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Gerarddm
01-31-2018, 12:45 AM
Andrew, or others knowledgable:

So we get a lot of maritime traffic passing by the house, and there are a lot of towed barges, and a few pushed barges.

Query: why the difference between the two? My honey opines that it is due to maneuverability issues at the port of destination. I thought it might be ocean going versus Inland Passage stuff.

Curious minds want to know.

Nicholas Carey
01-31-2018, 01:15 AM
I grew up in Cincinnati, on the Ohio. Every tow on the Ohio and Mississippi is a push. The batprge string is lashed together. The towboat (that's the local terminology!) sidles up behind and pushes.

My theory is that it makes navigating the bends easier.

Dangerous, being a deckhand is. Everything is lashed together with wire rope and is under a lot of tension. Steel has a lot of elasticity in it. If/when something lets go, you don't want to be nearby, lest you lose a limb or worse.

https://upload.wikimedia.org/wikipedia/commons/2/27/Towboat_Dakota_Storm_upbound_at_Matthew_E._Welsh_B ridge_near_Mauckport_Indiana_USA_Ohio_River_mile_6 48_1987_file_87j089.jpg

Jimmy W
01-31-2018, 01:54 AM
I grew up along the lower Mississippi River. As Nicholas said, all barges here are pushed. I don't think that towing could produce the required precision to position the barges in other traffic in sometimes narrow channels.

Come take a ride through Vicksburg


https://youtu.be/WGuJZ6mH4Z0

Andrew Craig-Bennett
01-31-2018, 06:27 AM
We can make a useful distinction between river traffic and open water (sea and Great Lakes) shipping, because, obviously, in open water there are waves and swells which cause the elements of a tow to move in relation to each other.

At sea, towing is difficult, and is quite a specialised branch of seamanship.

As a spectacularly embarrassing example of a very well known shipowning company making complete fools of themselves with an ocean tow, try this:

http://www.dmaib.com/Ulykkesrapporter/Marine%20accident%20report%20-%20Loss%20of%20tow%20-%20MAERSK%20BATTLER.pdf

In open water, one way in which pushing can work is where there is a very substantial connection between the pusher unit and the cargo unit, resulting in what we call an ITB (Integrated Tug Barge Unit), where the pusher unit has the same draft as the barge unit and pitches and heaves with it. These units are NEVER disconnected at sea; all attempts to do so have resulted in the loss of one or both components. Whilst the "sales pitch" for the ITB concept emphasised that the pusher and the barge can be separated in port, so the push tug can pick up another barge unit and leave the barge to be discharged, this did not happen in practice and there are many tales of pusher units and cargo units becoming rusted together and refusing to separate for dry docking.

So what was the idea of the ITB? Simple; it was a Jones Act "rule beater", never copied outside the USA. US manning regulations allowed an ITB to sail with a crew calculated on the tonnage of the pusher unit, rather than the tonnage of the whole thing, and this allowed a big saving in crew cost.

So far as I know, the ITB fell out of favour, and none have been built since the 1980s.

However there is a more modern version called the ATB ("Articulated Tug Barge Unit") in which the connection allows the pusher tug to move separately and if I recall correctly Crowley, to name one, have a number of tanker ATBs. There is a link to their web page here.

http://www.crowley.com/What-We-Do/Petroleum-and-Chemical-Transportation/Articulated-Tug-Barges-ATBs

and here's one:

http://www.towingline.com/wp-content/gallery/maritime-news/sea-reliance.jpg



and a page from a design firm here:

http://ral.ca/wp-content/uploads/2015/12/Nt3000110-Model.png

http://ral.ca/articulated-tug-and-barge-systems/

As noted this is basically an American idea aimed at cutting manning costs in the Jones Act trades, although you do find a few examples in other nations that use cabotage.

In river traffic, we can pretty much say that big rivers have pushers - the Rhine for example has seen the traditional "Rheinschiffs" replaced by pusher tug and barge set ups.

In smaller systems, tugs still tow and this is done in places like the Port of London where a tug can easily pick up and drop off lighters, but large scale operations use pusher set ups for the reason given above - manoeverability.

Hwyl
01-31-2018, 07:33 AM
OOh, I thought the thread was going to be about this kind of barge. They are also in ACB's bailiwick.

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS4up-3bg_ZsSiCgMDEc-gYdGJL2sNgtBgziaBjHOULloq1s22NXg

Ian McColgin
01-31-2018, 07:34 AM
The unit Andrew shows in #4 shows a stage in one evolutionary trend for pushing.

My tug work was coastal NYC to Boston, mostly a single fuel barg up or down, heavy or light, interspersed with ship work. So we were using basic single and twin screw harbor tugs, fairly conventional. We also did a little salvage tows. We had a couple of barges with a bit of notch for the tugs bow but mostly not. Just center the bow and secure. Then get a wire each side from the tug's stern to the aft corners of the barge and winch them bar tight. Further down evolution's path are tugs very exactly made to fit specific barges, pins in the notch and such. It's really an oil tanker with a detachable engine. The coastal fuel business we did is a huge part of the economy because tug and barge can get into places tankers cannot. The larger single units still need at least the possibility of shelter but really do longer runs than we did around the coasts. Theses units have tugs so highly evolved for their job that they are actually useless for other work. But they come into their own on routes where you might use a small tanker but these units are cheaper to run, mainly due to drasticly reduced crewing requirements. It's a dodge.

For us, if we were going to push from port to port we'd set up the wires, but if the route was going to be a bit bumpy we'd push out bow to bow with fiber rather than wire and the main tow line (wire) laid on deck and up to the barge. Once in the clear, we'd release the push gear, get ourselves turned around and head off. Tow length is regulated according to sea state and where we are. Sometimes we'd get tug and barge so close that we'd rig a "gateline' putting the barge bow all but touching the tug's stern, a very good place for tight maneuver on flat water.

So in the busy waters of New York harbor all up the Sound and to Boston, you'd hear on VHF 13 from a tug pushing an empty fuel barge something like, "Security. Security. Security. This is the ----- with a light oil can on the head approaching the Throg's Neck Bridge . . . "

Andrew Craig-Bennett
01-31-2018, 08:23 AM
Thanks Ian - hope you enjoy the Danish Maritime Accident Investigation Report I linked to. The German and Dutch deep sea tug Masters I used to work with would all be laughing like drains.

Chris Smith porter maine
01-31-2018, 10:14 AM
A couple of other things you can push faster than pull even with a small notch you just can't push with a conventional tug once the seas get up. The crew size is a difference the tankers I sailed on might have a crew of 25, the big tug barge units almost the same length a crew of 6 we would push when calm pull when rough.
For long haul towing we used heavy chain on our tow line to weigh it down so the slack in the wire acted as a cushion in rougher weather, coastal work and rig moves we used a snatch line 150' of 12" nylon as crew the snatch line was so much easier, for tight work the snatch line might be much shorter, for real tight work with a barge with no notch we would just hip it.

ahp
01-31-2018, 11:18 AM
Along the Connecticut coast there were YO's (Yard Oilers) that had been sold out of the USN and were delivering home fuel oil into places that were challenging. They have probably all worn out by now.

Dave Wright
01-31-2018, 03:13 PM
https://www.workboat.com/news/shipbuilding/fincantieri-bay-shipbuilding-delivers-atb-wawa/

Chris249
01-31-2018, 03:52 PM
Thanks ACB, Ian and Chris - great information!

gilberj
01-31-2018, 04:00 PM
ACB has pretty well covered it....We have, in BC, a number of operations using ATB Articulated tug and Barge units. Basically they push when conditions are good, which is most of the time, but when things get nasty, mostly when they poke outside.....they tow. The Nathan E Stewart was the ATB that grounded last year near Bella Bella BC and caused extensive pollution. This actually illustrates the fact that a smaller crew (7 persons I think) was able to operate the tug/barge unit and in this case the officer on watch fell asleep and the watch did not include a second person on the bridge.....A ship of the same combined tonnage would have needed about twice the crew to meet minimum safe manning requirements.

I had a quick read of the report posted by ACB. I am astonished, that they tried to tow the two vessels side by side on a deep sea tow. I just cannot think it would be possible for that to go well, unless they had the great good fortune to have calm weather all the way......As if that is even vaguely possible in December in the North Sea and English Channel and Bay of Biscay...
It all boggles the imagination....

the_gr8t_waldo
01-31-2018, 09:58 PM
I spent a few months doing atb conversions on tugs. the ones we did had what I consider, a unique set up. no lines are need between the tug and barge. the tug had a set of hydraulically actuated pins ( ficc they were about 24-36 inches in diameter, and extended somewhere around 30pluss inches from the bow of the tug, into sockets. built into the tugs cutout on the barge.(both sides, of course). once the pins were extended there is no other attachment needed. and the combination becomes one vessel. the tug's steering was sufficient to control both and the two rode over rough seas with hinge action the pin and socket provided. at the same time. the pilothouse was relocated to allow the pilot to see over the barge so a second look out is not needed-Ficc about 40-50' higher than the org position...my understanding of tugs who tow with cables, they have a high rate of accidents..mostly from the offending craft not realizing there's a cable stretched between the two. have to say it was a fun job, but damn dirty work! I never saw any provisions for power to the barges running lights, so assume that a simple Honda generator sitting on the barge deck was going to be used

willmarsh3
01-31-2018, 10:27 PM
I can picture a skipper sailing behind a tugboat moving along, not noticing the trailing barge up to 1/2 mile behind only to find his boat suddenly stopping and being cut in half. It seems to be a really easy mistake to make.

http://www.yachting-life.net/new%20index/frames2/avoiding%20tugs%20and%20barges_frame.htm