Making "P"-Mines

Courtesy of Don Jones - Association of Minemen (AOM) newsletter.

One day at Long Beach we were told to "manufacture" ten inert "P"-Mines (contact-fired) for planting by the YFU. They were called "P"-Mines in honor of CDR Plank (USN Retired), whose name appeared on the Distribution List of the now-defunct Mk 59 Mine's OP. Since I didn't attend the COI taught by CDR Plank at Long Beach, I had a lot to learn about the mine-design once used by then LT Plank in support of Chiang Kai-shek's KMT forces on Mainland China. Those must have been exciting days for the young LT, who recalled that one day the thatch roof of his TNT filling plant caught fire. We could tell that some of the wooden "P"-Mine tool kits we had at Long Beach had been in a fire. One of the never-seen-before tools was called a "kluge." That may have been the device used to drill a hole into the TNT charge in order to accommodate the boosters on the end of the long Mk 8 Demolition Initiator (DI). Another tool we used was the "bung-extractor/wrench."   

MN 2 Frank Styles's crew mixed the concrete and quickly manufactured the concrete anchors, counter-weights, & ballast blocks. The 55-gallon oil drums (mine cases) were carefully selected & partially-filled with 100-lbs of concrete vice the TNT main charge. I liked the Mk 8 DI used as the contact firing device, however, I did not trust the color-coded chemical pencils used for delay arming (DA). I was concerned about the large plus or minus factors on the DA-settings. I think we used a 30-minute DA, with a 5 to 8 minute +/- factor.

The Mk 8 DI was fired by a 1-g blow to the awash mine case or by a mercury switch if the mine case inverted in cases where the mooring cable between the mine case & counter-weight was cut or broke. Flashlight batteries (C-cell size) were used to fire the detonator. Getting the desired 0.5 to 0.75-inch case clearance on the water's surface was frustrating but doable at pier-side. 

We were excited when we went out on the YFU to plant the "P-Mines. When the skipper assured us that we were minutes away from launch, I activated the chemical pencils on the ten mines by twisting the knob & breaking the vial of acid inside the DI which started eating away at the spring-loaded wire. Then the unthinkable happened. We were off-course & out-of-position. Styles was the time-keeper & he kept loudly reminding everyone, including the skipper, that we were fast approaching the point at which the Mk 8 DI's could start arming. I believe the skipper took the initiative to "screw the course-correction" and told us to launch the mines. During post-analysis, we discovered all of the detonators had been fired by the time the mines were recovered, however, we didn't know when they had fired. Some could have fired during the launch & mooring phase. At any rate, it was a unique experience for all concerned & I owed many heart-felt thanks for its success to Frank Styles, who also answered to the nickname "Saigon Sam." 

Don Jones, MNCM, USN Retired