By design, our thrusters are fully flooded, with water moving through all parts of the internals. This means that the brushless motor stator and magnetic rotor have water moving over then, and the magnets of the rotor can pull ferrous particles out of the water which will then stick. Our thruster have a larger than normal air gap between the rotor and stator, which does slightly reduce efficiency, but allows for some stuck particles to accumulate without interfering with thruster operation. However, as part of regular maintenance, the thruster should be periodically disassembled and these particles removed to prevent too large of a buildup from occurring.
When our thrusters were originally developed, we did a lot of sand and particulate testing to ensure that this was a non-showstopper issue that could be mitigated to a satisfactory degree with maintenance. However, we did only test with what was available to us at the time, California beach sand. We’re learning that marine sediment from around the world can have a very different makeup with varying particle sizes, and some with significantly higher proportion of ferrous particles. Its entirely possible that the issue is far more significant in certain environments. We’re always looking to refine our products and address areas for improvement in our thrusters; it would be great if you could provide more information! If possible, we would really appreciate additional details and pictures- could you share some of this with us over email (firstname.lastname@example.org), and perhaps help us get in contact with these customers?
Maybe we could start a collection of sand and marine sediment from around the world…