Years ago I put a variable speed pump in a previous boat. Didn’t last 2 weeks before I pulled it out. It didn’t have great flow and it made lots of loud noises. It would actually groan like it was straining. I went back to a regular pump and accumulator tank. Maybe they are better now but I don’t think I will try one. Too much work putting one in and possibly having to pull it back out.
If you are one there is no explanation necessary.
If you aren’t one, there is no explanation possible.