Ours has over 3300 hours on it mounted to the engine beds. I align with the belt off then tighten the belt just enough so it does not slip. It only causes a very slight vibration when motor sailing with 12+ degrees of heel, which we normally don't do when motor sailing. Our engine & drive train is smooth as glass even with the Sea Frost mounted to the engine beds. I initially wanted to move it but it has proven to work just fine. Ideally I'd love to have it on the engine but that compressor is rather large and heavy and would require a monstrous mounting bracket. 85-90%% of the boats I work on with Sea Frost have it mounted to the hull not the engine and they all seem to work ok...