This video shows Mine Sweeping Boat Division ONE launching Four LCVP Magnetic Minesweepers from the USS Cabildo LSD-16 in April 1952. MSB-1 had a variety of boats, including modified USN Motor Launches (40′ and 50′), and 36′ Landing Craft Vehicle Personnel (LCVP’s) outfitted with Oropesa sweep gear for moored minesweeping. The four LCVP’s outfitted for magnetic minesweeping could not be launched by cranes from the LSD, because the magnetic minesweeping gear was powered by several 750 lb submarine batteries stored in the boat, making it too heavy to launch via the mother ship’s cranes. Therefore, the LSD would ballast down, flooding a portion of the well deck, and the boats would simply sail out via the stern gate. Recovering magnetic boats at night, were the reverse of the process. The LSD ballasted down, flooding the well deck with enough water to float the boats, and the boats would sail into the well deck under their own power.
The magnetic minesweeping tails were approximately 1,500 feet long, with bare electrodes hanging into the water at 1,000 and 1,500 feet, alternately pulsed positive and negative, setting up large and powerful magnetic fields to detonate magnetic mines 1,000+ feet behind the towing boats. This of course was predicated that the minesweepers be as non-magnetic as possible, because they first had to sail past these magnetic ground mines lying on the bottom of the harbor.
The video shows the boats connecting to their mag tails, retrieved from these same boats using sailor-power (by-hand) following the previous days sweep operations and “flaked-down” on the well deck.
Following the magnetic mine sweeping boats, there is an LCVP moored minesweeping boat shown cutting a moored mine. Following the severing of a moored mine cable or chain, the mines float to the surface, and generally are sunk from a safe distance away by gunfire. However, in this video you see two Mine Squadron Three Explosive Ordnance Disposal Officers in a rubber dinghy paddling to these Russian made mines, and disarming then (Rendering Them Safe) for the purpose of exploiting the technology and returning then to EOD Headquarters located in Indian Head, MD during the Korean War. Generations of EOD Divers have been trained to disarm live mines on the dozens of Russian mines captured by Mine Squadron Three Officers in Wonsan, North Korea during our 900 day seige and occupation of this enemy harbor.
In fact, one of these 1,200 lb Russian MKB behemoths was discovered floating down the Long Tao Shipping Channel (Saigon River) on December 31, 1966, and the EOD Diver LtCdr Frank Talarico disarmed the MKC Chemical Horn Mine in the river near the Saigon Port Complex. He tied a rope to an eyebolt in the mine and dagged it to shallow water, he and another EOD person removed the cover plate, and pulled out the detonator and Tetryl booster. Their training at Indian Head kept them alive. The 506 lbs of cast TNT is later steamed out of the 984 lb steel case to for return to EOD HQ.
I apologize for the abrupt end to the video. Evidently, the hosting service truncated the video due to it;s size.