Section 4 Design Loads and Supporting Structure

401. Design loads

1. The following principles are to be applied when design loads are established.

(1) The application part is the weakest structure

(2) Progressive strength of components, so that hydrodynamic lift generating part is weakest link

(3) All relevant cases of asymmetrical loading during maneuvering

(4) Absence of ice

2. Specific loading criteria are given for the different applications.

3. Design loads are to be submitted together with documentation for approval.

Pt 4 Hull Equipment

Ch 2 Hull Appendages Pt 4, Ch 2

402. Foundations and strengthening

1. Major load carrying members are to be supported by properly aligned members inside the shell plating (floors, additional intercostal stiffeners).

2. It is essential that the supporting structure extends well outside the area of the supported append- age, and is well integrated with the craft's primary structure.

3. For appendages welded to the hull, major load carrying members may be required to be carried continuously through the shell plating to connect with the internal primary structure.

4. Shell plating in way of any appendage is to have a thickness not less than 1.5 times of thickness for shell plating at that location.

5. Floors, bottom girders and other internal structures are to have welding/bonding requirements in- creased by 50 %.

403. Connections

1. Flanges and machined areas prepared for bolted connections are to be of substantial thickness, nor- mally not less than 3 times the thickness for the shell plate at that location. The extent of sub- stantial thickness flange plating are to be such that it is directly supported by internal structure (e.g., passing closest floor plating forward and aft of flange).

2. Machining of the bolted area is to take place after all welding in the area is completed.

3. Bolts are to be pretensioned according to an accepted standard.

4. When chockfast or similar is used, specification of type and pretension of bolts is to be documented.

5. After mounting, it is to be ensured that all gaps and corners are filled with compound. Smooth waterflow is to be ensured, to avoid undesirable cavitation creating surface erosion.