329

1 INTRODUCTION

This is an Industry‐academia Research and

Technology (R&T) collaboration with Innovate UK

part‐funding including a contribution from the

Defence Science and Technology Laboratory (Dstl).

PartnerswereRolls‐Royce,ATLASELECTRONIKUK

Ltd, Lloyd’s Register EMEA, Queen’s University of

BelfastandWarsashMaritimeAcademy.WhenIwas



asked to join this project, I wondered whether it

would be easier to teach the seafarer the science,

ratherthanthescientistthe“InternationalRegulations

forthePreventingCollisionsatSea,”morefamiliarly

knownastherulesoftheroad.

Collisionsatsearesultinlossoflife,damageto

the

environment and economic loss for the ship‐owner

andthecargoownerandtheircustomers.Thecause

of a significant numberof collisions is the failure of

the human element. Research has shown that

mistakes are made not because of deficient or

inadequateregulations,butbecausetheeducationof

the

officerincharge ofthewatchisdeficientor that

the officer has chosen to disregard those standards

andregulations(Acar,2012).IntheUnitedKingdom,

Merchant Shipping Notice 1781 refers to the “The

Merchant Shipping (Distress Signals and Prevention

of Collisions) Regulations 1996,” which is statutory

instrumentno.75of

1996.Theycameintoforceonthe

 May 1996 and implemented the changes to the

InternationalRegulationsforPreventingCollisionsat

Sea1972(asamended).Theseregulationscommonly

knownasthe “Collision Regulations”areaseriesof

rulesthatregulatetheinteractionofvesselsatsea.

Theregulationshavebeenwrittenbyhumansfor

the direction of

human application. So they are a

series of rules to be applied to real life scenarios.

Considertwovesselsmovingalmostparalleltoeach

Codifying Good Seamanship into Machine Executable

Rules

I.R.Salter

WarsashMaritimeAcademy,Southampton,UnitedKingdom

ABSTRACT:Enablingunmannedsurfacevesselstocomplywiththecollisionsregulationsisoneofthemost

interestingchallengesfacingtheshippingindustry.The“MachineExecutableCollisionRegulationsforMarine

Autonomous Systems” (MAXCMAS project aims to develop a comprehensive capability and demonstrate

satisfactory execution of marine

 ‘rules of the road’ by autonomous vessels. This is an Industry‐academia

ResearchandTechnology(R&T)collaborationwithInnovateUKpart‐fundingincluding acontributionfrom

the Defence Science and Technology Laboratory ( Dstl). The project partners include Rolls‐Royce, ATLAS

ELEKTRONICUKLtd,Lloyd’sRegisterEMEA,Queen’sUniversityof

BelfastandWarsashMaritimeAcademy.

This paper discusses how the regulations that have been written by humans  for human consumption were

portrayed to the researchers by the Master Mariner to enable the generation of intelligent MAXCMAS

algorithms.



http://www.transnav.eu

the International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 12

Number 2

June 2018

DOI:10.12716/1001.12.02.14

330

other on a slightly converging course at nearly the

samespeedReffigure1.



Figure1.Exampleofvesselsconverging

Itisentirelypossiblethatatsometime inthefuture

the two ships may converge. Ship A may consider

that Ship B is an overtaking vessel (consider B was

further away and more astern than above) and

therefore should give way. Whereas Ship B may

considerthatShipAis

acrossingvesselandtherefore

shouldgiveway.Inbothevaluationsofthescenario

theybothconsidertheothervesseltobethegiveway

vessel. This is very similar to an actual case, the

Pacific Glory and the Allegro 1970. Both vessels

closedtoaposition1minutebefore

thecollision,until

theytookactioninextremis,astheyattemptedtoturn

away from each other their sterns came together

(Cahill,2002).

2 EXPLAININGTHECOLLISIONREGULATIONS

Theauthor’spartintheprojectwastothentakethese

seriesofrulesdesignedforhumans andexplainthem

in another format

 by the use of diagrams or tables

thatwouldenablethescientisttodesignasystemof

intelligentalgorithmstoguideanautonomousvessel.

Step 1 was to produce a breakdown of the Rules of

theRoad andwhattheconductofvesselsare inthe

three conditions of visibility

i.e. Any condition of

visibility; in sight of one another and in restricted

visibility.

An early consideration was how manoeuverable

vessels actually are, using a couple of books

publishedbythenauticalinstitute,theauthorstarted

investigating at how quickly vessels could alter in

extremis. (Lee and Parker 2007, p129) say

 that own

ship should turn through 90° in approximately 7½

shiplengths. (Knight’s 1921, p333) this handbook of

seamanshipshowstheadvanceandtransferofships 

in turns, so this is not new. This was considered in

deciding the closest point of approach for different

sizesofvessels.Theother

factorsthatshouldbetaken

into consideration are made clear in Rule 6 (Safe

speed) of the collision regulations. Therefore in any

conditionofvisibility,whenvesselsareinsightofone

another and when in or near an area of restricted

visibility the collision regulations dictate what the

appropriateaction

shouldbeineachcase.Fromthis

we decided to test MAXCMAS on two vessels with

different maneuvering characteristics, a bulk carrier

and a small ferry in both open waters and closed

waters. MAXCMAS uses configurable TCPA and

CPA limits, these limits depend upon the type of

vesselthevisibility

andthetypeofencounter.Inthe

caseofanon‐complianttarget,MAXCMASwillwait

halfthesetlimittobeforemakingalargealterationor

willstop.

3 CONSIDERTHECONDUCTINSIGHTOFONE

ANOTHER

As the rules have been written for human

consumption,theauthorproposeda

wayofshowing

the scientist illustrations to demonstrate what the

regulations and appropriate actions would be in

variouscircumstances.The first diagraminFigure 3

wasproducedtohighlighttheinsightsectorsandthe

actiontakenwhenvesselsenteredthosesectors.

Thesectorsarecoveredbythefollowingrules:



Yellowsector–Headonsituation–Rule14;

 Greensector–Crossing situation–Rule15

andActionbygive‐wayvessel–Rule16;

 Redsector–Crossingsituation–Rule15

andActionbystand‐onvessel–Rule17;

 Whitesector–overtakingsituation

–Rule13.

Additionally,wehavealsotakenintoaccountthat

Rule16mandatesthatthegive‐wayvesselmusttake

earlyandsubstantialactiontokeepwellclearwhilst

Rule17permitsthestand‐onvesseltotakeactionto

avoid collision if it becomes clear that the give‐

way

vessel is not taking appropriate action, or mandates

thestand‐onvesseltotakeactionwhensoclosethat

collision can no longer be avoided by the actions of

the give‐way vessel  alone. In these latter scenarios,

thestandonvessel,mustthenprobablymakealarger

alterationof

courseorspeed.



Figure3.InSightdiagram

331



Figure2.BasicCollisionFlowChart(Visio)



Table1.EncounterTable



Figure4GreentoRedEncounter

Oncetherulesarecoded,thenextstagewastotest

thealgorithmonthesimulator.

Table4wasusedtodescribewhichruleappliedto

the encounter that the autonomous vessel was

engagedinandwassubsequentlycoded.

4 CONSIDERTHECONDUCTINRESTRICTED

VISIBILITY

Asimilartablewasproduced

byconsideringthetwo

vesselsaspecttoeachother.



Figure5.RestrictedVisibilitydiagram

332



Table2.RestrictedVisibilityEncounterTable

Early on in the process we looked at some

diagramsonadvanceand transfer soifashipalters

course using say 10 degrees of rudder, how many

ship lengths before she has turned through 90

degrees?IMOmanoeuveringcriteriastatesthatships

mustbeabletoturnthrough90degrees

in4to5ship

lengthsalthoughthiswouldnormallybealastditch

mane.Finelinedshipssuchas passenger shipstend

to have a larger turning circle. So ship size is a

significant factor when considering a manoeuvre as

wellasthespeedthatavesselwillcover

thatdistance

in.

Asanexampleinthe“MAXCMAS”trialsweused

twomodels.

AFerry35.5meterslong;Speedof22kt.

A Bulk Carrier 215.4 meters long; Speed of 16

knots.

Sousing5shiplengths.

TheSmallFerry5x35.5m=177.5metersat22kt

she

covers22x1853.2/60=679.5mperminutesothe

minimumtimeis177.5m/679.5m=15.7seconds.

The Bulk Carrier 5 x 215.4 m = 1072.5 meters at

16ktshecovers16x1853.2/60=494.2mperminuteso

the minimum time is 1072.5m / 494.2m = 2 m

10

seconds.

In MAXCMAS the bulk carrier will begin its

manoeuvrebeforethesmallferry.

However ships do not tend to alter at the last

secondwithmaximumruddertheytendtoalterwith

less rudder atmuch greater distances, to reduce the

loadontheengineandtoincreasethe

comfortofthe

passengers,buttokeepthedesiredeffect.Sothenext

thingtotakeintoconsiderationwastheclosingspeed

of the two vessels. For example two ships 

approachingonareciprocalcourseat15knotsmeans

a closing speed of 30 knots, therefore at 6 nautical

milesapart

theywillhiteachotherin12minutes.In

thecaseofoursmallferriesthat’saclosingspeedof

44 knots so at 6 miles that’s time to contact of 8

minutes 11 seconds. So detecting ships at adequate

rangeandmakinganalterationingoodtimebecomes

paramount.

The

responsibilityofvesselssowhentwovessels

meetwhoseresponsibilityisittoaltercourse.Insome

casesitdependsontheaspectoftheothervesseland

its position relative to you, it might depend upon

whetheryoucanseetheothervesselornot,oritcan

depend

onwhattypeofvesselsareencounteringeach

other.ThisiswhereRule18comesintoplayasTables

7and8seektoillustrateandtoalesserextentRule12.



Table3.FurtherEncounterTableNotUnderCommand

It is good seamanship to avoid passing ahead if

possiblebutthatdepends on the sea roomavailable

formanoeuvre.

TheideaofaWhiteport andWhitestbdmaybe

oddjustthinkoftheWhitesectorbisectedintwo.



Table4.EncountertableforRule18ships.

The next consideration for codifying the

regulations was the possibility of specifying which

rulestakeprecedence overtheotherrules.Asstated

above the Rules set out the criteria for making the

decisionastotheresponsibilitybetweenvessels.That

depends upon the vessel type, its aspect to you in

relation

toyouandwhetheryoucanseeitornot.In

theUnitedKingdomMGN369(M+F)hasclarifiedthe

position of the conduct of vessels in restricted

visibility to say “If you cannot see the other vessel

visually, then Rule 19 shall apply, regardless of

whetheryourvesselis

inornearanareaofrestricted

visibility.” Considerations as to whether you need a

persontoseetheothervesselshouldbelefttoanother

forum.Sothepriorityaruletakesisdescribedinthe

rulesthemselves.Dependinguponeachcircumstance

orscenario,differentprioritiesmayseemlogicalfrom



theirpointofview.

333

Prioritieswerediscussedatlengthandwetriedto

comeupwithatablesimilartoabove(seeTable5).As

mariners tended to view the table differently, the

authorwasnotsureifonetablewouldfitallviews.

As the own ship alters course to keep out of

 the

way of the other vessel, the relative position of the

othervesselwillchangewithregardtoourselves,this

should not influence which rule applies until the

alteration has resolved the situation. Where the

relative positon of the target vessel changes with

regardtoourownshipcanbe

illustratedbyRule13

Overtakingwhere  section(d)says:‐anysubsequent

alterationofthebearingbetweenthetwovesselsshall

not make the overtaking vessel a crossing vessel

withinthemeaningoftheseRulesorrelieveherofthe

dutyofkeepingclearoftheovertakenvesseluntilshe

isfinally

pastand clear. MAXCMAS uses the TCPA

and when that goes negative it continues on that

courseuntilitreachesthesubwaypoint.



Table5.ContentiousPriorityTable

Innarrowchannelswhenavessel is crossing the

channelthecrossingrule15appliesbutwhenvessels

arenavigatingupanddownthechannelthenrule9

applies. Rule 9 (d) says, “A vessel shall not cross a

narrow channel or fairway if such crossing impedes

thepassageofa

vesselwhichcansafelynavigateonly

withinsuchchannelorfairway…” However whatif

thevesselisnothamperedthenitmustcomplywith

rule15.EmpireBrent‐Stormont(Cockcroft,2011,page

76).MAXCMASproducesborderswithinthechannel

thatitwillonlycrossinspecificcircumstances.

Apragmaticway

ofdecidingwhatactions that a

shipsmastermighttake,wastopresentthatsituation

to a few Master Mariners in the form of a

questionnaire and then compare the results for

example.

ThefollowingsituationwaspresentedtoaMaster

Marinerwiththefollowingquestion(Fig.6).

The red spot

 is our ferry, overtaking the other

ferry, having blue spot on the port bow. Q2, What

actionshouldredspottake?

If there was sufficient time and sea room and if

riskofcollisiondoesnotexistwithyellowspotandit

doesnotcreateanotherclosequarter’ssituationthen

an alteration of course to starboard could be

considered. If however that was not possible then a

markedreductioninspeedtoallowtheothervesselto

passaheadshouldbeused.



Figure6.ViewofMaterial

For collision avoidance manoeuvres to be

successful a large amount of anticipation of the

situation needs to be employed well in advance.

Leaving the manoeuvre to the last minute is a very

risky proposition. Lee and Parker 2007 suggest on

page130thatthereisa fatalzone;dangerzone;high



riskzone;andariskzonedependinguponthevessels

TCPAandhowfarittravelsinthattime.Theydefine

anormalorplannedzoneasthetimeittakesavessel

to travel 10 ship’s lengths. So if your vessel is 200

meters long that would be 2000

meters. If for

calculation purposes we say 1 nautical mile equals

1852meters.Thenat15knotsthat’s27,780metersan

hourso{(2000/27780)*60}=4.32minutes.Theauthor

feels that most mariners navigating vessels of

approximately200metersinlengthwouldbealtering

with a TCPA of at

 least 12 minutes, this allows the

marinertouselessrudderbutachievethesameends.

The closet point of approach is the minimum

estimated distance that two vessels will approach

each other based upon their current course and

speeds.Itisusedbyseafarerstohelpranktherisk

of

collisionwhendealingwithmultipletargets.Itisalso

used by masters to leave in there standing orders.

Interestingly when MAXCMAS was run in human

company,thehumanstendedtoalterearlierbutthat

can be configured into MAXCMAS by altering the

TCPA.

Inordertocomeupwithwhat

weconsideredtobe

theappropriateactionsinvarioussituations.Isenta

questionnairearoundtoafewofmycolleagues,inthe

formofpowerpointsusingscenarios verysimilarto

thatinFigure10.ThenIcollatedtherepliesandthen

sentthembacktothesamegroup

tocomeupwithan

agreedactionplanthattheywouldtakeinthevarious

scenariosthatIcameupwith.Thisalsoenabledusto

take scenarios the algorithm had not handled well

and break them down and understand exactly what

wasrequiredineachcaseandaddtoor

developthe

understanding so that could be applied to the

algorithmslogic.

334

5 CONCLUSION

Ifyouputsixmasterstogetherandputascenarioin

frontofthem,youcancomeupwithsevenviewsof

what should be done. The factors that affect human

decisions is an area of cognitive psychology that

expertshavespentlifetimesinvestigating.Inourfield

you

 would expect that an individual’s training,

experience, the type of ships they normally sail on

and the stress or pressure they are under will all

influencetheireventualdecision.Theymayalldecide

todooneactionbuthowmuchofanactiontheywill

take and how long they

will continue an action for

will vary. However it does mean that Humans  will

occasionallymakeerrors.

At Warsash we did over 300 assessed collision

encountersthatwerecarefullyconstructedreal‐world

scenariosincludingrecreationsofhistoricalincidents

and Navigation Aids and Equipment Simulator

Training scenarios accredited by the Maritime

Coastguard

 Agency. Some of these were one to one

andsomeweremultipleencountersinbothopenand

restricted waters using both simulated traffic and

vesselscrewedbypersonnelinadjacentsimulators.

The MAXCMAS technology, once trialed and

accepted should enable ships both manned and

unmanned to interact safely. The algorithm

will not

sufferfromemotionalbaggageorfatiguesoItshould

be able to follow a rule based decision system

successfullyallthetimeratherthanmostofthetime.

REFERENCES

[1]Acar,U.,Ziarati,R.andM.Ziarati,2012.Collisionsand

groundings–major causes of accidents at sea. An

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pp.40‐47.

[2]Cahill, R. A. 2002. Collisions and their Causes. 3rd ed

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[3]Cockcroft,A.N.andJ.N.F.Lameijer,2011.A

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Causation_Probability_Modelling

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