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What is the ship's ETA in UTC and port time?

ETA from distance and speed over the ground · speed for a requested arrival · current along and across the track · ship's and port's UTC offsets, zone descriptions · US Notice of Arrival deadline · Updated 18 October 2026

Published by ShipCalculators.com. Method checked against NGA Pub. 9 (2024), IMO A.893(21) and 33 CFR 160.212 on 18 October 2026. How calculators are checked

Answer

A ship's ETA is the departure time plus the hours on passage: nautical miles to go divided by knots over the ground (NGA Pub. 9). At 13.5 knots, 720 nautical miles takes 53 h 20 min, so a ship leaving 08:00 UTC on 2 March 2026 arrives 13:20 UTC on 4 March, 21:20 at a port on UTC+8.

Change the inputs below to recompute.

On this page

What a ship's ETA is

A ship’s estimated time of arrival (ETA) is the time it is expected to reach a stated point, the pilot boarding place (the pilot station) or the berth, worked from the passage plan’s distance and the speed the ship will make good.1,3 IMO ship reports give it as a day, hour and minute group in UTC unless they state another zone.2 A requested time of arrival (RTA) is the time the port asks the ship to arrive, and the speed that meets it follows from the same arithmetic.3

Work out the ETA

Start from a passage, or enter your own below

1The port's request

The port's UTC offset from the Admiralty List of Radio Signals or the agent; a requested time of arrival (RTA) from the port or the agent. An ETA without its point can mean the pilot boarding place or the berth, by “several hours in some ports” (IMO Just In Time Arrival Guide, 2020).

Port time, UTC offset

UTC
Port in the United States
2The passage plan

Distance to go along the planned track to the point the port asked for (IMO A.893(21)); a buffer only if the plan carries one.

Distance to go

Buffer added to the passage, optional

3The ship and the sea

Speed through the water from the log; the current from the tidal stream atlas or the pilot chart, resolved along and across the track.

Speed through the water

Current along the track, + following, − against

slack

Current across the track

slack
4The clocks

Departure in ship's time from the deck log, with the ship's UTC offset.

Ship's clock at departure, UTC offset

UTCport
−12UTC+12Out UTCPort UTC+8ZD 0 (Z)ZD −8 (H)
UTCMon 2 Mar 08:00Wed 4 Mar 13:202 d 5 h 20 min steaming34UTC+8, port timeMon 2 Mar 16:00Wed 4 Mar 21:202 d 5 h 20 min steaming34

The passage as you type: UTC above, port time below, midnights numbered by date.

720 nm to go at 13.5 knots through the water, leaving Mon 2 Mar 08:00 UTC for a port on UTC+8.

ETA Wed 4 Mar 21:20 UTC+8, 13:20 UTC

ETA, port time
ETA
21:20

Wed 4 Mar · UTC+8 · 13:20 UTC

UTC13:20Wed 4 Mar
Port time21:20Wed 4 Mar

720 nm at 13.5 knots over the ground takes 53 h 20 min: ETA Wed 4 Mar 21:20 UTC+8, 13:20 UTC.

The passage in UTC and port time

UTC13:20Wed 4 MarUTC+821:20Wed 4 Mar
−12UTC+12Out UTCPort UTC+8ZD 0 (Z)ZD −8 (H)
024487296120hours on passage61422knots over the groundhours = 720 nm ÷ speed53 h 20 min13.5 knots: 53 h 20 min
Out 2 Mar 08:000 nm3 Mar 00:00216 nm4 Mar 00:00540 nmIn 4 Mar 13:20720 nm
ETA, UTC
Wed 4 Mar 13:20
ETA, port time
Wed 4 Mar 21:20
Port zone
UTC+8
Zone description
−8 (H)
Passage time
53 h 20 min
Speed over ground
13.5 knots
Departure, UTC
Mon 2 Mar 08:00
Speed needed
no RTA set
US Notice of Arrival, UTC
not a US port

Ship report lines, IMO A.851(20)

B/ 020800 UTC
F/ 135  (13.5 knots)
I/ PORT 041320 UTC
   (Wed 4 Mar 21:20 UTC+8)

US Notice of Arrival, 33 CFR 160.212

Rule that applies
before sailing, 24 h
NOA by, if a US port, UTC
Mon 2 Mar 08:00
ETA at other speeds
The same passage at other speeds through the water
SpeedETA, port time
11.5 knotsThu 5 Mar 06:37
12.5 knotsThu 5 Mar 01:36
13.5 knotsWed 4 Mar 21:20
14.5 knotsWed 4 Mar 17:39
15.5 knotsWed 4 Mar 14:27
Speed to arrive on a six-hour mark
Speed over the ground to arrive at a round hour, port time
ArriveSpeed
Wed 4 Mar 18:0014.4 knots
Thu 5 Mar 00:0012.9 knots
Thu 5 Mar 06:0011.6 knots
Thu 5 Mar 12:0010.6 knots
Thu 5 Mar 18:009.7 knots

Ship's clocks go forward 8 h on passage, from UTC to UTC+8. A ship report gives the ETA in UTC unless it states the zone (IMO A.851(20)).

Cite this result ·

What this ETA means

At 13.5 knots over the ground the ship covers 720 nm in 53 h 20 min.

Leaving at Mon 2 Mar 08:00 UTC, the ship arrives at Wed 4 Mar 13:20 UTC. The port keeps UTC+8, zone description −8 (H), so the ETA there is Wed 4 Mar 2026 at 21:20, and the ship's clocks go forward 8 h on the way.

Cite or share this calculation

ShipCalculators.com, “Ship ETA Calculator: Arrival Time, Speed and Time Zones.” Method: passage time = distance ÷ speed over the ground, added to the departure in UTC and shown in the port's zone time. Inputs: 720 nm; 13.5 knots through the water; departure Mon 2 Mar 08:00 UTC; port UTC+8. Result: 53 h 20 min; ETA Wed 4 Mar 2026 13:20 UTC, 21:20 UTC+8. https://shipcalculators.com/calculators/ship-eta

The citation names ShipCalculators.com as publisher; copying it adds today's date.

Drawing of the passage

The passage in UTC and port time

UTCMon 2 Mar 08:00Wed 4 Mar 13:202 d 5 h 20 min steaming34UTC+8, port timeMon 2 Mar 16:00Wed 4 Mar 21:202 d 5 h 20 min steaming34

The ETA on two clocks

UTC13:20Wed 4 MarUTC+821:20Wed 4 Mar

Distance made good each midnight, UTC

Out 2 Mar 08:000 nm3 Mar 00:00216 nm4 Mar 00:00540 nmIn 4 Mar 13:20720 nm

Time zones

−12UTC+12Out UTCPort UTC+8ZD 0 (Z)ZD −8 (H)
The ship leaves at Mon 2 Mar 08:00 UTC and makes 13.5 knots over the ground for 53 h 20 min, arriving at Wed 4 Mar 13:20 UTC, Wed 4 Mar 21:20 in port time (UTC+8); ship's clocks go forward 8 h.

Calculating a ship's ETA by hand

Divide the miles to go by the speed in knots to get the hours on passage. Add the hours to the departure time in UTC, carrying whole days into the date. Add the port’s UTC offset to get the port’s clock time, and check the date again. For a set arrival time, divide the miles by the hours left instead.

Formula, assumptions, and limits

A ship’s ETA is the departure time plus the time on passage, and the time on passage is the distance to go divided by the speed over the ground. The arithmetic is the speed, time and distance relation of NGA Pub. 9, The American Practical Navigator (Bowditch), 2024, Appendix B: D = ST/60, with D in nautical miles, S in knots and T in minutes.

Formula

t=DSOG+Bt = \frac{D}{SOG} + BSOG=STW2−cx2+caSOG = \sqrt{STW^2 - c_x^2} + c_aETAUTC=T0+tETA_{UTC} = T_0 + tETAport=ETAUTC+ZETA_{port} = ETA_{UTC} + ZSOGreq=DRTA−T0−BSOG_{req} = \frac{D}{RTA - T_0 - B}
  • DD: distance to go along the planned track, nautical miles.
  • STWSTW: speed through the water, knots, from the log.
  • cac_a, cxc_x: the current along the track (positive when following) and across it, knots.
  • SOGSOG: speed over the ground along the track, knots.
  • BB: a buffer in hours, zero unless the passage plan carries one.
  • T0T_0: the departure from the last port, in UTC; tt the hours on passage.
  • ZZ: a UTC offset in hours, +8 for a port on UTC+8; the nautical zone description is −Z-Z.
  • RTARTA: the requested time of arrival, in UTC; SOGreqSOG_{req} the speed over the ground that meets it.

Derivation

A knot is one nautical mile an hour, and the nautical mile is exactly 1,852 m: the BIPM’s SI Brochure, 9th edition, version 4.01 (2026), lists both in its Table 8 of non-SI units, and notes that neither has an internationally agreed symbol. Hours on passage are therefore miles over knots. The speed in that division is the speed over the ground, the speed the ship makes along the track, which the log does not show unless it is a ground-referenced log. IMO Resolution MSC.96(72) requires a log that can measure either speed to say which one it is showing.

A current along the track adds to the speed through the water, or takes from it. A current across the track does not push the ship along or back, but the ship has to head into it to stay on the track, and only the part of its speed that lies along the track carries it forward: STW2−cx2\sqrt{STW^2 - c_x^2}. Pub. 9’s section 1008 works the same current triangle by drawing; its second example, 12 knots through a current of 2.5 knots setting 170° on a track of 095°, makes good 12.4 knots, and the formula here gives 12.40.

The ETA is worked in UTC so that a change of zone on passage, or a crossing of the date line, cannot add or lose a day. The port’s zone time is UTC plus the port’s offset. The speed for a requested arrival runs the same relation backward: the hours left are the requested arrival less the departure and the buffer, and the distance over those hours is the speed of advance, which Pub. 9’s glossary defines as the average speed to maintain “to arrive at a destination at an appointed time”.

Assumptions

  • The speed and the current are averages over the passage. A ship that slows for a traffic separation scheme, a pilot or a tidal gate makes a lower average, and the distance should be split into legs.
  • The current is resolved into its parts along and across the track. A tidal stream that turns every six hours averages toward zero over a long passage; on a short one, the stream at the time of passage matters.
  • The UTC offsets are the ones the ship and the port keep, summer time included. Pub. 9 notes that “local time within a country is the prerogative of that country’s government”, so check the port’s offset in the Admiralty List of Radio Signals or with the agent.
  • The buffer has no standard figure. IMO Resolution A.893(21) asks the plan to allow for “necessary speed alterations en route” without a number, so the calculator adds none unless one is entered.

Worked example

A ship has 720 nautical miles to go at 13.5 knots through the water, with no current. It leaves at 08:00 UTC on Monday 2 March 2026 for a port that keeps UTC+8.

  1. Passage time: 720 ÷ 13.5 = 53.333 hours, 53 h 20 min.
  2. ETA in UTC: Monday 2 March 08:00 + 53 h 20 min = Wednesday 4 March 13:20 UTC.
  3. ETA in port time: 13:20 + 8 h = 21:20 on Wednesday 4 March, UTC+8, zone description −8, letter H.

If the port instead requests arrival at 08:00 port time on Thursday 5 March, that is 00:00 UTC on 5 March, 64 hours after departure. The speed to meet it is 720 ÷ 64 = 11.25 knots, and at 13.5 knots the ship would arrive 10 h 40 min early.

Edge cases and limits

A current across the track as fast as the ship leaves no heading that holds the track, and the calculator says so. A foul current as fast as the ship leaves no way made good. A requested arrival before the departure plus the buffer has no speed that meets it. A passage across the date line changes the date of the ETA but not the hours on passage: Pub. 9’s section 1709 example 6 leaves 177°23.9′E at 08:00 zone time on 31 December, zone description −12, steams 40 hours and arrives at 01:00 on 1 January in zone description +11, and the calculator gives the same.

Regulatory basis

SOLAS Chapter V Regulation 34 requires the master to plan the voyage before proceeding to sea, and MGN 610 states that the plan follows IMO Resolution A.893(21). Its paragraph 4.1 has the plan executed “as soon as time of departure and estimated time of arrival can be determined with reasonable accuracy”. IMO Resolution A.851(20) sets the format of the ETA in a ship report. Notice of arrival is national: in the United States, 33 CFR 160.212 sets the deadlines.

Common errors

  • Zone description sign. The nautical zone description is the negative of the UTC offset: a port on UTC+8 has zone description −8. Adding the zone description where the offset belongs moves the ETA 16 hours.
  • Speed through the water as speed over the ground. A 2-knot foul current on a 720-nautical-mile passage at 12 knots turns 60 hours into 72.
  • The ETA to which point. The IMO Just In Time Arrival Guide warns that an ETA without a location “could refer to either ETA Pilot Boarding Place or ETA Berth”, a difference of “several hours in some ports”. Measure the distance to the point the port asked for.
  • An unstated zone. A.851(20) asks a report to state the time zone if it is not UTC; an ETA sent as “2130” without one is read in two ways.
  • Summer time. A port on summer time keeps an offset an hour ahead of its standard zone; enter the offset it keeps on the day of arrival.

Voyage time by speed

Voyage time falls as the speed rises, but by less for each further knot: on 720 nautical miles the step from 10 to 12 knots saves 12 hours, and the step from 18 to 20 saves 4.

Speed over the ground720 nm takes1,440 nm takes
10 knots72 h 0 min144 h 0 min
12 knots60 h 0 min120 h 0 min
13.5 knots53 h 20 min106 h 40 min
16 knots45 h 0 min90 h 0 min
18 knots40 h 0 min80 h 0 min
20 knots36 h 0 min72 h 0 min
810121416182022020406080100knots over the groundhours on passageHours on passage = 720 nm ÷ speed72 h60 h53 h 20 min45 h36 h
Hours on passage for 720 nautical miles against the speed over the ground, from 8 to 22 knots: 72 hours at 10 knots, 60 at 12, 53 h 20 min at 13.5, 45 at 16 and 36 at 20. Each further knot saves less time than the one before.

This is the trade-off behind just-in-time arrival. The IMO Just In Time Arrival Guide makes the requested time of arrival at the pilot boarding place, the RTA PBP, “the most crucial timestamp and the real prerequisite to JIT Arrival”: a ship that knows it can arrive later steams slower and burns less fuel, and the curve shows how much later each knot makes it.

Zone time, UTC and the date line

At sea a ship keeps the time of the zone it is in, and Pub. 9 section 1709 numbers each zone by its zone description: the whole hours added to zone time to get UTC, “positive in west longitude and negative in east longitude”. Its Table 26 gives each zone a letter, Z for UTC, A to M (without J) east and N to Y west.

Port timeZone descriptionLetter13:20 UTC reads
UTC+8−8H21:20
UTC+1−1A14:20
UTC0Z13:20
UTC−5+5R08:20
UTC−8+8U05:20

The clocks change at sea “as convenient, usually at a whole hour”, in Pub. 9’s words, so the ship’s time and the port’s time can differ on the day of arrival. Ashore, half-hour zones exist: Pub. 9 gives India’s as −5h30m in its own sign, UTC+5:30 as an offset. The calculator takes offsets in quarter hours from −12 to +14 and works every passage in UTC.

Notice of arrival and the requested time of arrival

In the United States, 33 CFR 160.212(a)(4) requires the Notice of Arrival on a voyage of 96 hours or more “at least 96 hours before arriving at the port or place of destination”; on a shorter one, “before departure but at least 24 hours before arriving”. The calculator shows that deadline when the port is in the US. Other states set their own; check the port’s own rules.

The second figure is the speed for a requested arrival. The IMO Just In Time Arrival Guide (2020) defines the RTA at the pilot boarding place as “the time at which the local authority/Harbour Master requests the ship to arrive at the Pilot Boarding Place in order to meet the RTA Berth”. Enter it in port time, and the calculator gives the speed over the ground and through the water that meets it, and how early or late the speed entered would bring the ship in.

Where to find each input

  • Distance to go: the passage plan or the ECDIS route, measured along the planned track to the pilot boarding place or the berth.
  • Speed through the water: the speed log, or the speed the plan assumes; the speed over the ground from GNSS shows what the current is doing.
  • Current: the tidal stream atlas, the pilot chart or the routeing chart, resolved along and across the track.
  • Departure time and ship’s offset: the deck log, in ship’s time.
  • Port offset: the Admiralty List of Radio Signals, The Nautical Almanac’s standard times, or the agent.
  • Requested arrival: the port, the pilot station or the agent, in their time.

Your ETA worked step by step

  1. Passage time: 720 nm ÷ 13.5 knots = 53.3333 h = 53 h 20 min.
  2. Departure in UTC: Mon 2 Mar 08:00 UTC = Mon 2 Mar 08:00 UTC.
  3. ETA in UTC: Mon 2 Mar 08:00 + 53 h 20 min = Wed 4 Mar 2026 13:20.
  4. ETA in port time: 13:20 UTC + 8 h = Wed 4 Mar 2026 21:20 UTC+8, ZD −8 (H).

Regulatory basis

SOLAS Chapter V Regulation 34 requires every voyage to be planned before departure, in line with IMO’s voyage planning guidelines; notice of arrival is set by each port state.7,1

Voyage planning
SOLAS V/34; IMO Res. A.893(21) 4.1, the plan executed once the departure and ETA can be determined with reasonable accuracy7,1
Ship reports
IMO Res. A.851(20): ETA as day, hour and minute, UTC unless another zone is stated2
Just in time arrival
IMO Just In Time Arrival Guide 2020: ETA and RTA at the pilot boarding place and the berth3
US Notice of Arrival
33 CFR 160.212(a)(4): 96 h before arrival, or before departure and 24 h before on a shorter voyage4
Units
1 nautical mile = 1,852 m; 1 knot = 1 nautical mile an hour, BIPM SI Brochure, 9th edition, version 4.01, Table 85
Speed logs
IMO Res. MSC.96(72): a log showing speed through the water or over the ground says which6

Frequently Asked Questions (FAQs)

How do you calculate a ship's ETA?

Divide the distance to go in nautical miles by the speed over the ground in knots for the hours on passage, add them to the departure time in UTC, then add the port's UTC offset. The IMO Just In Time Arrival Guide's 247-nautical-mile container run at 19 knots takes 13 hours: leaving at 08:00 UTC, the ship arrives 21:00 UTC, 22:00 at a port on UTC+1.

How long does a voyage take at a given speed?

Hours equal nautical miles divided by knots, because a knot is one nautical mile an hour. NGA Pub. 9, The American Practical Navigator, writes it as D = ST/60 with the time in minutes. 1,440 nautical miles at 12 knots is 120 hours, five days exactly.

What speed is needed to arrive at a set time?

Divide the distance to go by the hours left before the requested arrival, less any buffer: that is the speed over the ground to hold, the speed of advance in Pub. 9's glossary. 720 nautical miles in 64 hours needs 11.25 knots. Through the water, add back any current against the ship.

Is a ship's ETA given in UTC or local time?

In IMO ship reporting it is UTC unless the report states another zone: IMO Resolution A.851(20) gives the ETA as a day, hour and minute group with the instruction to state the time zone if it is not UTC. Where an agent or a pilot station asks for port time, give both, each labeled with its zone.

What is a zone description?

The whole hours added to zone time to get UTC, positive in west longitude and negative in east longitude (NGA Pub. 9, section 1709). A port on UTC+8 keeps zone description −8, letter H; the US east coast on UTC−5 keeps +5, letter R. The sign is the opposite of the UTC offset.

How does a current change the ETA?

A current along the track adds to or takes from the speed through the water. A current across it costs speed too, because the ship heads into it to hold the track: the speed over the ground is √(STW² − cross²) + along. At 13 knots through the water, a 5-knot cross current leaves 12 knots over the ground.

When must a US Notice of Arrival be sent?

Under 33 CFR 160.212(a)(4), at least 96 hours before arriving on a voyage of 96 hours or more, and on a shorter voyage before departure but at least 24 hours before arriving. Updates have their own deadlines in 160.212(b).

What the ETA leaves out

  • Legs and speed changes. The calculator takes one average speed and one current for the whole distance; split a passage with a pilot, a canal or a speed restriction into legs.1
  • Tidal streams in time. A stream that turns during the passage is entered as its average along and across the track; the calculator does not step through the tide tables.1
  • The port’s clock. The UTC offsets are entered, not looked up, so summer time and a state’s own legal time are the reader’s to check.
  • A ship already at sea. The US Notice of Arrival test counts the voyage from the departure entered, so for a ship already on passage enter the last port’s departure and the whole distance; the deadline under 96 hours also assumes the vessel is not one of the exceptions in 33 CFR 160.212(a)(2) and (a)(3).4
  • Notice rules outside the US. Only the US Notice of Arrival deadline is worked; other port states set their own.4
  • Weather and delay. No sea margin or weather allowance is added; the optional buffer is the reader’s own figure, since the voyage planning guidelines give none.1

How to use this calculator

  1. Choose what to work out: the ETA, or the speed needed to arrive at a time the port or the agent has requested.
  2. Enter the distance to go along the planned track, in nautical miles, to the point the ETA is for: the pilot boarding place or the berth.
  3. Enter the speed through the water from the log, and the current along and across the track if the tidal stream atlas or the pilot chart gives one.
  4. Enter the departure date and time in ship's time with the ship's UTC offset, and the port's UTC offset; add a buffer only if the passage plan carries one.
  5. Read the passage time and the ETA in UTC and in port time; in the second mode, read the speed that meets the requested arrival. Say yes to a US port to see the Notice of Arrival deadline.

Test cases this calculator passes

Every build of this site runs these cases through the calculator above and stops the release if any figure moves outside its tolerance. Load a case to put its inputs into the calculator.

InputsExpected resultTraced toLoad
720 nm at 13.5 knots, no current, leaving Mon 2 Mar 2026 08:00 UTC for a port on UTC+8ETA, UTC: Wed 4 Mar 13:20ETA, port time: Wed 4 Mar 21:20Passage time: 53 h 20 minSpeed over ground: 13.5 knotsNGA Pub. 9, The American Practical Navigator (2024), Appendix B: D = ST/60: 720 ÷ 13.5 = 53.333 h = 53 h 20 min; 2 Mar 08:00 UTC + 53 h 20 min = 4 Mar 13:20 UTC; + 8 h = 21:20 UTC+8.Load inputs
12 knots through the water with a 2-knot following currentSpeed over ground: 14.0 knotsPassage time: 51 h 26 minETA, UTC: Wed 4 Mar 11:26Along-track current adds to the speed through the water (Pub. 9, 1008): SOG 14 knots; 720 ÷ 14 = 51.4286 h = 51 h 26 min.Load inputs
12 knots through the water against a 2-knot currentSpeed over ground: 10.0 knotsPassage time: 72 h 0 minETA, UTC: Thu 5 Mar 08:00SOG 12 − 2 = 10 knots; 720 ÷ 10 = 72 h.Load inputs
13 knots through the water with a 5-knot current across the trackSpeed over ground: 12.0 knotsPassage time: 60 h 0 minETA, port time: Thu 5 Mar 04:00Current triangle (Pub. 9, 1008): SOG = √(13² − 5²) = 12 knots; 720 ÷ 12 = 60 h; 2 Mar 08:00 UTC + 60 h = 4 Mar 20:00 UTC = 5 Mar 04:00 UTC+8.Load inputs
Requested arrival Thu 5 Mar 2026 08:00 port time (UTC+8)Speed needed: 11.3 knotsETA, port time: Wed 4 Mar 21:20Speed of advance (NGA Pub. 9 glossary): RTA 08:00 UTC+8 = 5 Mar 00:00 UTC, 64 h after departure; 720 ÷ 64 = 11.25 knots, shown rounded up to 11.3 so that holding it meets the time.Load inputs
The other 6 test cases
InputsExpected resultTraced toLoad
NGA Pub. 9, 1709 example 5: ten hours from ZT 14:30 on 30 Nov in ZD +3, entered as 100 nm at 10 knots, arriving in ZD +4ETA, port time: Mon 30 Nov 23:30ETA, UTC: Tue 1 Dec 03:30NGA Pub. 9 (2024), 1709 example 5: ZT 1430 Nov 30, ZD +3, GMT 1730; + 10 h = GMT 0330 Dec 1; ZD +4 gives ZT 2330 Nov 30.Load inputs
NGA Pub. 9, 1709 example 6: forty hours from ZT 08:00 on 31 Dec in ZD −12, entered as 400 nm at 10 knots, arriving in ZD +11ETA, port time: Fri 1 Jan 01:00ETA, UTC: Fri 1 Jan 12:00NGA Pub. 9 (2024), 1709 example 6: ZT 0800 Dec 31, ZD −12, GMT 2000 Dec 30; + 40 h = GMT 1200 Jan 1; ZD +11 gives ZT 0100 Jan 1.Load inputs
1,440 nm at 12 knots to a US port on UTC−5Passage time: 120 h 0 minETA, port time: Sat 7 Mar 03:00US Notice of Arrival, UTC: Tue 3 Mar 08:0033 CFR 160.212(a)(4)(i): voyage of 96 hours or more, NOA at least 96 hours before arriving: ETA 7 Mar 08:00 UTC − 96 h = 3 Mar 08:00 UTC.Load inputs
The default passage, 53 h 20 min, to a US portUS Notice of Arrival, UTC: Mon 2 Mar 08:0033 CFR 160.212(a)(4)(ii): voyage under 96 hours, before departure but at least 24 hours before arriving; departure 2 Mar 08:00 UTC is earlier than ETA − 24 h (3 Mar 13:20 UTC).Load inputs
The default passage with a 2-hour bufferPassage time: 55 h 20 minETA, UTC: Wed 4 Mar 15:2053 h 20 min + 2 h = 55 h 20 min.Load inputs
A 5-knot cross current against 5 knots through the waterShows “no heading holds the track”√(STW² − cross²) has no real value when the cross current equals the speed through the water.Load inputs

Who publishes this calculator and how it is checked

Publisher
ShipCalculators.com, an independent site of maritime calculators.
How it is checked
Each figure is traced to the instrument that sets it, and the test cases on this page run against the calculator code on every build; a build that moves one of them does not deploy. Last method check: 18 October 2026.
What it is not
Not a passage plan: the plan on the bridge, the port's notices and the agent's requested arrival decide the ETA of record.

Change log

Each change to the method, a coefficient or a test case, with the date it reached this page.

  • First published, replacing the ETA at pilot station calculator, with test cases for the default passage, a fair, a foul and a cross current, a requested arrival, Bowditch’s zone change and date line examples, a US Notice of Arrival and a buffer.

Calculators used with this one

Planning the turn at each waypoint is the rate of turn calculator, which gives the wheel-over distance for the course alteration.

Positions read off a chart plotter in degrees and decimal minutes convert in the DMS to decimal degrees calculator.

Regulation and sources

  1. IMO Resolution A.893(21), Guidelines for Voyage Planning, 25 November 1999
  2. IMO Resolution A.851(20), General principles for ship reporting systems and ship reporting requirements, 27 November 1997
  3. IMO GloMEEP and the Global Industry Alliance, Just In Time Arrival Guide: Barriers and Potential Solutions, 2020
  4. 33 CFR 160.212, When to submit a Notice of Arrival (eCFR)
  5. BIPM, The International System of Units (SI), 9th edition, version 4.01 (2026), Table 8: nautical mile and knot
  6. IMO Resolution MSC.96(72), amending A.824(19), Performance standards for devices to measure and indicate speed and distance, 22 May 2000
  7. Maritime and Coastguard Agency, MGN 610 (M+F), SOLAS Chapter V: Guidance on the Regulations, 2020