Gravel barge just flipped in Seattle ship canal

These barges are typically so overbuilt that it matter not how they are (un)loaded.

The 'under 200' sized little barges in the gravel trade are made to withstand being grounded while being (un)loaded that it is not a stress issue with them.

However, the free surface inside the tanks (which ARE supposed to be free of water) is often an issue. I have seen several around New York harbor flipped in my career. The water being pumped out is an issue. Keeping it out is another issue. The front barge (Bernoullis' principle) in a tow is susceptible to being constantly head down, thus the forward tanks being full of water.

Here is a crude drawing of how free surface affects the list on a barge, and (since there is no pumping ability installed) it necessitates manually hauling pumps around the barge to empty the tanks.

Of course this is simplified, but the method of the barge capsizing is a known event, and when a barge is 'lurching' side to side is a huge warning sign to both crew ON the barge as well as the tug operator to pump the tanks dry.

I don't have pictures, but I flipped a 130' deck barge over, using water ballast in the barge, and one tug pulling the barge sideways, and My tug pulling the barge the opposite way, with the wire bridles wrapped around the side of the barge. The barge slowly tips over on her side, and lays upside down. The deck hatchs with the water in them have water hose suction fittings installed to pump out the water and the barge is flipped. It works the same in reverse, but a diver must be used to remove the hatchs' underwater and install modified hatches with hose fittings to pump water in, or out as needed.

Freight barge loading/unloading can be seen in quasi real time here, for those interested:

There is a barge in Great Harbor in the BVI that we usually dive every time we are down there. It sank by the stern and sat that way for some time partially submerged until it eventually over a lengthy time sank to the 80' bottom. It rests on its side and the last time i dove it it was still partially buoyant, laying on its side... still holding air in its tanks after a number of years.. it rocks back and forth.. even at 50' of depth the the shallowest part.
If anybody goes down there it's a great dive and often one gets rewarded with tasty mollusks hiding in its shadows...
We just spent time skiing on the Snake river and it is amazing how they load the grain barges from the stern first... and often the deck is awash until they balance the load.

HOLLYWOOD

Sorry, here:
Webcams | Alaska Marine Lines

Padeen said:

Sorry, here:
Webcams | Alaska Marine Lines

Click to expand...

That looks familiar! The company that tows their barges is who I worked for for some years. Western Towboat, Seattle. Worked for them between 1980 and about 1993 or so.

Padeen said:

Sorry, here:
Webcams | Alaska Marine Lines

Click to expand...

These barges in the video are not the same as what has capsized. The barge capsized is a deck load of gravel which is bulk loaded (dumped on) and scooped off by some unloader (bucket, scoop or rotary vacuum)

Although the deck load is the same, the method of (un)loading on the two is distinctly different.

http://www.ccibarge.com/cah/cahpublic.nsf/ProceduresRules?OpenPage

Safety rules for loading dry bulk cargo established by Cargill Grain. While hopper barges are depicted in the diagram the basics are similar to most any vessel.

The barges in the original post appear to be semi-ocean going deck barges in the 300' x 50 range with cargo, in this case gravel, being carried on the deck. Initial Stability is the relationship between the center of buoyancy (B) and the center of gravity (G). In the case of a loaded deck type barge G is relatively high due to the placement of the load being higher than in a hopper type barge. As B is effected, normally by seaways wave action this change in B with G remaining the same creates a "righting moment" or tendency. Without getting into transverse metacenter and the metacentric height there is an explanation as to the actions that may have possibly caused the problems shown in the provided pictures.
Three loaded barges secured abreast and to the dock. Inside barge (I) middle barge (M) and outside barge (O). Consider all barges are facing the same direction with I being port side to the dock and likewise O being secured port side to M. I barge is being unloaded as it is being unloaded it increases the buoyancy on the port side of M due to the lines or cables securing the barges together. In other words as I is unloaded M's port side is being lifted. Buoyancy (B) is shifted to the port of M while G remains the same increasing the angle between B and G (greater than those one might find in a seaway or at initial buoyancy. At some point G shifts to M's strb. side due to gravity shifting the load. Then things start speeding up as the angle between B and G increases rapidly. The securing lines between I and M have parted at this point. Some of the gravel rolling off of M lands on the port side of O making the port side of O go slightly deeper in the water. As the port side of M comes out of the water the distance between I and O is reduced and in that the position and forces acting between M and O still tied together drives O closer to the dock and under M. As this action increase M is flipped onto 0's deck.
That is my speculation of how this occurred. Poor unloading practices - always check your lines.

Very common occurrence. frequent scenario is on compartment takes on water until she shifts and dumps deck load. Most of the companies that do aggregate work have people that routinely pump these but not always in time. We are in Norfolk raising one now for the Navy, 600 tons.

Yep, the same one that is usually responsible for checking and pumping is the one that checks the lines. He may have been off that day.

Salvage has commenced. Manson brought in a mega crane (400 ton) this morning. So far they are just setting up. It will be real interesting to see how they untangle the barges and right the one that's flipped.

If you have a good vantage point and a weather proof Go Pro handy now would be a pretty good time to set it up Peter.

Unfortunately the work barge blocks a lot of my view, but I've been watching it over the past two days.

Day one they got the flipped barge lifted up enough to slide out the full barge from underneath it. It's now tied up and being unloaded per usual procedure.

Now the flipped barge is floating on its own, just upside down.

Today they spent the whole day prepping for what I expect will be a righting exercise tomorrow or
Monday. I couldn't see directly, but think they were welding anchor points onto the barge for lifting cables. Near the end of the day it looked like they were rigging the big lifting cables.

I did run the GoPro in time lapse mode for the first couple of hours on the first day. But very little happens visually. Plus, the GoPro is wide angle so not well suited for this. I discontinued, but still have it set up in case things get interesting.