Increase Your Dredging Knowledge At The End Of The Discharge Line

Keeping watch at the end of the discharge pipe line
Keeping watch at the end of the discharge pipe line

Solving something at the end of the pipe is usually a less desired approach. However, in dredging, it is the place where the valuable stuff is delivered, it might be a good place to start monitoring your process. Let me explain this to you by going back to latest discussed exhibit at the Damen Dredging Experience1.

Pump power exhibit at the Damen Dredging Experience
Pump power exhibit at the Damen Dredging Experience

You might have observed in the pictures of the pump power exhibit, that the velocity of the water flow is indicated by the parabolas of the trajectory. The arc of water is bound by gravity and obeys this trajectory always; independent of the density of the mixture. The two equations of motion can be combined, where the time parameter falls away and the height for a certain distance is only depending on the initial horizontal velocity2. As such, it is fairly accurate indication of the pipe flow. The calculation is universally applicable on earth and the results can be presented in a very simple graph to take with you. Every parabola is labelled with the corresponding horizontal velocity.

Nomogram to find end of pipe velocity
Nomogram to find end of pipe velocity

The above example is a straightforward method to measure the mixture velocity. The US Geological Survey even extended this approach as a standard method to measure the production of wells3. The resulting nomogram has a slightly different layout, as it is intended for finding the production instead of the velocity. For production planning, this will be useful. For monitoring your dredging process, the velocity might be more important. Both approaches of this elegant method do have the benefit, that there is no obstruction needed as in the case of an orifice measurement4.

Nomogram to find the end of pipe production
Nomogram to find the end of pipe production

There is an unconfirmed anecdote that my old professor de Koning started his career as a velocity measurer. In the old days, when he was working as a twelve year old boy with the dredging company of his father. He was assigned to keep watch at the end of the pipe and monitor the mixture pouring out. He had a simple beam with a plumb bob. The beam was moved along the top of the pipe, until the plumb bob was touching the arc of mixture. On the beam were two markings. When the beam was moved in and passed the first mark, the mixture velocity was too low and a red warning flag had to be displayed. If the beam had to move out and the mixture velocity was too high at the second mark, a green flag had to be flown. There was also another white flag, in case only water came on the reclamation area. With this very simple setup, the dredge master could check through his binoculars what the state of the dredging process was.

Working principle and explanation of end of pipe meter
Working principle and explanation of end of pipe meter

They were clever in those days. But the physics still apply. So, even today, one might have a situation, where there is no electronic velocity measurement available (broken, not supplied, not (yet) purchased) and you have to push the limits of the operating envelope of the dredging process. Then, there is probably always somebody around that might be appointed volunteer to be head of the velocity measurement crew. Who knows, he might have a bright future in the dredging academia.

Professor de Koning of the dredging chair at the TU Delft (1981-1993)
Professor de Koning of the dredging chair at the TU Delft (1981-1993)

References

  1. Presenting Pump Power Peculiarities, Playing With Pumps And Pipes, Discover Dredging
  2. Projectile motion, Wikipedia
  3. Estimating discharge from a pumped well by use of the trajectory free-fall or jet-flow method, US Geological Survey
  4. ISO 5167 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full, ISO

See also

How A Ship On The Shore Became a Beacon For My Dredging Career

Stranded Yo, us and another vessel to the rescue (Credit: Co Winkelman)
Stranded Yo, us and another vessel to the rescue (Credit: Co Winkelman)

Long ago, we were sailing with my parents and my brother into the Venezuelan archipelago of ‘Los Roques’.1 After clearing customs, we learned that there was another sailing vessel in trouble. It was stranded on the reefs at the east side of the islands. As we had some spare time we decided to lend a hand in getting them afloat. By eyeball navigation through the channel behind the coral reef, we found the stranded English catamaran ‘Yo’, but had to anchor 200m away. First we learned from a Swiss captain on another assisting yacht they had been pulling together with a maxi yacht on a long hawser to pull them off by power and sail. Alas, to no avail.

Location and map of the islands of Los Roques
Location and map of the islands of Los Roques

The next day, the swiss captain had to leave and we undertook the journey by dinghy to visit the crew on ‘Yo’. It turned out to be a couple with their son and two deckhands. They told us that the maxi yacht was ‘Drum’2 and one of the crew was no other than rock star Simon Le Bon3 himself. We just missed them by a day! He did all the best to cheer them up and you can image what a support that visit meant to these people in such a desperate situation.

Salvage plan to float ‘Yo’
Salvage plan to float ‘Yo’

As my dad was a chief engineer from the merchant marine, he surveyed the damage professionally. ‘Yo’ was sitting exactly on top of the reef. One keel was broken of and the other only half, but was sheared below the wreck and stuck between the coral heads, preventing any movement. After evaluating the state of the boat, the equipment and the location, he actually said: ‘We’re gonna science the shit out of this.’4 Together we devised a cunning plan:

  1. Lift/Float: Remove the rest of the keel. Plug the holes left by the bolts and increase buoyancy of the craft.
  2. Dredge: Lower the rock bottom to increase support from the buoyancy and create a channel to freedom.
  3. Move: Assemble all winches and tackle to leverage the pulling forces. The forces would be so high that we feared we would pull the catamaran in half. So we had to distribute the forces all around the hull.

The structural repairs on the hull were performed by my father. My brother and me were in charge of the winches and tackle. Any spare time was dedicated to cutting the rock below the wreck. For sure, that is a nasty job, we tore our clothes and cut ourselves on the sharp edges of the coral. By practice, I learned the different angles to aim the pickaxe for the best results and the lowest effort: an introduction into Specific Cutting Energy!5 Because we did our calculations careful and our assumptions were right, the boat moved exactly the moment we predicted and in the way we wanted. It was a great moment of revelation: you could actually use all this knowledge from physics classes6 to get you out of a nasty position. It set me on a path where I am now and you are reading this story.

The best home schooling: toolbox meeting for a salvage operation. (Credit: Co Winkelman)
The best home schooling: toolbox meeting for a salvage operation. (Credit: Co Winkelman)

Actually, we did not see them completely get off, as we had other obligations and had to leave. We were confident they would come off, but it was a mystery to us where they did end up. Finally after thirty years, I did a Google search and to my surprise I found they did get off indeed and were even reunited with their first rescuer, Simon Le Bon.7

‘Yo’ is away, but still scars are left behind in the coral where it all happened. (Credit: Google)
‘Yo’ is away, but still scars are left behind in the coral where it all happened. (Credit: Google)

That was my own story on dredging and salvage. Currently, there is an interesting exhibition at the National Dredging Museum8 with better documented cases and very interesting displays. Still, the three steps used for ‘Yo’: ‘Lift, Dredge and Move’ can be distinguished for the other cases there, also.

Exhibit of the salvage operation of the ‘Faustus’ from the Rotterdam breakwater
Exhibit of the salvage operation of the ‘Faustus’ from the Rotterdam breakwater

Remarks

Please keep in mind, that these events happened more than thirty years ago and were about saving the lives of five people in immediate danger. Dredging in coral should only be done under very strict conditions with the health of the ecosystem in the first place and in balance with the necessity of the operation.

References

  1. Los Roques archipelago, Wikipedia
  2. Drum (yacht), Wikipedia
  3. Simon Le Bon, Wikipedia
  4. The Martian: Mark Watney Quotes, IMDb
  5. Experiencing The Cutting Edge Of Dredging Technology, Discover Dredging
  6. BINAS, Noordhof
  7. Rescued woman reunited with pop star, BBC
  8. Scheepswrakken bergen of baggeren? National Dredging Museum

See also

The Good Side And The Bad Side Of A Statue At Port Said

Statue of Ferdinand de Lesseps in a garden at Port Said Shipyard
Statue of Ferdinand de Lesseps in a garden at Port Said Shipyard

As you’ve probably already guessed, I am quite fond of old stuff. Especially when it has some relation to dredging. Last post on Omar’s graduation1 not only brought back my memories on the interesting lectures by professor de Koning2, it also rekindled my inspiration to write about something that I have up my sleeve for a long time already. Although, due to the current global turmoil3, the message that I want to convey has been drastically altered. It turns out to be more of an opinion than an informative perspective on the history of the Suez Canal.

It was in the early years of my career, that I was building dredge ‘10th of Ramadan’ for the Suez Canal Authority4. We designed the dredge and prepared the components at Damen Dredging Equipment5, but the actual construction took place at Port Said Shipyard6, a subsidiary of the client. I’ve spent many hours roaming over the yard to locate components that were sent there and we needed them to inspect or install. On one of those excursions, I encountered the statue of Ferdinand de Lesseps.

Ferdinand De Lesseps was an interesting figure7, who owed his success to being the right person at the right time at the right place. In his earlier career, during a quarantine period in 1832 in Alexandria, he received a book that discussed Napoleons ideas about connecting the Mediterranean with the Red Sea8. Captivated by this idea, he was able to use his connections and positions to get the concession to dig the canal as we know it in 1859. In honour of this achievement a impressive statue was placed at the beginning of the Canal at the Port Said side after the opening in 1869.

As it happened in those days, the Compagnie Universelle du Canal Maritime de Suez, claimed the canal and all involved land and business for the French government. All revenue from the Canal ended up in France and not in the country that had worked so hard for the Canal. This has been a great disappointment for Egypt. When Nasser declared the Suez Canal a national property in 1956, the statue was removed as a gesture that Egypt was independent and no European country had any business ruling it as a colony. In a careful act of historical awareness, the statue was not destroyed, but placed at the Port Side Shipyard to be taken care of until the future would find an appropriate purpose. There it is kept in honour by a select group of craftsmen, who depend for their subsistence on his legacy.

Statue of Ferdinand de Lesseps at the entrance of the Suez Canal (Credit: Google)
Statue of Ferdinand de Lesseps at the entrance of the Suez Canal (Credit: Google)

In 1956 it was not so much vandalism by the people that the statue was removed from public space.7 It was a statement by a public conscious government with history awareness that prevented further harm from mindless destruction. Now, over half a century later, we see more acts of iconoclasm to historical statues, and then in a so called civilized world… A lot of historical figures were children of their own time. And for sure, those times were not very civilized in hindsight. OK, I am history aware and enjoyed my history lessons. There I had to learn that the raids of the barbarians on Rome, the Crusades to occupied Jerusalem and the iconoclasm in our own Reformation era were to be condemned. So, imagine when a lot of historical figures were removed from the street by emotional destruction, would later generations not condemn us in turn? What I would find even worse, is that future generations would not be aware of the dark side of those old ages as there are no statues to remind them to it. Maybe we can reintroduce a penalty for those ‘heroes’ from their own days: ‘the pillory’9. Just as with all sentences, the penalty can only awarded by the government, or an appointed committee, not the public. If that fails, store them under the custody of people who take good care of them without reverence. And at least let the pedestal remain to remind people of their history. ‘Those who cannot remember the past are condemned to repeat it.’ (George Santayana)10

Possible implementation of a statue with a pillory sign?
Possible implementation of a statue with a pillory sign?

References

  1. Graduation Omar Karam: Rock Cutting The Egyptian Way, Discover Dredging
  2. Boundary Conditions for the use of Dredging Equipment, Lecture notes i82 A+B, prof. J. de Koning
  3. Violence and controversies during the George Floyd protests, Wikipedia
  4. The Ancient History of the Cutter Suction Dredge ‘10th of Ramadan’, Discover Dredging
  5. DTC – Think Global, Act Local, Damen Shipyards
  6. Port Sid Shipyard, Suez Canal authority
  7. Ferdinand de Lesseps, Wikipedia
  8. Mémoire sur la communication de la mer des Indes à la Méditerranée par la mer Rouge et l’isthme de Soueys (p.352), Google
  9. Pillory, Wikipedia
  10. George Santayana, Wikiquote

See also