Capt Popeye
Well-known member
Many thanks for that info ; reading the listof incidents being investigated make grim reading , for sure
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Another tugboat capsize in the Clyde today
- Thread starter dunedin
- Start date
Many thanks for that info ; reading the listof incidents being investigated make grim reading , for sure
Capt Popeye
Well-known member
The usual failure mode for tugs whilst towing is girting/girding. Basically the tow line pulls athwartships instead of fore/aft.
Thanks for the more Technical explanation , much more precice than my attempt
I notice that nearly all the Tugs that I see , have the towing Bollard (??) about a third of the way forward of their stern
ProMariner
Active member
For a little background reading, the MAIB report of a similar sized tug doing similar work.
MAIBInvReport-10_2016.pdf
A good tug has its towing point about midships, to allow the tug to manouver. If you try and tow anything bigger than you with the towline attached to the stern, the thing you're towing will have more control over where you end up than your rudder will. But if you start to be pulled by midships, bad things happen quickly. The gog rope is a line attached to the stern that moves the effective towing point closer to the stern, for if the worst should happen, but they get in the way, reduce manoeuvrability, they can get caught up on things, they can chafe the precious tow rope, and they form another thing that can get dragged into the screw, so sometimes they are left off. Think of the gog rope like a gybe preventer, you know you should always rig it, but sometimes life gets in the way. The tug should also have a way of releasing the tow line in a hurry, but sometimes the system doesn't work properly, or isn't attached, or is painted over etc, as unplanned tow releases are a nightmare too. Sometimes the crew is unaware of how the quick release functions, and hasn't trained with it.. This is like having the pull to inflate tag on your lifejacket tucked inside, to avoid false activations. We know it's wrong, but...
This clip shows just how quickly things go south:
watch
MAIBInvReport-10_2016.pdf
A good tug has its towing point about midships, to allow the tug to manouver. If you try and tow anything bigger than you with the towline attached to the stern, the thing you're towing will have more control over where you end up than your rudder will. But if you start to be pulled by midships, bad things happen quickly. The gog rope is a line attached to the stern that moves the effective towing point closer to the stern, for if the worst should happen, but they get in the way, reduce manoeuvrability, they can get caught up on things, they can chafe the precious tow rope, and they form another thing that can get dragged into the screw, so sometimes they are left off. Think of the gog rope like a gybe preventer, you know you should always rig it, but sometimes life gets in the way. The tug should also have a way of releasing the tow line in a hurry, but sometimes the system doesn't work properly, or isn't attached, or is painted over etc, as unplanned tow releases are a nightmare too. Sometimes the crew is unaware of how the quick release functions, and hasn't trained with it.. This is like having the pull to inflate tag on your lifejacket tucked inside, to avoid false activations. We know it's wrong, but...
This clip shows just how quickly things go south:
watch
Capt Popeye
Well-known member
For a little background reading, the MAIB report of a similar sized tug doing similar work.
MAIBInvReport-10_2016.pdf
A good tug has its towing point about midships, to allow the tug to manouver. If you try and tow anything bigger than you with the towline attached to the stern, the thing you're towing will have more control over where you end up than your rudder will. But if you start to be pulled by midships, bad things happen quickly. The gog rope is a line attached to the stern that moves the effective towing point closer to the stern, for if the worst should happen, but they get in the way, reduce manoeuvrability, they can get caught up on things, they can chafe the precious tow rope, and they form another thing that can get dragged into the screw, so sometimes they are left off. Think of the gog rope like a gybe preventer, you know you should always rig it, but sometimes life gets in the way. The tug should also have a way of releasing the tow line in a hurry, but sometimes the system doesn't work properly, or isn't attached, or is painted over etc, as unplanned tow releases are a nightmare too. Sometimes the crew is unaware of how the quick release functions, and hasn't trained with it.. This is like having the pull to inflate tag on your lifejacket tucked inside, to avoid false activations. We know it's wrong, but...
This clip shows just how quickly things go south:
watch
Yes thank you ProMariner for your post and info : much appreciated
Supprising just how quickly the Tug gets turned over beam by its own Tow Line
Suppose it partly happens due to the Real Power /torque of its own engine
ProMariner
Active member
The power of its own engines plays a part, but the energy is mainly kinetic energy from the tow. With a dumb barge, like the clip, the barge is going too fast for the tug to control it in a turn, had the tug allowed the barge to slow down before commencing the turn, there would have been less kinetic energy for the tug to manage, and more time for the helm to react. But with ship handling, the ship can quickly apply more power and speed than the tug can can respond to. When you’re manoeuvring a yacht around a marina, 2.5 knots is quite fast, same for a tugboat dragging something big around a confined space, but a ship can be at 4 knots almost without noticing, like the Southampton incident. Looking forward to the report on this one, these incidents are a bit too close to home for me, I survived doing this kind of work for many years, sometimes the difference between success and not is luck, and maybe a window to climb out of.
NormanS
Well-known member
The really difficult situation when towing, is acting as stern tug, when the tug is being towed along backwards, so that it can exert steering to the vessel being towed. I know from personal experience that this can be a very scary experience, having once had to slip a tow line to avoid being girt. This was with an old fashioned single screw tug. Most modern tugs are driven by steerable nozzles.