FWIW, I like the suggestion to find out what the recommended thruster size would be and then upsize from there. If you noticed the photo of my boat that I posted in the “feeling inadequate” thread, I returned to that dock this afternoon as the current was really coming in with the 16’ tide change today. The current was pushing me directly away from the dock and the wind was at my stern pushing me forward. I have about 6’ of clearance from the boats fore and aft. The boat in front has a 17’ beam and the barge looks about 25’. Today was the first time I felt I could use stronger thrusters. The thrusters couldn’t overcome the current.
My first approach was a failure. My second approach I aimed at the dock right in front of the barge and then start to spin the boat so my wife could step off the swim step on the dock and get a line wrapped about a cleat. Then I put it in forward and the combination of that and the bow thruster were enough to get me close enough to step off with the bow line.
I’ve never had to use the thrusters more than in brief, short pulses. Today, was the first time I have ever been concerned about thermal cutout. Granted, the longest I probably ran the thrusters continuously was 30 seconds, but to me that seemed like an eternity.