Originally Posted by Conrad
We installed identical 13 HP Wesmar thrusters on Blue Sky, and I can't say that there is a noticeable difference in the forces provided.
One thing that is obvious when using the thrusters is the concept of equal and opposite reactions. I.e., if you use the stern thruster for example, the bow moves in the opposite direction, at least on our NT 42. Meaning that I seldom use just one thruster as Blue Sky otherwise tends to spin on her own axis.
Also, for some reason that escapes me, when just using the stern thruster the boat moves backwards. I'm sure there's a technical reason for that.
Originally Posted by Peter B
Conrad, I'll stick my physics neck out here and suggest it is because the thruster is forcing water away from the stern on the one side, while sucking it in from the intake side, with the net effect being a bit like a that of yacht sail, creating in effect a modest negative pressure area behind the stern, which draws the vessel into it. Just a thought....others..?
I have both and they are the same model SidePower.
Some movement at opposite end is to be expected - watch what happens if someone fends off at one end - the other end moves opposite...never tried to gauge whether it is the same amount or not.
My sense is that I get more bow movement w/ that thruster and less opposite stern movement - similar w/ stern unit - more movement of stern and less opposite at bow.
If you want to move pure sideways you simply employ both in same direction - It can be simultaneously or pulsed bow then stern - I usually do the latter to avoid overheating especially if wind is strong and I need a lot of thruster.
If I want to turn in place just use them both in opposite directions and you spin
Haven't noticed moving astern but will pay more attention -
Peter - wouldn't you have negative pressure on inlet side and positive on output side w/ net being zero??
I'm wondering if there is a prop walk affect? if so i'd think it would be astern on direction and ahead in the opposite.
Don't have a good answer - I'm usually using thrusters while backing into slip so will have to play w/ them in other situations standing still.