I recently received an invitation from Peter McArthur, a Class 1 Pilot on the Canal, to trip with the Manchester Ship Canal Pilots and witness ‘first hand’ the investigations undertaken into marine Hydrodynamics and Interaction. MGN 199(M) and A.960 require pilots to be fully conversant with the effects of interaction and that is exactly what has been researched on the Manchester Ship Canal.  As Peter McArthur put it “the Manchester Ship Canal is probably one of the largest test tanks in the world.  Enclosed by locks, with no tide and good shelter from the elements, it provides an ideal venue for exploring theories and demonstrating exactly how hydrodynamic principles apply”.

I remember when I was training, Senior Pilots would go on about not passing to close to other vessels on their berths, or would describe the effects of dragging them off the berth, or how a ship would behave in shallow water. A favourite topic was the peculiar behaviour encountered by vessels in the river.  Tripping on the Canal was an excellent opportunity to see how it all worked in practice and to have the principles involved explained in some detail.

The M.V Bramau a 90 metre vessel, loaded with scrap, was boarded at Latchford lock ready for her 21 mile outward Pilotage to Eastham. At first the vessel had to navigate with a metre air draft to spare under the bridges whilst sections of the canal narrowed as swing bridges were negotiated.  Peter McArthur was very good with his running commentary and explanations about the effects that were building around the vessel.

Peter McArthur

Mike Robarts & Peter McArthur

Being a tripper meant I could roam around the vessel and actually study the hydrodynamics that were going on, not just from the bridge.  I was able to move around on deck, observe the bow wave from the foc’sle and examine negative pressure fields forming amidships.  It was interesting to see these different pressure areas that were influencing the vessel and observe directly where they were having an affect – not only around the hull but also on different structures of the canal.  Over a number of years, Peter has developed his theory of ship generated ‘Super Cells’ which has significantly advanced our understanding of marine hydrodynamics.  The theory explains why, even with a 90 metre vessel, the effect of the bow positive pressure field quickly builds up and is felt more than 200 metres ahead, with corresponding effects being experienced astern.  These effects became increasingly apparent as the vessel picked up speed and the bow and stern wave became more exaggerated.  At the same time, I observe areas where water was being dramatically sucked in towards the hull, thereby creating sudden washes on the nearby bank.  Peter demonstrated that once you understood the underlying theory, the resultant effects were entirely predicable.

….water was being dramatically sucked inward towards the hull

As we passed a moored working boat it was interesting to watch it surge, then draw away from the bank as our pressure field took effect on approached.  With this demonstration, I could appreciate, more fully, the reasons for extreme caution in our district when passing moored vessels.

The effect on a moored work boat

Nearing the lower reaches of the canal the extreme hydrodynamic effects became more evident. As the vessel passed off chutes of docks, suddenly a whirl pool effect would develop for no apparent reason.  This, as was explained, was entirely predictable when hydrodynamic field interaction started to take place.  The effects were most noticeable off knuckles, on dock edges, and around the stern and bow of moored vessels.  You could actually see the mooring lines of vessels start to tense or slacken well ahead of us and old disused dock gates start to surge long before our vessel had passed.

The effects were most noticeable off knuckles…

The UKMPA attends various functions and events throughout the year and it is thanks to those Pilots, and their districts, who contribute dedicated research like this that UK Pilots’ stand out in the Marine Industry as consummate professionals.  Peter McArthur and his team have researched both Hydrodynamics and the legal aspects of Piloting (Peter is also a qualified lawyer);  the Liverpool Pilots have developed their specialist Maritime Resource Management Course and have implemented their own bridge simulator for training;  the Belfast Pilots have developed a course on safe embarkation and disembarkation at sea; the Section committee and the executives represent many working groups and the T&TC has recently been involved in the updating of the National occupational standards and A.960.  On behalf of the UKMPA I organise the Seaworks exhibition in Southampton and attend the UK Trade and Industry (UKT&I) seminar for Global ports (sponsored by HRH Duke of York, Prince Andrew).  At the last UKT&I I attended Port representatives from various Embassies and consulates, were very complementary in their recognition of UK Pilots and their exceptional abilities.  Every time I attend these events, I am able to point to contributions that have been made by the UKMPA Section committee, T&TC committee, along with the individual contributions from research undertaken in districts such as the Manchester Ship Canal, Liverpool and Belfast. Clearly, such research and development helps make UK Pilots stand out as serious professionals, earning us the correct recognition in the Marine Industry and justifiably assists with our move towards CPD.

Many thanks to Peter McArthur (Norwest Interaction Ltd), Ben Stroude  (Manchester Ship Canal pilot) and Mr Alan Feast (AHM) for a most enjoyable, and very educational, trip in their district.

Further information: Norwest Interation Ltd: