Most of the boats of the MRF were rebuilt from WWII vintage LCM-6 landing craft, and some were purpose-built to fit the need for armored vessels for close combat in restricted waterways. The swift boat hulls were taken directly from the civilian market and fitted with gun mounts. The French had tried using boats when they fought their war with the Vietnamese. Our boats improved on their concept.
Speed was secondary to armor and firepower on the troop carriers. Surviving the first 10 seconds of an attack, or even the first shot, could determine the fate of the boat and all those aboard. The steel hull stopped small arms fire and bar armor stopped RPG rounds (sometimes). They needed a .50 cal gun to shoot through the boats and that was a difficult weapon for the VC to move around in the delta. We returned sniper fire and B40 rockets with 105, 40, and 20 mm cannon rounds, .50 caliber and 7.62 mm machine gun fire, 81 mm mortars, M79 grenades and flame throwers. Add to that all the infantry's weapons. It made the VC think twice before firing the first shot. But they did. I was always astounded by the balls that it took to do that.
The Monitors or "Mike boats" had the heaviest firepower. These were built from the same landing craft hull as all the boats but they were fitted with a conventional bow. They were equipped with turrets on their bows that housed a variety of guns, from twin 40mm Bofors guns to a 105mm howitzer. The rear of the boats had two turrets with .50 cal. machine guns and one with a 20mm gun. A recessed deck in the middle of the boat held the pedistal mounted Naval version of the 81mm mortar that was used mainly for close indirect fire, but was also capable of direct fire. A .50 cal machine gun was mounted to the top of it. Variations in armorment were common. I remember seeing a Monitor with a belt-fed fully automatic 40mm grenade launcher and I heard about one with a minigun like the helicopter gun ships used. Another version of the Monitor was the CCB (Command Control Boat) with radios instead of guns in the well deck. The crews also carried M79 grenade launchers and M72 LAWs. Monitors provided the firepower to fight our way out if need be.
If you took the gun out of the forward turret of a Monitor and replaced it with a flame thrower, you got a Zippo boat. There couldn't have been a better name. Some Zippos had two turrets on the bow so they could light up both sides at the same time. The center well deck held the fuel tank for the flame throwers. When it was full the boat rode low in the water. After a 10 or 15 second run at a target with both nozzles spraying flames, the boat would ride a few inches higher. I witnessed this once from the next boat in line behind a Zippo. It was a truely awesome experience. It left both banks of a 75' wide canal on fire back about 100 ft, for the length of a city block. It was a truely awesome and effective machine.
Most of my time was spent on Tango boats. These were the boats with the ramp in front that you've seen hitting the beaches in most of the WWII movies, with a little added armor. They were our trucks. They could be beached in the narrowest canal to drop the ramp and let us out. They were covered with bar armor and had turrets with machine guns like the Monitors. The well deck was covered with a canvas roof. Later versions were equipped with flight decks that could handle helicopters as big as a Huey. The well deck slanted down from the ramp in front to a little past midships and had bars welded at intervals accross it for footing purposes. We rode sitting with our backs to the sides on long rides or stood with weapons aimed to the sides and front when there was danger. With all guns (Army & Navy) firing we were a force to be reckoned with. When we got out in the big rivers where we were safer from small arms fire, we could climb out and sit on the gunwales or flight deck to dry out our feet, or just escape the heat below.
Sometimes the lead element of a column of boats was a PBR (Patrol Boat Riverine). These were the kind of boats that Martin Sheen rode up the river in "Appocalypse Now". There was no armor to speak of. Their defense was speed. They could duck in and out of trouble faster than the other boats and do it in shallower water. They could make strafing runs at targets and then turn around and do it again, all at high speed. They were not usually used in the narrowest canals with the Tangos where their speed could not be utilized. Armored vessels did that. They were often used to patrol the traffic on the main rivers and canals.
The ASPBs filled the space between the PBRs and the Monitors. The Alpha boats were armored, and had a 20 mm gun turret mounted high up on top where it could give 360 deg. coverage. They were used as patrol boats, minesweepers, and sometimes used to insert SEAL teams. They normally lead the boats in small waterways, and they would go ahead and prep the area sometimes, but from where I was, I rarely saw them in action.
I feel that it's important to mention the the Army had its own boats too. 16' Boston Whaler fiberglass tri-hulls with big outboard motors. Their designation was PAB for "Plastic Assault Boat". That name has always seemed like a joke that someone in an office in the Pentagon got a big kick out of. I imagine some little kid asking "what did you do in the war daddy?" "Well son, I drove a plastic assault boat." "Did it come with GI Joe actions figures Daddy?" The truth is we didn't use them to assault anything. Their main job was as a water taxi between the ships and shore, but they were also sent out at night with a driver, a rifleman with and M16 and a sniper using an M14 with a Starlight scope. They would shut the motor off and drift with the current and look for targets along the banks. They had to be very quite and be ready to start the motor for a quick exit. Holes in the boat were easy to patch because they were fiberglass, and there were a few patches.
A typical operation started with a formation of the Army troops on the pontoon tied to one of the ships that were the base to the MRF. There were two companies on each ship. We were checked by our squad leaders to make sure we had everything we were assigned and we were issued whatever equipment was specific to the operation. Weapons were given extra attention to make sure that they were ready for the task at hand. We weren't always told where we were going or anything else about the operation. It was just "going out." The information did get to us through the grapevine eventually. Some places were worse than others. I hated the area just northeast of Ben Tre. Quite often, the area of operation was all that was known and the details were worked out as the mission progressed.
The Riverine craft were normally tied up 4 or 5 deep to the side of the pontoon. To load the Tangos directly from the pontoon, all the boats were cleared away. Three boats could be loaded at a time. With all the stuff we carried, if you fell overboard you'd go down like a rock. So there were people stationed on the pontoon to hang onto us and pass us off to someone on the boat. Entering the well deck via the space between the closed ramp and the front of the roof structure, 35 - 40 fully load troops could be loaded in about 5 minutes. An infantry company could fit in four Tangos. As the loaded boats left the pontoon, they would form up with the rest of the boats into a single line that was typical for riverine operations.
The journey from the big river, would lead us to progressively smaller waterways where the alertness level increased according to the width of the passage. The Navy manned their guns and we kept our heads down. If anything did happen, there were three ways of dealing with it; (1)Shoot back and keep going, (2)Shoot back until the incoming fire stopped, or (3)Shoot back and unload the troops to go after them. More often than not it would be choice #3. Some operations were planned expressly for choice #3. We would slowly cruise the backwaters shooting at bunkers and stuff along the banks and when they shot back, we got out and chased them.
In an ambush the VC/NVA would fire from as close as 20 ft. if the waterway was narrow. It's hard to miss with an RPG at that range. They would shoot one shot and then run like hell! The first shot of an ambush usually hits what it's aimed at. We would shoot back, and call in ARTY and air strikes or maybe even get out and chase them, but a one-shot ambush would rarely yield an enemy body count. Done as a target of opportunity, as harrassment, as a delaying tactic, or just for fun, it kept our heads down and the pucker factor up.
When we stepped off a Tango's ramp we could be stepping into waist deep mud and thick vegetation or onto dry land. Or we might step right into the middle of a fire fight. When the ramp dropped it left the well deck without frontal armor. Sometimes the VC/NVA took advantage of that time when we were most vulnerable, bunched together in a confined area, by waiting to fire a B-40 rocket or small arms fire into the open bow. There was nowhere to hide if that happened. Small arms fire would bounce off the bulkheads inside untill it hit someone. A B-40 rocket only took a second to fire and its results were devastating. The Navy would prep the landing point with MG and canon fire if there was a threat. But it still happened often enough to make that moment when the ramp started to fall increase the pucker factor by 6 untill it was down, and we were out!
The battalion commander observed the operations from a helicopter. He and his radio operator flew in a LOH overhead directing traffic. If contact was made he could direct our movement, arrange fire support, and coordinate operations with the Navy. When the situation allowed, they would set down at the closest fire support barge or on a Tango boat with a flight deck near the CCB, and follow the operation by radio. If anything happened they could be airborne in minutes.
If the operation was based on good intelligence and we knew what we were looking for, we would be dropped off and the boats would move to a spot where they could provide the best fire support for us, or to our pick-up point. If the mission was expected to last a few days and we were within the range of our own fire support, the boats would go back to the big river and hold position, or go back to base. Sometimes one group of boats would drop us off and then head back to base while another group of boats would form a blocking force, and wait for us to drive the VC/NVA to them. Sometimes we would be dropped into an area by chopper, and then be picked up by boat. No two operations were the same but it was a rare occasion to be without the Navy.
I spent 13 months in the Army in the Mekong delta of Vietnam. We fought the war differently than the guys up north did. When I think back on the war, I always think about the boats.