OpenThruster: An open-source, mostly 3D-printed thruster for marine vehicles.

Thrusters are essential components of marine robotic vehicles for surface or underwater use. However, their high cost often makes them inaccessible to hobbyists, early-career researchers, and citizen scientists. With advancements in 3D printing, several do-it-yourself (DIY) thruster designs have emerged, allowing assembly using off-the-shelf components. However, most existing designs provide only printable files. These often lack detailed source information and, more importantly, performance data. This work presents the design, and an updated and expanded evaluation of the open-source OpenThruster project, with a focus on performance variability, fabrication methods, and dynamic modeling. OpenThruster is an open-source, low-cost, and mostly 3D-printed thruster for marine applications. The thruster itself is designed and simulated using open-source software. Performance evaluation is performed using off-the-shelf components and, wherever possible, open-source hardware. To ensure broad accessibility and long-term availability, we selected one of the most widely available drone motors and tested units with identical specifications from various vendors to assess consistency. Experimental validation involved a VESC6 driver board and bollard thrust measurements using a load cell setup in pool water. We also evaluated propellers produced, via three different 3D printing techniques. The thrusters consistently produced an average peak thrust of 18 N at 310 W, with fabrication costs kept under 500 INR (approximately $6). While thrust variation across ten motors from different vendors reached up to 11%, a one-way ANOVA test indicated no statistically significant difference between them. However, propellers made with different printing methods demonstrated significant differences in thrust output.