Continuous/fail proof position/clearance monitoring

#shiphandling, #Navigation, #Pilotage

Continuous/fail proof position/clearance monitoring

A mix of visual and equipment must be used to monitor positions. If using buoys, keep in mind possibility of buoy out of position. Normally pilots are up to date if any buoy is not in position.

You will be surprised to know how much pilots trust simple methods like transit bearing, beam of berthed vessels, etc. to achieve fail proof position monitoring. I recommend one must practice observing transits and develop their visual senses and practice below techniques or develop your own methods

Visual means:

Whenever possible use fail proof references instead of just estimation and over relying on your sense of judgment. Your judgment of distance may be greatly affected with what height you are standing, day time, night time, clear visibility, hazy.

1. Transit of buoys

If you see 2 consecutive stbd buoys of channel in line/transit or open on your stbd side, it gives you idea that you are on inside of the stbd edge of channel, and must quickly complete the turn so that your are steady by the time your reach center of channel.

2. Leading light

Distance of leading light off the berth helps you to check clearance from berth while turning/swinging

3. Using Beam of other vessels

Say you are turning in front of berth and vessel berthed fwd. or aft of your berth has beam 32 mtr. Then officer at fwd. or aft mooring station can monitor if bow/stern is in line with beam of vessel or closer/further from 32 mtr just with a glance, he can also monitor if clearance is opening or reducing.

4. Checking gantry cranes

Usually gantry crane booms are 70 mtr long. So you can check if in line with edge of gantry crane boom, or outside/inside the edge.

(Image: Using gantry edge and beam of berthed vessels for reference)

5. Using laser rangefinders

Most of the vessels calling JNPT are required to have laser range finders to check distance from vessels while swinging.

6. Using beam bearing to check position at the berth.

Say is berth lineup is 280/100 and your intended bridge position is marked with a cone or flashing light. Then look at 010 on your stbd bridge wing repeater. That will give you exactly position of your bridge wrt jetty irrespective of vessels heading. Trusting only looking in sides may give wrong judgment if your vessel is not parallel to berth, so always use gyro repeater. Once you are very close say less than 50 mtr off the berth, you can monitor by plain sight. No need to use gyro bearing. By using above fail proof technique you will be saved from getting too close to vessel berthed fwd. or aft of your position.

If you rely only on fwd. or aft officers reporting of distances, again their estimation may vary and you will have lot of anxiety.

For more detail refer below article

Setting up RADAR for monitoring:

1. Setup 2 VRM on your radar to check bow/stern clearances while turning in turning circles.

Say your vessel is 300 mtr, bridge to bow 200 mtr, bridge to stern 100 mtr. 1st VRM will be 0.17 Nm (185X1.7=300 mtr approx.) to monitor bow clearance, same way 2nd VRM at 0.11 (185X1.1=200 mtr approx.) to monitor stern clearance. During entire turning if these 2 VRM do not touch any buoy or obstruction, we will have 100 mtr clearance. You can adjust your VRMS as per the dimensions of vessel.

Image: VRM set at 0.15 i.e. 270 mtr, EBL set at 306, to check of buoy(300 mtr off the berth) is exactly abeam or fwd/aft of beam

Note: Radar set on True motion, true vectors 6 min

2. Using EBL

Set EBL same as the lineup of berth. If you know the distance of a fixed object of buoy off the berth. Say you have a buoy 250 mtr off the berth. Berth lineup is 290. So you will set this at 290. While swinging off the berth or in turning circle, is any time this EBL touches the echo of buoy, you know that your bridge is exactly 250 mtr from the berth.

3. Centering in channel using VRM:

Just measure the width of channel, setup VRM half the width of channel. If anytime this VRM is going out of channel buoys then you know you are not in center of channel.

4. Approaching alterations using EBL

Many pilots set EBL to their next planned course. And they start altering once that EBL hit a reference point say next port hand channel buoy.

5. Approaching alterations using VRM

Also you can set VRM to make reference for you alterations e.g. Say start altering once jetty knuckle is edge of knuckle...

Image: EBL set for next course VRM set 1 cable to monitor distance off the berth while passing

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