Advance speed-hull-pump-jet interactions in small asv

This paper is related to the technological development of an innovativesmall-size Autonomous Surface Vehicle designed to meet the requirementof accessing, monitoring and protecting the shallow waters peculiar of the Wetlands.The first prototype of a fully electric, modular, portable, lightweight, andhighly-controllable Autonomous Surface Vehicle (ASV) for extremely shallow waterand remote areas, namely SWAMP, was developed by CNR-INM and DITENUnige.This catamaran is equipped with four azimuth Pump-Jet Modular (PJM)actuators designed for small-size (1 to 1.5 m long) ASV. The main advantage ofPump-Jet thrusters is that they are flush with the hull, thus minimizing the risks ofdamages due to possible grounding. This system is used to increase the manoeuvrabilityin narrow spaces and to increase the spacial resolution by allowing the accessalso in extremely shallow waters with smaller risk of loosing manoeuvrability. Theknowledge of the hydrodynamic characteristics of the thruster and of the vessel allowsto partly or fully identifying the vessel for a better controllability. With thisaim a series of tests have been conducted in the DITEN towing tank. In particularadvance resistance on the SWAMP hull in deep and shallow water, bollard pull andself-propelling tests with the Pump-Jet Module working have been carried out. Theresults of the tests with the effects of advance speed on the PJM performance isreported in this paper together with the description of the modelling of the thrusteritself.