8
$\begingroup$

No, I am not talking about space ships, I am talking about water-based ships sailing the oceans on planet Earth.

What would be a plausible cruise speed and maximum speed for what would be the equivalent of a modern destroyer after about 100 more years of technological progress? Please assume that the human civilization manages to continue on as it currently does without any large-scale disasters or society collapse slowing down the speed of technological progress.

$\endgroup$
  • $\begingroup$ In WW2 what is the cruise speed and maximum speed for a military ship? Depends on the ship! There are lots of different ships. It is relevant what the size and job of this ship is. $\endgroup$ – Willk Oct 31 '18 at 15:57
  • $\begingroup$ Would help if you define a size parameter for your "military ship" within the question. Modern navies don't build battleships (as in the technical definition) any more. $\endgroup$ – Ash Oct 31 '18 at 15:57
  • 1
    $\begingroup$ @Ash It's hard to tell how technology in the next 100 years will affect the roles of the navy and thus the roles and sizes of ships. But I have to start the design process somewhere, so I decided to start with what's possible speed-wise. But for the sake of the question, let's assume a vessel which has about the size of a modern guided missile destroyer. $\endgroup$ – Philipp Oct 31 '18 at 16:00
  • $\begingroup$ I think not much will change with the ships. In future the ships maybe have a turbo which they might use to dodge missiles & more, but thats pretty unrealistic, since we have even today tracking missiles. As long physical laws don't change there will probably not much change in speed. For what is the speed needed? For an operation on the otherside of the globe? $\endgroup$ – Jannis Oct 31 '18 at 16:09
  • 1
    $\begingroup$ US Navy R&D efforts currently list a mid-small vessel which can plane at ~ 60 knots - non hydrofoil - actual planing hull - the larger catamaran high speed transfer vessel program started in 2008 has been plagued with issues, and though specced to do ~ 35 knots with a loading of 1.2 M pounds cargo 1200 nautical miles, it underperformed severely as ~ 23 knots for some 850 nautical miles with serious issues at attempted at-sea cargo transfers. Many commercial "fast" ferries run at around 40 knots now. $\endgroup$ – GerardFalla Oct 31 '18 at 18:02
12
$\begingroup$

Conventional surface ships will likely continue to sail at around the same speeds as today, simply because the laws fo physics are not going to change. A wet navy monohull ship today is approaching the maximum possible hydrodynamic efficiency, and there are good reasons to suspect the monohull form will survive into the 22nd century, since it is well developed, has a considerable volume for equipment, fuel, and other consumables, is stable even in high seas and can provide persistence (the main reason to have a navy in the first place: the ship can remain on station for weeks or even months, something aircraft, orbiting spaceships or may other potential systems cannot do).

Looking for the ability to go faster would require firstly defining the parameters of how fast the ship should go, how long it can sustain flank speed and "why" it needs to go so fast? There are a number of ways to go about this.

Sustaining a modest increase in surface speed can be best done by minimizing the friction between a ship and the water. The ship can inject air or some sort of slippery polymer between the hull and the water in order to minimize friction. The amount of speed that you can gain might be limited, especially by the amount of energy needed to inject the "interface" fluid, and the amount of fluid carried if you are not using air. Research is ongoing today, and it is a relative to the Prairie/Masker system used to reduce noise on US Navy ships.

enter image description here

Air lubrication system

For higher speeds, we need to lift the hull from the water entirely. Hydrofoils, lifting bodies and surface effect systems use different means to do this. Hydrofoils are essentially wings, and lifting bodies are similar, but larger and likely more robust than foils, although the large size may result in lower potential top speeds. Lifting bodies also have the potential to lift larger displacement ships.

enter image description here

1970 era test hydrofoil HMCS Bras d'Or on display today

enter image description here

Sea Flyer, a modern experimental vessel using lifting body technology

Surface Effect Ships are forms of hovercraft, using the body of the ship and "skirts" on the bow and stern to trap air (usually injected by a powerful turbine engine) to lift most of the hull out of the water. The advantages are Surface Effect Ships are more efficient than hovercraft, but like hovercraft, are very power hungry.

enter image description here

SES 200 test bed

The SES series of test ships achieved speeds of 100 knots, so transit and dash speeds are very impressive, and when the air cushion is off, the ships can still remain on station like a conventional ship.

Beyond the 100 knot speed, we need to leave the water entirely, and are now in the realm of airplanes or Ground Effect Vehicles. One intermediate step is to use wings to partially lift a ship from the water, in effect inverting the idea of a hydrofoil (Aerodynamically Alleviated Marine Vehicle). This has not really been demonstrated to date.

enter image description here

Aerodynamic alleviation concept

Of course, a true flying boat provides the ability to fly to deployments anywhere on the globe, and then land and float on water to provide persistent presence. The apogee of flying boat design is likely the Martin "Seamaster", a jet powered flying boat roughly the size and performance of a B-52. This should qualify as a true "boat" once at sea, and provides a high subsonic speed performance as well.

enter image description here

Martin Seamaster in the water

enter image description here

Seamaster in flight

enter image description here

Amazingly, the Seamaster is an amphibian!

I would suspect that by the 22nd century, most wet navy vessels would actually be some form of flying boat, to make the force as versatile and rapidly mobile as possible.

enter image description here

Blended wing body flying boat

$\endgroup$
  • $\begingroup$ Correction: the Seamaster was not an amphibian. It could have wheels bolted on to beach it for maintenance and storage, but could not operate with those wheels attached. $\endgroup$ – jwenting Nov 1 '18 at 6:12
  • 3
    $\begingroup$ And I have to disagree with your assertion that all naval vessels will become flying boats. The major advantage of a ship, endurance, goes out the window that way. A ship can remain at sea for weeks, months, on end if needed, a flying boat only for a few days. I can see coastal patrol craft and other short duration vessels going into the air, IF we can reduce the operating cost of aircraft as compared to ships per hour significantly. $\endgroup$ – jwenting Nov 1 '18 at 6:14
  • 1
    $\begingroup$ Thank you for the answer. I think I can get quite a lot from it. The air lubrication system seems particularly interesting to me, because it doesn't seem to affect the aesthetics much. Do you have any numbers regarding how much speed improvement one could expect from this technology? $\endgroup$ – Philipp Nov 1 '18 at 8:59
  • $\begingroup$ With any sort of system, adding capacities and making it able to do more things makes it worse at doing its original tasks. A flying boat would need wings, turboprops/fans, etc to fly, and would not be able to carry as much supplies/munitions/etc as a regular ship, and would therefore not be used. $\endgroup$ – Richard Smith Nov 6 '18 at 3:11
  • $\begingroup$ +1 and kudos, but you could do just a bit better by adding information about hull speed. Simply put, no displacement vessel can ever go faster than 1.34 times the square root of waterline length, because physics. A vessel that tries to go faster will come "out of the hole" and on to plane, which most small pleasure boats do all the time. Much harder with a warship. $\endgroup$ – cobaltduck Dec 19 '18 at 12:34
11
$\begingroup$

If you look at the last 200 years, the top speed seems to have levelled off because aircraft (manned, unmanned, or missile) will be faster than watercraft, so trying to win the sprint race is pointless. Watercraft excel in range and endurance, not speed.

There are several things to keep in mind regarding destroyer speeds. There is the difference between trial speed on the measured mile and top speed on the open ocean, plus possibly for modern craft military secrecy. (For decades the US Navy declared that their subs did more than 20 knots. True, but they did much more than 20 knots.)

But the tendency is clear. Destroyer speed has stopped to rise.

$\endgroup$
  • 2
    $\begingroup$ One of the reasons for decrease in destroyer speed is a change in mission. Destroyers were originally designed to intercept small, fast torpedo boats (thus the name, originally "torpedo boat destroyer"), then to act as fleet scouts and as torpedo boats themselves, so speed was essential. With the advent of sensors such as radar and with aircraft, and the mission change to act as close escorts and multirole ships with a large increase in size (Mahan - 341 ft, 1500 tons, Spruance - 529 ft, 8000 tons) they don't need or can afford the sprint speed any more. $\endgroup$ – Keith Morrison Oct 31 '18 at 20:28
  • $\begingroup$ I'd generally agree - I think that as propulsion technology improves along with technology to make vessels more hydrodynamic (for efficiency as much as speed) that we will see a gentle rise in warship speed, but nothing dramatic - probably into the 40's. The LCS already achieve these sorts of speeds; however this is presently at the cost of other capabilities. $\endgroup$ – Matt Bowyer Oct 31 '18 at 22:17
  • 2
    $\begingroup$ Modern ships are designed more for speed under normal or unfavorable sea conditions, while WWII ships were often designed for top speed under favorable conditions. $\endgroup$ – David Thornley Oct 31 '18 at 22:38
  • 1
    $\begingroup$ Also to note that a modern computer designed ship's propeller is only 5% more efficient than the one Brunel designed for the SS Great Britain in the 1830s. $\endgroup$ – Separatrix Nov 1 '18 at 8:19
5
$\begingroup$

Ekranoplan.

ekranoplan https://www.pinterest.com/pin/854628466758762209/?lp=true

Needing speeds to rival those of aircraft and without the need for armor, future destroyers will be massive ground effect vehicles with hovercraft capability. These vehicles leverage ground effect to achieve efficiencies better than aircraft and because they ride just over the water, are much faster than draggy conventional ships. Ground effect vehicles ("sea skimmers") exist. The sweetest is the ekranoplan.

https://en.wikipedia.org/wiki/Ground-effect_vehicle

Some manned and unmanned prototypes were built, ranging up to eight tons in displacement. This led to the development of a 550-ton military ekranoplan of 92 m (302 ft) length. The craft was dubbed the Caspian Sea Monster by U.S. intelligence experts, after a huge, unknown craft was spotted on satellite reconnaissance photos of the Caspian Sea area in the 1960s. With its short wings, it looked airplane-like in planform, but would obviously be incapable of flight.[5] Although it was designed to travel a maximum of 3 m (9.8 ft) above the sea, it was found to be most efficient at 20 m (66 ft), reaching a top speed of 300–400 kn (560–740 km/h; 350–460 mph) in research flights.

740 km/hr is good and fast and is only a little less fast than a modern passenger jet. That was 1960. Your future can be the past: a destroyer size ekranoplan made of titanium and carbon fiber with an aircraft like drive system moving it at 1000 km/hr.

$\endgroup$
  • 1
    $\begingroup$ While this is interesting, I'd had to disagree that this is a good answer. Ships and Planes are fundamentally different things and serve different purposes. Its all good being able to travel fast and fly far, however your planes need to land, refuel and restock. Ships allow you to transfer more supplies, more people and operate in areas with limited supplies for much longer than a plane could ever support. $\endgroup$ – Shadowzee Nov 1 '18 at 1:15
  • $\begingroup$ @Shadowzee did you downvote because you consider the ekranoplan to be an airplane? It cannot fly higher than a building! It it, as the quote states, "obviously incapable of flight" - tied to the surface by its dependence on ground effect. $\endgroup$ – Willk Nov 1 '18 at 1:54
  • 1
    $\begingroup$ Mostly because the question asks for a military ship which an ekrnoplan isn't. Its its own category, but to me, if offers advantages that are more closely related to a plane than a military ship. $\endgroup$ – Shadowzee Nov 1 '18 at 2:20
  • $\begingroup$ @Shadowzee the Ekranoplan seems to disagree with your assertion that ships and aircraft are fundamentally different things. It is a hybrid between both. $\endgroup$ – jwenting Nov 1 '18 at 6:08
  • $\begingroup$ @Shadowzee, the Caspian Sea Monster was most definitely military, and equally most definitely tied to the water. $\endgroup$ – Separatrix Nov 1 '18 at 7:59
1
$\begingroup$

using Supercavitation you can remove most of the friction from travelling through water. This seems to be designed much more to work with submarines, but I have seen designs to apply it to the front of cargo ships to reduce fuel consumption.

Currently it's mostly used for torpedoes but there are plans to scale it up for larger vessels allowing speeds of up to 100 knots

From the Wiki page:

The submarine's designer, Electric Boat, is working on a one-quarter scale model for sea trials off the coast of Rhode Island. If the trials are successful, Electric Boat will begin production on a full scale 100-foot submarine. Currently, the Navy's fastest submarine can only travel at 25 to 30 knots while submerged. But if everything goes according to plan, the Underwater Express will speed along at 100 knots, allowing the delivery of men and materiel faster than ever."[14]

EDIT: I found a surface ship project working on this concept, Ghost, the capabilities don't seem to be public, but rumoured to be capable of around 100knots,

“We’re basically riding on two supercavitating torpedoes. And we’ve put a boat on top of it,”

Scaling this up to destroyer size would probably be very difficult, but you have plenty of time to work it out for 22nd century

$\endgroup$
  • $\begingroup$ Supercavitation only occurs where air isn't available. Surface vessels can draw down air from the surface using grooves and hence avoid the major downside of supercavitation, that being collapse of the voids causing surface damage. $\endgroup$ – Separatrix Nov 1 '18 at 8:02
  • $\begingroup$ It's also pretty noisy--something you don't want in a warship that has to prowl the waters with enemy subs about. $\endgroup$ – Loren Pechtel Nov 1 '18 at 11:26
1
$\begingroup$

After invention and successful miniaturization of fusion plants 100 years into the future ships will just fly. They will anchor and refuel on water (there is a lot of deuteruim in oceans). but will fly to move. There would be little reason to move in water when everything they have can be put in air because of very light and cheap energy generation. As not really aerodynamic they will be able to easily reach 900 km/h and probably be able to go faster than the speed of sound for short amount of time. Computers will be faster and will be able to correct all pilot errors.

Just look at "Back into the Future". They installed a fusion power plant instead of the main engine and made the car fly.

ITER (fusion power plant experiment) will generate energy in 2035 (planned). DEMO (next fusion power plant experiment) will be able to generate electricity in production scale in 2060 (planned). After the explosion of fusion science in 2070 (expected as fusion is supposed to lead to enormous cheap power generation) and focus of all countries to build fusion plants the technology will be optimized and miniaturized until at the beginning of the 22nd century a common fusion power plant will be the size of a car engine.

$\endgroup$
  • $\begingroup$ OK for the ships. But aircraft getting to escape velocity? Aircraft (admittedly, as we know them today) are fundamentally based on pushing air (whether prop or jet) and lift generated by wings flying through air. Rockets are an entirely different type of machine - not just a faster airplane. $\endgroup$ – manassehkatz Nov 1 '18 at 5:09
  • $\begingroup$ Obligatory $\endgroup$ – Euphoric Nov 1 '18 at 9:24
1
$\begingroup$

Well over 100 knots plausible.

The most significant speed limiter of a boat hull through water is frictional drag. That is the result of wetting properties and adhesion forces at the hull/water boundary. As nano-scale material science progresses it's plausible that physical nano-scale structures could be applied to the surface of ship hulls that greatly limit the ability of water to wet and thus adhere to them making them effectively friction-less. This would have an effect similar to supercavitation without the additional complexity, and it should be noted that since the 1970s there have existed supercavitating torpedoes that can exceed 200 knots underwater. For ships, the limiting factors at that point would be aerodynamics and the system of propulsion (the torpedoes are propelled by solid rocket engines). Turbo fans would be a natural choice.

$\endgroup$
0
$\begingroup$

Since a ship can be made from different materials that would affect their ability to interact with the water. a lighter weight vessel should go faster. Consider the concept of a hydrofoil craft that today achieves fifty knots with a sail and the use of a magnetic hydro dynamic engine. By the 22nd century the addition of gravity manipulation might allow a sizable ship to achieve over one hundred and fifty knots

$\endgroup$
  • $\begingroup$ This answer could benefit from adding some more details. How much more lighter could vessels plausibly become in the next 100 years and to how much speed would that translate? What's a "magnetic hydro dynamic engine" and how much better could it be than today's ship propulsion methods? And is gravity manipulation within 100 years plausible? AFAIK physicists currently do not even have an idea how it could be done, if it is possible at all. But maybe you have read something I didn't. $\endgroup$ – Philipp Nov 1 '18 at 9:09
-2
$\begingroup$

If civilization continues on as it currently is, warships would become pointless*. There would be no adequate power source, as fossil fuels will be exhausted and nuclear would be unacceptable (per the "current course" requirement). Furthermore, small drone missiles would easily destroy them.

*Even today, their only real use (other than nuclear submarines) seems to be aircraft carriers, and that in instances where the opposing force does not have practical capacity to reach the carrier. Otherwise they tend to be sitting ducks. See for instance the sinking of the General Belgrano in the Falklands war.

$\endgroup$
  • $\begingroup$ so we go back to sailing vessels... $\endgroup$ – jwenting Nov 1 '18 at 6:14
  • $\begingroup$ @jwenting: But not as warships. The point is that with (forseeable) advances in technology, it becomes easy to destroy a large investment in ships with a relatively small investment in e.g. steath drones. $\endgroup$ – jamesqf Nov 1 '18 at 18:14
  • $\begingroup$ countries are starting to come back on the drone thing as being too expensive... May change of course in time. And as those drones require power to operate, power that can't be reliably obtained in quantity except using fossil fuels or nuclear, those drones aren't going anywhere when there are no power sources left that can operate a ship. $\endgroup$ – jwenting Nov 5 '18 at 4:56

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.