing a framework for maritime spatial
planning[Directive,2014].TheEUMemberStatesare
obliged to develop maritime spatial pla
ns until 31
March2021, that is why the Act includes legislation
necessarytopreparespatialplansforPolishmaritime
areasthat don’tarisedirectly fromthe Directivebut
are necessary for its full implementation. In
particular,theprovisionsgoverningthecourseofthe
Determination of the Territorial Sea Baseline – Aspect
of Using Unmanned Hydrographic Vessels
C.Specht,A.Weintrit&M.Specht
GdyniaMaritimeUniversity,Gdynia,Poland
ABSTRACT: Determining the course of the territorial sea baseline (TSB) of the coastal state is of primary
importancetodefineitsmaritimeborders,andhenceitisindirectlyapartofthestatemaritimepolicy.Besides
thelegalandmethodicalaspectsdescribedinconventions,laws,standardsandregulations,equallyimport
ant
istheissueofmeasurementmethodologywithrespecttotheinternallimitoftheterritorialsea.
Thearticlediscussesaneffectiveandoptimalmethodofrealizationofbathymetricmeasurementsthatallows
determiningthecourseoftheTSB.Itproposes‐asanalternativemethodtoclassicmeasurements‐theuseof
unmanned hydrographic vessels, justifying theirdesirabilit
y. It reviews the currently available solutions, as
wellashighlightstheadvantagesandlimitationsoftheproposedmethod.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 10
Number 4
December 2016
DOI:10.12716/1001.10.04.15
650
TSBandthelimitsofPolishmaritime areasmustbe
introduced[MaritimeInstituteinGdańsk,2016].
2 CLASSICALHYDROGRAPHIC
MEASUREMENTSANDTHETSB
MEASUREMENT
Bathymetric surveys in the coastal zone, internal
waters and inland waters are specific in terms of
hydrography of those reservoirs. They are
characterized by the
presence of shallow waters (at
depths below 1 m) and high variability of seabed,
which can significantly hinder or even prevent the
implementationofhydrographicmeasurements.
DeterminingthecourseoftheTSBisperformedon
shallowwaters,usuallyata depthofseveral tensof
cmbelowthe currentwater
level(Fig. 1). Therefore,
performing classical hydrographic measurements
usingmannedhydrographicvesselsisimpossibledue
toexcessivedraftof suchboatsand placingon their
bowechosoundertransducers.
After summing up the current limitations of
classical measurement methods in hydrography, in
thecontextofdeterminingtheTSB,itisclear
that:
hydrographic vessels, due to the draft, don’t
actually perform bathymetric measurements at
depthsbelow1m;
commoninhydrographythemappingofshallow
waters (without real measurement data) is
performedontheerroneousassumptionofalinear
decreaseindepthintheareaofthesmallestdepths
(0‐1m);
substantialsizeofelementsofbathymetricsystems
(echo sounder and sonar transducers) prevent
performingmeasurementsonshallowwaters;
lackoftheprecisepositioningsystemofavesselin
Poland, operating in real time at the expected
accuracy of calculating ofposition coordinates of
lessthan5cm(2dRMS);
significantreduction (low accuracy or lack of the
positioning solution by the receiver due to the
small number of satellites) of the possibility of
positioning of the vessel using only the GPS
system, in close proximity to field obstacles
(hydraulicstructures,vegetationetc.),justifiesthe
useofmulti‐GNSSsolutions;
the use of GNSS geodetic measurement methods
enables the TSB measurements, however, it
requires from a measurer working in the water
[Specht&Czaplewski,2016];
thegeodeticmethodensuresveryhighaccuracyof
measurements[Specht,2016].
Above restrictions lead to considering the use of
those unmanned hydrographic vessels available for
several years on the market, which specific design
features(smalldraftandconsiderabletimeefficiency
in implementing measurements) justify their
applicationindeterminingtheTSB.
3 HYDROGRAPHICMEASUREMENTSWITHTHE
USEOFUNMANNEDVESSELS
Thebeginningofthe21stcenturyistheeraofusing
unmanned boats in various measurement
applications. Modern autonomous and unmanned
vessels(AutonomousSurfaceVehicle–ASV,Unmanned
Surface Vehicle – USV) offer a variety of design
solutionsintheconstruction
ofthehullandtheboat
propulsion: single hull,double hullwith a screw or
screwless propulsion with a small draft. Theyallow
theentryintothereservoirwithadifficultaccessdue
tothepresenceofshallowwaters[Romano,Duranti,
2012].Bathymetricsurveysasapartofhydrographic
measurements (aimed
at measuring the seabed
topography) require adequate positioning accuracy
[IHO, 2008], hence the use of unmanned boats in
hydrography cannow be regarded as the beginning
ofanewerainthisfield.
Depending on the size and displacement of the
unmanned vessel the equipment is of vital
importance here
(in particular echo sounder
transducers,singleandmultibeam).Singlebeamecho
sounders,whichcanbe usedhere,aresmall devices
that usually don’t require Motion Reference Units
(MRU) to determine the spatial orientation. Hence,
they can be mounted on smaller vessels [Makar &
Naus, 2003]. Whereas multibeam echo sounders are
placed
onlargersurveyvessels.
Figure1.DifferencebetweenthelevelofKronstadtandthelowestobservedwaterlevelinPoland,registeredon12water
gauges(ownstudy)
651
An unmanned hydrographic vessel is a remotely
operated floating vehicle, radio‐controlled, enabling
equipmentintegrationwiththeGNSSreceiveranda
single beam echo sounder (the minimum measuring
equipment). It is designed to perform hydrographic
measurementsof:portbasins,lakes,riversandsmall
reservoirs. A comparativeanalysis of currently used
vesselsofthistypemadeitpossibletodeterminetheir
preferred technical and operational characteristics,
whichare:
radiocontrol;
remoterange–1km;
min.speed–5kts;
batteryendurance–6h;
min.recommendedsize:150x100cm;
permissiblemass,enablingtomovefreely–40kg;
doublehullvesselispreferred;
maxpossibleseakeeping.
ExamplesofvesselswerepresentedinFig.2.
SeafloorEchoBoat‐ASV
SeafloorHyDrone‐ASV
SeafloorEchoBoat‐RCV
Figure2. Examples of design solutions of unmanned
hydrographicvesselsby[SeafloorSystems,2016]
It should be emphasized that commercially
availablevesselsinmostcasesrequiredirectcontrol,
which means that the keeping of a boat on the
measurementprofilerequiresfromtheiroperatorthe
acquisition of appropriate skills. However, currently
available are unmanned hydrographic vessels that
enabletherealizationofmeasurements(amission)in
afullyautonomousmanner.
4 EQUIPMENTREQUIREMENTSFOR
UNMANNEDVESSELSDURINGTHETSB
MEASUREMENT
This section will present the technical analysis of
unmannedhydrographicvesselsandtheirequipment
thatallowstoperformthe expectedmeasurement.It
isassumedthattheminimumtechnicalequipmentto
enable the performance of TSB measurements
(required to be placed on an unmanned vessel)
includes:
aGNSSreceiverusingtheGNSSgeodeticnetwork;
aportablesinglebeamechosounder.
Thesolutionthatwouldprovideanopportunityto
implement bathymetric measurements using GNSS
geodetic networks could consist of the following
elements:
basic positioning system – using a commercial
geodetic network Leica SmartNet, which has the
ability to provide a network solution to a GNSS
receiver(locatedonthevessel)usingtwosatellite
systems simultaneously: GPS and GLONASS. It
should be noted that the location of reference
stationsofthatnetworkis
themostbeneficialfrom
thepointofviewofusingitonseaareas(covering
theGulfofGdańskbynetworksolution);
backup positioning system – using a geodetic
network ASG‐EUPOS, which has the ability to
provide
anetworksolutiontoaGNSSreceiver(locatedon
thevessel)usingonlytheGPSsystem.Currently,
themodernizationofthenetworkisunderwayin
ordertoprovidetheGPSandGLONASSsolutions;
emergencypositioningsystem–anownreference
station(located,forinstance,onthebuildingofthe
Faculty of Navigation of Gdynia Maritime
University).This solution prevents the use of the
networksolution, whichresults indecreasing the
accuracy of the calculating of a hydrographic
vessel position in the process of
increasing the
distancefromthestation;
monitoring station – which task is to control the
reliabilityofthepositioningsolutionimplemented
byaGNSSnetwork,andinthecaseofexceeding
thedefinedalarmthresholds(toolargepositioning
error,lowsignalleveletc.)tosendawarningtoa
person performing the measurement. In Fig. 3
it
wasplacedintheGdańskHarbourMasterʹsOffice.
652
Figure3.LocationofGNSSreferencestations,anemergency
station and a monitoring station for the sample reservoir
(ownstudy)
Using the monitoring station (none of the GNSS
geodeticnetworkshasanysuchstation)isnecessary
toensurethereliabilityofgeodeticandhydrographic
measurements. That reliability of measurements is a
key element in geodetic positioning, as well as in
navigation.Fig.4presentsa„window”ofthesoftware
of
suchstation.
Figure4.Conceptofthemainscreenofareliabilitycontrol
station for the subsystem of precise positioning of
hydrographicmeasurementsby[Specht&Nowak,2012]
The basic measurementelement of an unmanned
hydrographic vessel should be a GNSS receiver
primarilycapableofintegratingtheequipmentwitha
hydrographicsurveydrone,moreover,itshouldhave
the option of operating as a stand‐alone measuring
device(areceiver+apoleandatripodwithatribrach
+
a controller). Below are presented selected
characteristics of a GNSS receiver, recommended
(optimal)foritsuseduringtheTSBmeasurements:
satellite signals tracked simultaneously: BDS: B1,
B2,B3;Galileo:GIOVE‐A,GIOVE‐B, E1,E5A,E5B;
GLONASS: L1C/A, L1P, L2C/A, L2P, L3; GPS:
L1C/A,L1C,L2C,L2E,L5;SBAS:L1C/A,L5;
positioningrate–20Hz;
min.numberoftrackingchannels–400;
positioning accuracy (min.): static GNSS
surveying: horizontal 3 mm + 0.1 ppm (RMS),
vertical 4 mm + 0.5 ppm (RMS); GNSS geodetic
networks: horizontal 8 mm + 0.5 ppm (RMS),
vertical15mm+0.5ppm(RMS);
built‐in: radio modem, compass and
accelerometer;
controllercontrollingoperationofthereceiver;
GPRS communication with GNSS geodetic
networks;
performing GNSS measurements during the loss
of communication with the GNSS geodetic
network;
supported formats: RTCM 2.1, RTCM 2.3, RTCM
3.0,RTCM3.1(input)andNMEA(output);
carbonfiberpole;
internalmemory–6GB.
Fig. 5 presents a few selected types of GNSS
receivers‐working with GNSS geodetic networks‐
thatmeetthequalityrequirementssetoutabove.
TrimbleR10
LeicaVivaGS15
TOPCONHiPerSRGSM
Figure5. Selected GNSS receivers that can be mounted on
an unmanned hydrographic vessel by [Leica Geosystems,
2016;TPI,2016;Trimble,2016]
The minimum measuring equipment of a
hydrographic survey drone should also include a
portable single beam echo sounder that should be
integrated with the GNSS receiver, capable of easy
assembly and disassembly on the pole placed in a
droneorothervessel.Itsbasiccharacteristicsinclude:
frequency:150‐250kHz;
maxbeamwidth–10°;
min.pingrate–5Hz;
depthaccuracy(min.):2cm±0.5%depth;
min.depthrange:0.5‐50m;
wirelessdatatransfer;
supportedformats:NMEA,ASCII(output);
batterypower;
maxdimensionsoftheechosounder:30x20x10
cm;
maxdimensionsofthetransducer:20x10x10cm.
653
An example of such an echo sounder solution is
presentedinFig.6.Itshouldbenotedthatsince3‐4
years on the market have been also available
multibeamechosounders thatsignificantlyaccelerate
theimplementationofbathymetricmeasurements.

Portablesinglebeamecho Multibeamechosounder
sounderwithtwoGNSSreceivers
Figure6. Apparatus for measuring the depth with the
application of an unmanned hydrographic vessel by
[SeafloorSystems,2016]
The minimum measuring equipment for an
unmannedhydrographicvesselispresentedinFig.7.
5 DATAELABORATIONANDROUTE
PLANNINGSOFTWARES
The software includes two packages for processing
the results of geodetic and hydrographic
measurements:
geodetic – a software package that allows the
elaborationof geodeticmeasurement results with
theapplicationofGNSSsystems(inrealtimeand
post‐processing). It is advisable to ensure full
functionalityinthefollowingenvironments:CAD
and GIS. In addition, it should be able to create:
terrain models, surface
models, profiles, cross
sections, alignment of the GPS and TS networks
(jointly). An example of the software that meets
the above requirements include, among others,
TrimbleBusinessCenter(TBC);
hydrographic–asoftwarepackageusedtoprocess
hydrographic measurements. It enables the
analysis of measurement results, as well as
creating:adigitalseabottommodel(underwater)
and maps in coordinate systems compatible with
IHO requirements. An example of the software
thatmeetstheaboverequirementsinclude,among
others,HYPACK.
Anadditionaloptionisthesoftwareusedforroute
planning for unmanned hydrographic vessels. It
allows planning measurement profiles based on a
givenmeasurementarea‐usuallyonthebasisofan
orthophotomap derivedfrom Google Maps(Fig. 8).
Thistypeofsoftwareisusedonlybyveryadvanced
unmannedhydrographic
vessels.

GNSSreceiverPortableechosounderwith
pole
Completevesselwithmeasuringequipment
Figure7.Minimummeasuringequipmentofanunmanned
hydrographic vessel intended for the implementation of
TSB measurements by [Seafloor Systems, 2016; Trimble,
2016]
Figure8.MissionPlannersoftwareofthe3DRcompanyfor
planningthemeasurementcampaignby[3DRobotics,2016]
Similarsoftwarewascreatedbyateamofstudents
fromtheGdynia MaritimeUniversity(AutoDron) in
the framework of the Space3ac accelerator. The
application requires entering: the coordinates of the
selectionarea, the droneposition, the coordinates of
the directional point and the distance between the
measurement profiles. Based on the
drone position
and the coordinates of the directional point the
direction vector is calculated. Then the entered
coordinates are transformed from the geographic
coordinate system to the local cartesian coordinate
system (the origin of the coordinate system is the
droneposition),andtheseinturnareconvertedtothe
polar
coordinate system. All the points are rotated
withrespecttothedirectionvector,thatis,fromeach
pointinthepolarsystemissubtractedtheanglethat
isformed by that vector with the OX axis. Thenthe
coordinates are transformed back to the cartesian
system. In the system prepared in
that way are
calculatedcoordinatesoftheprofilepoints(beingthe
654
drone route), that are perpendicular to the direction
vector. When this is completed all operations are
carried out in reverse order until a route in the
geographicalsystemisreceived(Fig.9).Theresulting
dataarepreparedina formatsuitablefortheMission
Planner software of the 3DR company
(used to
uploadthedronerouteintheautopilot).
Figure9. Application window for planning the
measurementcampaign(ownstudy)
Tomaketheprogrammoreaccessibletheycreated
asimpleandintuitiveuserinterface(Fig.10).
Figure10. Application user interface for planning the
measurementcampaign(ownstudy)
6 CONCLUSIONS
FortherealizationofTSBmeasurementscanbeused
an unmanned hydrographic vessel (including its
measuring equipment), owned by the Gdynia
Maritime University. It is characterized by the
followingadvantages(aftermodernizationwithinthe
frameworksoftheSpace3acaccelerator):
automaticcontrolofthevessel,usingthePixhawk
autopilotofthe3DRcompany;
planningbathymetricmeasurementsusingGoogle
Maps,includingboththechoiceofthereservoir,as
wellasplanningthemeasurementprofiles;
ensuring the high accuracy and reliability of
bathymetricmeasurementswiththeapplicationof
theGNSSreceiverusingGNSSgeodeticnetworks
andaportablesinglebeamechosounder;
small draft of a vessel (20‐30 cm) enables the
performance of bathymetric measurements at
depthsbelow1m;
aswellasdisadvantages:
controlsystem(forchangeofcourse)isbasedona
(remote)telemanipulator,whichrequiresconstant
manoeuvring of a vessel in the manual mode, as
well as visual keeping of a boat on the
measurementprofile,pluschangingtheprofilein
thedirectcontrolmode;
no system of measurement data transmission to
theoperatorandtheirdisplayinrealtime;
low accuracy of the GPS receiver (several‐meter
positioning error) from the module dedicated for
thePixhawkautopilotpreventsthekeepingofthe
vessel along the selected measurement profile,
which results in uneven coverage of the whole
reservoirwithmeasurements;
lowseakeepingofavesselweighingapprox.20kg
allows for bathymetric measurements to be
realizedonlyincalmweatherwithlittlewaving.
Thisscientificworkwasfinancedfromthebudget
for science in years: 2016‐2020, as a research project
within the frameworks of the „Diamond Grant”
programme.
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