[Somes J (OP)]

I was doing some internet research on the idea of using nuclear reactors for cargo ships, and a couple of sites I found discussed the possibility of building fast cargo ships (> 30 knots) that would run on nuclear power so that they wouldn't face the economic difficulties with fuel price. E.g. here [nofollow]'s a description of a hypothetical nuclear container ship with a 32 knot speed and here [nofollow]'s an example of a conventional ~30 knot design that ran into trouble because of fuel costs.

I was wondering, suppose we did switch to nuclear powered cargo ships in the future (maybe when oil runs out), would one expect to see a general across the board decrease in ocean shipping times as a result? I understand the uranium is a very small part of the cost of a nuclear vessel ($165/kg [nofollow], with a single kilogram being enough to run a ~100 MW engine for days based on calculation from energy density of uranium fission) so in terms of fuel costs running faster should be more economical with uranium than oil, at least going by this [nofollow] (thousands of dollars a day in fuel costs with oil).

Are the speeds of modern cargo ships limited mainly by fuel/energy costs, or other factors like the cost of equipping them with more powerful engines?

[CliffordK]

Most of your links are broken.  Here are a couple.

http://en.wikipedia.org/wiki/MV_M%C3%A6rsk_Boston
http://onlinepubs.trb.org/onlinepubs/archive/marineboard/fall08/cushing.pdf

Speed is limited to some extent by hull length and design.  So Aircraft Carriers can often outperform Battleships due to a longer hull.

Hydrofoils are also very fast.
http://www.hydrolance.net/page7.htm

But, the hydrofoils would not be economical for ordinary transportation of bulk goods.  However, if one could make a cargo ship that ran at 135 knots, it could be used for delivery of perishable goods, as well as certain rapid response and rapid delivery needs.  I could see a niche halfway between air freight and surface freight.

From the PDF you found, it would seem to indicate that there is a cost per KW for the capital construction costs.  Thus, there is more capital cost for the larger engines.  But, the fuel cost is significantly less than "conventional" fuel costs, and might favor the higher speeds.

But, then again, the cost of fuel is not insignificant, so if it cost $6 million per year to run the ship at a faster speed, a manager may choose not to do so.

There are likely two types of shipping.

Those who wish the lowest cost, and can wait a month or so for the shipping.  And, those who can not wait. 

Many customers might be unwilling to pay a premium to get their merchandise delivered faster, and the customer may not reap any benefit from cheaper shipping methods.

I suppose another not insignificant factor might be resource turnover.  If you have a billion dollar capital outlay on your ship.  It might be more economical to run it at twice the speed which would make it equivalent to two half-billion dollar ships.  In fact this resource turnover on high capital cost ships might become the primary driving factor for faster ships.

[Somes J (OP)]

Most of your links are broken.

Sorry, I copied and pasted this from a post I made on a different forum, that's probably what caused the problem.

[CliffordK]

You can edit the original post.

Your problem with the links is that they have "http" too many times, and the quotes need removed. 
I.E.  Make the links look like:    http://abc.com/...

Plagiarism is prohibited.
Cross posting of identical questions between forums is discouraged.

http://www.physicsforums.com/showthread.php?t=513094
http://www.bautforum.com/showthread.php/117956-Nuclear-powered-cargo-ship-question?p=1911966#post1911966

-------------------------------------------------------------------

One of the questions in the other threads is whether proliferation of Nuclear Cargo ships would become a target for pirates and terrorists.  It would be difficult for pirates to steal a nuclear carrier, but a nuclear cargo ship might have much less protection.  But, it would also mean that one would need more trained security onboard.

Despite all the modern technology advances, we still occasionally have groundings and shipwrecks.

Imagine a mobile version of the Fukushima Nuclear Plant.  Yes, smaller, but still entering estuaries around the world.

No doubt the controversy of a sunken nuclear cargo ship would dwarf the controversy surrounding the Exxon Valdez.  And, wile the Valdez was eventually refloated, many ships break up, and are lost.

One would really need to design a reactor module that could survive a wreck intact.  Automatically go into "standby mode" in the event of a wreck, and still maintain cooling without contamination.  Then, be easy enough to separate from the wreckage that recovery would be relatively easy, even in extremely deep water.  And, of course, have a well defined emergency plan with emergency response equipment on standby.

[Somes J (OP)]

You can edit the original post.

Your problem with the links is that they have "http" too many times, and the quotes need removed. 
I.E.  Make the links look like:    http://abc.com/ [nofollow]...

Done, thanks.

[Don_1]

Leaving aside the technicalities, it is already the case that nuclear powered warships are not welcome visitors to many ports. I think the same might apply to nuclear powered cargo ships.

But perhaps the greatest objection to nuclear powered cargo ships would come from the IAEA (International Atomic Energy Agency). Imagine Somali pirates boarding and taking captive such a prize!!!

I would think, and hope, that cargo ships would revert to wind power, such as this

[imatfaal]

Unfo Don - those kites whilst seemingly massive, just won't cut it for decent size cargo ships.  MS Beluga is big in human terms - but compared to the majority of the work-horses of the deep water routes she is tiny.  FYG big container ships carry around 20 times the number of containers, and big tankers and bulkers will carry around 100 times cargo by mass.

I think the main concern for nuclear powered ships - other than the excellent points you and Cliff raise - are the availability and training of crews.  We only carry a dozen or so engineers (from cadets to experienced chief engineers) - I find it hard to believe that this would be acceptable for a nuclear power plant.

[Don_1]

Certainly the MS Beluga is tiny by comparison to modern cargo vessels and perhaps the kite idea is just a little too much to expect to pull the 1000's of tons most cargo vessels carry. It was just something I quickly pulled off the net as an example. But perhaps a more conventional 3 or 4, maybe even 5 or 6 masted ship with conventional sails might be the way forward.

[imatfaal]

For niche cargoes that could attract a sales premium due to the green methods of transportation then sailing vessels might be workable.  However for everything else the way forward is a reduction in consumption not transportation costs/carbon costs.

As an example the Flying P Liners Preussen / Passat are the biggest sailing cargo ships I can think of - they max out at below 8000 tonnes carrying capacity (ie deadweight).  The current large-size tanker and bulker fleet is around 930 million tonnes carrying capacity!

I raise this point not to be contrary, but because I think the figures in the shipping game are beyond normal conception - and betray the fact that we have become far too reliant on cheap movement of goods

[graham.d]

There are ways to reduce the fuel cost on cargo vessels but they have yet to be taken up to any large extent. The are aerofoils that can be fitted with computer control to maximise the gain available from the wind strength and direction. The weight is not an issue compared with the total cargo so no need to have a flimsy kite or fabric sail. They can be made of solid carbon fibre composites or a strong alloy with a more sophisticated shape control too. The idea would be to motor-sail but just reduce costs where possible. Admittedly, retrofitting of these structures would not be easy or cheap.

An even simpler technique is to simply optimise a course according to the ocean currents operating, tidal effects and the wind direction and speed. This is done to some extent and software is available. Racing yachts use such a means to get more speed but, despite the fact that such systems would repay the cost of their purchase within a few months, not very many ships employ such systems.

I think the nuclear option is out, at least because of the security issue, though there are plenty of other reasons.

[CliffordK]

That is a most interesting sail.  And a $1500 a day fuel savings isn't anything to scoff at, although that could get quickly eaten up by increased labor costs.  The BBC article never lists the actual fuel costs/consumption with and without the sail though.  It looks awfully small compared to the ship.  The Cushing article above lists an annual fuel cost of $89,000,000.  That would be about $300,000 a day worth of fuel.  So, the sail is saving on the order of 0.5%.

It would seem as if the sail would be very much wind direction dependent.  While a sailboat can tack into the wind, that might not be efficient for motor assist sailing as it would lead to increased travel distance.  A sailboat often gets its best speed with wind at a 90° angle.  Is the same true for this parasail?  Can the ship deal with the cross wind?

I also wonder how easily the sails can be scaled up.  If the goal is to make a sail 200 times larger, it would take some big ropes and cables.  And, it would be an extraordinary amount of power to be transmitting through a single cable.  It may also create hull stresses that the ship was not designed to withstand due to the lift component.

You would certainly need a break-away at the ship's deck, and some kind of recovery options for a lost sail.  But, a broken rope would still be wicked.

Green Technology will get incorporated only if it becomes economical.  And, one has a lot to play with when one has a $90 Million per year fuel bill.

I found a good writeup of the sail on NakedScientists with some more info including wind direction.

http://www.thenakedscientists.com/HTML/content/interviews/interview/1485/

[imatfaal]

90 Million a year is a gross exageration in order to sell a competing technology:
1.  Using Emma Maersk (the most grotesquely over engined ship in the fleet) as a representative is like using an F1 car as the model for car petrol consumption
2.  The Cushing sums use 9000 hours per year - thats 375 days per year!
3.  No ship steams for 100% of the time - you have to stop at port
4.  Only clinically mad shipowners are running ships at max service speed - at present most owners are at normal or economic speed; perhaps saving 50% of the fuel costs
5.  Even if Emma Maersk runs constantly at full speed the bunker bill would be 36 million

Ship-owners are in it for the cash - if they thought that a new technology would save money - then I promise you they would look at adopting it.

[Geezer]

2.  The Cushing sums use 9000 hours per year - thats 375 days per year!

Maybe it was sailing East all the time and kept crossing the date line?

[Somes J (OP)]

Honestly my question was less motivated by curiousity about the specific issues with using nuclear power and more by curiousity about how the design of these big ships might be different in a world where fuel cost wasn't a serious issue. I read about some fast container ships that ran into economic trouble because of high fuel prices (the Algol SL-7 [nofollow] and Maersk B [nofollow] types), and I was wondering whether we'd see a lot more fast ships like that in such a world.

Any thoughts on that?

[CliffordK]

It really depends on a number of factors.

A lot of cargo will be shipped at the lowest cost possible.  And, thus the "high speed" conventional cargo ships were likely doomed to fail as nobody was willing to pay the extra cost to get the cargo...  just a little faster.  And in fact many customers might not even know that the option was available.

Of course, one of your links was for Military Ships.  The military, or perhaps first responder disaster relief ships would need to have different needs than normal civilian freight.  Optimally, military cargo ships should be able to keep up with their escorts, and fast deployment would be a major advantage.

One concept in manufacturing and distribution is called "Just in Time".  The idea is that products, or parts sitting on a shelf are costly and a liability.  The goal is to produce and deliver products to the stores which in turn sell them to the customers "just in time" for the need.  Personally I think businesses spend way too much money on high speed postal services.  High speed shipping may augment Just in Time manufacturing/stocking.  But, if one can accurately predict demand, then it may be beneficial to select the cheapest method of transportation, especially for items that might cost more to ship than to produce.  The expensive, custom items might be another story.

As far as the Nuclear.  As mentioned, if the capital cost of the ship is high.  Perhaps also high associated labor costs.  But, very low fuel costs.  Then it may actually be more economical to choose a speed that would lead to high turnover of the resources.  I.E.  it might be most economical to run the ship very fast so that it can make more trips in a year.  Of course, that may also mean higher ship construction costs like a vicious circle, but it could be money saving to run faster ships. 

Above, I also mentioned the possibility of a hydrofoil that could run in excess of 100 knots.  In theory it could compete with air freight, and could compete in markets shipping fresh produce.  It might or might not be a growing market.  However, cheap fuel would be imperative.

A monster hovercraft would also be an extraordinary vehicle that also has the benefit of very low draft to the point that it can park on concrete for loading and unloading.  Again, cheap fuel would be imperative.

[graham.d]

Neither hydrofoils nor hovercraft can cope with big waves.

[Atomic-S]

I think the solution is underwater rail.

[CliffordK]

A submarine railway in water would have very high resistance. 
A railway at 10km deep would be awfully deep, and have tremendous pressures
A floating railway, either on the surface, or subsurface would be "interesting" to say the least.  Subsurface floating, you would likely have a significant deflection as the train crossed.  It may also be affected by storm and seismic activities.
If you were pushing a tunnel through bedrock.  The sea floor is not flat, and in some places one would be going very deep.

And, if submerged, you would have to deal with air circulation, emergency access, and emergency exits. 

And, don't forget the Mid Atlantic Ridge and Pacific Ring of Fire.

At some point, one may choose to connect railways from Alaska to Russia, or across the Strait or Gibraltar, somewhat like was done in the English Channel.  But, straight across the Pacific or Atlantic would be impractical.. 

A highway & railroad through Panama and Columbia would also have extraordinary benefits.

Container ships may still compete well with the cost of railroads, with the railroads specializing in relatively fast transport of moderate cargo capacities.

[CliffordK]

Looking at this a bit more.
I think there are real proposals for a Gibraltar Bridge or Tunnel. 
http://en.wikipedia.org/wiki/Strait_of_Gibraltar_crossing
http://www.skyscrapercity.com/showthread.php?p=63919803

Major problems for a tunnel would be the fault lines, and perhaps the depth at the shortest distance.  The proposals for a bridge include a 24 lane wide bridge.  That is one massive bridge!!!!!!!!!  However, indications are that the project may be started in the next decade or so.

There are also notes about a possible Bering Strait Bridge/Pipeline complex.
http://en.wikipedia.org/wiki/Bering_Strait_crossing

As well as a Japan/Korea tunnel, and other globally connecting projects.
http://en.wikipedia.org/wiki/Trans_Global_Highway

Perhaps we should concentrate more on building bridges and less on building bombs.  Several of these projects could have been completed for the cost of the Iraq/Afghanistan Wars.

A highway through Panama and Columbia would get at least as much traffic as a Gibraltar highway.  But, there are some real questions on whether we really want that much traffic through the area.  The costs/benefits of a Gibraltar highway and other inter-continent spanning highways will have to be carefully monitored, especially spanning areas with highly different socioeconomic standards.

Anyway, over the next few decades there will be a lot more work on local connections which will shut down some ferry services, and perhaps some shipping companies.  But, in many cases, if the tunnels and bridges are too far out of the way, sea surface freight will remain a mainstay of the shipping industry.  And, container ships as well as barges are still reasonably economical for bulk transport of goods.

(sorry if Global Transportation got a little off topic [])

[imatfaal]

Some very large boats have to transit gibraltar straits in a ballast condition Clifford.  It would need spans that were quite wide and high - over what can be very heavy seas and in poor general weather conditions.  It would be sight to see though.