Saturday, November 19, 2022

Ugly and awesome

 We had a pretty average week here since last I wrote. Work 2 days, rest one, work 2, rest one.  And by 'rest' I mean we didn't have cargo so we'd take half of each watch and do work , so 12 hours of maintenance and projects got seen to, and 12 hours of leisure time, which was welcome. 

       Demand for bunkers is pretty steady this week, and one supplier in particular got the bulk of the jobs. This company charters some of our tonnage, but even working all out they have more work than they can do with existing equipment reserved for their use. 

       Enter guys like me, who run equipment that works on a 'spot' basis- that is, we're not on charter here on the HQ, but rather, we CAN work for multiple companies when they need us, on a short-term basis. In a given week, I'll usually have jobs from 3-4 major suppliers, companies you've heard of and some you wouldn't too. 

    So this week with work so steady and the temperatures cooling, some of our tugboats were out of town running longer-distance jobs out of state. My company chartered a tugboat from another company to be available as needed, and that tugboat was the ugliest and weirdest-looking tugboat on the East Coast. 

     Some guys call it 'the wedding cake tugboat' for sort-of obvious reasons. 

            So, this is a pusher tug. It's got two cushioned 'push knees' on the square bow to shove stuff around without causing point loads.  The knees are watertight compartments, so they dont' drag the bow underwater. The house, way, way up high, offers unbelievably good visibility. She's got a modest 3,000hp of power, but must be turning big wheels, because she doesn't have a lot of speed but she's got a LOT of 'ass' which is to say torque. 

 Oh, and the push cables that hold her against the hull of a barge being pushed? They're on automated spools. Push one button to tighten, another to loosen.  Normally, messing with push cables, getting them positioned and tensioned, is one of the most common evolutions where tankermen get injured on the job.  Shoulders get torn up, and fresh handsburger gets served up with a side of  I screams.

 So, push knees, lots of ass and low-strain making up. This tug is as ugly as an ape's foreskin, but she's a a pleasure to work with. It really helps that the crew have been polite, friendly and hard working too. We've had a good week working with them. 

  With the push cables in place, you can see they're made of Dyneema, which in the commercial boating world is called 'Spectra."  It's a synthetic rope that is far stronger and lighter than steel. Push cables have to be screaming tight to be effective- Sadly, it's also enormously expensive, but no bullshit, one guy can pick it up and return it to the tug without much effort. A steel cable of similar strength would be familiar looking- you see them on suspension bridges, and they're far, far beyond what mere men can pick up and walk around with. 

 Edit: I should be more careful and note that while mariners use the names dyneema and spectra interchangably, they are actually different. Dyneema is made by a Dutch company and Spectra is made by Americans. Chemically, they're identical, although both companies vary in what other fibers they include in their lines, as neither company usually sells lines made of the pure material, instead adding other fibers like aramid (kevlar) or nylon, polypropylene or other low-weight high strength synthetic material.  It should be noted that Dyneema and Spectra are braided differently, which makes them easier to differentiate, and this makes them behave differently. All ropes have Creep- initial elongation as the braid tightens as loads are applied for the first time. This is not stretch or elastic modulus or anything like that, just the braid 'fetching up' or 'shaking hands' as they tighten. Spectra has more creep than Dyneema, just because of the lay of the braid, which means that it might be necessary to retension it as it settles into use the first few times. 


Jess said...

Your post reminds me watching a push boat that ran aground after making a tight turn from the Intracoastal Canal into the Sabine Neches Ship Channel. The strong north wind pushed the lead barge into the bank, and the skipper was rocking the tug in reverse.

A deckhand was on the front of the barge with a flashlight, and as I watched, one of the steel cables snapped, whipped about, and slapped the deck next to the deckhand. The cloud of rust was remarkable in the strong wind, which showed the enormous power of the steel cable.

The deckhand moved away from the bow of the barge, the skipper finally rocked the barges free, and they continued up the channel. I imagine the deckhand needed to change his underwear. He was inches away from being cut in two.

Paul, Dammit! said...

Yup, that happens. Another advantage of spectra line is that it has almost zero stretch, and so when it does part, it just drops without snapback. No getting cut in half. The downside is that it has almost zero abrasion resistance.