Dominant Logistics
A 21st Century Monitor - The Abrams HoverTank
Some have suggested bringing back an old type of vessel called the Monitor. These were heavily armed and armored, similar in concept to a small battleship. The idea is for a survivable combat vessel capable of operating in areas where larger ships cannot. But most Monitor proposals are based upon existing technologies packaged in a new way. While they may improve the capabilities of the Navy, I think there is a better option available.
When most people think of hovercraft, they think of vessels like the Landing Craft Air Cushion, or LCAC. Many other examples are available but they are generally larger craft designed to carry large amounts of personnel and materials over water and on to land. What most people aren't familiar with is the rich history of the hovercraft in operating over wide varieties of terrain. As far back as the 1960s, hovercraft were used for expeditions through the jungle and desert regions of South America and Africa. During Vietnam, hovercraft played a critical role in operations in marshes and swamplands. Hovercraft have also been operated in the polar regions as well. As long as the terrain is relatively level and even, hovercraft can operate there regardless of circumstances.
Hovercraft are also unique in that their method of riding a cushion of air makes them nearly impervious to mines. Hovercraft float sufficiently above the ground that most mines fail to go off when a hovercraft passes over them. These vessels are also highly resistant to conventional arms as well. While the skirts that form the air cushion are not bullet proof, they are heavy enough to resist some shrapnel and small holes are insufficient to affect a hovercraft's operations. Unfortunately, the same cannot be said for the cabin of a hovercraft - and this is where the hovertank comes into play.
Instead of building the hovercraft as a sort of floating truck, why not build it as a floating tank? Instead of carrying a payload, the vessel can carry armor and guns. Recoil from the main gun may be a bit of an issue but not a major one as the vehicle will have a high amount of mass to absorb much of the recoil. This type of a vessel could make heavy direct fires available in a variety of useful situations. For example, in the case of an amphibious assault, no heavy direct fires are available to support the landing troops as the ships and boats are either too vulnerable to go to the shore or are too small to support a major gun. The same advantage would be available in riverine warfare as well.
This vessel could also be useful in conventional land operations as well. Large open areas are often heavily mined or formed of loose terrain like sand and a hovertank can simply fly over these with no problems. Or it could be used over lakes or swamps to gain tactical advantage through manuever. But instead of being just another hangar queen waiting for the right war, this vessel could be used today in a fast attack boat role supporting Coast Guard and other operations where boarding other vessels is necessary. Hovertanks can chase down even the fastest of modern boats or engage them with weapons if need be. And since the hovertank is a well armored vehicle, if the vessel being chased opens fire on the hovertank, it won't necessarily need to fire back but the option is there if need be.
An Abrams HoverTank
Since there are currently thousands of excess Abrams tanks, these would probably be our best bet for developing a hovertank. We should use the turret as configured for the suggested M1A3 with a 30mm secondary cannon. For the commander's weapon, we should also go with a 30mm cannon instead of the 40mm GMG. The vessel should also have three additional fighting positions, each with a 30mm cannon and a 7.62mm machine gun. Two of these should be mounted on the top of the hull towards the rear of the vessel while the third should be positioned in the front as a bow gunner.
The vessel should be long enough to accomodate a full squad of infantry or Marines or up to two teams of Special Operations Forces. Alternatively, the hovertank could carry critical cargo or additional ammunition in the open space in the rear. This could also be used as space for an additional fuel tank to increase range. While this vessel is going to be pretty large at roughly 20' wide by about 40' in length it will be very well armored and well armed. This excess size should also enable the hovertank to float or even to operate in the water without hovering at slow speeds.