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Section 4 Principles of Manufacture and Construction
401. Construction
1. Where cranes are used for launch and recovery, measures are to be taken to prevent the uncon- trolled turning or slewing of the crane in a seaway. The turning or slewing gear is to be capable of holding the crane in any position. The gear is also to be designed to ensure that all movements are initiated and arrested smoothly.
2. Launch and recovery systems using an “A” frame are to be so designed and constructed that, at full reach and whatever the trim and heeling condition of the ship, the “A” frame is always subject to an outwardly acting moment. They are also to be designed to ensure that any loads occurring during the recovery of the submersible, e.g. a load change resulting in an inwardly acting moment, can be fully absorbed.
3. Launch and recovery systems are to be equipped to prevent excessive torsional forces being exerted on the submersible during recovery (e.g. by the use of non-spin ropes).
4. Measures are to be taken to prevent the submersible from striking against the ship's hull or against
the launch and recovery gear.
5. All interchangeable single components such as blocks, hooks, shackles etc. are to conform to recog- nized standards and are to be designed for twice the working load.
6. The driving power of the launch and recovery system is to be sufficient to lift 1.5 times the work- ing load. The capacity of the mechanical brake is to be sufficient to hold the test loads.
7. All interchangeable single components are to undergo, before being fitted, a component load test in accordance with the Pt 9 of Rules for the Classification of Steel Ships for Lifting Gear.
8. The rupture strength of ropes shall be verified by testing to destruction.