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[Terry]

My current build, a paddle ship, has a Length of 94cm, Beam 17cm, width across the Sponsons 33cm, and an all up weight of 5kg. It is a bit unresponsive to the rudder, and struggles against even a small sidewind. This before it even has a superstructure. I am going to fit a Raboesch bow thruster. I would welcome any advice regarding the size of Bow Thruster to use, don't want to over-engineer it!! Power for this boat is 6 volt.


Cheers, Terry.

[GG]

Terry,
       Well you've given us some information to work on but a little more is needed before anyone should attempt to give you a detailed response.
You say the model is "a bit unresponsive to the rudder" which, along with the idea to install a bow thruster suggests that you do not have independent operation of the paddle-wheels?
The comment that it " struggles against even a small sidewind" sounds like a lack of power which could be due to inadequate motor power, poor paddle-wheels and perhaps the wrong immersion depth?  My own experience, admittedly with smaller models than yours, is that the wheels ought to be immersed to 1/4 - 1/3 of their diameter and rotating at more than about 200 rpm gains little (well it does if you are into noise and froth).
If it's a scale type of rudder, it's likely to have inadequate area plus operates the the slow moving water flowing next to the hull.  More area, especially if it can extend below the line of the hull bottom, can greatly improve the rudders effectiveness.
Finally, if you want better steering whilst sailing the model, then a bow thruster might prove to be a disappointment.  In my experience with models, they are best with the model stationary or only moving slowly.
These general comments are be best I can do without knowing more about your model and it's problems.


Glynn Guest
 
 

[nemesis]

Welcome to the faults that a few paddlers have, Sandy Thomson, he of  Waverley fame always had a "big " rudder and the rpm of the paddles was geared to about 120. Paddles were the feathering type. hope that helps, nemesis

[Colin Bishop]

Terry,

You have asked the same question on the Model Boats website - see the responses (including mine) on there.

As Glynn says, the basic solution is independent control of the paddle wheels. It's really the only practical solution for models.

Colin

[radiojoe]

Hi Terry,,  I've got a bow thruster in my 1:48 Brocklesby MCMV in my experience their only use is stationary manoeuvring, when the boat is underway they have little or no effect, I'd have to agree independent paddle control in conjunction with a large rudder is the way to go, bow thrusters are quite expensive and would need it's own ESC so a large layout for little gain.


Joe.

[GG]

Colin,
           I don't think Glynn did say "the basic solution is independent control of the paddle wheels.  It's really the only practical solution for models".


Agreed, it's one option but not the only or best one for all models.  I've built a couple of paddler models and just used a rudder for steering.  They handled just as well as most models because, accepting they were model boats, I used a sensible model sized rudder.  In fact they were just like a twin screw single rudder model in that the initial sideways kick possible when setting off with full rudder and a single screw set up was absent, but once moving the rudder was in-charge of steering. Also, worked OK when moving astern.


In fact I have found steering with independent screws or paddles to be quite tricky and for precise maneuvering and actually prefer a rudder.


It still comes back to my first comment of the described problems with poor rudder response and affected by side-winds.  Which suggests any solutions might well lay elsewhere.  We really need more information on the model under discussion before any advise with value can be given.


Glynn Guest

[john44]

I agree with joe, a bow thruster would be useless in your situation. On my old Glasgow paddle tug
I changed to independent paddle control, that was quite costly, as Glyn said you will definitely need
An oversized rudder fitting and possibly a faster drive unit depending on type of paddles and
how much of the paddles are in the water at the waterline.
You have not left much info to go on.


John

[RST]

It possibly doesn't help having 2 recent threads running on essentially the same subject.  Perhaps you could ask a mod to merge the threads?  It will bering more of your info together, and save you ending up with what might be pretty much the same advice twice over.  I can't help you personally as never bitten the bullet on a paddler yet.  Never seen a model one with a bow thruster for afforementioned reasons, they have all had massive over-sized rudders though.

https://www.modelboatmayhem.co.uk/forum/index.php/topic,64689.msg685991.html#msg685991

[Terry]

Thanks for all of your replies, you have given me plenty to think about. At the moment I will try an oversize rudder, it's the simplest option.
Glynn you are correct, I do not have independent control of the paddle wheels. The motor, paddle wheel immersion, and paddle wheel design and size, give enough forward propulsion against a headwind. I was referring to the boats weakness turning into a wind. I will see how the oversize rudder works out.


Cheers, Terry.

[Terry]

Thanks everybody, oversized rudder fitted, problem solved.
Cheers, Terry.

[ChrisF]

On both boats! 


Chris