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

Book Review: Donald Duck A Muddy Fine Business; Artistic Equipment Design

Front page of Penny Pincher magazine with Donald Duck as dredge master (Credit: Disney)
Front page of Penny Pincher magazine with Donald Duck as dredge master (Credit: Disney)

Donald Duck is a Jack of all trades, that he eventually he would end up on a dredge was inevitable. The story was already published in 1977 in a Donald Duck comic magazine. It is written by Freddy Milton1 and drawn by Daan Jippes2. At that time, I read it and already liked it very much. Later, I had it in a comic album3, but lost it moving to a new house. I wanted to review this story here already for a long time. Eventually, I consulted ‘Bul Super’ in Delft4, he advised me to search for Daan Jippes. That helped to find the story back on the internet.5

Opening scene of ‘Muddy Fine Business’ or ‘Success Test’ (Credit: Disney)
Opening scene of ‘Muddy Fine Business’ or ‘Success Test’ (Credit: Disney)

The story revolves around the endless feud between Donald Duck and Gladstone Gander. This time they have to compete in a success test by operating two different vessels: a ferry, ‘Seagull’ and a dredge ‘Aristoteles’. They have varying degrees of success and the outcome is unexpected.

The best known illustrator of Donald Duck is Carl Barks6. But Daan grew into his footsteps and eventually his stories are at the same level as the original master. He was with the Disney studios in the USA, but was working mostly in the Netherlands. In this edition, Jippes drew one of the most Dutch professions: dredging. Jippes had a keen eye for the elements that make up a dredge, tough the execution lacks some reality. Here I want to highlight some shortcomings that will help to illustrate the tricks that should have made it work and explain how real life dredging equipment functions.

Various details of the ‘Aristoteles’ (Modified from Disney)
Various details of the ‘Aristoteles’ (Modified from Disney)

The ‘Aristoteles’ is a truly multi-functional dredging vessel. It features both a grab and a bucket chain and the sediment can be loaded unto the vessel itself like a hopper or into a barge in tow. It is also self-propelled, although there seems to be a magical power generation as there is no visible exhaust pipe. Maybe Donald is again ahead of his time and running fully electric already?

Than the dredging equipment; the grab is suspended from a gantry, but it does not seem to be able to swing. Loading the tow barge would be difficult, as he has to reposition either the dredge or the barge. Apparently Donald should know about the technology of a rotating crane, as the picture on the front page has such a crane. And how would the material end up in the hopper?

Discharging buckets with reception carriage on a bucket ladder dredge
Discharging buckets with reception carriage on a bucket ladder dredge

Maybe with the other dredging tool: the obvious bucket chain? Though it is not supported on a ladder. Maybe that makes sense, as the buckets seem to be positioned on port or starboard in various panels. The material falling from the buckets might end up in the hopper. The vertical orientation presents some difficulty, as the material will fall onto the previous bucket and eventually through the well. In a normal operation, this is controlled by moving a carriage receiving the load and bringing it to the chutes. With a real vertical orientation, this would not be helpful anymore.

I once saw a solution for working with a vertical bucket chain on an exhibit in the National Dredging Museum7. A manual operated drawer-like slide was moved between every passing bucket to catch the load. It seems very labour intensive and prone to accidents.

Even after breaking down these operational details in the design of the ‘Aristoteles’, the vessel serves its purpose in the story: it is a really useful dredge for dredge master Donald. Well done Daan.

Exhibit with vertical ladder at the national dredging museum
Exhibit with vertical ladder at the national dredging museum

Call to the audience

The exhibit is still there, but unfortunately, it is broken. The mechanism has to be repaired, any model building fanatics are invited to help the museum restore it. There is a special event for new volunteers, now!

References

  1. Freddy Milton, Wikipedia
  2. Daan Jippes, Wikipedia
  3. Oom Dagobert En De Ondergrondse Kluis, nr34, Disney
  4. Stripboekhandel Bul Super
  5. Read online Walt Disney’s Comics Penny Pincher comic – Issue #4, ZipComic
  6. Carl Barks, Wikipedia
  7. Nationaal Baggermuesum

See also

Our Interview About New Pump Designs In The Latest Damen Nieuws

Headline of our interview in ‘Damen Nieuws’
Headline of our interview in ‘Damen Nieuws’

Another magazine dropped on my doormat, albeit a digital edition of ‘Damen Nieuws’1. The internal magazine for Damen colleagues. It featured an article with Suman Sapkota and me. Suman is our pump design specialist2 and at a Damen wide R&D convention he presented a poster on his pump design workflow within Damen Dredging Equipment. This caught the attention of the editorial board and we were interviewed on what we actually do for a living. Although we can’t share the exact details of the article or the poster, it is still an interesting message that we can highlight here.

Pump design workflow (inspired by Suman Sapkota)
Pump design workflow (inspired by Suman Sapkota)

The design of a dredge pump is based on the required specifications(1). The most important properties of the pump are: efficiency, NPSH, wear and ball passage. The first important property we try to fix is the ball passage3. We do use our own geometry generator(2) that assist us in creating a pump with a big ball passage. Unlike normal pumps, dredge pumps have to cope with debris and boulders that have to pass the impeller. The bigger chunks that can pass, the more uptime the dredge will have. Once we are satisfied with the geometry, we feed this through a file format converter(3). The resulting 3D file can be used on several platforms. This will enable us to create the digital solid for the engineering4, but it also gives us the negative volume, also known as fluid. Then to do mathematical operations on the digital fluid, we have to divide the volume into tiny cells. This process is called meshing.(4) When the mesh is available, the fluid flow through the mesh can be simulated with computational fluid dynamics.(5) All the fluid properties of every cell are calculated and the results are shared with the adjoining cells. This can be repeated until all properties of the cells don’t change very much anymore, a stable solution. Integrating all the properties of the cells give the resulting performance of the pump.

Balancing the four dredge pump performance properties
Balancing the four dredge pump performance properties

The estimated performance can be evaluated against the four properties.(6) The head times the capacity divided by the power required will give the efficiency. That is one of the items we wanted to know, as it relates to how much fuel will be consumed. The other parameter obtained from the CFD is the NPSH, or roughly: the suction performance. Wear cannot be estimated yet, but we are working on that2. Although the calculated turbulence might give a clue what wear to expect. If the properties are not satisfying our requirements we make an iteration in the geometry for improving the performance. However, changing the geometry will usually result in a smaller ball passage. If the parameters are OK to our requirements we have a pump design.(7) Manufacturing it is a completely different game.5

The design process of the dredge pump takes quite some effort and we are continually looking to improve the workflow6. Eventually we would like to be able to cater for all special requirements each individual customer might have.

Working for a dredge manufacturer, I am happy we design and produce our own pumps. It gives us the confidence, that when we supply dredges, they are as we like them to be. Another benefit is in discussions with the customer. It is easier when we can sit at the table as experts on their equipment assit them in finding a solution for their dredge.

Pump experts immersing themselves in checking the design of their pumps
Pump experts immersing themselves in checking the design of their pumps

References

  1. Damen Nieuws, Juni 2020, Damen
  2. Graduation Suman Sapkota: Where wear parts were worn down, Discover Dredging
  3. On The Relation Of Maximum Ball Passage And Recirculation Losses In Dredge Pumps, WODA
  4. Graduation Of Carsten Markus: Designing And Casting Of Impellers
  5. Don’t Play Games With Your Wear Part Planning
  6. Innovation, Damen

See also