The U.S. Navy’s ‘Douche Boat’ Washed Away Viet Cong Bunkers
Powerful water cannons blasted river forts
In the early morning hours of June 10, 1969, U.S. Navy vessels sailed down a stretch of the Vam Co Dong River in South Vietnam. The force included a special weapon sailors called a “douche boat,” which could literally wash away Viet Cong fortifications.
“My assigned mission was to search out and destroy … bunkers, spider holes, trenches, booby traps and cashes [sic],” retired Master Chief Boatswain’s Mate Ray Longaker, Jr., who served for a time as commander of both of these craft, wrote in a message posted at WarBoats.org. “My crew and I did just that.”
Over the course of the June mission, the sailors on the boat blasted more than 20 bunkers and other fighting positions and safely tripped a number of booby traps. Over the next five days, the craft nearly tripled those figures after two more missions on the Vam Co Dong.
And they did all this primarily with a high-pressure water cannon rather than some sort of gun or more traditional weapon.
In 1966, American and South Vietnamese forces were fighting for control of the Southeast Asian nation’s rivers and canals. Communist guerrillas routinely built fortifications and traps along vital routes to harass government forces and commercial shipping.
“The Viet Cong was … choking off the flow of rice to market,” according to an official U.S. Army history of the riverine campaign. “Far from being ‘totally cleared of Communist forces,’ … the delta was more than ever under Viet Cong control.”
In response, the top American command in South Vietnam proposed the ground and sailing branches partner up to take back control of these inland waterways. Better prepared for major battles on the open seas, the Navy quickly developed a fleet of smaller craft suited to this entirely different kind of warfare.
The sailing branch purchased newly designed river patrol and assault support boats to hunt down the enemy and patrol the brown waters. Command ships carried communications gear to coordinate the missions.
Above — one of the two “douche boats.” Ray Longaker Jr. photo via WarBoats.org. At top — a regular armored transport. Army photo
In addition, technicians converted World War II-era landing craft into armored warboats bristling with machine guns, cannons mortars, howitzers and even flame throwers. The biggest types were called “monitors” in reference to the American Civil War ironclad USS Monitor.
Other old landing craft became transports to ferry Army and South Vietnamese soldiers up and down the rivers. Some boats had helipads and medical facilities to treat troops wounded in battle.
But Viet Cong rockets, recoilless rifles and underwater mines were still a serious threat. The militants made homemade mines in a variety of sizes using whatever materials were available. American forces captured examples made out of sheet metal packed with nearly 290 pounds of TNT — more than enough to blow apart the relatively thin-skinned river boats.
“Booby traps consisting of hand grenades or B-40 [rocket] rounds with trip wires were discovered along paths from V.C. bunkers to the river,” an official Navy history recalled of one river mission. “Other booby traps were found which were designed to detonate as boats beached along the shore.”
And hidden inside mud bunkers reinforced with logs, insurgents were well-shielded from attacks. The earthworks often simply absorbed the explosive force of large caliber artillery shells and air-dropped bombs.
Enter the douche boats.
Engineers converted these unique ships from the existing armored transports. Just over 56 feet long, these craft could carry more than 24,000 pounds of troops or gear. With a crew of seven, the ship could make up to 8.5 knots — nearly 10 miles per hour — in water as shallow as four feet deep.
But instead of soldiers or equipment, the cargo area housed a huge, diesel-powered pump that sucked in water from stern of the vessel. The system then shot the high-powered spray out of one of two, turreted nozzles above the deck.
“The water cannons put out 2,700 gallons of ‘river’ water a minute at 250 pounds of pressure at the nozzles,” Longaker explained. “If you stood to the side of the water cannon discharge and tried to drive a baseball bat through the stream of water, the water would tear the bat out of your hand and the resulting momentum would quite possibly fling you over the side!”
This is comparable to a regular fire hose, which can shoot out water at between 100 and 300 pounds per square inch depending on the pressure setting. A typical swing of a hammer onto a nail generates about 80 pounds per square inch of force.
After the douche boats were finished, troops sometimes went ashore to finish off the targets with explosive charges. Friendly forces would arrive to recover any stashes of buried supplied uprooted in the process, too. On one mission on Nov. 21, 1969, one of the vessels disturbed a cache containing more than 5,000 bullets and 15 fuzes for mortar shells.
Despite the effectiveness of their main weapon, the craft still had to get dangerously close to the shoreline to do their job. Like regular armored transports, the douches had three machine guns and 20-millimeter cannon for self-defense. Bar armor around the crew areas helped stop or deflect rockets and other projectiles.
But as the unique boats were clearing the riverbanks, Washington was pushing to turn over more responsibility for the fighting to South Vietnamese authorities. In June 1970, the sailing branch turned over one of the two douches to Saigon’s Navy, according to Longaker.
Though the river unit were shrinking quickly, American sailors continued to operate the second boat for a period afterwards. Focused on training South Vietnam’s forces, the Pentagon increasingly took a back seat in the fighting on land and on the waterways.
In April 1971, the Navy stopped escorting commercial shipping on the Mekong River. The officer in charge, Rear Adm. Spencer Matthews Jr., turned his duties over to Vietnamese naval officer. Matthews went to coordinating operations from a stationary barge on the river.
“I sure wish I was in that boat,” the admiral reportedly remarked at one point as he watched a South Vietnamese patrol boat sail past, according to Combat at Close Quarters: Warfare on the Rivers and Canals of Vietnam. “This is the damnedest war I ever fought!”
In January 1973, Washington’s involvement in the conflict in Vietnam formally came to an end. The Navy’s handed over many of their remaining boats and ships in the country to their South Vietnamese partners. The douche boats became an obscure often overlooked footnote in the sailing branch’s history.