Paddle tug Scotia

[David Allinson]

Hi there.
I started this tug around 5 years ago and after various diversions have finally got back to it again.
I have posted some pictures to give an idea of the progress(?) if that is what it is called when takes this long.
The foredeck needs some more sanding but the front end (sorry bows) is definitely taking shape.
The machinery is pretty well done bar some wiring and installing the radio. The paddles may need some rings a round them but I will see how they go first.
The scale rudder looks every small but the paddles each have their own motors, so hopeully it can be made to go round the corners.
The snaps are in my album and in the latest photos section.
All the best
David

[mjt60a]

Looking good!
On my small tug (paper boat no 2) I've tried to overcome the 'small rudder' problem like this...
...the servo arm is connected to the rudder arm using a length of rod fixed with a pivot at the rudder and run through a hole in the servo end. The servo arm is almost twice the length of the rudder arm. There's a small spring from a ballpoint pen on each side of the servo arm, held in place by a piece of brass (from a strip of electrical cable connectors) screwed to the rod. Rudder travel is limited to about 45 degrees either side of straight ahead, further movement of the servo is taken up by the springs (this also allows the rudder to strike underwater objects without damage to the steering mechanism). A pair of microswitches are operated by the steering servo at almost full travel, these are wired to 'cut power' to each motor....
So, when the steering 'stick' is moved through two-thirds of its travel, the servo moves through two thirds but the rudder goes FULL travel. More movement of the stick switches off one of the drive motors.... I haven't tried it in water yet but hopefully it should improve the models turning ability  :?
  steering servo is the lower one in the picture, micro switches are under the (mechanical) speed control...
For the next model (alumchine/paper boat no 3) I'm going to try the same thing but instead of switching off one or other motors, I'll switch into it a high wattage resistor (value yet to be determined) so the motor slows instead of stopping dead. If it works, I may use the system on the Freshwater model (and if not, I suppose I'll have to get one of those mixer circuit thingies......)

[David Allinson]

Mick.  
That looks a very neat way round it. In my mind I have been considering a much bigger rudder in the form of a sleeve that slips over the existing rudder when out sailing. The rest of the time it would live loose inside the hull somewhere. I think that will see how it performs before doing anything.  
I very interested to know how your rudder modification works in the water.  
While on the subject of sailing modifications. A friend of mine made a lead torpedo which clips onto the keel and hangs down under the boat to correct a stability problem. I made my hull a little deeper than scale, so hopefully I will be able to ballast it sufficiently to avoid that. However I have it in the back of mind if it is required.  
All the best  
David  
   
         
 
From: mjt60a [mailto:construction@paddleducks.co.uk]
 Subject: RE: Paddle tug Scotia  
 
   
Looking good!
 On my small tug (paper boat no 2) I've tried to overcome the 'small rudder' problem like this...
 ...the servo arm is connected to the rudder arm using a length of rod fixed with a pivot at the rudder and run through a hole in the servo end. The servo arm is almost twice the length of the rudder arm. There's a small spring from a ballpoint pen on each side of the servo arm, held in place by a piece of brass (from a strip of electrical cable connectors) screwed to the rod. Rudder travel is limited to about 45 degrees either side of straight ahead, further movement of the servo is taken up by the springs (this also allows the rudder to strike underwater objects without damage to the steering mechanism). A pair of microswitches are operated by the steering servo at almost full travel, these are wired to 'cut power' to each motor....
 So, when the steering 'stick' is moved through two-thirds of its travel, the servo moves through FULL travel. More movement of the stick switches off one of the drive motors.... I haven't tried it in water yet but hopefully it should improve the models turning ability
 steering servo is the lower one in the picture, micro switches are under the (mechanical) speed control...

[derekwarner_decoy]

Hi PD's & yes I know the five year bit David #$@%^_%$#!!!!!!!    , however all PD's will wait with great interest to see the completion of the only [to date] true     clinker planked hull......................... regards Derek

[mjt60a]

Mick....I very interested to know how your rudder modification works in the water....

Early tests are very promising, although there isn't much room in a flooded dry-dock (ie. in the bath!) it certainly 'turns' much more effectively than the PBM paddler does, as the tug doesn't rely on the rudder alone....I'll know more when I get a chance to take it to bluewater one of these weekends...

[David Allinson]

Hi there.
Before introducing PS Scotia to water for the first time I have given the outside of the hull a coat of varnish to waterproof the wood. I grabbed the opportunity while it was unscrewed from the building board to take a couple of snaps of the hull from the underside. See my album or latest photos.
The inside of the hull is lined with epoxy and thin fibreglass mat. It is hoped that this will serve two purposes. One to help hold it all together and second to stop the water pouring in.  Thus, when I put it out in the sun after the varnishing it came up with a few bubbles where there was air trapped inside. At least it shows that the epoxy is good!!
In due course the hull will be painted  green under the waterline and black above.
All the best
David