Silt Happens 2

Silt indeed happens. Witness all the work taking place up in the northeast with dredges correcting (or attempting to do so) all the damage wrought by Hurricane SANDY. Our problems stem from silt being carried down The Sound and being deposited in some now expected areas. A survey discovers some unanticipated silting in St Mary’s River Entrance channel in this particular case so Great Lakes Dredge & Dock comes to the rescue. This was a win for everyone. Dredge ALASKA was transiting from a job in Louisiana to North Carolina, NAVY needed the dredge NOW and there was time in between jobs for ALASKA to respond.


Here are her particulars:
Length: 220 ft (67.1 m)
Breadth: 56 ft (17.1 m)
Depth: 12.5 ft (3.8 m)
Overall Length: 312 ft (95.1 m)
Draft: 8 ft (2.4 m)

Operating Parameters
Dig Depth Range: 11 to 87 ft (3.4 to 26.5 m)
Suction Diameter: 34 in (864 mm)
Discharge Diameter: 30 in (762 mm)
Ladder Weight: 335 tons (303,907 kg)

Machinery & Power
Cutter Power: 1,400 hp (1,044 kW)
Total Installed Power: 11,315 hp (8,438 kW)

ALASKA was put into service in 1959. According to her Chief Engineer she was electrically and electronically upgraded in 2010. I never considered dredging to be a precision affair, I mean there is always silt being deposited, they dig stuff up, pump it somewhere. A hellacious mess is created and they leave. I couldn’t have been more mistaken. This IS precision work with equipment and computers that lend to that kind of detail.

In the back of the Operators Shack looking to starboard
Looking to port

Some view screens with SCADS of data:
In this case, the data indicates slurry density, slurry pressure, how much material moved, how fast, where it is in the pipe, etc. Amazing amounts of data for the operator to be cognizant of as he swings the cutter head left to right.

This one tracks the cutter head and it’s progress in the channel, the bottom part illustrating the rise in the bottom.

He additionally has cameras tracking these points, anchor points and other things necessary for him to get the job done. Again – NOT a job fer a flunky.

I haven’t been able to find an accurate diagram of the lay out. Five anchors total. One stern anchor with a long lead. Port and starboard breast anchors. Port and Starboard bow anchors. The bow anchors are heavily tended. Meaning Starboard wire eased while port wire is heaved in – cutter head sweeps to the right. Reverse and sweep left. Complete the sweep, heave around on stern anchor to move and reposition.

Cutter head. Ran into the replacement head on my way out.
BIG. It’s about 8′ across and those teeth are just shy of 9″ long

So the Chief Engineer (or ‘Chief’ in industry vernacular) takes me for gander inside. Chief is a PERFECT moniker as he is a Retired NAVY Chief Petty Officer who served in one of OUR boats here at Kings Bay. First thing we see is BIG RED

This is the main pump impeller that essentially sucks the material off the bottom and and pushes it to the booster station. That bad boy is 94″ across.

THAT is powered by two mains

Electric for the for all of this provided for here

MUCH like a tugboat she’s a floating engine room

These guys eat like kings. It was Friday therefore it was Seafood day. Fried fillets of Grouper, catfish, tilapia and fried MAYPORT shrimp accompanied by a seafood gumbo.

That booster station? It’s about 3 miles west of the dredge and can BARELY be made out in this pic at the end of the floating hose

Presence of the booster is gauged by the distance from dredge to beach and the quality of the slurry being moved. Far away and thick material equals need for booster.

This dredge operation AIN’T no one man show. Support services are also required. This support barge is moored inside the Amelia river and it’s sole function is to support operations by staging possible repair parts and acts as a separate work space.

There are people on the beach moving dredge spoils to replenish the beach in a CLASSIC recycling maneuver. With a peak of 3000 cu/m of material an hour it’s more than just a couple guys with shovels. Everybody wins as well – channel is cleared, essentially free material to replenish the beach and the dredge company doesn’t need to add another step to spoils removal.

Moving this whole kit and kaboodle is no mean feat. It reminds of the Supply Trains of days gone by that supported Armies. At 3 miles from the beach, that’s a lot of hose AND pipe. Hard pipe that sits on the bottom to no impede channel traffic. It needs to be moved. Haul it up, weld blanks on the flanges, pump some air in to create buoyancy, raft them together and tow them.THAT requires people. THAT requires equipment. Tug CHAMPION slings the anchor barge that is used to set/recover anchors and set/recover piping. I’m QUITE sure that don’t happen in an hour or so. And THEN, once in a new location, flanges are cut and pipes again sunk in place. Amazing.
Length (ft.): 66
Hull Depth (ft.): 7.6
Hull Breadth (ft.): 22.1
Gross Tonnage: 86
Net Tonnage: 58

ALASKA can’t move herself. Enter Dawn Services ATLANTIC DAWN
Length – 85’
Beam – 27’
Minimum Draft – 8’
Maximum Draft – 9.5’
Speed – 10 Knots

As it happened, they made the final cut when I was in the control room. With the cutting done the channel needs to be surveyed. ACoE’s FLORIDA is on hand for that

And with that It’s time to head for the beach. THAT will be done aboard crewboat COOPER RIVERShe has a flexible schedule. Shifts are from 0600L – 1800L and from 1800L – 0600L. Therefore the boat is moving crew to and from to support those shifts and to move any supplies that arrive or need to go to the beach.

SPECIAL thanks go out to Project Manager W.E. Mitchell who took GREAT care of me and made it all happen with fairly short notice.

All pix snapped by me

JED sends

This entry was posted in Harbor, Local, Tug, Vessel and tagged , , , , , , , . Bookmark the permalink.

2 Responses to Silt Happens 2

  1. deckiewoman says:

    I LOVE this write up, and photo’s!! I cadet shipped on a hopper dredge, which of course is a lot different, but I can appreciate how important and in depth dredging can be!! This cutter suction dredge and pipeline you wrote about involves a ton more other vessels and teamwork than what I learned about on the hopper. On the hopper dredge it worked as an independent ship, and could not dredge in areas that a cutter suction and pipeline could. We would sweep back and forth in straight lines, pretty much, and when we were full we would go to a dumping area either in the river or out to sea. I got to do a lot of shiphandling, and it was just plain awesome spinning it around on a dime, putting the dragarms down and bringing them up, like vacuum-cleaning!! I had more fun playing in the dirt and maneuvering the ship than I ever did with K-Sea. Reading this wordpress article of yours makes me want to get up off my butt and out of this deep depressing rut I am in!! You take care, CPO Dupee!!

  2. dchap578 says:

    Another excellent post. Thanks.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s