d. Plate Patches. Prefabricated patches can be made with a square piece of 10-pound (1/4-inch) steel plate. One
method is to place a thick gasket near the edges. Strips of old rubber tires will do, but a far better gasket is a thick tube
of canvas stuffed with oakum or cloth. It can be secured to the plate with machine screws, washers, and nuts, but the
holes through the plate must be reamed so the screws will not hold the plate away from the ship. The gasket can also be
held in place with retainer strips. At the center of the inner side weld is a ring or eyebolt to secure a line which holds the
patch close to the skin of the ship.
Another method often used is to drill a hole through the center of the plate and to insert a line through the hole, with the
outboard end knotted. The line used may be either wire or manila. Wire is stronger and it does not give easily. When
coated with fuel oil, however, wire is very slippery. Manila line is recommended. These plates are made in various sizes
up to 5 feet square. The larger sizes are very heavy and it is necessary to weld an eye at the top center to secure a
handling line, which also can act as the vertical support with the patch in place. Similarly, eyes may be welded in place
at the forward and after ends for securing guys. This patch is lowered over the side by the handling and supporting line.
A crew member inside the ship reaches out through the shell hole, grabs the center line, and pulls the patch tight against
the ship's side. The center line then is made fast to a stanchion.
Every ship carries a large amount of material from which almost identical patches can be improvised, such as
mattresses, pillows, blankets, mess tables, joiner doors, planks, floorplates and gratings.
e. Hinged plate patch. A variation of the plate patch is a circular plate 18 inches or less in diameter cut in two and
so hinged that it may be folded and pushed through a hole from inside the ship. The plate is to be fitted with a gasket
and a line for securing it to the ship. This patch is designed for use over a relatively small hole as it has no vertical
support to hold it in place.
f. Flexible plate patch. A flexible variety of the plate patch has been suggested for use over curved surfaces, such
as the turn of the bilge. The plate is made of lightweight sheet-metal reinforced with parallel strips of light angle iron,
welded in place, about 6 or 8 inches apart. The plate is provided with four eyes for securing lines, and it should have
some kind of soft gasket on the facing surface. It is, in effect, a stiff, metal collision mat.
g. Patches inside ship. Sometimes it is desirable to place the patch inside the ship, not only to make it accessible
but to reduce the danger of having the patch knocked away by sea action. For inside patches, innerspring mattresses
are preferred principally because they hold their shape better while being placed, are thicker, and adjust better to
protruding edges. It would be well to use at least one thickness of blanket as a facing for an innerspring mattress. Two
thicknesses of crew mattresses generally will be more effective than a single mattress.