Keith Said:
OK, I'm confused. Are you talking about *just* a bow thruster operation?

**Yes, ONLY Bowthruster, maybe also piped to SternThruster ?? Just for
smooth docking/undocking or dead-slow movement in calm water.. I can
and do bring my 22' Inboard CuddyCabin to shore / rock points with the
canoe paddle. But having a fully-controllable couple of horsepower
should allow total maneuverability. The marine engine would be in
neutral, just running the pump...

Question: How much thrust do typical electric bow-thrusters give in
the smaller sizes?? (We'd expect them to be more efficient).. BTW,
they are expected to be used at close-to-zero hull speed, so the
thrust measurement is reasonable here.

My understanding is that they are considerably more efficient than
typical outboards, since the "ring" around the prop eliminates a
significant amount of prop slip relative to having an open prop.

Keith Hughes

Right! Apparently this is a significant factor in dead-slow
operations. There are huge (Kort Nozzles ?) on big tugboat propeller
installations. Interesting idea...

We've had some excellent information in several above posts. What I'm
getting from all this is:

- Inboard pumps to various outlet nozzles can be effective for
maneuvering and very slow speeds.

- Efficient forward-motion propulsion up to 3 or 4 knots is much more
efficient using external propeller (such as 'trolling motor' types).

My idea is a different one: I have conventional marine propulsion for
running underway, but I wish I could have good fine-control
maneuvering / docking / dead-slow sightseeing based on an inboard pump
driven from my regular marine engine. Especially with a conventional
fixed-propeller / rudder type boat that steers for c*** in reverse,
and is very difficult to turn in a short radius, this would be "Nice".

Regards, Terry King ...On The Mediterranean in Carthage

wrote:
Keith Said:


We've had some excellent information in several above posts. What I'm
getting from all this is:

- Inboard pumps to various outlet nozzles can be effective for
maneuvering and very slow speeds.

- Efficient forward-motion propulsion up to 3 or 4 knots is much more
efficient using external propeller (such as 'trolling motor' types).

I'd say that covers it.

My idea is a different one: I have conventional marine propulsion for
running underway, but I wish I could have good fine-control
maneuvering / docking / dead-slow sightseeing based on an inboard pump
driven from my regular marine engine. Especially with a conventional
fixed-propeller / rudder type boat that steers for c*** in reverse,
and is very difficult to turn in a short radius, this would be "Nice".

I certainly agree with that. Our Catalina 30 is in a very tight slip,
and we get a lot of prop-walk with our 3-blade prop. A couple of
thrusters would certainly be handy at times. Cheers,

Keith