Good to hear from you. I've had a little bit of experience with bow
thrusters on fishing boats. They are bow thrusters and really need to
be at the bows to work properly.The best one was one a 20m purse
seiner with the bow thruster in a pod attached to the front of the
bow. There is always the problem of drag having a hole at right
angles to the boat Unless you have a small thruster running ll to
the hull feeding onto the forward rudder- is this what you had in
mind. My own feelings are that the paired rudder system with a single
outboard drive would give enough manoeverability for just about any
circumstances. This would be my preference but a paired set of fixed
screws that fed onto the rudders would also work. How about an out
board for the main propulsion and a small thruster to use while
docking .
Robert


-- In harryproa@..., "jjtctaylor" <jtaylor412@c...>
wrote:
>
> Been so long nearly forgot my password !
>
> With the progress so far with Johnnie's boat, the visionarry in
> latest stage of development, the aux drive has left me with some
> questions and possibilities for input from our distinguished
> forum. Albeit a quiet forum.
>
> Outboards is the current plan, a pair of 15 horse honda's which
> is a highly reliable 4-stroke. Certainly the most economical
> choice and most likely to succesfully get it in the water.
>
> The question I have,... is there better choices ? Lot's of history
> with swamped outboards and propulsion woes with prop out
> water in sloppy seas. I find the outboard closest to the WW hull
> most at risk since it is not really close to the hull itself but
> suspended part way across the beam due the WW hull
> expansion. Yes OB's are a workable solution in moderate seas,
> and perhaps a little awkward with initial manuevers in close
> marineas cause the motor is not evenly spaced across the
> beam, but functional. Rob's & Mark's plan includes 24 hours of
> fuel aboard.
>
> As food for thought to kick off the discussion I suggest a single
> electric drive near the LW hull either as outboard or extendable
> from inside the LW hull. Must be kept close to the hull,
> upstream of the rudder to insure better helm control and the prop
> stays in the water. At the other end would be a bow thruster
> likely just aft of the leading rudder. An electric drive is
sufficient
> to replace both outboards (an equivalent 20-25 HP diesel) and
> slow speed maneuvering can be deftly handled by the bow
> thruster.
>
> Anybody ever had a bow thruster ? Some issues remain such
> as the thruster tube nacell, will it cause excessive drag in a
> bi-directional shunting kind of mode ? There are retractable
> options but much more costsly than an electric thruster and 2
> batteries. (est 210-220 Lb force required)
>
> Taking input, preferences, previous experience, or technical
> saavy !
>
> Regards,
>
> JT