I’ll agree with this, in fact I actually had typed up something similar to this about a ship in still water with no force being applied to the anchor as an example of when the chain would do the job, but I deleted it at the last second because it seemed like surplusage since we’ve all been talking about how the anchor does it’s job, digging into the ground and holding the ship. So I assumed a ship anchored in perfectly still water, with a huge pile of chain connected to a undug-in anchor underneath it was not really relevant to the discussion. But yea, I do agree with you on this example. As for being a shock absorber, since a heavier-than-water anchor-ship connection will always form a catenary curve rather than a straight line, it’s always going to act as a shock absorber. But if there is enough force pulling the ship so as to get the anchor to dig in and do its job, there won’t be any chain laying on the ground.
Maybe this is just a disagreement about semantics. I am only saying the chain isn’t doing the job in situations where there is enough tension on the line that the anchor is doing the job. The chain will lay on the ground and do the job until the tension gets high enough, and then the anchor will take over doing the holding. We were talking about anchors, how they dig in, how they are not meant to hook onto things, how they are not meant to be just dead weight, etc. So I figured for purposes of this discussion we’re talking about scenarios where the anchor is actually doing the work, thus situations where the water is not perfectly still and there is a lot of tension on the line.
Oh and as for the notion that I’m a huge hypocrite for not knowing when an anchor would realistically be used on a super-huge vessel but now have the gall to be telling others how anchors work… get over it, and it’s not hypocrisy at all. I never questioned how anchors work, and additionally I think the Wikipedia article on anchors explains how all the various types of anchors work quite well.
Also, as I noted in my previous post, there may be more agreement between us all than we think as I was referring to situations where there is enough tension on the line so that the anchor is dug in to the ground and doing the holding. We were talking about anchors, then someone said anchors are pointless and it’s just the line that does all the work, and that turned this thread into an entirely different discussion. And that’s cool… it’s interesting and I already got the answers I was looking for, some very good ones in fact from people with 1st hand knowledge, which I greatly appreciate.
I thought of that, too, but if the rode near the anchor is supposed to lay along the seabed, I expect there are conditions where durability can be a factor.
Military fiction/alternate universe, on an Earth were the dinosaurs didn’t get killed off. Sea critters larger than supercarriers exist, but don’t figure large in the main narrative. So to speak.
I know you keep asserting this but you are wrong. RedSwinglineOne’s comment bears repeating:
People who actually know what they are talking about are trying to help you here but you are just asserting something you made up over and over without any indication you are listening to or dealing with the logic and examples you are being given. The chain does not have to lift off the bottom to be exerting a linear force on the anchor.
That’s dragging the chain. If the end of the chain were nailed or otherwise attached to the ground, then assuming I pull hard enough yes - the entire chain WOULD lift off the ground. I’m assuming the ship is pulling hard enough to make the anchor do its job. And a ship has a LOT of mass and tugs with a lot of force on that anchor.
Also I’d be holding the chain at most a few feet off of the ground. I’m about 6’ tall, if I held the chain above my head at most it would be 8’ above the ground, and I wouldn’t be able to pull very hard holding it like that. Ships, especially the huge ones, are certainly anchoring in deeper water than 6-8 feet deep, and the anchor can drop from up to what, like 60-70 feet above water level on an aircraft carrier, adding that height in addition to the depth of the water. So the “person dragging a loose chain” example is completely incomparable for this reason as well.
Look, a few seconds googling comes up with any number of authoritative links that say that the chain lies horizontally on the bottom. In fact, it’s that horizontal pull on the anchor that allows the anchor to work.
It is a fairly good analogy for the point I am trying to make. If what other have said is correct, the amount of chain let out is something like 5-8 times the depth of the water. That would be like you holding a chain 15-24 feet long. If you were to drag a chain 15 feet long, how much would be in the air and how much would be on the ground?
Look, I’m sure most of the time the water is calm enough so that the chain does lie flat on the ground. But I cannot pull a chain with the force of a huge ship, and if there is enough force, i.e. rough enough current/waves/wind/etc to pull on the chain hard enough to get the anchor to dig into the ground and do the holding, there won’t be any chain on the ground.
Example: think of the strong high-tension steel cables attached to the ground (“anchored” would be another word) and attached at or near the top of very tall communications towers to hold them upright and prevent them from falling over, even in strong winds. Even if these high tension cables (3-4 of them, obviously) were each 20 times the height of the tower (thus anchored far away from its base), and assuming they have sufficient tension to hold the tower up, even during heavy winds, then none of the cable will ever be laying flat on the ground. Not an inch. One of these cables is perfectly analogous to a ship pulling very hard on its anchor - hard enough to cause the anchor to really dig in hard and do the anchoring.
At ANY point between minor current and wind and a shitstorm that ends up with the anchor ripping out of the ocean bottom there is one constant.
A heavy chain means that any given load exerted on the anchor by the boat will be MORE horizontal (and therefore generally better) than it would have been had there been some neutrally bouyant rope/whatever instead of the chain.
This means the anchor holds better than it would otherwise. It also means the point at which it will quit holding will be at a higher load than it would be otherwise.
For a fixed length of distance between the boat and the anchor, the heavier the chain the better.
I don’t know much about this subject, but I was told long ago that anchors were necessary for proper maneuvering in tight spaces, and in case power is lost. By raising and lowering anchors at either end a ship can change it’s direction and position. Apparently before the steamship anchor maneuvering was an important skill for ship’s captains to master. IIRC it was critical in John Paul Jones victory over that English ship.
A person dragging a chain is a good example. The way you are looking at is wrong.
Imagine you have a 200 foot chain on a cart. Your are standing on the cart with a 6 foot tall brace that can withstand a heavy pull. At the top of the brace you can lock the chain in place to the cart. On the end of the chain is a anchor that will dig into the ground.
You feed out 30 feet (5 times the height.) Your friend starte to pull the cart with a small force the cart moces and begins to drag the chain until the anchor diggs in. Cart stops some chain begins to lift off the bottom and drags the anchor. The anchor digs in. If the force being applied is less than the force required to lift all the chain some chain will remain on the bottom and cart stops. As more force is applied more chain will lift off the bottom and pull harder on the anchor, if this does not drag the anchor cart moves only a little and stops again. If the force is increased again and the anchor does not drag all the chain can be lifted. But now the hold the anchor has in decreased because of the bad angle and will probably drag. So now you feed out more chain, the force to lift the chain is increased. If the applied force is increased more chain will again be lifted. The point is to lay out enough chain that the force to lift all the chain is greater than the force to drag the anchor.
Deck Midshipmen take classes to determine how much chain should be laid out to properly anchor out. It is some guess work not a exact science though. On a ship the captian or mate will take in all the factors, ship size,type of anchor, size of anchor, chain weight, depth of water, wind and currents, then make an educated estimate of how much chain to lay out. The idea is to layout enough chain where it will not all be lifted off the bottom.
Also when a ship is at anchor sightings are taken often to besure the ship is not dragging the anchor. In windy conditions or where there are high currents are present sightings will be taken more often.
There’s one other traditional use of anchors – using lightweight “kedge anchors” to move a sailing ship when the wind is too calm for sails to work. It’s enormously labor-intensive – the ship puts boats over the side with the kedge anchor(s) and rows them out in front of the ship, where they are dropped overboard. Winches, such as the capstan, are turned by hand to drag the ship to the spot the anchor was dropped (or as close as they can get until it pulls up off the bottom). The process is repeated as necesary.
[QUOTE=Wikipedia]
Hull sighted five ships off Egg Harbor, New Jersey, on 17 July and at first believed them to be Rodgers’ squadron, but by the following morning the lookouts determined that they were a British squadron out of Halifax: HMS Aeolus, Africa, Belvidera, Guerriere, and Shannon. They had sighted Constitution and were giving chase.[85][86]
Finding himself becalmed, Hull acted on a suggestion given by Charles Morris, ordering the crew to put boats over the side to tow the ship out of range, using kedge anchors to draw the ship forward, and wetting the sails down to take advantage of every breath of wind.[87] The British ships soon imitated the tactic of kedging and remained in pursuit. The resulting 57 hour chase in the July heat saw the crew of Constitution employ a myriad of methods to outrun the squadron, finally pumping overboard 2,300 US gal (8.7 kl) of drinking water.[88] Cannon fire was exchanged several times, though the British attempts fell short or over their mark, including an attempted broadside from Belvidera. On 19 July Constitution pulled far enough ahead of the British that they abandoned the pursuit.
[/QUOTE]
Have been on board the SS Badger when they did this. Coming into port at Manitowoc, the captain starts a turn, and then drops anchor; its bow held fast by the anchor, the ship does a 180-degree spin within a far tighter radius (basically pivoting around the anchor) than it could accomplish using only its rudder. Once that’s done, they back the ship into the dock.
If you want this to be analogous to an anchor with a chain attached to it, then that antenna support cable should have a 50-pound weight attached to it every couple of feet along its length. Do that, and then it’s a fair bet that some length of this weighted cable (closest to the anchor point) will be laying on the ground.
