Posted by: towmasters | November 19, 2008


Warning: before you read any further , please be advised that these are my definitions. Others, including the U.S. Coast Guard and maybe some naval architects, may disagree. C’est la vie. I get asked this question often and what follows is my standard answer. It is, I believe, based on sound and clear logic, not regulatory doublespeak or wishful thinking.

There exists a sub-category of towing vessels known as ATB’s. This stands for Articulated Tug & Barge. There is another category of vessel known as an ITB, or Integrated Tug & Barge. They are not, and never were, the same. Nor are either of them, with some limited exceptions, a “tug” in anything but name.

There are very few ITB’s in existence so many of you might never even see one, and they bear no relation whatsoever to a real towing vessel. They were designed from the keel up as nothing more than regulation-beaters, capitalizing on the uninspected vessel-status of towing vessels to get away with lower manning, construction and operation standards. They’re simply small to mid-sized ships with detachable propulsion / control units that are rigidly connected and do not move independently. An ITB “tug” disconnected from its “barge” is a sight to behold: unstable in anything but the calm waters of a well-protected harbor, and having the ability to do absolutely nothing remotely tug-like besides moving about under its own power. Here is an example of one.

An ATB, on the other hand, is a somewhat different story. There are two basic types of them, purpose-built and conversions, and they usually use either an Intercon or JAK connection system. The generally-accepted slang term for them is pin boats, the reason for which should be obvious. An ATB pivots on the transverse axis provided by the pins, allowing the “tug” to pitch separately from the barge.

The purpose-built type are generally not very seaworthy outside of the notch in exposed waters, although some people might try to bullshit to the contrary, and even in protected waters they’re very limited in what they can do. For the most part, unless there’s another compatible barge around for them to move, they’re pretty much useless. The idea of getting out of the notch at sea and taking the barge in tow is sheer lunacy. Unless they’re pre-rigged to an emergency hawser and can just back out of the notch and roll around on the barge it isn’t going to happen. Furthermore, you wouldn’t want to be up in that high wheelhouse getting whipped around by the seas. The probability of seriously injuring or even killing someone while attempting this maneuver would be unacceptably high. Suffice it to say that you just don’t ever get out of the notch on purpose unless you’re in port. Unintended/unexpected pin retractions have occurred on the West Coast and I understand that it was pretty ugly.

The conversions, older conventional boats with new pin systems and upper houses installed, can also be limited in their operational capabilities out of the notch, but it depends on the specific conversion job. Depending on which pin system is chosen, whether or not the hull underwent drastic shape modifications to accomodate it, and whether the new fendering offers adequate hull protection determines whether that particular boat can perform basic barge-docking assist work and/or do conventional alongside towing and pushing. Some can, and some can’t. Towing astern, although maybe a little more more feasible than with the purpose-built ATB’s, is still a dicey proposition. Most of the conversions have had their towing machines removed and only have an emergency synthetic-line hawser and a capstan in their place. As ATB’s become more numerous, captains and mates possessing the traditional towing skills are becoming scarcer. Crews that can do softline hawser work (including deckhands and engineers) are even rarer.

Most interesting to me are the few Bouchard ATB’s that were pinned and yet kept their lower pilot houses and big double-drum towing machines. They look like they can do it all: alongside, pushing and towing astern on the wire, plus some limited assist work if needed. I’d love to hear from someone with firsthand experience with them who could give us a report.

So if these ATB’s can’t really tow, astern or alongside, are they still legitimately tugs? I say no. And that brings up a whole hornet’s nest of licensing/TOAR/manning issues that need to be addressed soon, before an even bigger mess is created. More on this subject later…..

…..later has arrived please see ATB vs. ITB, v2.0


  1. Good post, but TOAR? – Looking forward to more on this subject. These manning issues have always been a puzzle to me.

  2. These seem like pretty strong opinions by someone with an ax to grind. I would be interested to learn the facts and experiences the author has to back them.

  3. Yes, it is a strong opinion, and the axe I grind is poorly thought-out, nonsensical or obsolete regulations and operating procedures. Is there some particular part of it that you don’t understand or disagree with? The information contained in the post is basic common knowledge within our industry, which is the target audience for this blog.

  4. When I see dismissive blanket statements such as “The purpose-built type are generally not very seaworthy outside of the notch in exposed waters” I get suspicious of the motives of the person who wrote it, that’s all.

    It’s hard to know from just a picture, but that Crowley tug looks quite seaworthy to me. Yeah, the pilot house is a bit high for heavy seas, but “heavy seas” are a relative term. These AT/Bs are supposed to enable tugs to move barges in weather conditions where traditional hawser boats would have difficulty or be forced to remain at home, but every vessel has its limitations. It stands to reason that if the tug had to work unpinned, it would be subject to the same limitations as a hawser boat and would have difficulty in heavy weather. And if it began as an AT/B and had to un-pin while in heavy weather it would be a serious situation. But it seems like a decently designed boat would be no less dangerous just because it had pins in the bow. Perhaps your beef should be pointed at poorly designed boats rather than the general concept. No, I’m not in your industry now, but having worked on a couple of conventional tugs in Alaska I must say that the AT/B concept looks pretty good to me.

  5. I direct your attention to the specific word I used: “generally.” Generally does not mean always or in every case. It means generally, which I’ll define as meaning “more often than not” or even “most of the time.” I think most reasonable people would accept that definition as well. That being said, purpose-built ATB tugs are, in fact, generally not seaworthy in exposed waters outside of the notch. They are, in fact, very tall for their length and quite top-heavy. The normal pitch and roll of a vessel at sea is greatly amplified on such a vessel. Imagine, if you will, being in the wheelhouse of that Crowley ATB tug while out of the notch and in heavy seas. Now imagine trying to engage in taking your drifting barge into an emergency hawser tow. Does this sound doable, let alone remotely safe, to you? It is a highly-dangerous activity for everyone involved. So dangerous, in fact, that the designers of these tugs explicitly warn those operating them that it is highly inadvisable to ever get out of the notch unless you are in port. Tugs with a lower wheelhouse are much safer in such circumstances. But this is really off-topic…..

    What you’re mistaken in is that “my beef” is with the concept of ATB’s. Generally, they’re a proven vessel design and in several fundamental ways they are significantly safer than conventional towing vessels. They’re also more efficient and capable of operating safely in weather that would leave conventional tugs either weather-bound or engaging in unnecessarily risky voyages while trying to compete with the ATB’s. They are not, however, towing vessels in any honest sense of the term. So why should they be regulated as if they were? If a given vessel is essentially incapable of towing then how can it be considered a towing vessel? Why would you want to treat it as a towing vessel? The knowledge and seamanship skills required to operate a conventional coastwise tug are much more involved. But because ATB’s are classified as “towing vessels” the deck officers are required to have towing licenses. Those whose sea service is exclusively on ATB’s can’t get the license they need to operate an ATB unless they can manage to get sufficient service on conventional tugs as well. This is silly/stupid in all but just a few cases where some of the converted ATB’s (owned by Bouchard), which you would not have seen in Alaska because they’re exclusive to the East & Gulf Coasts, still have their lower wheelhouses and towing machines and are capable of being operated in the conventional manner. It leads to more time-wasting and counterproductive bottlenecks in getting people trained and licensed to operate ATB’s in an industry that has long been suffering from qualified-personnel shortages. It’s time to put ATB’s in their own vessel and licensing classification and be done with this nonsense.

  6. OK, OK. I was linked in to this posting. It is apparently part of an ongoing series, but I saw it alone.

    I must say though, if an ATB is not a tug/tow and if it should never be disconnected in weather, then it is basically a ship with a disconnectable drive system. Once connected, it’s a small cargo ship, just like any other, no? The Coast Guard has master’s licenses for such vessels already.

    What change of regulation do you think is appropriate? (If it’s already in a previous posting, just point me to it.)

  7. Now you’ve got it! Purpose-built ATB’s are really just ships with pivoting engine rooms that can run off to get their own fuel, lube and water when they’re in port. They’re very attractive to owner-operators because they can be built and regulated / manned as a tug, not a ship, thus saving a lot of money. The trap was that by taking advantage of the relative regulatory laxity allowed for towing vessels they also had to have towing licenses for the deck officers, which are not so easy to legitimately get. Conventional tug service is something the Coast Guard has been requiring at least a little of for these licenses, so a company operating primarily or only ATB’s may find it very difficult to provide a place for their employees to get the required sea time and training. It’s quite a vicious circle…..

    The simple answer is to put ATB’s that are practically and realistically incapable of engaging in conventional towing activities in their own category and allow anyone with a license of sufficient tonnage / route to operate them. Perhaps adding a question pool with ATB-specific questions related to the different connection systems to the written test, and some minimum amount of service time on them for familiarization, would be appropriate. This all can and should be debated by the greater maritime community. With towing vessel inspections on the way over the next few years the uninspected advantage is disappearing anyway, so the time to fix this licensing / manning problem is now.

  8. I sit here looking out my west coast window and see tugs go by all the time pushing barges. These are towboats. They have really high pilot houses, just like AT/Bs, they cannot work ships and I’ve never seen one with a barge on the hip. They only push the barges. It’s all they’re good for. But nobody would dispute that they are tugs. So should they also be reclassified and work under different regulations along with the AT/Bs?

    Also, while I do see your reasoning on the need for changes to the licensing regulations for AT/B operators, I question the contention that a high pilot house makes the vessel not a tug. Many tugs are not designed to work in heavy seas but they are still tugs. Most inland towboats would meet disaster at sea in all but the most gentle conditions, yet they are still tugs and work very hard within the conditions they were designed for.

    And since hawser tugs don’t even go out (with tows) in heavy seas, I do not think the argument that AT/Bs are dangerous if they disconnect is necessarily valid. Neither type of tug should be working with a loose barge in heavy seas.

    (I’m not so much arguing as exploring the issues.)

  9. […] an ITB in sight.    On site here. If looking for specific “word” in archives, search […]

  10. Maybe this will shed a little more light on the ATB aspect of Tug and Barge applications.

  11. […] original ATB vs. ITB post, from November 2008, was due for a major updating, including lots of photos, so here it […]

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