As a a student of naval history and engineering I have often pondered this question: why have there never been REALLY large submarines built to carry cargo overseas.
I am not neccessarily thinking in terms of wartime military applications.
The suggestion here is to build submarines capable of carrying profit-making tonnages of cargo through really rough seas during any time of year. North Slope (Alaska) oil could easily be sent south under the polar ice caps or even through the Bering Sea any time of year, regardless of surface conditions.
Here's the kicker: the subs could even be unmanned. This would not even been thinkable a generation ago.
Using nuclear power (ironic, I know) to ship oil could be a paying proposition if the costs of supporting crews could be eliminated. So far as I know, this has never been experimented with, at least not on a large scale. GPS systems enable tracking to within a few meters. The only time a 'crew' is on board is when the ship is leaving or entering port. Then it would only be a few people to pilot the sub on the surface to berthing and safe the reactors and other systems on board.
Artificial intellligence has gotten to the point where even a fairly large vessel can cope with or avoid relatively predictable conditions. Collisions are a different problem, but that would be the case for manned subs anyway.
Since this is not a military sub, there is no need to preoccupy about deep diving capability as the vessel only needs to go about fifty meters down to escape ravages of most rough seas. At those depths the sub could easily be communicated with if there was a problem with, say, the reactor, or the control system. The situation is very much like communicating with space probes, only the time lag is very much shorter.
Pirating such a ship would be difficult because A) its under water most of the trip and B) it can be completely sealed against intruder entry and C) it could likely be regarded as an act of war to intercept or otherwise molest these subs. They would be separated from the 'Law Of The Sea' provisions regarding 'abandoned' vessels in open sea.-- Moonguy, Jun 17 2008 http://www.ebenhops...%201982/Tankers.htm [2 fries shy of a happy meal, Jun 17 2008] Submarine Cargo Vessel http://www.ckb-rubi...p/uwaters/index.htmThis page shows the essences of the proposed concept along with other similar projects. I recommend one click through some of the links. They’re interesting. The projects shown are run by ‘State-Owned Enterprise Central Design Bureau for Marine Engineering “Rubin” ‘ or SOE CDB ME "Rubin" for short. It is a Russian state owned enterprise. [CwP, Jun 18 2008] Good'un.[link]-- 2 fries shy of a happy meal, Jun 17 2008 Sealed, underwater, and act-of-war or not, a tankerload of oil, not to menation the very large nuclear-powered craft, would be a tremendously attractive target.-- Voice, Jun 17 2008 The above post does not overuse commas. If you accuse me of such, I do hereby declare you to be a poopy-head.-- Voice, Jun 17 2008 You could name you first huge oil sub the “Exxon Valdez 2”. ;-)-- CwP, Jun 17 2008 neat, but would the extra drag of the water covering the *entire* hull be less than that with only 1/4 covered but subject to the ups and downs of surface travel ?-- FlyingToaster, Jun 17 2008 Sub hull design is very well advanced for low turbulence, hence low drag - to keep them "quiet". And since it's a square-to-cube ratio for surface area to volume, doubling the volume doesn't double the drag, so bigger vessels are more efficent.
For a low speed system capable of moving huge volumes of material slowly but cheaply, it's not a bad idea; but [Voice] has hit on its weakness - slow moving, high value, unmanned .....
Admittedly piracy would be more difficult - a few AK-47's and a speedboat would not suffice - but for a big reward, a way would be found-- 8th of 7, Jun 17 2008 Pirates wouldn't have to go too deep either - that's just barely outside recreational diving depths.
Regardless of depth, it would be possible to foul the prop/s with some lines, trigger floatation attached to those lines, and float this Captain Nemo / truck driver vessel.
Not that I've ever thought about being a pirate (puts rum bottle back in desk drawer).-- normzone, Jun 17 2008 [8th] no, I mean look at a tanker, much more than half the surface area is *above* water and not subject to hydrodynamic drag. If you put that entire tanker underwater...-- FlyingToaster, Jun 17 2008 Fouling the props of a submarine being tracked while underway would signal a problem. Coast Guard or other units could be vectored in to the area, making it hot for pirates. Also, merely stopping the sub does not matter if A) you cannot access the cargo from outside, particularly when under water, and B) you cannot get the sub to surface 'cause there are no external control elements. Torch your way in? Into a giant sub loaded with oil and possibly just enough oxygen. . .?-- Moonguy, Jun 17 2008 //it could be brought to the surface with a relatively small upward force//
That is true of all submarines. They have to maintain neutral bouyancy while submerged; the mass displaced only depends on the physical size of the sub, not the cargo. Carrying a load of helium or osmium, the displacement is the same.
Which means if your return trip is made empty, you have to ballast up to the tonnage of a full load - or run on the surface.
You could pull up an Ohio-class sub just as easily; and it would sell for far more on the black market.-- lurch, Jun 18 2008 Isn't "SuperSub" a contradiction in terms?-- spidermother, Jun 18 2008 Since the sub is designed to be unmanned, couldn't you simply add a toxic substance (or something - obviously nothing that would taint the cargo) to the design to prevent piracy?-- lostdog, Jun 18 2008 [Spidermother] No, it isn't. [lostdog] Probably. Anything would help. [lurch] Right on! Based on your comments I will now likely have to revise my retirement plans. . .-- Moonguy, Jun 18 2008 // add a toxic substance (or something - obviously nothing that would taint the cargo) to the design to prevent piracy? //
This is reading less and less like a practical idea and more and more like the plotline for a gloriously improbable Hollywood screenplay.
"Runaway nuclear-powered booby-trapped sub full of crude oil and toxic gas has had a computer failure/been hijacked by terrorists/Evil Megalomaiac and is heading at full speed for [Insert name of City] and {Hero/Heroine/Trained Chimp/Dolphin/ten year old computer genius] has only [NN] hours to save the City/Country/World...... [again]"
We want a percentage of the gross if it gets made.-- 8th of 7, Jun 18 2008 //why have there never been REALLY large submarines built to carry cargo overseas.// sp: underseas colon hyphen close parenthesis.-- 4whom, Jun 18 2008 [Moonguy]: [lostdog] was being facetious. Watch out for low flying puns...
What if this was an engineless capsule that was towed by a tug - or it did have an engine and had some kind of guide-boat?-- Jinbish, Jun 18 2008 Drug runners have been towing submersibles for years. The coast guard has that one figured out. One ping detects things for miles. Towing works but the tug itself defeats the premise that it would avoid the worst of weather. Plus, subs deal with underwater weather and currents.
I reject the sub concept only for the use specified. Time is money and once oil is pumped, crops harvested, or products made, any delay getting it to market is money lost. Subs are slow. Big subs are slower yet and thus cost even more in time and money.
SubArtic (pun intended) trips are the only thing close to viable. I think it could happen. [+]-- CwP, Jun 18 2008 [2 fries shy of a happy meal]: I love your link.
I have added another Russian link that references the same GD proposal along with their own ideas.-- CwP, Jun 18 2008 Why not take this further? If you want to ship oil, you need a really big sub. So, construct a sub whose length is equal to the distance between the loading and unloading points. Then, just slice the bow and stern off the sub. Strip out the propulsion and navigation systems. Now load the oil in one end, and collect it from the other end, all without the sub having to move. The whole thing could be anchored in place, and could be called, oh, I dunno, maybe "Permanently Installed Petroleum Escalator".-- MaxwellBuchanan, Jun 18 2008 Tree huggers hate those underwater "Permanently Installed Petroleum Escalator" lines even worse than the surface versions. Those versions are boring and are only worth a few days press.
The Super-Sub would give them something to rally around in little boats on every launching. The rally is over once it submerged. If we let everyone know where it would surface, the press may score some impressive footage of Green Peace boats being beached atop the massive Super-Sub. Despite their terrified squeals, the unmanned Super-Sub would carry them off into the horizon toward a Super-Sub pin surrounded by barbwire.
Wow… this just keeps getting better and better!-- CwP, Jun 19 2008 Why not just have crew? Modern ships have crews don't they? Someone to watch the radar screen and be ready to radio for help. Or even steer the thing. I don't think they're that expensive compared to the cost of a huge submarine.
Otherwise, a neat idea. bun-- Bad Jim, Jun 19 2008 How do you keep the thing underwater? Oil is lighter than water.-- BunsenHoneydew, Jun 19 2008 1 volume steel per every 44.8 volumes oil gives neutral buoyancy.-- lurch, Jun 20 2008 A typical VLCC (very large Crude carrier) is 42,000t lightweight (vessel weight) and 300,000t deadweight (cargo capacity).
But if 1 volume of steel (7.86t/m3) for every 44.8 volumes of oil (0.84t/m3) give neutral buoyancy (actually, I calculate 37, using Crude=0.84, Steel =7.86 and Sea-water=1.025), then Sub: 1 ton of steel for every 4.78t of oil. VLCC: 1 ton of steel for every 7.1t of oil.
Cost of fabricated steel, Let's say, is about $3350/t (based on old price = $120m for a VLCC and added the recent steel price increases of about $500/t, so becomes $141m). A VLCC equivalent Sub will cost $210m, without any allowance for extra design constraints i.e. just simply looking at buoyancy.
(If 37:1 ratio, then $253m.)
And what to do if the return journey is empty? I think most VLCC's are semi-submersed anyway, when full. Look at the Knock Nevis with a draft of nearly 30m.-- Ling, Jun 20 2008 A bun to [spidermother]'s anno.
And a plus to the idea, but I'm dubious now as to the inefficiency of ploughing your way through water when there is less drag when floating on the surface. Perhaps this drag could be reduced by making the sub really long and thin, like an underwater train.-- theleopard, Jun 20 2008 //Someone to watch the radar screen and be ready to radio for help//Since neither works particularly well under water, you've just saved a crew member (probably three; one for each watch) right there.-- coprocephalous, Jun 20 2008 [Ling] - good math. There's quite a wide range of crude oils out there; I couldn't remember how light/heavy Middle Eastern oils are (they being the ones I would guess are targeted for long shipments) but I thought they were on the heavy side and didn't bother to look it up - I just used a heavy crude density.
I think that hull strength is not going to be a big design issue - there will be liquid on both sides (don't need a pressure hull like a sub with human critters inside) (at least for the cargo section) and the thing doesn't have to support itself up in the air as freeboard, either.
So as far as just having metal for mass - a lot of it could be just thrown in as slag, or rocks, or whatever's cheap and dense. Sand. I just did the simplest version of the math.-- lurch, Jun 20 2008 Please halfbake subtrains-- Voice, Jun 23 2008 // or whatever's cheap and dense //
The French ?-- 8th of 7, Jun 24 2008 I think the "cargo sub" idea only works with a cargo that has close to the density of water: heavier and you run the risk of sinking if something happens; lighter and the drag would probably be less if you took a surface vessel... so petroleum transport would probably be safer than using surface travel, and ice or freshwater transport the safest of all.-- FlyingToaster, Mar 22 2009 random, halfbakery