4 ms·

Sorta makes me wonder why another ship, larger than a tugboat, couldn't hitch it with a tow rope (whatever the marine term) and give it a jerk. I get that ships

by aasasd 6y ago

Sorta makes me wonder why another ship, larger than a tugboat, couldn't hitch it with a tow rope (whatever the marine term) and give it a jerk. I get that ships aren't normally expected to do that, but you know, probably need larger tugboats for gigantic ships.

morei 6y ago
Amusingly enough, the tugs not uncommonly have more thrust. Large ships are _heavily_ optimized for the common case, which is sailing at about 13.5 knots. They take a very long time to get up to speed because their propulsion is sized to be just enough to overcome resistance at their typical cruising speed. Consequently, it would be difficult to get another ship up to any sort of speed in a short enough distance. Even if you could, the the momentum is absurdly high so it's much more likely that any sort of chain would snap, or the attachment point would break than that the aground ship would actually move. (The aground ship has a deadweight of approx 200,000 tonnes)
- emmelaich 6y ago
  Related - These Mini-Ships Teach Pilots How to Navigate Major Waterways https://www.youtube.com/watch?v=tEDrFiQq1_k https://www.youtube.com/watch?v=tEDrFiQq1_k Looks like fun actually!
- NamTaf 6y ago
  Expanding on your comment, it's analogous to torque vs speed in cars. You wouldn't use a Ferrari to tow just because it has a high top speed and lots of top-end power. You'd use something with high torque down low and good gearing. Similarly, tugs use different propeller setups (e.g. ducted props for extra power, or vectored systems such as azimuth thrusters or cyclorotors for extra manuverability), which just cause extra drag if all you're doing is cruising at a fixed speed throughout oceans. A big container ship trying to tow something is not unlike having a high-speed racecar spin its wheels. It's not designed to put that torque down at low speed and lift a big trailing mass.
justin66 6y ago
Based on the photos, the most useful vector a tug (of any strength) might take is not available. Yanking the ship backwards, off the bank, would work nicely but pulling its bow 35 degrees through the bank is pretty rough.
- sandos 6y ago
  They need to pull the aft sideways while keeping the bow steady, that way it would angle slightly and then pull back. Requires no space behind the ship, and is likely the reverse of what happened...
- cwillu 6y ago
  I thought virtually all modern tugs can apply their full thrust in any direction, regardless of their hull's visible “heading”.
jhayward 6y ago
Apparently the limiting question is how much force can be exerted on the ship and from what locations without damaging it (or, damaging it too much). That's why recovery specialists are flying in. They know how to do that kind of engineering calculation, as well as all the weight & balance calcs needed to e.g. move ballast in unusual ways, etc.

by aasasd 6y ago

morei 6y ago

Amusingly enough, the tugs not uncommonly have more thrust. Large ships are _heavily_ optimized for the common case, which is sailing at about 13.5 knots. They take a very long time to get up to speed because their propulsion is sized to be just enough to overcome resistance at their typical cruising speed. Consequently, it would be difficult to get another ship up to any sort of speed in a short enough distance. Even if you could, the the momentum is absurdly high so it's much more likely that any sort of chain would snap, or the attachment point would break than that the aground ship would actually move. (The aground ship has a deadweight of approx 200,000 tonnes)

emmelaich 6y ago
Related - These Mini-Ships Teach Pilots How to Navigate Major Waterways https://www.youtube.com/watch?v=tEDrFiQq1_k https://www.youtube.com/watch?v=tEDrFiQq1_k Looks like fun actually!
NamTaf 6y ago
Expanding on your comment, it's analogous to torque vs speed in cars. You wouldn't use a Ferrari to tow just because it has a high top speed and lots of top-end power. You'd use something with high torque down low and good gearing. Similarly, tugs use different propeller setups (e.g. ducted props for extra power, or vectored systems such as azimuth thrusters or cyclorotors for extra manuverability), which just cause extra drag if all you're doing is cruising at a fixed speed throughout oceans. A big container ship trying to tow something is not unlike having a high-speed racecar spin its wheels. It's not designed to put that torque down at low speed and lift a big trailing mass.

justin66 6y ago

Based on the photos, the most useful vector a tug (of any strength) might take is not available. Yanking the ship backwards, off the bank, would work nicely but pulling its bow 35 degrees through the bank is pretty rough.

sandos 6y ago
They need to pull the aft sideways while keeping the bow steady, that way it would angle slightly and then pull back. Requires no space behind the ship, and is likely the reverse of what happened...
cwillu 6y ago
I thought virtually all modern tugs can apply their full thrust in any direction, regardless of their hull's visible “heading”.

jhayward 6y ago

Apparently the limiting question is how much force can be exerted on the ship and from what locations without damaging it (or, damaging it too much). That's why recovery specialists are flying in. They know how to do that kind of engineering calculation, as well as all the weight & balance calcs needed to e.g. move ballast in unusual ways, etc.