Another advantage of using a Portable Pilot Unit (PPU)– I say yes: Julian Parkin, (Plymouth)


Error!! Is it the PPU or the chart? Photo: Julian Parkin

My first introduction to a PPU system was initiated when an SHA who I work for as part of my contract with my CHA as a pilot asked a question ‘What is the largest cruise ship we could bring into the port?’ As there are a significant amount of ferry moves an idea came about to trial a PPU system on the largest ferry and compare that relatively prior to a simulator trial.

The by-product of this would be for pilots to use it in our own harbour to familiarize us with the PPU

equipment on the various types of commercial ships, as well as to self monitor acts of pilotage. What happened next inadvertently has helped our Harbour Authority rectify some ongoing issues raised whilst using the PPU.

Prior to becoming a pilot I was a little sceptical on using a PPU – a train of thought that changed after numerous conversations with fellow pilots from other ports at various UKMPA conferences.

The port recently had a sector light changed to a nice new LED spec. This had been on order for a while so when it was fitted we were all suitably impressed. In the meantime it coincided with the use of the PPU. I had a suspicion the turning basin buoy was out of position on approach to the basin – this was checked by the Harbour Authority and was found to be correct. As I got to grips with the PPU system it was consistently showing a conflict between the position of the buoy and the coloured sectors of the newly fitted headmark light. The PPU system showed a TRUE heading marker line accurate to 1/10 th of a degree. Zones of Confidence in this area are the most accurate.

Again the issue was raised with the Harbour Authority and a Naval Hydrographic inspection was carried out on the light, which was found to be accurate in accordance with the chart data. Here lay the issue for a pilot – something did not look right? But I was informed all was well.

As the duty watches passed, my familiarity with the equipment was improving and another issue was raised further up the river. Cement ships are taken to two berths, which in most cases require the vessels to be swung. The Zone of Confidence for this area is the most inaccurate so the PPU was used for positional information (due to the chart surveys). The system was used for accurate course and speed data, however. On berthing these ships a number of times there was a consistent error in a North / South direction with a discrepancy of between 10-15m to the North. I asked myself the question, is this down to the satellite giving me the wrong information (i.e. questioning the reliability of the PPU) or is it something else? Could the chart be incorrect? I reported it to the Harbour Authority



Not long after I was seconded to assist with the annual Trinity lighthouse inspection. I mentioned the sector light/buoy issue and took the surveyor out in the pilot boat to show him the concerns. He agreed something did not appear to be quite right and filed it in his report.

On receipt of the report the Harbour Authority decided to conduct another survey. Prior to the survey taking place, it was decidedd that the hydrographer should take the position of the buoy and the southern part of the berth in question where discrepancies have been stated. The buoy was found to be 17m to the North of its charted position and the sector light correct. That problem was resolved. The jetty issue position was taken and its charted position was found to be 12m south of its true position. The last survey to be conducted in this area was in 1983.




All in all the PPU identified issues by giving accurate Satellite Based Augmentation System data that a pilot’s eye sometimes cannot see. It proves that the PPU was invaluable in identifying navigational /charting errors, in turn assisting all stakeholders within the port.

I used to be sceptical I am not now.

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