This article presents the design and manufacturing approach behind the thruster system developed for use in the ROV (Remotely Operated Vehicle) competition of a student team from University of Stavanger (UiS) called UiS Subsea. Starting from 2014, this team participated in an international student competition organized by MATE (Marine Advanced Technology Education) in North America. The thruster discussed in this article was design and developed for the competition that took place in NASA buoyance laboratory in Houston. The work focused on finding alternative methods to reduce production costs for the ROV thrusters and increase the thrust by, among others, reducing friction losses. Compared with the first design version of the 2014 entry, this new design shows a 29.4 % increase in thrust. The increase of thrust can be attributed to use of a Multi Jet Printing (MJP) technology whose better surface quality has decreased friction on the surface of the propeller blades. Extensive testing of different propeller parameters, such as number of blades per propeller and propeller pitch were compared. The best all-around parameter combination was discovered to be pitch of 50 degrees and three propeller blades. Although the propeller principles were only used as guidelines, it is recommended to put more emphasis on the propeller's angle of attack and foil-shape in future projects.
An ROV (Remotely Operated Vehicle) is a tethered unmanned underwater robot commonly used in deepwater industries such as oil and gas exploration and mineral exploration. Driven by the extremely complex marine underwater environment, which is characterized by physical and chemical processes as well as biological population (Conte et al, 2017a), recent developments of unmanned underwater vehicles have focused on the guidance, control and related sensor systems. Among available unmanned underwater vehicles, ROVs are the most often used and they are equipped with propulsion systems and controlled only by thrusters. Based on the size of the machine, the sensors and the tool capacity, ROVs are categorized as micro, mini, general work class and heavy work classes (Moore et al. 2010). The micro and mini versions are lightweight machines up to 3 kg and 15 kg respectively and mostly deployed for underwater observation purposes for locations inaccessible for human divers. These vehicles are equipped with video cameras, light systems, thrusters and few light duty sensors. The work class categories are additionally equipped with diverse capacity manipulators and sensors. They have both larger size and capacity (100 to 150 hp) and operate at water depths varying from 1 km to 3.5 km.