Posted by: towmasters | May 22, 2010

Towing Assembly Inspections: When Do You Pull The Pin?

Wear and tear, and corrosion, they get everything eventually. That is why the regulations require equipment inspections, especially of critical items whose failure could be catastrophic. One area that is of particular concern to towing vessel mariners is the towing assembly: that is, the tug’s towing winch, tow wire, and the poured socket at it’s end, as well as the pennant wire or shock-line, surge chain, towing plate, bridles, and padeyes belonging to the barge you’re going to tow. Most importantly, the various shackles, detachable links and associated hardware (nuts, bolts, lock-washers, cotter pins, etc.) that hold it all together must be given a careful look too. The towing assembly, alternatively, also includes all of the lines, wires and assorted hardware used in towing alongside and pushing. The required pre-voyage inspections (33 CFR § 164.80) cover all of these items, as well as navigation safety equipment aboard the tug or towboat.

My regularly-scheduled inspection of the towing assembly of the barge we normally tow, as opposed to and conducted apart from the required pre-voyage inspections, revealed a level of wear on some of the components that had reached the point that it warranted their replacement, so out came the cutting torch and the sledge hammers. The three stud-link chain links at the ends of the surge chain and bridle legs that connected to the shackles at the towing plate had significant wear on two or three different planes: on one or both faces (where they rub up against the inside of the shackle jaws) and in the grip (where they rub against the shackle pins), so we cut them off. The next links in line were in good condition and had little wear, so they’d be fine for some time to come.

The bows of the shackles where they chafed against the inside of the towing plate’s eyes had lost some metal…..

…..as had the inside faces of the shackle jaws (from the opposing faces of the chain links)…..

…..and the pins that secure them, rubbed continuously by the grip-area of the chain links.

Here are two views showing exactly where the multiple points of contact are and how the wear occurs simultaneously on the shackle pin, the inside faces of the shackle jaws, and on the opposing faces and grip-area of the chain links…..

…..and the multiple planes of wear at one spot in the grip and face areas of the chain links.

The eyes of the towing plate had worn too, mostly in the forward eye where the surge chain attaches, but it was still well within accepted tolerances.

As for what the acceptable tolerances are and the specific procedures for checking them please consult the previous posts Wired and Unchained, which are derived from the U.S. Navy Towing Manual. Also see When The Wire Breaks! for information on emergency towing equipment, procedures and drills. For now, here’s the condensed version: any one of these items with a loss of more than 10% of its nominal diameter (from whatever the cause) in any direction at any single point should be replaced straight away. If the wear has occurred in two directions (or planes) at a given point, and averages more than 5% of the nominal diameter on each plane, then it is also time to change it out.

In our case, when all the various wear was considered in combination, it was clearly time to do the right thing and replace what needed replacing as a precautionary measure, so we did. This required that my company provide the down-time, materials, equipment and manpower to get it done, which they did. This cost money, obviously, but they wisely understand and believe that it must be done and that it’s merely a cost (one amongst many) of doing business. Not every company chooses to behave in this way, however, RCP or no RCP.

The key term to remember is precautionary measure. Don’t wait for a failure to alert you to the fact that you should have replaced something long ago. This rig was over 5 years old at that point and surely didn’t owe us anything. We haul black oil around, so why take a chance? These components of our towing assembly are chump change compared to the value of the barge we tow and the cargo it carries, let alone the monetary, environmental and social costs of a major spill. Not to mention the value of the lives of any individual mariners riding on the barge. But the inspections won’t get done unless someone decides that they’re important enough to do and then does them, regularly. That’s the only way you can catch normal wear that is progressing (or already has progressed) into excessive wear, or a crack or other defect that could lead to real trouble. The last time I checked there was no gauge or alarm that automatically warns us that there’s a previously-undetected and worsening problem that’s going to fail some time next week. You have to go and look diligently for them. Which brings up another problem and its root cause.

One person, no matter how driven, can’t do it all alone. Others must be willing to help if it is ever going to happen, but good old-fashioned territorialism can get in the way of this. One of the barge’s tankermen, who has over two decades of experience in this business and has generally always been disinterested in as well as resistant to helping me facilitate these inspections (making the whole process of doing so thoroughly unpleasant), looked at these pieces of worn metal and drew exactly the opposite conclusion of what I was hoping to hear: “Sure,” he said, “they’re worn some, but they don’t look like they’re about to break or anything.” How the hell would he or anyone else know if something was about to break when they refuse to regularly inspect them or act deliberately in ways that functionally impede or obstruct someone else (me, in this case) from doing so because they don’t want to be bothered and don’t think it’s important in any case? You would think that the two tankermen who ride the barge and stand to suffer badly if it becomes separated from the tug in bad weather or in a potentially dangerous location would show a keen interest in making sure that these inspections were done regularly and correctly, if for no other reason than because it’s their own physical safety that’s directly at risk, but you’d be wrong. Trying to recover a loose barge on the emergency wire/hawser in heavy seas is dangerous for everyone, particularly the tug’s deck crew. How selfish and short-sighted can people be? Maybe it’s better not to know sometimes. If it were me I’d be doing my own inspections, regardless of what the tug’s captain and mate did or didn’t do, but that is surely not a universally-held view amongst bargemen. Some care and some don’t. Some are enthusiastic and want to help, some couldn’t care less but will still help when asked, and others will fight you every inch of the way. The responses range all over the scale but territorialism definitely plays a very significant role in the problem. Mitigating this particular problem clearly requires some action from management: forcing the captains and/or mates by default to always be the “bad guys” just leads to crew disharmony, which can make for a poisonous atmosphere in the tight confines aboard tugs and barges during multi-week hitches. Without some solid back-up from above it makes it tough to do what is supposed to be done, and if it gets too tough then the usual result is that it just doesn’t get done at all. We all know full well what that leads to. Regardless of bargemen’s bad attitudes, captains and mates are still required by regulation to conduct these inspections and no one is going to cut you any slack if something goes wrong. You surely won’t be able to assign any of the responsibility to the bargemen, that’s for sure.

The other primary root cause of this is the “if it ain’t broke don’t fix it” mentality, which needs to be stamped out without mercy like an invasive species. That line of reasoning clearly just played a large part in the recent Deepwater Horizon disaster that is still unfolding like a slow-motion train wreck and can be found as a contributing factor in many other, if not most, maritime accidents. Do we continually have to commit the same fundamental mistakes again and again? We can and must do substantially better.

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