To date, I have been a supporter of the “What is Going on with Shipping” YouTube channel although would offer commentary on this just released video.
At the window of 8:43 ~ 9:15 he makes commentary on the dangers of tugs being lashed up in transit …….both bow to bow and centre lead aft. I would absolutely agree with the opinion on the forward bow to bow tug as this operation is dangerous and not particularly effective. The forward tug would have been far safer and far more effective being made fast on the starboard shoulder.
From Sal…….”this is one of the reasons why we don’t have tugs hooked up on vessels all the time”. I would take issue with that statement and it may turn out that tethered escort towage centre lead aft may be one of the solutions for transiting under bridges in the future.
EDIT: I have sent an email to Sal with a copy of the above text. I have received a very timely reply from Sal.
EDIT 2: I would also go on the record and thank Sal for his later commentary, within this video, on the treatment of the crew by the boarding members of the FBI. Disgraceful.
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I agree entirely with Ausmariner on the better position for the tug would have been alongside vice on the bow.
I do think that once Dali is clear and the full channel is open, Baltimore may require a trailing tug for all bridge transits. I am not sure if Baltimore has a tractpr tug of sufficient size for ships the size of Dali or the bulkers that frequent Baltimore.
I also did not mention, but tugs did not escort the ships through the Bay Bridge. The bridge does have better protection than the Key Bridge, but it could be a factor in future planning.
Thanks for the comments and watching.
Sal
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Escort tugs are not my area of expertise.
However, the center bow lead tug makes sense in this particular case. It’s a slow speed transit of a very narrow temporary channel adjacent to a lot of hazards and salvage activity. Putting the tug ahead reduces the overall beam of the ship and tugs. The bow tug is probably towing the ship, with the ship using its engine sparingly, if at all. Would you want your 25 foot diameter propeller turning in the middle of a debris field that is supposedly cleared to 35 feet? The center lead aft tug is there to provide additional steering and braking ability, and to keep the stern of the ship in the center of the narrow channel.
Once the salvage activity is over and the channel is full width again, the ships will be transiting at much higher speed and a center bow lead tug won’t be safe or practical to use. A totally different scenario than today.
I expect that a center lead stern tug will become routinely used, if not required, on ships over a certain size, for transits of that bridge.
There is some merit to keeping an additional tug running alongside the ship that can be used to push on the bow if necessary. Tugs also occasionally are subject to loss of an engine, loss of steering, fires, parted lines, etc. The cost of two escort tugs might be something like $1 per container. Thats nothing compared to the $100 per move ($300 to $500 total) cost per container of the longshoremen.
I see a lot of merit in strongly considering a requirement for escort tugs at least through the Bay Bridge near Annapolis. I’m not sure how many new escort tugs that would require, but again, the cost per container would be modest.
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tugsailor,
I acknowledge your points regarding transit speed and channel width in this instance………I am basically not a fan of headline tugs be they bow to bow or stern to bow.
It can be practically proven……and I have done this whilst training junior Pilots, that if you tow ahead with a tug then the PP migrates to the forward tug’s staple thus significantly affecting the vessel’s steerage. As soon as you stop the tug towing the PP returns to the vessel and full steerage is re-established.
The look on the training Pilot’s face post exercise was always rewarding.
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Making up tugs fore and aft on the centerline is common in some port in Europe.
It may have to do with the characteristic of the port. In the Port of Gioia Tauro Italy for example it’s a straight shot then the ship is moved bodily laterally till alongside.
We used to tie up all the way at the end.
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As far as I know (and I’m not any expert) European ship assist tugs have a long history of towing ships from the bow and stern to put the ship alongside the dock, rather than pushing on the hull as American tugs do.
The Europeans did this for decades with single screw tugs. If you look at photos of older European tugs you can see that decks are very long (compared to American tugs) with the tow winch or tow hook positioned near the longitudinal center of the tug. This was done to put the pivot point well ahead of the wheel and rudder to enhance maneuverability.
Towing is quite an advantage in maneuverability for a single screw tug in a river current. A single screw tug working alongside on a head line cannot get into shape (at a 90 degree angle to the ship) if the ship has way on or there is a river current. Even a twin screw tug is limited.
It’s been quite a few years since I’ve watched European ship assist tugs work. Maybe ASD tractor tugs and larger ships have changed the methodology, but I suspect that they still prefer to tow rather than go alongside on an head line and push. No doubt recent YouTubes could be found.
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I’ve never seen it done fore and aft C/L in Baltimore. In that case it may be correctly considered to be somewhat higher risk by the tug captains there.
Don’t know if that’s the case or not.
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KC,
Definitely higher risk and less effective.
Pilotage/ship handling, as you no doubt are well aware, is about the control and correct tracking of the Pivot Point. In ballasted vessels moving ahead a large ASD tug can laterally displace the PP when made fast on the shoulder by squaring up and pushing. A percentage of the tug’s power will be absorbed whilst squaring up against the water column.
In larger loaded vessels underway in excess of 5 knots, both a headline and shoulder tug are unable to laterally displace the PP. The tracking is achieved by using the aft tugs……either a CLA tractor indirect or a quarter tug direct.
Additionally, a headline tug is unable to retard whereas a shoulder tug can.
In 1997 a bow to bow towage in the Port of Brisbane resulted in a collision. Admittedly, the speed was around 7 knots but this definitely represents elevated risk.
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That’s a generous assumption but I can’t make the claim that’s it true.
I’m thinking, in general the choice in arrangement has to do with the speeds involved. In Gioia Tauro the aft tug is often pulling astern to counter the dead slow ahead being used on the ship so the ship maintains steerage while speeds are kept low during the entire evolution.
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This is a technique which we constantly employed ……particularly when certain maximum speed profiles whilst passing loading vessels had to be met. Control the headway and maintain steerage.
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Disgraceful is an understatement. Good on Sal for highlighting this.
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It’s a matter of style and custom. Until tractor tugs Americans relied upon putting up a headline alongside at the ships shoulder or quarter and pushing or backing. Americans also used more tugs back in single screw era.
To improve the ability to get into shape alongside the ship, A second backing line from the same chock as the headline (or the next chock forward) on the ship can be run to the outside shoulder bit on the tug. This will get some angle on the tug, quite a bit of angle with a conventional twin screw tug.
If it’s essential to get a single screw tug out to a 90 degree angle, a long quarter line can be run from the outside quarter bits of the tug to a point about three chocks forward of the head line on the ship. The ship needs to be at the dock or drifting to rig this up. In the old days, American tugs had big crews and could handle these lines. In the past 30 years, many American tugs are often only manned by two or three men, including the captain.
Now, the American style of ship assist has changed completely with tractor tugs. They work mostly on one line on a big line handling winch. A center bow lead tug is common for bridges and locks or approaching a docking. They can easily shift to the shoulder flare to push without moving the line. If they need to back it only takes a few seconds to get to 90 degrees from the center lead chock to pull.
I see tractors running backwards at 7 knots off the bow and walking in to put up their line. I typically see two or three guys on most tractor tugs. The big tractors have more.
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