Regarding flopping on a barge, breaking away from barge, as well as towing with a AHTS or a conventional tug(on the wire). Looking for constructive experienced input/advice on when it is best to have the tow pins(which are center and aft within a couple feet of each other) up with wire in between them or down and the benefits/restrictions for either position. Usually dealing with a light barge under 300 feet.
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I am surprised that none of the very learned people on this forum have answered your question. I only have experience of offshore vessels but have done a bit of barge towing. The big advantage of the towing pins is that the wire, being used for whatever purpose, is held in the centre of the deck, and so anyone working near it is likely to be safe. The disadvantage is that they reduce the ability of the ship to turn unless it has a lot of big thrusters. I just watched a video of an traditional tug doing this job and it would have been unable to do it, had the wire been trapped in the middle of the deck.
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Sometimes it’s easy to let these basic questions slide.
Generally, it’s simple enough with a twin screw tug to flop on a barge with the wire (or chain surge gear) in the tow pins. This is how it’s usually done.
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IMHO, problems, once they start, get compounded by maneuvering with the pins down. But most of my experience is towing with surge gear and a pigtail of studded chain.
The original query mentions nothing about the configuration of the barge and tug gear.
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Offshore only! They work great as a fairlead/chafe guard but once shortened up or getting ready to come alongside you need your pivot point further forward
Mr Juicy:
With all due respect that is exactly backwards.
When flopping onto/off a barge you have it between the pins so you can secure the connection (surge chain/shackle/link) in the shark jaws or pelican hook to make/break tow.
Coming off the barge is typically a non event as you really only need to come off a few feet and angle out 15 to 20 degrees. After that ease ahead and the barge will turn and come into trail. When flopping onto a barge conventional tugs often do it between 2 and 5 knots because the want the barge to come to them and they have the maneuverability to make that happen safely. It takes longer to top around on an AHTS so I recommend slowing the barge as much as practical.
The only reason to lower the pins is because when the wire is under tension and between the pins your pivot point is stuck at the stern, and steering by rudders alone is less effective. Basically not able to turn well without the assistance of a bow thruster. In tows utilizing multiple tugs this becomes really apparent. This condition is typically referred to as being in irons. When flopping onto/off of a barge there should be no tension, just wire and chain weight.
After getting on the string and applying power you can lower the pins if needed thereby freeing up the stern. Never under any circumstances lower the pins under heavy side loads.
On “AHTS” there is typically a “hogging strap” or “deadman chain” installed between the winch and stern that the wire runs through. Which serves a couple of purposes, one of which is to establish a pivot point somewhere between the winch and the stern after the pins are lowered. This allows the boat to turn with rudders but keeps the wire from running too far forward. On a conventional Tug, the winches are usually far enough aft in relation to the Norman pins for this to not be needed.
Hope this helps.
Juicy. No. That is a myth. The barge generally maneuvers quite well, often better, with the pins up. It doesn’t matter whether you are hipping up offshore , or 50 miles up river, the basic process is the same.
There are many disadvantages to putting the pins down and having the chain up at the quarter bitts.
There are certain circumstances when it’s advantageous to put the pins up and down while maneuvering, or hipping up, or to have the chain leading over the quarter, especially with a single screw tug. That’s why we have hydraulic tow pins. So they can be quickly and safely be put up or down as needed.
There are methods of working the wire / chain back into the tow pins after hipping up with the wire over the quarter, but this is best avoided.
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correct sir, lol…and you are right not really preferred.
Being in the pins also stops girding according to the TSB. Especially on a short line: https://youtu.be/JgC2SOQNCTk
Aside: I broke in as mate in the 70’s on this very boat and barge on the BC Coast. TSB also mentioned the abort system and lack of reserve power.
Oh man! That hurts to watch. The engines didn’t seem to care, but I bet the pilothouse would have been more comfortable if they’d kept those doors shut.
The full video has the time the engines roar then stop. One guy was below but swam out.
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