The U.S. Navy has adapted surveillance balloons (aerostats) to operate from the rear deck of a high-speed transport vessel. This increases the ability to detect small drug smuggling boats from 8 kilometers to 80 kilometers and provides the ability to spot the smugglers in all weather, day or night. This is a big deal for naval reformers advocating the return of untethered blimps. After over half a century of effort, blimps (helium filled lighter-than-air aircraft, tethered or not) have returned to favor on the battlefield. The last time blimps were widely used was World War II, when hundreds roamed coastal waters looking for enemy warships (mainly German submarines), and thousands of tethered ones served to prevent low altitude bombing attacks. The U.S. continued to use blimps for maritime patrol until the early 1960s, and advocates have been trying to get blimps back into action ever since. Now, combat commanders who have used can't get enough tethered blimps. The key difference here is the tether, which allows the “blimps” to stay in the air for weeks at a time because they don’t run out of fuel and the “crew” is on the ground. It’s the same for aerostats at sea, where sudden changes in weather have destroyed many blimps, often with no survivors.
The high-speed ship that has been turned into an “aerostat carrier” is the USS Swift (HSV 2), a twin hulled catamaran. This vessel is 103 meters (320 feet) long and displaces 1,900 tons. It can carry up to 800 tons of cargo and has airline style seating for 300 troops, although up to 600 can be carried. The cargo can include vehicles of up to 70 tons each, including M-1 tanks. Vehicles are driven on and off. There is a trade-off between tonnage carried, and speed and range. The twin hull design is also slowed down quite a bit in rough seas. This is not the kind of ship you can use much in the north Atlantic or Pacific. But in the Caribbean or off the west coast of Central America the Swift can stay out for a long time and, barring nasty weather, keep the aerostat in action 24/7.
The U.S. Army has used over a hundred aerostats in Iraq, Afghanistan and elsewhere. Originally designed to operate with vidcams, in 2010 the army added the AN/ZPY-1 Starlite lightweight radar. The Starlite radar weighs 29.5 kg (65 pounds), occupies 34 cc (1.2 cubic feet), uses 750 watts of power and costs about $2.3 million each. The Starlite was originally designed for use in the army's 1.5 ton MQ-1C Sky Warrior UAV. Starlite can deliver photo quality black and white radar images of what is down there, in any weather. The army has developed software that enables the Starlite images to be transmitted to video terminals and automatically appear on electronic versions of standard maps. Starlite is used in combination with vidcams and heat sensors (infrared or thermal) making it possible to see anything on the water within 80 kilometers of the aerostat equipped ship no matter the weather.
The army aerostats usually float at about 320 meters (a thousand feet) up, tethered by a cable that provides power and communications to the radar and day/night vidcams up there. The navy uses a 640 meter (2,000 foot) cable because the aerostat tends to trail behind the slow moving ship. During land operations the aerostats could stay up for 30 days at a time, but if the enemy was shooting at them some of them came down every few days to get patched up.
The USS Swift has a helicopter pad and space for two UH-60 or CH-46 class choppers but when carrying an aerostat that is where the aerostat sits. The basic crew of the Swift is only 20, but there are crew quarters for 51 and the galley can feed up to 150. Additional personnel would be onboard to operate the aerostat sensors round the clock.
The important aspect of the HAV is speed. The Swift maintained a speed of 83 kilometers an hour for four hours during sea trails. The ship can cruise at 63 kilometers an hour for 2,000 kilometers, or 7,200 kilometers at 36 kilometers an hour before it has to be refueled. The HSV has four water-jets, in addition to its normal engines, making it very maneuverable. The Swift was going to be used mainly as a mine warfare support ship, but additional HSVs will serve as high speed transports.
Weapons can include manned 25mm automatic cannon and remote controlled 12.7mm machine-gun or 40m grenade launchers.
The Swift can also carry high speed inflatable boats to carry boarding parties to suspicious boats. But the main advantage of the aerostat equipped Swift is to spot drug smuggler boats and alert other navy and coast guard ships to intercept.