As stated before, tanks have always been able to fire from LCU/LCMs, but the pitch and roll of an LCU/LCM made fire wildly inaccurate. Even in perfectly calm water, the recoil caused by firing the main gun made the LCU/LCM wobble for a minute. However, the M1A1 tank has a stabilized gun which allows it to fire on the move, on the ground or at sea. These tanks would not need to run their engines for power since the newer versions have small generators.

Although an LCU can carry three M1A1 tanks, this is discouraged for "safety" reasons. In addition, the M1A1 tank carries only 40 rounds, so space is needed to embark extra ammo. Therefore, an LCU gunboat should carry two M1A1 tanks (LCM-8 1 AFV) and a couple ammo crates to provide powerful fire support. They can be launched from amphibious ships a hundred miles offshore and approach within 3000 meters to blast targets ashore.

An LCU/M has a extremely small profile, so it would be difficult to see and hit. An amphibous force could launch six LCU/Ms at night to sneak up on an enemy position near the shoreline. This would allow six-twelve highly accurate 120mm guns to open fire. Anyone attempting to return fire or approach in small boats would face instant destruction. The Corps will quickly realize that LCU/M gunboats are necessary to provide cover fire for amphibious assault vehicles heading ashore. The Army could use LCU/M gunboats to conduct Special Operations.

The LCU/M may embark artillerymen to control tank fires and 120mm fragmentation rounds to fire indirectly on targets up to 10 miles inland. LCU/M gunboats may also venture into bays and up rivers to attack inland targets or support operations ashore. These gunboats would become key weapons in many low intensity operations, such as the Delta region during the Vietnam conflict.

I recommended this idea to the Marine Corps two years ago. A Colonel thought it was a good idea, but his research identified two problems. Although the M1A1 tank can fire from an LCU, direct fire is difficult because the sides of the LCU interfere with turret movement. In addition, he was concerned that the gun blast could break the LCU's window. The enemy's inter-locking machine gunfire will do more damage to LCU windows if we don't kill him. With these two problems identified, he dismissed the idea. (Good 'ole American bureaucratic can't-do in action)

But these two problems are easy to correct. Railroad ties or (Medium Girder Bridge) MGB planks can be used to line the deck of the LCU. This would allow the tanks ride a foot or more higher on the LCU to solve the turret movement problem. In addition, if the windows break, replace them with heavier glass.

An even better solution would be to fulfill the forgotten LAV and U.S. Army Airborne Assault Gun requirement with a 120mm turreted gun-mortar system on LAVs and M113A3s. The only cost being the turrets. These stabilized platforms could fire from landing craft with both direct and indirect fire, and roll off onto the beach and keep the pressure on the enemy during the inland fight. The 120mm heavy mortar is heavy enough to smash buildings in a rapidly urbanizing world and has smoke rounds capable of projecting a heavy smokescreen ahead of landing troops by sea or air. Both light AFVs are air-droppable.

Roof fired turn-table mortar systems on the LAV/M113A3 (M1064A3) already in service can also be used on landing craft but do not have direct fire capability like a gun-mortar has to point/shoot at targets that appear suddenly. These mortars can be dismounted and fired directly from the landing craft using sandbags and perhaps a stabilized mount to counter-act landing craft motion.

The Army and Marine Corps have complained loudly about the loss of fire support since the battleships were retired. A LCU gunboat is not the complete answer, but they can provide effective amphibious fire support today at zero cost.

FEEDBACK!

"There are several ways to attack the smokescreen/ obscuration problem you propose. I'll begin with two that are less effective.

The first (and most obvious) should be the smoke that the AAVs themselves produce. Im not sure what you mean by "Not emanating from the AAVs (too late)", but the AAV Plts use a technique which involves pouring oil onto the engine manifold. This oil burns (just as it would on your car engine) and produces a thick, white smoke. Its a mechanism actually built into the current vehicle and most video clips or photographs of AAVs in the water usually show this technique being used. I'm surprised that you haven't seen it used. The biggest challenge is twofold. Firstly, you're right, it is too late if the screen is coming from the assault vehicle and actually helps defenders to target the vehicles (that are otherwise difficult to see from even a few hundred yards) while still in the water (thier most vulnerable time). The other is that wind mechanics are such that most of the time (especially during summer days and winter nights) there is a land breeze (wind blowing from land to sea). This makes any smoke blow right into the attackers' face and actually clears to the defenders' advantage. The one saving grace of this technique, is that in the absence (or inadvertant dissapation) of other masking smoke, although this smoke will not mask the vehicles, it will at least provide some masking for the troops disembarking.

A second, admittedly rare technique involves embarking a mortar team on board an LCM-8 along with an M1A1. The LCM-8 is just as impervious to small arms fire as the AAV (as far as not stopping the vehicle) and the tank has the ability to fire its main gun over the LCMs drop ramp while the tank is embarked! This makes for a pretty good tertiary fire support asset that doesn't require spotters. Back to the mortar team.

The LCM-8 provides little armor protection for embarked troops, so its no good for a first wave assault filled with troops, but the tank does provide armor protection and this protection can be used by the mortar team. The dismounted mortar team (preferably 81s) can then lob smoke rounds onto the beach. This can be done with the spotter observing from the LCM8. This is effective because the team can lob rounds all the way up to and through danger close, thus providing a good screen through the movement. And they can carry a much larger load of smoke/WP rounds while embarked and expend them prior to landing without having to worry about carrying them. I have never witnessed this technique but I have talked to Marines who were a part of assaults that included such. I imagine any mortar section could be trained to do this well, though it does seem to me to be a rather special skill.

A third is to use aircraft delivered munitions. However, its tough for an aircraft to carry enough smoke or WP rounds to mask a large enough area effectively AND still be able to carry out its attack mission. Since aviation is pretty much our only source of indirect fire until we land, its best to use them for other things.

The last of course is the most obvious. Naval surface fire support (NSFS). Both destroyers (DD) and guided missile cruisers have 5" guns with a range of over 21 km (about 12 mi). Both have the MK-86 fire control computer which enables the ship to fire on two targets simultaneously. Both can fire the WP round that screens 40m of beach. Both are found within the carrier battle group, and as such available to the ARG during an amphibious landing. Not saying anything about other capabilities (or disadvantages) of the 5" guns, they can (and usually do, at least in exercises) provide masking fires.

The best possible solution using presently available equipment and organization is a combination of all three techniques along with various deception methods (such as screening an entire 20k beach and concentrating the lending to either far left/right/center or some combination).

The only reason I advocate for a mortar team, or the actual LAV-M vehicle instead of a mortar system mounted to the LCM/LCU is because the landing craft will eventually need to make a return trip, maybe even under fire, while the Marines on the beach will still need the weapon. With an embarked team or LAV-M (thats a good idea, I hadn't thought of that) you can disembark the weapon and use it in the fight.

One thing, though. None of these things are new ideas and I know that the gunboat idea has actually been accomplished (although I wish that I had dates, places and units). I'm not really sure that I understand any opposition to the idea. Especially since the M1A1 could actually roll off the boat during the first wave! Its better armored than the AAV and much better armed! The LCM/LCU is no more sinkable than the AAV and could actually beach, drop its ramp and offload the tank and be back in the water for its return trip within the time that it takes to land the AAV company and disembark the Marines. At least thats how I concieve it. Also, I know for a fact that the ramp (on a LCM-8) can be lowered from the 'bridge' of the boat without exposing sailors to fire. Just by armoring the cockpit of the boat we could make it a formidable weapon during the initial assault phase. Also, the LCM-8s don't require the railroad ties inside to allow for full turret motion (although this is a very minor point).

Anyway, keep it coming!

Semper Fi!"

Greg

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