Shoring, Pipe Patching, and Plugging
Large Plate Patch
Repairs that could be made with large plate patches were a major effort underway or at anchor that required several personnel and a large quantity of DC equipment. Plates of sizes up to five feet in diameter were used with great success during WWII. Holes larger than five feet almost certainly required that the work be done in a shipyard.

Some large patches were partially prefabricated, with the plate pre-cut and stowed for quick access. A final preparation was to weld a series of pad eyes onto the plate. Some pad eyes were measured to be inset to the existing hole opening, used to attach the long handling lines on the inside edge. The largest weight-bearing pad eye was placed in the top center of the patch for lowering it on the outside of the hull and hauling it into position. Two pad eyes were welded to each top outside corner of the plate to aid in lowering, especially for plates more than two feet across. Two additional pad eyes were welded on a horizontal plane inside so as to secure additional lines or guys to stabilize the patch and hold it in place. Guys were also used to support the patch after installation.

Either the chain falls or block and tackle was used in lowering the plate over the side of the ship. The handling line was attached to a stanchion or other secure stable structure topside, the slack let out as the plate was lowered into position, and tied off when in place. The chain falls’ hook was secured to a steel wire rope strap that was secured to a solid stout structure or pad eye.

Eleven Sailors plus the diving team were generally required for large plate patch repairs. Personnel were most always from repairs 1, 5 and 3, and also their unit lockers. For rigging pad eyes, lines, chain falls or block and tackles in these big damage control evolution repair jobs, it was preferred have a boatswain’s mate chief (BMC) from repair 1 in charge; three to five additional boatswain’s mates were required for rigging, especially if more block and tackles with jiggers were being used. Three damage controlmen (DCs) or carpenter’s mates helped to handle setup for the installation. Three shipfitter-metalsmiths (SFMs) were required for fabrication, setup, installation and welding.

If the damaged space was accessible, a Sailor stood by in it with a long pipe with a “J” or boat hook to pull the line and patch into position. If the damaged compartment was inaccessible due to flooding, a qualified shallow water diver with the hose air-line mask outfit dove down through a hatch opening into the compartment to secure the patch in place. When the plate was being lowered into position, the main handling line was attached and wrapped around a stanchion or other secure stable structure. A Spanish windless was then fabricated, with a small pipe or a wooden stick inserted in the lines and turned several times to tighten the line. Once tightened, the pipe or stick was secured with a small ½-inch line to prevent it from spinning out of position. This procedure created tension on the line holding the plate patch in place from the inside. The patch was sealed with a rubber gasket or rolled canvas after all hot work was completed.

This type of patch had to be inspected frequently, as they tended to shift and slip with the movement of the ship, especially if semi-permanent welds to brackets, clamps or other types of holding devices were not made. A watch had to monitor the installation, similar to a shoring watch.

Once a plate patch was installed, the compartment was dewatered using the portable P-500 pump, in combination with eductors, to dramatically improve the ship’s stability and reserve buoyancy, which were prime considerations. This was especially the case if the damage had approached or exceeded 15 percent of the ship’s length and reserve buoyancy.

Appropriate reports were made to the on scene leader (the BMC) when the hole was under repair and when the repairs were completed.

For more information, see the Index.