DC Stations, Section 17, Shoring Tip 001: Shoring Overview Damage Control casualties can range from the simplest of casualties to large scale catastrophic casualties such as collisions, groundings, and weapons attacks. Some of these casualties resulting in minor structural damage to more complex structural damage or to complete devastation of compartments and even loss of the ship. While every casualty provides its own unique characteristics and strategy to attack, there are some basics that can be applied to each and every casualty and the tactics, techniques and tips for use of shoring equipment and shoring layouts will provide the user with a good working knowledge of the shoring process. Shoring is the process of placing supports against the side of, beneath or above a structure to prevent metal fatigue, sagging and bulging. Shoring is the best way to temporarily support a structure until more permanent measures are possible. Shoring is not intended to force the damaged area back into shape. Shoring Materials. Metal (mechanical) and Wood shoring are described in-depth in their particular Evolution Tip. Allowances of shoring materials can be found in the particular ships class AELS and are stowed in Damage Control Repair Stations and various other locations throughout out the ship. Repair Party Manuals, the Ships DC book and various other documents will indicate where shoring racks are located.

Shoring structures from simple to complex Wedges. A wedge is a block, triangular on the sides and rectangular on the butt end made of wood, which can also be shaped as needed to support shoring. Soft woods such as douglas fir and yellow pine are generally used and are cut with a course saw and left unpainted so that they can absorb water and better grip the area into which they are wedged. Wedges should be approximately as wide as the shoring with which they are used. They are made with various angles at the leading edge, but since the blunt edges do not hold well, sharp wedges are preferable. A good wedge has a length of about six times its butt thickness. Shoring Tools. Shoring tools are stowed within the Damage Control Repair Station as Shoring Kits. The shoring tool kit (figure 1.) consists of a measuring device, framing square in 12ths of an inch, aggressive cut hand saw, hammer, pencils, nails, shoring mauls, battens, C-clamps, and various size wedges. Allowances of shoring tools can be found in the particular ships class AELS.

Figure 1, Shoring Tool Kit

The main objectives of shoring are to reinforce straining bulkheads, doors and hatches against abnormal pressures and to support damaged and weakened structure and fittings. Both of these objectives are achieved by distributing the stresses exerted on straining or weakened members to sound parts of the structure. Main watertight bulkheads are built to withstand stresses which occur when compartments are flooded statically (compartments are tested during building to ensure this). To conserve timber and avoid wasting valuable time, shoring should not be carried out on an otherwise sound structure merely because the compartment is flooded. Extensive damage in the vicinity, however, may weaken the structure significantly enough that it becomes incapable of standing up to its designed stress point. Shoring is then necessary. The primary purpose of shoring is to support weakened structures, which can result from battle damage, heavy seas, collision or excessive weight. Straining of a structure is usually readily apparent and can be recognized by any of the following:

a. Panting - the alternate bulging and contraction of plating (caused by uneven pressure or locked up stresses) resulting in metal fatigue and often accompanied by a groaning or pinging noise.

b. Buckling of deck beams or bulkhead stiffeners. c. Bulging of bulkhead or deck plating. d. Fracture or splitting of plating, especially alongside stiffeners or where bulkheads or decks abut hull

plating.

When choosing shores, the principal concern is with stresses exerted on the shoring under the following two conditions:

1. When the shore is in direct compression; that is, when the pressure acting on the shore is parallel to its axis.

2. When the shore is subject to pressure acting perpendicularly to its axis. When designing a shoring structure, it is important to have as few shores as possible under cross-axial stress and as many as possible under direct compression. Shores will support far greater weight in direct compression than they will in a cross-axial direction. It makes no difference whether the shores are placed horizontally or vertically; it does make a great deal of difference how the pressure is applied in relation to the axis. There are three basic shoring types; I Type Shoring. Basic I type shoring also known as Direct Compression consists of a beam(s) between anchor points and strongbacks. It is pressure acting parallel to its axis, can be erected either vertical or horizontal and is the simplest, quickest and strongest shoring type. K Type Shoring. K type shoring also known as Triangulation consists of two beams between anchor points and strongbacks. It is a more complex method of shoring and requires more resources and time. K type shoring is at its strongest when the angles between the shores are 90 degrees or less. K type shoring is normally used when ships design and equipment configuration prevents I type shoring from being applied and the maximum length of the shore would be exceeded. H Type Shoring. H type shoring also known as Cross-Axial is basically a form of I type shoring in both the vertical and horizontal planes and consists of beams between anchor points and strongbacks. It is pressure acting perpendicular to its axis, normally used when the maximum length of the shore would be exceeded and K type is not practical. It can also be used to extend anchoring points in larger spaces. Strongbacks. A strongback is a bar or beam used to distribute pressure or to serve as an anchor for a patch, it can be all or part of a shore and should be as thick as the shore. Scraps of wood obtained when cutting shores should be retained for use as strongbacks and short shores. If available steel bars, angle irons and pipe can be used as strongbacks, although their tendency to spring back and forth under variable loads must be considered. Semi-permanent repairs can also be made when steel bars, angle irons and pipe are used and time permits. (Stongbacks are set up to distribute pressures on box patches, ships structures, doors, hatches and scuttles; they are arranged on watertight fittings to put as many points of pressure on the closure as it has dogs). Sholes. A shole is a flat plate used under strongbacks to distribute pressures over the damage area. They can be made from wood planks however most ships carry very limited lumber if any onboard and sholes are neither necessary nor desireable to be prefabricated therefore sholes can be made from sheet plate, doors, tables and packing crates if available.

The Shoring Flowchart shown in (figure 2.) will aid you in the decision process for determining the best shoring type to be applied for the structural damage situation.

Figure 2, Shoring Flowchart