i finally got my bow thrusters working. there are 2 'whale' inline pumps (used on low pressure water systems to boost pressure). i didnt have enough space to fit a conventional thruster and this arrangement works surprisingly well even though it doesnt look pretty. the copper tees are air release valves to help with initially bleeding air from the system and the box is for the battery. i used servo operated microswitches and an independant power supply which wasnt really needed but helps with ballasting issues.
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