Technical Question: How to they get the ropes from the ship to the pier when docking?

[chengkp75]

And just as a reminder, as it was mentioned above, those big ropes are known as "lines".

 

Now, can anyone one tell me what a "spring line" is?

 

Rope is a piece of line that has no specific purpose.

 

Spring lines will go from the bow and lead aft somewhat, or from the stern and lead forward, and today are used primarily to position the vessel exactly where desired along the pier. Hauling in on the forward spring, and slacking the after spring will move the ship aft, and vice versa.

 

They are called spring lines because before the advent of thrusters and powerful tugs, they could be used to "spring" the bow of the ship away from the dock, without the ship moving foreward or aft. In tight berthing (one ship ahead and astern), this was beneficial. All lines would be let go except the after spring lines, and then these would be hauled very tight. This would pull the stern closer into the dock, and swing the bow out away from the dock.

[chengkp75]

This youtube video start with the small line being pulled by the shore workers. This small line is attached to the big line that holds the ship to the dock.

 

When I've cruised, it looks like this small line is "shot" to the shore crew from the ship, maybe with some type of air gun/cannon. As already said, this small line has some weight on the end of it to hold it on the shore once it is shot. The shore crew starts pulling on this small line, which has the big line attached to it. That's where this video starts.

 

When the ship is ready to depart, the ship releases the tension on the big line, the shore crew detaches the line, and the ship reels it in.

 

The problem with heaving lines and cruise ships is the enclosed nature of the mooring decks on these ships, which hampers the deck hands' ability to "heave" the line to the dock. So, line throwing guns are used. Some of these use a .22 cal blank cartridge to shoot the float with attached line to shore, and some use compressed air, like a potato cannon.

[chengkp75]

Or sometimes the smaller rope is tied at the end in a complicated knot called a monkey's paw. It makes it look like a ball on the end, so it can be thrown.

 

On one line, I think it was Hurtigruten though I'm not 100% sure, they sometimes used shore-based boats to carry the rope ashore. Possibly because they're docking 6 or 7 times a day, they didn't want the main ropes to get wet.

 

Line handling boats are a "personal" preference of the ports. Sometimes the configuration of the ship doesn't allow the crew to be able to heave the line ashore, or they don't want to use line throwing guns. Sometimes, when lines have to go to "dolphins" (those clusters of pilings that are not connected to the main pier, or only by a small walkway), or if the lead of the line is really long, they will use a boat to take the line to the bitt.

[chengkp75]

Okay, so this is probably more of a "large boats" question then a cruise-specific question, but I figured that plenty of people here have watched ships dock. When the ships are docking, they usually come up along-side the pier using thrusters/azipods, and then are guided the rest of the way in using the ropes. My question is: how to they get the ropes from the ship to the dock?

 

In the following video, it looks like the ropes are just dropped in the water and then pulled up on the pier.

 

Are they actually using the wake from the azipods to push the ropes, were the ends of the rope connected to a thinner rope that can't be seen on the video, or is there some other method? Does anyone have better videos of this process?

 

Of course, none of this has ANY impact on my upcoming first cruise, but as an engineer, I'm curious. Maneuvering a large boat the size of a city block into a tiny concrete wharf is an amazing feat.

 

Actually, you will note that when the ends of the two lines are just entering the water, they shut the azipods down, until the officer on the stern informs the bridge that the lines are well towards the dock, and there is minimum slack in the line. The worst case scenario is when a line is in the water, and the Captain thrusts with the azipod, thruster, or propeller, and sucks the end of the line around the shaft. This results in not only damage to the mooring line, but will require divers to cut the line from the shaft. Older manila lines were not so bad, but the synthetic lines will tend to melt into a big clump around the shaft and seal.