The Art of Dredging

Dredging and shipping

TSHD "Wheeler"

 

The trailer dredger  "Wheeler" is operated by the United States Army Corps of Engineers (USACE). "Wheeler" was built 1983, with a hopper of 6000 m3.

The ship reflects the completely different requirements for dredgers in the U.S. .

"Wheeler" is solely built for maintenance dredging, with focus on the Mississippi, although this dredger (homeport New Orleans) operates along the whole Gulf coast and Puerto Rico.

Agitation was a common practice when "Wheeler" was built, hence the very large pumping capacity (hopper can be filled in 11 minutes). Nowadays dredging in the U.S. is very much in the public eye, environmental concerns became core, and agitation dredging lost its lustre of gold.

"Wheeler" is built for the federal government, it's not a Jones Act ship.  USACE dredgers do not compete in the dredging market, but are built to lead the industry and provide maintenance dredging, and research and development to maintain knowledge of the latest dredging principles, technology, and design. 

Many dredge systems are designed in-house, by the Engineer Research and Development Center
(ERDC), and the ships are designed by the Marine Design Center. 

The U.S. government made a conscious decision to turn over dredging functions to the private
sector, to spur competition and development in hopes of cutting costs. This may not be considered a complete succes, more on that later.

USACE does only maintenance dredging (except for emergencies), but the private dredging companies do capital dredging, beach reclamation, harbor building, etc., and due to their multi-mission abilities,
you'll find their designs mirror European-style dredgers, but of a smaller size.

"Wheeler" was the largest trailer in the U.S. arsenal,  for 25 years. In 2005 TSHD "Glenn Edwards" was built in Mobile, Alabama, with a 9175 m3 hopper capacity surpassing the "Wheeler". However, "Glenn Edwards" is privately owned.

  

The "big three" dredgers of USACE: "Essayons", "Wheeler", and "MacFarland", from top to bottom.

McFarland is a sidecasting dredger, though she has a hopper as well.

 

 

SHIP'S DATA

 

Built by: Avondale Shipyards, New Orleans
Year: built 1981, commisioned 1982

Total installed power: 7.755 kW
Hopper capacity: 6.120 m3
Length o.a.: 124,6 m
Breadth: 23,8 m
Draught: 9,0 m
Speed: 14,5 kn
Suction pipes: 2 x 660 mm + 1 x 1000 mm in midships well, dredge depth 16.8 m 
Dredging depth: 29,0 m
   

 

"Wheeler" has three suction pipes, which can be operated simultaneously: two x 660 mm standard pipes with underwater pumps and one 1000 mm pipe in a central hopper well (photo left).

This central pipe has some operational restrictions regarding underkeel clearance and sideways drift.

 

This whole setup, with three suction pipes, is unique in the world.

 

Central moonpool for third suction pipe, from aftschip looking forward.

The pipe is of a common type, but mounted in a very uncommon place.

The design idea obviously sprouts from bucket- and cutter dredgers.

 

 

 

 

 

 

 

 

 

 

 

 

 

Standard California draghead with two loose visors, with the famous turtle deflector in front.

These dragheads work solely on the erosion principle, but perform well enough for maintenance dredging of fine particles.

 

 

  

 

 Engine control room

 

 

 

 

 

 

 

 

Main navigation console and the original ECP (Efficiency Control Panel), designed by IHC, which is largely unused today. 

Today, cabinet space is used for newer, in-house designs, featuring touch-screen PLC controls
and integrated (networked) systems. 

 

 

Since these ships have a projected lifespan of 40-50 years, they are updated with new navigation and dredging electronics, engines and monitoring systems halfway their lifespan.

Funding comes through US Government and Congress, sometimes political issues hold back the U.S. government dredging industry, in order not to hinder the private sector.  

 

 

 

Dredgedesk.

Note the levers for control of the third pipe at starboard desk.

 

 

 

    

 

 Helideck aft

 

 

 

 

 

 

                                                                                                                                                              

The angled rudders allow for a larger size.
allowing for smaller,  therefore more protected,
propellers, with higher rpm and resultant thrust.  

Gives the ship a high
maneuverability from controllable pitch propellers without the need for
Kort nozzles.

 

 

  

TURTLES

USACE is very keen on its turtle  conservation program. The U.S. dredging industry goes the extra mile to preserve turtle species in the Gulf and East coast of the U.S..  

When dredging in certain area's, trawlers advance on the dredger to catch away turtles before they got caught by the "Wheeler's" dragheads. 

More on turtles and dredging:  http://el.erdc.usace.army.mil/seaturtles/index.cfm

and on "Wheeler:  http://www.mvn.usace.army.mil/pao/bro/wheeler.htm

 

 

Marc Van de velde

 

Photo's courtesy captain Edward A. Morehouse, who also supplied a lot of info. E.A. Morehouse is captain of the "Wheeler".

 10-2008

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