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Speed Control in Maritime Pilotage


An optimum speed at various legs of pilotage passage is core of safe and efficient maritime pilotage.


As a ship handler we should be able to calculate our time to next landmark/turning, how much time until entering breakwater, how much time until another vessel will clear channel.

Vessel’s displacement and momentum is very important factor in ship-handling.

 

Pls try to remember below highlighted data:-

At 20 Knot you are travelling 1 NM every 3 minutes

At 1 Knots you are doing 30 metre per minute

At 0.3 kts you are doing 15 cm per sec or 10 mtr per minute

At 0.1 kts you are doing 5 cm per sec or 3 mtr per minute 

 

Always use Ground speed/Bottom track in pilotage/harbor

Pilots work with a fixed schedule, most of the time having done same passage several times, they would have devised their own ways of speed reduction wrt landmark or distance to berth.

 

I will give few practically followed yet generic guidelines:


When you are approaching the berth directly and in loaded condition. (I.e. not turning off berth or turning circle)

Type of vessel

2 Nm to berth

1 Nm to berth

5 cable to berth

1 Ship length

Container

7-8 kts

5

4

2-3

Bulk carrier/tanker up to panamax

6

4

3

1.5

VLCC (SBM)

4

2

0.8

0.2-0.3 (Picking up line)

Cape size vessel

4-5

2.5-3 kt

0.8

0.3 kt

 

1.       Be cautious when you are approaching last berth/dead end, consider reducing your speed earlier.

2.       When you are falling back for berthing, fall back speed should not exceed 2.5 to 3 knots as at higher speeds tugs will not be able to remain perpendicular to vessel and give adequate push/pull force.

3.       Since engine power ahead is more, in case of fall back, you will be able to reduce 2 knots speed to zero within half the sip length.

4.       As a pilot one must always have contingency thought out. Always anticipate possibility of engine not kicking astern when you are 1 ship length from your position. In case you are not approaching dead end, you will get time to reduce speed by asking tugs to pull in astern direction.

5.       But if you are approaching dead end, try to keep speed not more than 2 knot at 1 ship length. In case of 294 mtr panama, that will give you 5 minutes (30 mtr/minute) to ask tugs to pull and stop vessel. Same way in case of Panamax Bulk/Oil tanker of 230 mtr loa, you will get 4-5 minutes.

6.       If strong wind from astern, your speed may not reduce as desired. Don’t hesitate to go half or full astern on engines.

7.       Try to keep at least 100 mtr lateral distance from other vessels, (150-200 mtr if space permits) until your speed is less the 2 knots.

8.       If you have UKC less than 1.5 mtr, it might take more astern power to stop as compared to more UKC scenario. But Idea is to use/increase or decrease astern engine to achieve above speeds at given landmark/distance.

9.       Sometimes Pilot may keep higher speed while entering breakwater due to cross current or passing channel with cross current or strong beam winds.

10.    However always keep in mind that vessel engine may miss astern kick at speed higher than 5.5 knots, also you will have to use high astern power which will create strong transverse thrust and vessel may start to swing rapidly.

(One can test engine 100 times but it can still fail 101th time, that’s why it’s important to keep contingency plan, never fall back on single resource)

 

 

When you are approaching the turning circle, or tuning off the berth

Normally Cape/VLCC or even Panamax vessesl are not turned in loaded condition, so it’s not required do discuss same. For container vessels or loaded bulk or tankers up to 200 mtr I will discuss in details how to execute turn, how to monitor position and what is the optimum use of engine and tugs. One can enter turning circle at speed 4-5 knots. Entering turning circle with too less speed is not desirable as it puts you at mercy of environmental forces like tide and wind for longer time.

 

 Lateral berthing speeds:

 

Type of vessel

100 m to berth ( 3 beam )

70 m to berth (2 beam)

30 m to berth (1 beam)

10 mtr to berth (less than Half beam)

5 mtr till touching fenders

Container

1 kt

0.7

0.5

0.3

0.1

Bulk carrier/tanker up to panamax

1 kt

0.5

0.5

0.2

0.1

Cape size vessel

0.5

0.3

0.2

0.1

0.1

LNG/VLGC

0.3

0.3

0.2

0.1

0.1

 

1.       It’s ideal to completely stop vessel just 1-2 mtr off fender (idea is to take off all momentum), parallel to berth. Then come alongside very gently. This is very important when berthing vessels with displacement more than 100,000 tons. As long as you follow this practice, you will never have hard landing incidents.

2.       You cannot rely too much on Doppler to give accurate speed when your are at speeds less than 0.2 knots, so it’s better follow as described above in paragraph 1. Relying on GPS at such slow speed is absolutely of no use.

3.       If you land on berth with momentum, vessel will bounce off from fender and it will bounce several times, sometime at bow or sometime at stern, which is not desirable, especially on container vessels with large flare.

4.       How to judge distance: Normally vessels berthed fwd. or aft will have beam about 30-35 mtr (large container vessel beam may be up to 48 mtr, aframax tanker beam 43 mtr), so you can check once you are abeam.

5.       Idea is once you are at beam distance, you should have complete control of vessel, i.e. angle not more than 3 deg, within 5 mtr of your for-aft position, clear from vessels fwd or aft, your fwd and aft speed should be almost zero.

6.       Normally gantry crane boom is 70 mtr , that give you reference for 2 beam distance

7.       You have to use tugs for push/pull as required. One can use higher pushing force when you are far off, avoid using high pushing forces very close to berth.

8.       Allow time for tugs to change position from push to pull or vice versa.

9.       Approaching berth with like 0.2 to 0.3 knots from 100 mtr or more distance will take long time, in this time vessel will start moving fwd and aft due to wind or current, you will have to use several engine kicks to maintain position, it’s not desirable situation as you may run out of air. Also every time you use engine close to berth, transverse thrust will disturb your lateral momentum and angle. I have seen several time pilot taking long time to come alongside, using several kicks, then Both Pilot and Master sort of running out of patience and land on fender with momentum. Its best to save time while you are in channel or far from berth, never rush once your are 5 mtr off the berth. Most of the time pilots have back to back movements and also time bench marks, so they have that time factor little bit on back of mind always.

10.    For Cape and LNG vessel, yes it’s very important never to exceed above speeds. LNG berths have lateral speed, distance and angle displays and will give alarms if you exceed speed or angle criteria.

11.    Keep due account if wind is on shore or off shore, in onshore wind don’t wait too long to pull with tugs and check momentum. Never get into temptation to approach at higher speed so as not to build up high momentum which you will find hard to brake. Give due consideration to contingency of tug rope parting.  In case of tug rope parting don’t hesitate to drop outward anchor and dredge it to check momentum.

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