The other day I was watching a program that included a section on the "MV Firefighter", a fireboat in service in New York. Two things particularly interested me. The first was that the boat actually used a hybrid electric drive system. Many people have the impression that this form of powerplant is still experimental, but here is an example of a vessel that was commissioned in 1938 and is still in service. The other point of interest was the output of the hoses. The Firefighter has eight water guns, and it was stated that the output of the bow hose was around 20 tons of water per minute.
Online sources indicate that the Firefighter can pump 20,000 gallons per minute, which by my calculations is 75.7 metric tons of water every 60 secs. Or put yet another way every minute a weight of water greater than that of a Abrams MBT. The fireman interviewed observed
"You have to be careful. This water jet can remove a building's roof or kill a person."
And this got me thinking. Ralph Zumbro has been discussing various ways of removing a hostile with minimum collateral damage. One of his tricks is to use a vehicle mounted .50 HMG as a sniping weapon. Another is to use 25-105mm high velocity weapons loaded with training ammunition. In many parts of the world, control of the lines of supply and communication means control of the rivers, but riverine warfare is a very neglected field. I have some reflections on riverine warcraft on this page. Certain river boats in the Mekong delta made use of firehoses to flood VC bunkers. Suppose a river patrol boat was fitted with a water projecting system of the same order as that of the Firefighter? We now have a new magnitude of potential.
If the Firefighter's hose can take the roof off a New York warehouse, a water jet like this could literally shatter many of the riverside villages in many parts of the world.
It could blast a sniper clean out of a tree.
RPG teams would be literally washed away, probably sustaining serious or fatal injuries.
Such a powerful jet will probably knock RPG rockets and ATGMs out of the air, and deflect higher velocity projectiles.
As long as the boat has power, the water jet cannot run out of ammunition it is floating on a virtually limitless supply.
The water jet has less lethal applications as well. It can extinguish fires on friendly vehicles. It also has Winning Hearts and Minds applications such as fighting forest or domestic fires.
It should be obvious that a high pressure water compressor can also form the basis of a high output hydrojet propulsion system. The offensive water jet would in fact be a useful side product of the boat's engine. It's possible that riot or marking agents could be added to the water although at this output they would need to be pretty strong. Another idea is to project a dual stream at the target and place an electrical charge across each stream. Any target hit by the streams will receive a jolt of current, the magnitude depending on the tactical situation.
Ralph Zumbro adds.
Bunkers. A friend of mine, who was on the swift boats told me of a navy trick of taking the engine out of some downed piston engined aircraft, mounting it in an LCM and using it to drive a huge navy shipboard centrifigal pump. In service, they'd nose it up to a bunker, lower the ramp, and simply wash the bank out from under the bunker....The crews called it the "Dusch boat"
Ed Sackett writes: An idea occurs to me: at need, inject small projectiles into the stream of high-pressure water, say BBs or, more lethally, small steel tetrahedrons (~3 mm on a side?). They'd be entrained and sent down-range w/ great force. The injection can happen at or just beyond the muzzle, avoiding any erosion in the plumbing.
Mike Sparks, Airborne Equipment Shop, writes:- Offensive waterjets finest hour (so far): Suez Canal, 1973. Let's not forget waterjets washed away the Israeli berms so the Egyptian Army could cross into the Sinai for the Yom Kippur war:
Carlton Meyer, Editor of G2mil, writes:- I can adjust my water hose to put out a wide fine spray, which should cloud radar, lasers, and IR detectors. So what kind of screen could these water boats provide. Seems like they could throw up a huge cloud of spray and lead landing craft ashore. Perhaps combat ships could spit out a cloud of spray to confuse radar and laser guided missiles
Ed Sackett also adds:- You can also inject material (fluids, small solids) into a water jet or just beyond the muzzle. This could be optimized according to mission, e.g., chaff when your vessel is being painted by radar or lasers
PW: The waterjet is intended to be a byproduct of any vessel that has a powerful hydrojet propulsive system, so could be fitted to an vessel that uses this means of propulsion, including landing craft. Plain water spray should block any Infra-red system such as Thermal Imaging, FLIR or targeting lasers. Ed's idea about injecting other materials will need experimentation.