Seabees and Doodlebugs at Tinian

The Tinian invasion was a shore-to-shore operation from Saipan by landing craft. It began on 24 July 1944, when an advanced party of officers and enlisted personnel from the 121st and 18th Naval Construction Battalions (NCB) landed with the Fourth Marine Division on two narrow beaches on the northwest coast of the island. The assault troops were tasked to install landing ramps, used to expedite transportation of supplies and equipment over coral lined beaches at Tinian Island.


First completed Doodlebug with some of the Seabee and Marine personnel who built her. The 18th and 121st Naval Construction Battalions were attached to the 2nd and 4th Marine Divisions respectively at the time.

The Seabee assault organization on Tinian differed from the usual landing configuration for construction forces assigned to Marine Divisions. Assault patrols were trained, prior to the occupation, to perform certain specific tasks by patrols that could be activated or inactivated according to the operation requirements in the field. Seabees were organized into assault patrols under the Construction Officer on staff. These patrols worked in close harmony and coordination with the Marine Division engineer unit during the assault, and did not become part of the construction brigade until the island was secured. Twelve assault units were set up, as follows:

LVT-ramp maintenance                                                 Traffic Circulation

Beach Access                                                                     Railroad Demolition

Road Reconnaissance                                                     Railroad Construction

Road Construction                                                          Airfield Rehabilitation

Road Maintenance                                                          Civil Affairs Construction

Water Supply                                                                    Reserve

The landing at Tinian presented the Seabees with a unique problem: landing men and supplies on the Tinian invasion beach, which consisted of jagged coral cliffs up to 15 feet high that flanked the narrow landing beaches. Commodore Paul J. Halloran drew rough sketches of a plan to overcome the cliff obstacle, and described what he wanted built to mechanics of two Seabee battalions on Saipan, who then designed the apparatus using materials from an abandoned Japanese sugar mill. This apparatus became known as the “Doodlebug”. Seabees converted a LVT (landing vehicle, tracked) to supply the flotation and mobility necessary for putting the ramp itself in place. Ten of these assault ramps were built by the battalions in a short time, and enabled combat personnel and supplies to land across the ramp onto the Tinian shoreline.


Portable LVT-2 Ramp Details – Drawing 1


Portable LVT-2 Ramp Details – Drawing 2

Doodlebug drawings

Portable LVT-2 Ramp Details: General Notes

The ramp consisted of two 10-inch I beam side-rails, supporting a mat of 6-by-12-inch timbers, and was carried to the landing point by the vehicle itself. The side rails were suspended from the sides of the LVT, and sloped to permit their forward ends to clear the top of the bank. The first 10 feet of the timber mat was supported by the rails and the remainder by slides built over the vehicle’s cargo well. At the landing point, the forward ends of the rails were released and came to rest on the top of the bank; the LVT then backed away a few feet, allowing the after ends of the rails to rest on the bottom. Further backing permitted the timber mat to come to rest upon the rails for its entire length, allowing the vehicle to go ashore over the ramp.


Hooking ramp to cliff during test on Saipan.


Testing Doodlebug, 12 July 1944.


Demonstration of portable ramp for LVT-2 approaching the bluff and beach at Saipan, 12 July 1944.

A group of Seabees and Civil Engineer Corps (CEC) officers were assigned to ramp detail, and were responsible for maintaining the LVT ramps and ensuring that they were installed properly. The work lasted three days, as harbor facilities were non-existent and everything had to come across the barrier reef, to be unloaded and transported inland. As ramps were put into place and made ready, men and their equipment streamed onto the island. Seabee ingenuity was key to providing a tactical advantage that enabled the Marines to capture the beachhead and place Tinian under American control.

Coca-Cola and the Art of Seabee “Acquisition”

It’s no secret that Seabees “Can Do”, and during WWII, this extended to Seabee ingenuity with Coca-Cola bottling and bottles. While assigned to the Marianas, J.E. Lerch, a Chief Shipfitter with the 13th Naval Construction Battalion, designed a water carbonating unit after finding an adequate source of carbon dioxide. Lerch used objects he found onsite, a Japanese searchlight, oxygen tanks from a grounded B-25, scrap brass from which he fashioned a piston pump, hoses from a beached landing craft, and a motor from a damaged electric saw.  This fountain was capable of carbonating sixty gallons of water an hour, and was able to produce two thousand Cokes and other favorite soft drinks, a day.


Water Carbonating Machine, Tinian Island. U.S. Navy Seabee Museum. 13th NCB Collection.

By the time the U.S. entered WWII, Coca-Cola was an established symbol of American life. To American forces, soft drinks were a simple reminder of home. In an effort to improve troop morale, General Dwight D. Eisenhower requisitioned 3 million Coke bottles to be shipped to North Africa and the equipment to refill them twice a month. This inspired Coca-Cola to create bottling plants throughout the Pacific and Atlantic theaters. Over 5 billion servings of Coca-Cola were distributed to U.S. troops during the war, and true to form, Seabees found inventive ways to make use of the bottles for their projects.



The staff of the Coca-Cola bottling plant established on Saipan. Courtesy of the National WWII Museum.


In Milne Bay, New Guinea the 115th Battalion incorporated Coca-Cola bottles into their bus rack construction. This enabled them to use ½” brass pipes as sub-feeders, in lieu of cables, to carry the full capacity of the generators.


Coca-Cola bottles used as bus supports. U.S. Navy Seabee Museum, Walsworth Collection.


Ernest Schefer, Chief Electrician’s Mate was on Bora Bora in 1942 when he came up with the idea and designs for using Coca-Cola bottles as insulators. Early in his deployment, he observed an electrician-lineman up in a coconut tree, securing the wire with nails. These power lines carried 440-volts, and Schefer identified the current practice as being high risk, but there were limited options to do otherwise, as insulators and other appropriate equipment were not immediately at hand. Soon after, he noticed some Coca-Cola bottles lying along the beach, and began to conceive of a way to use these as insulators. He devised a system of using a metal band to hold wire loops at each ends of the bottle, and soon after, Coke bottles were being converted into insulators. He discovered that hanging the bottles downward allowed for variations, and greater flexibility in the heavy winds.


Coca-Cola bottles used as dead end insulators in lieu of porcelain standard insulators for overhead line work. U.S. Navy Seabee Museum, Walsworth Collection.

The Seabee Museum Archive is fortunate to have the Personal Collection of Ernest Schefer, which contains several original drawings for his Coca-Cola bottle insulator. These drawings highlight the ingenuity and “Can Do” spirit of the Seabees.






May 2, 2004

By: Julius Lacano

Historian, US Navy Seabee Museum


Seabees attend a memorial service on May 15, 2004, honoring seven Seabees from NMCB 14 who died as a result of hostile fire on April 30 and May 2. (Photo by PH2 Eric Powell)

Fifteen years ago today, seven Seabees serving in Naval Mobile Construction Battalion (NMCB) 14, a reserve unit based in Jacksonville, FL, were killed in action as a result of a mortar attack. Two days earlier, two Seabees from the same unit has also been killed when a convoy of Humvees en route to a school they were building came under attack.

Continue reading

Artifacts on Exhibit—Nothing to Brush Off

Capable of submerging below water, and of lifting a 2,800 ton naval vessel, at 389 feet long the Auxiliary Repair Dock Concrete (ARDC) Type Dry-dock, like the model located in our Civil Engineer Corps exhibit, was developed in the 1940s. At 3 ½ feet long, the model was constructed by the Design Division of the Bureau of Yards & Docks and is pushing and possibly exceeding 75 years in age. The U.S. Navy Seabee Museum began collecting, exhibiting, and caring for Seabee and CEC artifacts in 1949. The ARDC Type Drydock has been with us for at least 50 of those years.

The Auxiliary Repair Dock Concrete (ARDC) Type Dry-dock before conservation.

Removed from exhibit and from its case earlier this year, the Dry-dock received much needed tender loving care. With major help from one devoted volunteer (a retired Seabee), the painstaking task of making this piece of naval history shine was underway. Our experienced volunteer started the project with artifact conservation brushes for dusting; then moved to distilled water and Q-tips and cotton cloths to remove dirt and grime; next with toothpicks in hand began applying conservation glue to parts, repairing and reassembling railing wires, and loose, time-worn pieces.

“This is going to take a while,” our volunteer said. “There’s no rush,” the curator replied.

(ARDC) Type Drydock during conservation.

Approximately 50 hours and over 400 Q-tips later, the conserved 3½ feet long (ARDC) Type Drydock is back in its newly painted case and on exhibit. While many of the museum’s artifacts are stored in cases with clear Plexiglas vitrine covers, each artifact requires regular conditioning and cleaning care with the occasional “Temporarily Off Exhibit,” sign.

(ARDC) Type Drydock after conservation and back in CEC exhibit.

Next on our seasoned volunteer’s list, the WWII model of the “Seabee Special,” at 15 ½ feet long. “I’m not going to use Q-tips on this one,” he told the curator while holding a large package of sponge brushes.

The Seabee Special in storage at Seabee Museum.

USS Marvin Shields: The “Can Do” Ship

By: Julius J. Lacano

Historian, US Navy Seabee Museum

Ship’s crest of USS Marvin Shields (FF-1066)

On April 10, 1971, USS Marvin Shields (FF-1066), a Knox-class frigate, was commissioned at Puget Sound Naval Shipyard with Commander William J. Hunter in command.  Marvin Shields was built at Todd Shipyards in Seattle, Washington.  With a design based around the large AN/SQS-26CX sonar, she was armed with an eight round ASROC (anti-submarine rocket) launcher forward.  She also carried a Mk 42 5”/54 caliber naval gun for air and surface targets.  The Shields and her sisters were designed to provide the US Navy with a potent anti-submarine warfare platform.  While designed to carry the QH-50 DASH anti-submarine drone, the cancellation of the program led to the class carrying the SH-2 Seasprite Helicopter.  This helicopter included LAMPS (Light Airborne Multi-Purpose System) an advanced anti-submarine and anti-ship scouting and attack system, which added to the already potent anti-submarine warfare suite contained on the ship.

Continue reading

Crossing the Line: The First Marine Expeditionary Force Engineer Group during the Invasion of Iraq

By: Julius Lacano

Historian, US Navy Seabee Museum

Insignia of the I MEG. It consists of a Castle to symbolize the Army Corps of Engineers and the Marine Corps Combat Engineers, the Eagle, Globe, and Anchor of the USMC, and the Seabee insignia to symbolize that the bulk of personnel assigned would be Seabees.

On March 21, 2003, Seabees crossed the Line of Departure into Iraqi territory as part of the First Marine Expeditionary Force Engineer Group (I MEG). According to “Forward Together!”: I MEG in Operation Iraqi Freedom, “This marked the first time that Seabees crossed into enemy territory in Regimental strength as members of a Marine Expeditionary Force order of battle.” The First Naval Construction Division provided the bulk of personnel for the I MEG. This unit consisted of four Seabee Battalions (NMCBs 4,7, 74, and 133), three reserve Heavy Air Detachments, a Naval Construction Force Support Unit (NCFSU 2), a Construction Battalion Maintenance Unit (CBMU 303), an Underwater Construction Team, two Army Engineer Battalions (478th and 1092d Eng Bn), and a Korean Engineer Battalion (1100th ROK Eng Group).

Continue reading

Operation Crossroads and the 53rd NCB

53rd-logoThe 53rd Naval Construction Battalion (NCB) was established on December 22, 1942 and served throughout the remainder of WWII, primarily on the Pacific Islands of Guadalcanal, Bougainville, and Guam. As post-war activities were nearing completion, the battalion was scheduled for inactivation on March 1, 1946. The inactivation was cancelled when the unit was selected to participate in Operation Crossroads, a series of nuclear weapon tests conducted by the United States at Bikini Atoll in the Marshall Islands, in mid-1946. Operation Crossroads was the first test of a nuclear weapon since the Trinity nuclear test in July 1945, and the first detonation of a nuclear device since the atomic bombing of Nagasaki on August 9, 1945. Its purpose was to investigate the effect of nuclear weapons on naval warships, equipment, and material.

The 53rd NCB arrived at Bikini Atoll on March 13, and then transferred to the USS St. Croix, which was anchored in the atoll lagoon. This ship served as the battalion headquarters throughout the Bikini operation. Drawing on their wartime experience in fast construction, nearly 1,000 Seabees with the 53rd NCB transformed Bikini Atoll into a huge laboratory where instruments and structures were set up to record the blast.

The composite battalion of stevedores, pontoon builders, and construction men began the main construction projects which included the erection of several 90-foot towers and protected steel huts for housing the instruments used for recording the blast data, the day after they arrived on site.


Offloading of supplies and equipment

Heavy equipment, to include bulldozers, trucks, and cranes were brought by LST, along with more men and supplies arriving from Pearl Harbor and Port Hueneme, CA.


Seabees with the 53rd NCB constructing a tower to hold automatic camera as part of Operation Crossroads. The towers were built on an island near Bikini Atoll to document the Atomic Bomb explosion.

Seabees built 15 steel towers for photographic observation, several wooden frame towers, and advanced base magazines measuring 20 feet by 20 feet.


The Bikini Atoll is comprised of 30 islands, and Seabees completed projects on 9 of these. Among these projects were demolition operations to remove coralheads to enable LSTs and small craft to land on the beaches, along with the construction of recreational facilities for 35,000 men, to include baseball fields, basketball courts, tennis courts, and an archery range. Construction efforts were made extremely difficult by the constant churning of the black, sandy soil on the beach, which became choking dust clouds as vehicles were transported back and forth. DDT, then unknown to be hazardous to health, was sprayed repeatedly from low-flying planes to combat the hordes of flies that were constantly plaguing the Seabees as they worked.


Aerial view showing one of the many construction sites operated by the 53rd NCB at Bikini Atoll

Operation Crossroads5

The Baker Day explosion of the fifth atomic bomb, Bikini as recorded by an automatically operated camera on a nearby island. Characteristic atomic clouds forms, altered by steam from sub-surface detonation

Operation Crossroads consisted of two detonations, each with a yield of 21 kilotons of TNT (96 terajoules): ABLE was detonated at an altitude of 520 feet (160 m) on July 1, 1946; BAKER was detonated 90 feet (27 m) underwater on July 25, 1946. A third burst, CHARLIE, a deep underwater detonation planned for 1947 was canceled due to the inability to decontaminate the target ships following the Baker test.

With the completion of Operation Crossroads, the battalion was inactivated on August 3, 1946 after 38 months of continuous overseas duty. Some battalion members were transferred back to the United States for separation from the Navy, while others remained onsite for cleanup and restoration duties on Bikini. These members were assigned to the newly activated Naval Construction Battalion Detachment 1156.