May 16, 2012:
The 21st century is barely underway and much unknown technology is yet to be invented. Many of the key warship technologies were unknown in 1912. But we can already see some new stuff which is leading revolutionary changes in how navies will operate this century. Here are some of the more obvious ones.
Unmanned vehicles. Unlike aircraft, which were a new vehicle, UAVs (Unmanned Aerial Vehicles), UUVs (Unmanned Underwater Vehicles), and USVs (Unmanned Surface Vehicles) are radically new technologies. There are already examples of all three in service. There will be more and they will change everything by incorporating more powerful AI and new weapons. That said, UUVs were first developed in the 19th century (the modern torpedo) and 20th (guided missiles). But these two weapons were not flexible enough to change as many aspects of naval warfare as unmanned vehicles will be doing.
Super Sensors. Sonar (using sound to detect objects underwater) appeared during World War I (1914-18), while radar (using radio signals to detect objects in the air) was developed during the 1930s and widely used during World War II (1939-45). Widely recognized as the first electronic sensors (although the earliest sonars were all-acoustic), their 21st century descendants are much more capable. More powerful computers and transmitting technology has since produced several generations of cheaper, more reliable, and more powerful sensors. This is continuing and the power of new sensors will make it much more difficult to hide. Stealth is still important for spoiling the aim of long range guided weapons. But the super sensors make it much more difficult to achieve surprise by coming out of nowhere.
AI (Artificial Intelligence). AI is a 20th century development that is expected to become pervasive in the 21st. Current examples includes AI assistants built into a lot of software. For aircraft designers a long-sought goal was an AI assistant for pilots. Thus the computer's memory contains the experiences of numerous more experienced pilots as well as instant information on the rapidly changing situation. You can ask your electronic assistant what the options are and which one has the best chance of success. The pilot can then make decisions more quickly and accurately. When enemy aircraft are sighted the electronic assistant can suggest which of the many maneuvers available are likely to work. If the aircraft is damaged the electronic co-pilot can rapidly report what the new options are. One becomes quite fond of computers once they have saved your bacon a few times. Many of these capabilities are being installed piecemeal, as part of electronic countermeasures or radar systems. And, bit-by-bit, these "thinking systems" are being merged, producing an electronic co-pilot. Systems that completely replace pilots are in development as well. This is not radical but part of a trend. Completely autonomous naval weapons first appeared during World War II. Torpedoes are basically robotic miniature submarines. These were the original guided missiles, although for the first sixty years the guidance system just strove to keep the torpedo moving in a straight line. Running on batteries modern ones can use a combination of their own sensors, or sensors aboard the sub that fired them, to find a target. In the latter case the torpedo communicates with the sub via a thin wire. These "wire guided torpedoes" are very common because they allow the sub to control the torpedo, if need be. By the end of World War II homing (usually on the noise of a ships propeller but also the wake of ships) torpedoes entered use. These features became standard after World War II, although high-end torpedoes now have their own sonars.
All-Electric ships. Coal powered ships appeared in the 19th century, oil powered ones came early in the 20th, along with nuclear power later. But the big revolution now is maximizing the amount of electrical power a ship can generate. That means an all-electric ship (where the engines produce just electricity and all ship equipment is electric powered). Such a ship makes possible more powerful sensors and electrically powered weapons (like lasers and rail guns). An all-electric ship also means more efficient use of power and lower fuel costs. There's no mystery in this technology, as commercial ships began using it in the 1980s. But for warships this will be a 21st century innovation.
Stealth. No matter how much better sensor technology becomes, there is always an advantage to having ships that are a bit harder to detect. In the last few decades stealth technology has developed faster than sensor capabilities. The big limitation with stealth capabilities is that they tend to get very expensive. But if you can afford it, you get an edge in combat.
Composites. Materials science went on a roll in the late 20th century, and more new, non-metallic materials able to replace steel and other metals are in the works. Composites began showing up in warships in the last few decades but as the use of these materials spreads to all parts of a vessel it will increase protection, fuel efficiency, and stealth.
Networking. This is already underway but is becoming faster, more reliable, and including more distant ships and shore stations. This kind of communications can give the side with faster and more completely networked forces a major edge.
Space Based Services. In the late 20th century navies began using space satellites for weather forecasting, communications, and reconnaissance. It was good, and the sailors want more, a lot more. To get it your space satellites will have to play defense against efforts to shoot them down. The U.S. Navy is seeking to equip its ballistic missile subs with warheads containing mini-sats to replace those shot down. American warships already have missile systems that can knock down low orbit recon satellites.
Nanotech. These ultra-tiny carbon structures are revolutionizing everything from batteries to computers and just about every aspect of warship construction and operation. Nanotech might still turn out to be perpetually just around the corner but so far it is a strong contender as the source of big changes.
Laser weapons. These would seem ideal for warships, especially those with all-electric drive. While showing much promise, laser weapons may also perpetually be just around the corner. That's where they've been for several decades now.
Anti-Ship Ballistic Missiles. Two years ago many missile experts in the U.S. Navy believed that the long rumored Chinese anti-ship ballistic missile, the DF-21D, was operational. As far as anyone knows, or will admit, the complete system has not been tested. There are hints that there were some tests three years ago and that all the components of the system were present and working. There are photos of DF-21Ds on TELs (transporter erector launcher vehicles) and announcements of new units activated for the 2nd Artillery Missile Brigade, equipped with DF-21 missiles. In theory, such weapons are possible and for China they are an ideal way of attacking American carriers. It's an expensive way to hit a carrier, since each of these missiles costs over $20 million. But if you have to get it done that's a reasonable price. In the future the price will come down a bit and anti-missile systems available to warships will be better at dealing with them. Guided warheads could also be launched from space satellites. You can see where this is going and there will be a lot more of it this century.