The Concomitant Model Testing Approach for the Development of the Pendulous Installation Method of Heavy Devices In Deep Water

This paper synthesizes a method for model testing of non-conventional devices and operations. The basic idea is to perform numerical analysis in advance (or concomitantly) of the model test itself. This has been very effective over the years and its application to the development Pendulous Installation Method (PIM) of deepwater heavy devices has been effective as shown in the paper. Specifically, the PIM does not require boats with compensation systems for the usual vertical launching. The device to be installed is released from the free surface. It is hold by an auxiliary cable from a boat and connected by the installation cable to another boat some distance away. The auxiliary cable is then released and after an almost vertical trajectory of the manifold, the installation cable traction increases and the device rotates (pendulous motion) about the turning point on the other support boat. During the development of novel systems or operations, the industry is learning the importance of model testing. During the model tests, it has been understood that a two-scale problem had to be faced by the model test design. There are large bodies (the device) together with slender bodies (cables) in the same hydrodynamic situation. These two bodies have different scaling laws. How cope with it depends on the several aspects (inertia, damping, etc). However, with the help of a modern numerical model computer code, these problems may be anticipated by creating a framework of results that help in the interpretation of the model testing result itself.