Opinion

Positioning of vessel at berth by using bridge wing gyro repeater


by Capt. Girish Chandra - published on 14 April 2020 6007 -

This article was originally published on www.shiphandlingpro.com, reshared here on Marine-pilots.com


Today I will discuss a very simple and useful practical trick often used by pilots.

When we have to berth a vessel with small clearances forward and aft (say 20 to 25 mtr fwd and aft) it is very essential that you are able to estimate your position. Now most of the time you have a berthing supervisor on jetty who will help you with position. In addition you can inform your fwd and aft crew to give you clearances while vessel is being moved laterally towards the berth with small for and aft clearance.

But it can have following issues:
1. Estimate of your fwd and aft crew or berthing supervisor can be very vague at times and may cause you unnecessary concern and anxiety.

2. When vessel is not parallel to berth the position given by Berthing supervisor may not be correct.

I often find new pilots getting agitated and anxious in such scenario and loosing their concentration

Hence a proactive pilot will not entirely depend upon above feeds but will know his position fairly accurately by checking his bridge position.

So here we will look at systematic approach

First step is to calculate your final bridge position at berth.

1. For tanker, you can check your manifold to bridge distance and you can calculate what will be your bridge position wrt fixed objects on jetty i.e. mooring dolphins. Usually all pilots have access to berth drawings and they should know the distances between dolphins, so that they can calculate that bridge will be roughly ahead or behind of breast dolphin by so many meters.

2. For dry vessels generally berthing positions is given wrt to Panels/bollards. Pilot will have information about distance between bollards, and he can calculate his bridge position. Ex: A vl LOA 200 mtr is given berthing posn between Bollards 115 to 125 Distance between bollards is 20 mtr. From Vl bridge wing marking, we can find out bow to bridge distance is 160 mtr. So we know that bridge will be in line with bollard Number 123 ( from 115 to 123, 8 bollards with 20 mtr gap each i.e. 160 mtr)

3. Or if available Berthing supervisor can place Bridge Marker cones.

4. Now if berth alignment is 110-290. So the line 90 deg from berth alignment is 200. So Whenever you look at your bridge wing gyro repeater at 200 deg direction, you will exactly see your present bridge position.This will always give your correct bridge position irrespective of your heading. As can be seen in below picture.


Graphic by Capt. Girish Chandra


Graphic by Capt. Girish Chandra

One can also plan his Limits of bridge position something similar to NMT and NLT in chartwork and navigation. Eg. If bridge position is at bollard 122 or forward of it, that means Bow is not yet clear of vl ahead, or if bridge posn is at 124 of behind it, that means vl stern is still not clear from vessel behind hence in both situation we can not start to push vessel towards the berth.

Above is useful when you are far from berth, say 20 to 150 mtr. Once you are less than 20 mtr from berth, you can very effectively judge your bridge positions visually wrt to jetty markings/objects or by using side transits.

I hope you will find it useful and start using in future. You may please give your opinions in comments.
Editor's note:
Opinion pieces reflect the personal opinion of individual authors. They do not allow any conclusions to be drawn about a prevailing opinion in the respective editorial department. Opinion pieces might be deliberately formulated in a pronounced or even explicit tone and may contain biased arguments. They might be intended to polarise and stimulate discussion. In this, they deliberately differ from the factual articles you typically find on this platform, written to present facts and opinions in as balanced a manner as possible.

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LV
Louis Vest Houston Pilots, USA
on 1 November 2020, 02:55 UTC

This is a great idea if you have all the necessary information at your fingertips... and the information is correct, both the ship's information and the dock distances. In Houston we have more than 250 docks and a wide variety of ships going into each dock. My technique was different. I listened to the spotter on the dock lining up the ship but they were not often professional sailors. The crew on the ship was an unknown factor. They could be very good or very bad at estimating distances. You can't ignore them but they were never my first choice. I tried to maintain good relations with the linemen who served the port. They were a experienced and a known source. If they told me I had or didn't have room on the bow or stern I went with them. The spotter from the terminal was often amidship but these guys were standing at the bow and stern.

The other source was often the tugboat captains. Before the days of tractor tugs they made up some distance from the bow or stern but these days they are often pushing very close to the extreme ends and are very trustworthy.

Lastly, you have clues you learn to use over the years. Look at the drawing of the ship posted on the bridge somewhere. If the ship has a thruster note how far it is from the bow. Notice the position of the bits where the tugs will be made up. When docking the tug will usually be directly below those bits. When turning or approaching the dock look at the wheel wash from the thruster or tug. Your bow will. be a few meters from that. Of course that perspective will be different depending on whether the ship is empty or loaded but it's a sure indication for an experienced pilot.

Watch the shadow of the ship if it falls on the dock, especially in the early morning or at sunset. Not where the sun is and see if there is a gap between the shadow of the ship ahead and your ship's shadow.

Lastly, don't leave your nav laptop in the pilothouse if it will be a tight docking. Ours were accurate within a few meters and very reliable. We paid the software provider to actually walk the docks with our system so the dock position shown on our laptops was 100% congruent with the shown position. (Note: positions of other ships can be wildly inaccurate depending on how well their AIS was set up. Do not rely on them until you have somehow verified that are where shown on your laptop.)

Always remember you are being recorded on the VDR. Ask the mates at the bow and stern by all means. You will be faulted for not doing it, but make sure to ask your other sources too and be sure their replies are loud enough to be recorded.

Be safe out there.
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GK
Gajanan Karanjikar India
on 31 October 2020, 15:01 UTC

Thank you Girish. Elaborate this well into a SOP and we can implement this for the berthing manual being published by AIMPA
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