Posted by: towmasters | June 2, 2011

Tugboat How-To: Towing Alongside 101

Towing alongside is considered to be a bread-and-butter skill for anyone operating a towing vessel. To the novice deckhand or bargeman, or to an academy-graduate greenhorn, much of the process and the reasons for doing things in certain ways may seem mysterious. This post is intended to illuminate some of these principles and practices, as well as to serve as a starting point for others to contribute their ideas and opinions.

Here is an example in profile of the classic stern-first or “heads & tails” configuration (tug’s bow head-first with the barge’s stern tail-first when moving ahead, thus becoming the “working bow”) for towing alongside, which is usually the preferred method whenever possible, as demonstrated by the tug Mary Turecamo and the barge Portland in the Upper Bay’s Bay Ridge Anchorage…

…and…

…a close-up for more detail: 2-part head line, a strap (1-part), and a 2-part stern line. The strap is what transmits the vast majority of the forward pulling force of the tug to the barge, while the head and stern lines transmit the turning/twisting/pivoting forces that allow the barge to be steered. The head line also handles most of the backing forces.

These images of the Marie J. Turecamo and the barge Connecticut, with the same kind of make-up, shows all three lines…

…doing their respective jobs…

…as they slide by, headed for the Con Hook Range and the Kills.

Why is the heads & tails make-up the preferred way to do it?

Because most tank barges (as well as many other types) have skegs, or vertical stabilizers, at the stern…

…which allow for much better and more predictable handling characteristics when they are cutting through the water at the lead end of the tow. This greatly enhances directional control (the barge “tracks” better) and helps minimize the “slide” or crabbing-effect, wherein you and your tow will travel sideways a certain amount when moving forward unless you can counteract it with the rudder, sometimes a great deal of rudder. Some barges, literally, want to move you a barge-width or more to the side for every barge-length you advance and it will frighten the daylights out of you the first time you experience it. It’s like trying to walk in a straight line when one of your legs is a foot shorter than the other. In some cases it can be so extreme that you use up virtually all of your rudder, swung away from the barge-side, just trying to go straight and have to resort to twin-screwing your way through turns. A trick that will often help, when towing anything alongside, is to use only your “inboard” engine (the side where the barge is made up.) in situations where you need to temporarily minimize your slide. With the propulsion axis more closely centered on the overall width of the tow (tug and barge/vessel combined) the tendency to slide will be reduced, sometimes dramatically. This was a technique I used frequently in the days when I used to jockey barges in and out of Erie Basin, a place that allows scant room for error.

Here’s another view…

…which clearly shows the hydrodynamic forces at work.

Polyester (Dacron in North America, Terylene in most of the British Commonwealth) is the long-time standard for tug deck lines and, amongst the various desirable characteristics it possesses, it has just the right amount of stretch for towing alongside. Nylon is too stretchy (8-15% @ 30% of breaking strength), but that makes it highly suitable for use as a towing hawser. Spectra has very little stretch or elongation (just 3%) making it great for push gear, but this same characteristic means its utility for alongside towing is poor unless you only use it in slick-calm conditions and where the wakes of other vessels are never a factor. Polyester has just enough stretch (around 5-8%) to allow the lines to absorb enough of the forces that are exerted by the independent movements of the hulls of the tug and barge, while not being so stretchy that you feel like a yo-yo while trying to handle the barge. These powerful forces, if not absorbed at least partially by the lines, are transmitted directly to and absorbed by the metal of the respective hulls in and around the attachment points, which will gradually be weakened by it. It is for this reason that Spectra is unsuitable. One day you may find out the hard way that the cleats, bitts and staples, on either the tug or the barge, were unable to accept this punishment indefinitely when a catastrophic failure occurs and they are abruptly bent over, snapped off or torn loose altogether without warning. This phenomenon has happened (I have seen it) and probably won’t happen at a convenient time and location. Unless you always tow alongside where it is perpetually calm, forget about using Spectra alongside until the day Honeywell or someone else invents a variety that has more stretch to it. ‘Nuff said.

Personally, in most situations, I usually prefer to make just a little extra effort and use a 3-part head line like this make-up on the Zachery Reinauer

…or this one on the Potomac

…as it provides greater insurance against breakage by spreading the strain of any sudden shock loads (S.I. Ferry wakes, choppy waves, etc.) over a longer linear length of line. The downside is that it requires deck skills that are no longer common, as well as good coordination between the bargemen and the deckhands, to put up a 3-part head line on-the-fly: like when you’re rounding up on a barge and picking it up alongside, particularly when it’s very windy. In those cases it is often advantageous to make up to the barge in a more forward position…

…with the headline placed at the barge’s midships area, so that the still-connected tow wire serves as your stern line, as demonstrated by the Stephen Scott. By eliminating the need to put up a stern line you gain full control over the barge more quickly. You can sometimes use this method when making up further aft too, but it depends on the length of the barge’s pennant: you want to avoid having the socket of your tow wire (or the towing shackle) bent over, or too close to, the tug’s rail.

Below is a more detailed look at a 3-part head line make-up. When the individual parts can be kept well separated from one another, as they are here, you eliminate chafing by friction between the parts where they make contact, a desirable outcome whenever possible. Not all main bitt configurations will allow for this much of a spread, however.

Is a 3-part make-up necessary? No. It all depends on your level of tolerance for risk. When doing short local shifts at the same or an adjacent dock, or just sliding them down a face, it may be overkill. And lots of people routinely use just a 2-part line where I would use 3, and it usually works fine as long as the line is big enough and is in good repair. But breaking a head line is the most difficult line failure to deal with handling-wise, so if you want to give yourself the best chance of avoiding that potential nightmare then a 3-parter is definitely the way to go. Why take a chance? Certainly not because a deck hand or tankerman thinks it’s “too hard” and starts whining about all the “extra” work. My answer goes like this: “If you think this is a lot of work now, just wait until you see how much ‘extra’ work you’ll have to do later if and when this line breaks.” Been there, done that. It’s asses-and-elbows in a chaotic situation, and I don’t need to experience it ever again just for old time’s sake or to prove the point to a non-believer.

Ideally, you don’t just try to throw up a 2 or 3-part head line in a hurry from a line coiled (or left in a tangled heap) on deck: it needs to be set up in advance to enable a quick, snag-free deployment. For deck hands and tankermen the easy way to remember the sequence is that for a 2-part line the eye stays on the tug, and for a 3-part the eye goes to the barge. A frequent mistake made by deckhands is not leaving enough slack in both parts of the 2-part component of a headline (whether 2 or 3-part) to easily reach the fitting it will go around on the deck of the barge, which inevitably results in an unnecessary delay in getting made up and cursing from the bargeman having to deal with it. Better to be too long than too short in this situation.

How much pinch should you use? Pinch is the angular difference between the longitudinal axes (center lines) of the tug and barge once you are made up. Seldom would you ever find the optimal alongside towing make-up to leave you dead flat against the barge. Nevertheless, it can vary widely and there is no one correct answer: here you see a great deal of it…

…but a good starting point is to try ending up with the tug’s bow aligned with the near-side corner of the barge and adjust from there as you experiment to figure out how the barge handles best. Reinauer’s Putnam and Richmond were an old pair of notoriously poor-handling, shoebox-square-sterned, 300 x 60-foot inland tank barges that were absolute beasts alongside (bow-first or stern-first, it made no difference) unless you used a great deal of pinch. Typically, I’d make up with the tug’s bow pointed at the middle of the barge’s stern and, if it was very windy, nearly at the opposite-side corner. It was the only way to keep them from getting away from you.

In general, it is better to avoid towing barges, particularly large barges (relative to the size of the tug) alongside “head to head” (bow-first) if possible. Why? Because without the skegs at the working bow to provide “bite” into the water they tend to slide a lot more than they otherwise would, and a badly sliding barge is a hazard to you and everyone else around you. But not all barges behave badly when taken bow-first and, in any case, sometimes circumstances require it. Maybe the barge has to go into a slip berth bow-in and there’s no room, or not enough water, to back in with the tug. Or maybe you’re going alongside a ship to bunker it and you’ve got no assist tug to help you (With a small bunker barge, proper fendering, and the right amount of pinch you shouldn’t need one most of the time anyway). But if you’ve got a bad “slider” on your hands a lot of pinch will almost certainly be needed to keep it under control, and you might also want an escort tug along for the ride if you’re in a busy traffic area in confined waters.

Check out this sequence featuring Dann Marine’s tug Atlantic Coast

…moving one of Great Lakes’ dredge-spoil hopper scows eastbound through the KVK.

You may have noticed that the longitudinal axes of the tug and barge are, necessarily, not even close to parallel. This angle, plus the inevitable crabbing, makes the tow significantly wider than just the sum of the vessel’s respective beams. You will therefore need considerably more room to navigate within, so plan and behave accordingly. Nobody likes a channel hog with a wild barge showing up unannounced.

The goal is to get from Point A to Point B with your barge without crashing into anyone, running them out of the channel, damaging anything, or otherwise making your fellow mariner’s lives (or your own) more difficult than they already are.

In this case the Atlantic Coast‘s make-up affording them good control over the scow, so the extra width wasn’t a problem to the oncoming traffic.

And they all lived happily ever after…

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Responses

  1. I have been doing this for over 20 years and as you can imagine, I have seen it done at least 20 different ways. I like having a strap for the hip line and the bow as its always the same and we know where the barge is going to line up. (Assuming the same units are always together) Also its a lot easier to catch on the fly. The thing I see different on most make ups is how far forward the tug is on the barge and whether or not she is flat against the barge. I am of the opinion the tow handles better if the tug is as far back on the working stern as possible with the line almost abreast and the tug not be flat. Being back on the barge gives you a better pivot point. Also if you aren’t flat against the barge you have better control over your turns. I see tugs made up in the middle and flat and when they dock, all they do is move ahead and astern on the barge and have too much play in their lines. The one thing you have to watch is the tug’s stern doesn’t need to stick out too far as that affects the amount of rudder you have to use. As I said, 20 different ways and none of them are necessarily wrong.

    Another note you touched on I agree with. The quality of deckhands is sorely lacking. Academy grads are coming out here now as AB’s with no deck experience. They learned a book and nothing practical. I spent 4 years as a deckhand before I was allowed to progress further. I learned how to tow, hip, push, pass tows underway, tandem tows, tandem hips, and the old steamboat ratchet, etc. I tried to explain passing a tow to my AB a few weeks ago, and he told me I was nuts for trying it and he wouldn’t do it as it was unsafe. He’s never seen it. I did it weekly until a few years ago. These skills are missing in today’s deckhands. Half the academy guys can’t even throw a line. and almost none of the guys off the street. We have tankerman that spent 6 months as an OS, took a test and are now handling barges, and they can’t tie a Bowline knot, or throw a line, much less anything more difficult. Everybody on a boat is a seaman first and needs certain basic skills. They are not being taught either by Academies or old hawsepipers like me. The FNG’s don’t want to learn them, they just want to be a tankerman and pump oil or a mate and drive the boat.

  2. GREAT post

  3. Great reading! I have always been hesitant to make up too far forward for fear of stalling the rudders. I always thought it was more advantageous to be as far aft as possible to keep the rudders in clean water? When I have a tall barge that I can’t see over, and its draft is less than the boat, then I’ll move up around mid-ship on it so as to be able to see “around” it somewhat.

    It seems that the most important thing in all of this is being able to keep out of trouble by managing the space around the unit and paying attention to oncoming traffic. Like you said, if the whole unit has a beam of say, 100′ – I really need about 150′ to maintain a straight track. I hate meeting large units in that Bayonne Bridge – swimming pool stretch for instance. I’ve done it, and I know it’s doable, but why do it if I can cut it back and meet them further east or in the Rose Bowl? 10 minutes here or there is a lot easier than the moments of terror (or worse) of trying to push hit.

    Slow like a pro, they taught me – Fast like an ass.


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