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My 11yo son asked me why they did not connect a buoy to the submarine with a string. Lol

by J_cst 3y ago

jcrash 3y ago
Good question!
- deleted 3y ago
  [deleted]
parshimers 3y ago
don't they do this with crab pots? i'm not sure how far those go down though.
- BrentOzar 3y ago
  > don't they do this with crab pots? i'm not sure how far those go down though. Looks like at most, about half a mile: https://en.wikipedia.org/wiki/Alaskan_king_crab_fishing#Equipment_and_process https://en.wikipedia.org/wiki/Alaskan_king_crab_fishing#Equi...
orangepurple 3y ago
Do the math exercise with him for how much volume 2 miles of string takes up
- Flammy 3y ago
  Do the math for the weight of a string 2 miles long. Then take a look at how much weight a string can hold up. Then you're ready to be taking on space elevators
  - someweirdperson 3y ago
    > Do the math for the weight of a string 2 miles long. There are materials that are a bit more dense and others a bit less dense than water. It should be possible to craft a string with a "weight" of zero, when submerged.
  - deleted 3y ago
    [deleted]
  - flangola7 3y ago
    Weight and mass are not the same.
- deleted 3y ago
  [deleted]
- thehappypm 3y ago
  Seems doable to be honest—huge spools of undersea cables are deployed on ships all the time. A spool 20 feet wide has a circumference of ~60 feet, and 3 miles of cable is ~15,000 feet, so 250 loops around the spool. Seems doable.
- madaxe_again 3y ago
  You’re aware of ROVs? They usually communicate with an umbilical, which is considerably fatter than a piece of string. It’s deployed from the surface vessel, not from the ROV. The same could just as easily apply.
- rhyst 3y ago
  Using 9mm diameter semi static climbing rope as an example. For volume: Volume of 4km of rope is 0.009^23.144000 = 1.02m^2 which seems like an amount that would fit on a large spool on a ship. For weight: rope itself weighs about 60g per meter so 0.06*4000=230kg of rope. It has a breaking strength of 22kN, which is roughly 2000kg static load. Given everything is probably roughly neutrally buoyant seems like enough. Not saying its practical but it seems like the actual volume/weight of rope would not be a problem.
  - gcanyon 3y ago
    I haven't checked your math, but your volume should have a ^3 on it, not a ^2
- J_cst 3y ago
  Couldn't it be that the spool with the rope floats on the surface and only one end of it is connected to the submarine with a snap hook? It may work and saves me the maths exercise lol :)
- bagels 3y ago
  String would not work, it's not strong enough. Steel cable would likely work. Depends on tensile strength of the material.
HL33tibCe7 3y ago
I guess perhaps there’d be a risk of the string getting tangled in the wreckage of the Titanic. But then surely you could just cut the rope and free the vessel. I think your son is onto something!

My 11yo son asked me why they did not connect a buoy to the submarine with a string. Lol

by J_cst 3y ago

My 11yo son asked me why they did not connect a buoy to the submarine with a string. Lol

jcrash 3y ago

Good question!

deleted 3y ago
[deleted]

parshimers 3y ago

don't they do this with crab pots? i'm not sure how far those go down though.

BrentOzar 3y ago
> don't they do this with crab pots? i'm not sure how far those go down though. Looks like at most, about half a mile: https://en.wikipedia.org/wiki/Alaskan_king_crab_fishing#Equipment_and_process https://en.wikipedia.org/wiki/Alaskan_king_crab_fishing#Equi...

orangepurple 3y ago

Do the math exercise with him for how much volume 2 miles of string takes up

Flammy 3y ago
Do the math for the weight of a string 2 miles long. Then take a look at how much weight a string can hold up. Then you're ready to be taking on space elevators
- someweirdperson 3y ago
  > Do the math for the weight of a string 2 miles long. There are materials that are a bit more dense and others a bit less dense than water. It should be possible to craft a string with a "weight" of zero, when submerged.
- deleted 3y ago
  [deleted]
- flangola7 3y ago
  Weight and mass are not the same.
deleted 3y ago
[deleted]
thehappypm 3y ago
Seems doable to be honest—huge spools of undersea cables are deployed on ships all the time. A spool 20 feet wide has a circumference of ~60 feet, and 3 miles of cable is ~15,000 feet, so 250 loops around the spool. Seems doable.
madaxe_again 3y ago
You’re aware of ROVs? They usually communicate with an umbilical, which is considerably fatter than a piece of string. It’s deployed from the surface vessel, not from the ROV. The same could just as easily apply.
rhyst 3y ago
Using 9mm diameter semi static climbing rope as an example. For volume: Volume of 4km of rope is 0.009^23.144000 = 1.02m^2 which seems like an amount that would fit on a large spool on a ship. For weight: rope itself weighs about 60g per meter so 0.06*4000=230kg of rope. It has a breaking strength of 22kN, which is roughly 2000kg static load. Given everything is probably roughly neutrally buoyant seems like enough. Not saying its practical but it seems like the actual volume/weight of rope would not be a problem.
- gcanyon 3y ago
  I haven't checked your math, but your volume should have a ^3 on it, not a ^2
J_cst 3y ago
Couldn't it be that the spool with the rope floats on the surface and only one end of it is connected to the submarine with a snap hook? It may work and saves me the maths exercise lol :)
bagels 3y ago
String would not work, it's not strong enough. Steel cable would likely work. Depends on tensile strength of the material.

HL33tibCe7 3y ago

I guess perhaps there’d be a risk of the string getting tangled in the wreckage of the Titanic. But then surely you could just cut the rope and free the vessel. I think your son is onto something!