Ya - does raise the questions:
1 - why did the pins break, then? (rumour so far, but likely to be true),
2/ is it too rough for these (ITB/ATB) unit tugs on the open BC coast?, and
3/ wasn't there a back-up to this happening wrt tow attachment?
I personally find it unlikely the pins broke. Admittedly I know nothing about this particular tug design (wouldn't be too hard to find out I imagine, our designs are all touted in Western Mariner, I'm sure Americans do the same thing), but my initial reaction was hydraulic failure, or computer pins system incorrect command. IF they had pins at all, I know there are some new track and rail designs out there too, remains to be seen. Odd though that most pins designs feature a "fully deployed" mode during hydraulic failure, so, still many things to find out. Like I said before, the merits or failure from a design stand point will take quite a while to discover.
The reason companies have been moving towards ATB designs for fuel barges is efficiency. Pushing a barge is more efficient hydrodynamically, and thus more fuel efficient (and faster, every little bit counts big time over the lifetime of the unit). On our West coast you primarily see American ATB designs, but the biggest Canadian flagged fuel barge on our coast is an ATB design. They took a large ocean going tug from the 60's, spent a fortune converting it to run huge pins out the sides, which fit into the "teeth" of a notch at the stern of its matched purpose built barge. When the barge was picked up from China, they pushed it back across the Pacific deeming it safer than towing even though both the barge and tug were designed to be towed if necessary. That unit has seen some serious water across the Pacific, all up and down North Americas Coast, all over our Coast, and into the Arctic. No-one would have considered towing over pushing for safety in weather. With that design there would be more "weak" points towing than pushing. Would you rather hang something from a string or bolt it together? The old way used to be, tow your fuel barge to it's destination, and then stop and switch to push mode for the landing, which left you in the vulnerable position of not being towing or pushing while you switched from one mode to another, all with wires on drums instead of purpose built pin systems. (You have to realize some of these pins are the size and shape of a stop sign, but 10 feet long and made out of steel)
Interestingly enough though, the ATB design has proven itself SO efficient and safe that they are now designing the combinations without the ability to tow even if they wanted to. The tug hulls are now so efficient at the back of the barge, that they have lost their ocean going abilities as a stand alone tug. High centers of Gravity to see over the barge, and shallow drafts for hydrodynamics. Not the kind of thing you would want to tow with at all (they aren't even installing towing wire winches on the tug's sterns anymore!). Is this a mistake? I don't know, its above my pay grade to make those decisions. Most of these barges have emergency towing wires leading from the bow to the stern where they are connected to the tug in the event of an emergency break away. Ironically though, if it breaks away in heavy weather, the last place you want to be is in front of that barge with only a barge lengths worth of towline out, you want that thing at least a quarter mile behind you in the rough stuff. Again though, these things are designed to be safer than towing in the rough stuff. The evidence is right in front of us. ATB's are more expensive to design and build, but the companies hauling the most sensitive stuff (fuel), are all moving to ATB designs. If any of those companies imagined towing was a safer option in rough weather they wouldn't be moving into ATB's.
As
@california pointed out, there are way too many "barge broke loose" from the towline stories on this coast. This is the first ATB break up I've heard of here on our coast. The talk shows on the radio yesterday though when everyone who called in seemed to be an expert, mentioned other failures from the states, but it wasn't supported by facts, so maybe, maybe not I don't know.