History and some new ideas about ATB

This article in Marex may raise some questions and opinions:

It’s probably been well understood that ITBs offer mechanical and performance advantages over ATBs for decades.

However, the USCG has ruled that rigidly connected ITBs are ships subject to ship regulations and manning levels. That being the case, there is no economic advantage to building an ITB, rather than a ship, at least not in the US.

Even for ATBs, there is a practical size limit where the cost of operating ATBs approaches that of a ship, but without providing ship performance. Crowley found that out with their 750 ATB’s, and shifted away from building ATBs to conventional tank ships.

Over time, as Subchapter M is fully implemented, and tugboat manning levels increase to address fatigue in a meaningful way, and automation and economic pressures reduce ship manning levels, the practical size limits for ATBs will decrease.

ATBs and ITBs are primarily just an attempt to exploit regulatory loopholes and reduce manning levels. As those loopholes close, there will be few practical reasons to build ITBs or ATBs.

Unlike the US, the rest of the world never offered many regulatory or cost advantages to ATBs, or ITBs. Large foreign tugs have long been inspected vessels just like ships with larger crews holding unlimited licenses in the rest of the world. When third world seamen can be had for $600 a month, and officers for $1,200 a month, why build an ATB or ITB to attempt to reduce crew size?

I do not anticipate much future construction of ITBs. Moreover, the era of building large ATBs is probably coming to a close. Small ships will be built to replace ATBs.


I disagree with the point of ATBs being solely for reduced manning. They are the current pinnacle of tugs and barges in technology. No more worrying about having to tow or pick up in marginal conditions or all the fun that comes with conventional towing. There is definitely a benefit to crew size since they are tugs but they are also far safer in nearly all conditions to a conventional tug.

I find that one’s opinion on ATBs breaks down on where they’re coming from. Ship guys see them as Jones Act beaters and tug guys see them as the next generation of tugboating.


I work on hawser tugs and have worked wire boats and ATB’s. If building new, I see no benefit of building an ATB other than crew size and reduced regulations.(and maybe build cost)

Making an old tug into an ATB is a just good way to keep old equipment competitive, and nice for the operators.

ATBs were envisioned as rule beaters that could provide ship performance at tug and barge cost.

The theory was also that ATBs would be like standardized and interchangeable tractor/trailers where ATB tugs would pick up and drop off different barges for loading/unloading/repair/layup/etc. Just as truck tractors often do with trailers. If oil demand is up the tug would be pushing an oil barge. If dry bulk commodity demand is up, the tug would be pushing a bulk barge. If container freight is up, the tug would be pushing a container barge. And so on.

However, the reality is that ATBs are unique matched tug/barge combinations that usually spend their entire lives coupled to the same barge. Probably 95 percent of them are large oil barges.

It seems to me that most of the point of an oil ATB set was that the tug was uninspected while the barge had must simpler inspection requirements without propulsion machinery, navigation equipment, and often no crew accommodations. To my knowledge, there are no crewed oil barges on the West Coast. I hear that there are a declining number of crewed (two Tankerman) oil barges on the East Coast. Today, Subchapter M on a tug isn’t much of an inspection compared to Subchapter D and SOLAS on a tanker. Years ago, there was a huge difference between a 10 man crew on a tug and a 40 man crew on a tanker. Now it’s more like 6 men on a tug and what, 25 men on a tanker. ATBs may have some other repair cost and operational advantages.

However, I cannot see where a large ATB has any significant advantage over a tanker, except crew cost and fewer regulations. A ship with a huge slow turning propeller grabbing deeper water should have a big fuel consumption advantage over an ATB.

As ATBs have been implemented thus far, I don’t see any advantage over a ship, except as rulebeaters. If that’s the case, ATBs only make sense until the rules are changed.

The ATB technological advantage is not being utilized. If a company had 50 ATB tugs and 100 ATB barges of various types and sizes that all had the same standardized pin system (as trucking and railroad companies do), and every other company had the same standardized system (as trucking and railroad companies do), and tug and barge companies could hire on “owner/operators” to tow their barges during periods of peak demand (as trucking companies do), or hire out their tugs to other companies with more demand (as trucking companies do), or hire out their barges (as trucking and railroad companies do), then ATBs would really take over the tug and barge business. No more push wires, no more Beebe winches, no more push knees, no more head lines, no more towing astern in good weather, that would be wonderful, but it hasn’t happened yet. Ideally, it would also be possible to couple the barges to each other. Will any of this ever happen? Or will ATBs just be a passing rulebeater gimmick.

1 Like

As a kid, I spent some time on an ITB that was developed as a transportation system with two tugs and five barges with extensive use of “drop and swap” (and later augmented by a third converted tug that eventually sank in a storm and took one barge with it). However, as a naval architect I have zero tolerance for permanently-mated “rule-beater” ATBs which I see essentially as ships with a hinged engine room (just one more moving part that can go wrong without offering any benefit) and, having seen my father work on one, less crew (as if fatigue had not caused enough accidents already).

They tried a tug and a 10,000 tonne self discharging coal barge on the trans-Tasman run downunder. No one knew whether the voyage time was going to be one week or six and the crew stumbled off it looking like they had been on a roller coaster for the trip. There was some discussion about using an ATB on the coal run to the West Coast of the South Island of New Zealand but crossing the bar and the sea conditions encountered made this impractical. A video of two fishing boats crossing the Greymouth bar has been shown on this forum.
I noticed a number of tug and barge operations on the West Coast up near Vancouver and I have often wondered about the economics of it.
A 500 TEU geared container ship with a crew of 9 burns about 10.5 tonnes of IFO at 11 knots running a shaft generator and 20 reefer plugs.

There are some ATBs (they call them “pusher tugs”) operating in BC. Seaspan has a couple small ATBs with flat deck barges hauling roro trailers that are essentially run like ferries between the Mainland and Vancouver Island. They do some pretty impressive truck driving turning the trailers around on the barge. I recently saw an article about someone else in BC building two new units.

You must know something operators and charterers don’t, because this is the opposite of reality. You are going to see fewer and fewer wire boats and more and more ATBs as time goes on. They are simply superior to wire boats in all but the most extreme conditions. The charterers prefer them over wire boats and the crews prefer them as well. They are faster, safer, and lack many of the challenges associated with wire boats. There is a reason they are continuing to be built and is not because they are a fad. At some point they are going to take over nearly all market segments previously dominated by wire.

1 Like

Oh, I’d certainly agree that the trend is toward ATBs replacing wire boats in the large oil barge trade. There seem to be a growing number of specialized small freight ATBs, but not enough to call it a trend.

I’d also agree that the trend was for ATBs to replace tankers up until Crowley built the 750’s.

Crowley then shifted gears and built tankers at Philly Shipyard. Has Crowley built or are they planning to build anymore ATBs? Also noteworthy, is that Crowley has replaced their East Coast to Puerto Rico trade freight barges towed by wire boats with new ships, not new ATBs. It appears that Crowley at least, has figured out that ships are more cost efficient than ATBs. Crowley has reinvented itself as a shipping company, instead of a tugboat company.

I do not doubt that tug companies operating ATBs will continue to build more ATBs to replace old wire boats because that is the business they know. That does not mean that ATBs won’t eventually be replaced by tankers.

At some point in the future Subchapter M inspections will become real inspections, and impose real manning requirements on ATB tugs. When that happens, there will be no reason not to replace aging ATBs with more efficient new tankers.

Why is it that there are damn few ATBs anywhere else in the world, outside of the US Jones Act oil trade?

Some of your statements are debatable.

Some atbs out there are no safer than wire boats, however i’ll agree in general they are more comfortable for the crew. There are some stellar atb units out there and some real lame ones too.

Losing a tow at sea and coming out of the knotch would both be equally fucked scenarios for retrieving the lost tow.
I’m speaking from personal experience but what do i know.


Yes, they have plans to build more ATBs for Alaska.

In nasty weather a wire boat must heave to if it can’t tow into a river or harbor, delaying its shipment. An ATB can usually cruise right in.

Vane Bros has discovered this and they are now building more ATBs with talks to convert more.

1 Like

I don’t think anyone disputes the numerous advantages and benefits of a well designed and built ATB with an Intercon pin system over a conventional tug towing on the wire —- in most trades. That’s not the point.

The point is: What advantage, if any, does an ATB have over a tanker?

Are any of those advantages, such as regulatory loopholes, and tiny crew sizes, being diminished?

I don’t see a lot of demand for new ATBs in Alaska. Vitus has proven the advantages of its small shallow draft ATBs with Mitsubishi pins. Brice has two small freight ATBs, and AML has one. Kirby is just about gone (they were mostly working for Crowley). Harley has made an appearance. I expect to see a few more shallow draft ATBs built for Alaska, but not many, and nothing big.

Crowley, and others, are using foreign flag tankers to import foreign refined oil. The Alaska fuel business appears to be shrinking with more and more wind turbines, fewer fishing boats, fewer government projects, and a weak local economy.

Some say that many Native villages have grown beyond sustainable levels, and are now losing population.

The persistent rumor is that Crowley has been trying to sell its Western Alaska fuel business for years. They have been selling boats; only a few left.

Not the first time I have mentioned this but actually quite a few have been built outside the US. http://articouple.com/14-list_1.html

A little more information. http://articouple.com/16-history.html


258 with articouple pins over 40 years. About 6 per year, for this particular brand of pins.

The list includes CAVEK and NANAQ built 2010 for Vitus Marine of Alaska, and SAM B built 2000 for Brice Construction of Alaska. I didn’t see Brice’s AQULUAK (spelling?) or AML’s KRYSTAL SEA in Alaska. The list also includes a couple of Kirby boats.

The biggest advantage is the ability to drop the barge at the terminal, shift elsewhere to bunker, revictual, make repairs ect. Faster turn-around time.

Having sailed on both 750 Class and currently working on an Eco class tanker ship, I have seen first hand the advantages and disadvantages of ATB’s. The 750’s burn way to much fuel and do not make the speed as originally designed. It was a big deal when they first came out. They found out quickly that economics of scale did not pan out. Rumor is that Crowley will not build another ATB, sans the Alaska ones. Granted Crowley has shifted more to ship management now.

While the Eco tanker does have more crew, it can carry the same amount of cargo, burns 17 tons less fuel, and makes better speed. I do think that ATB’s have their place carrying smaller parcel and chemical carriers. Crowley seems to keep most if not all of their ATB’s on charter and running.


I put that into the category of keeping older equipment competitive.