PS Presto Build - American Civil War Blockade Runner

[Don]

August 2010.  The attached photo shows the boat on our local pond at speed on trials.  My initial trials in the local swimming pool showed that 57 RPM did not move the boat along very well.  So, I put a larger sprocket on the motor output shaft and got the RPM up to around 115 RPM.  You can see in the picture that at that speed the boat makes a nice wake and appears to move close to scale top speed.  I was real happy with how the boat moved through the water.  With no decks, bulwarks or superstructure the boat had a low center of gravity and little surface area for the wind to push around.  I knew all that would change when I added decks, bulwarks, funnels, but I was also comforted by the knowledge that blockade runners were purposely built low to the water with little superstructure to make them more difficult to detect.

This is where I learned that scale rudders do not have enough surface area to give a model boat a good turning radius.  I may retrofit with an extended rudder similar to Connaught at a later time.   

[Eddy Matthews]

Don, unlike boats with props, paddler rudders aren't really in the flow of water from the paddle wheels, so they are always poor at turning - That is also true of most of the full sized vessels!

The slower you go the less effect the rudder will have, so try to keep the power on at a reasonable level when turning - Of course increasing the rudder size will definitely help! If it's still poor at turning, you could look at installing seperate drives to each paddle wheel, and use a mixer, such as those made my ACTion Electronics http://www.action-electronics.co.uk/mixers.php

Regards
Eddy

[Don]

Eddy,
Makes perfect sense when you think about it.  With a screw in front of the rudder, the prop wash gets to push on the rudder.  So, now I'm not as concerned about the turning radius of the model and will probably keep it like it is.  I'd say it turns pretty well for a paddler.

Don 

[Don]

September, 2010:  See attached photos.  Now that I have the motor and paddles moving at a good speed I moved on to covering the paddleboxs.  These were a challenge for me but I was happy with how they came out.  I left slots in the paddleboxes where the steps are going to be.  My theory was that these would make it easier to align and mount the steps when I got to that part of the build.  I also stepped the two masts and was ready to move on to the decking after this.   

[derekwarner_decoy]

Hi PD's......Don....looking at your posting 000001.jpg of the rudder.....the rudder image is loosly triangular in shape 

A very simple alternate variation/fix would be to produce a "barn door" rudder [rectangular of square] in profile....if you kept to the same envelope dimensions you would have approx 30% more rudder surface area & hence proportionally better steerage

Keep the coming.....Derek

[Don]

October 2010:  You can see here that I'm planking the deck.  It took a while but I'm happy with the result.  The model is big enough that I was able to use the openings in the deck for the cabin between the paddle boxes and the cabin house aft, along with the two openings for the two boiler casings to access the motor, batteries, ballast and steering servo.  There appear to be a few advantages to building big.  The disadvantage will come when I'm finished and ready to display it.  Where am I going to put it?     

[Don]

Still October 2010.  I have finished covering the deck now and have moved on to making the bulwarks.  On the real ship the hull was made of iron and the bulwarks were made of wood.  On the first picture you can see where I tried a bit of nibbing into the king plank on the foredeck.  It came out pretty well for my first go at it, but I could use more practice.  Unfortunately, the best run of nibbing is covered by the turtleback now so you can't really see it.  Oh well, I know its there! 

[Don]

November 2011:  Work continues on the bulwarks and on the sponsons.  It was relatively straight forward and fun to do.  I especially enjoyed making the part of the bulwark that curves out onto the sponsons.  I think these graceful lines are one of the most beautiful features of the ship.  I also finished making the grating that comprises the sponsons.       

[kno3]

This is a very nice build and a beautiful model.

What are the spaces between planks on the paddlewheel top/back covering for?

[Don]

I made the spaces for the steps that went up the paddle boxes.  I had never built a model like this and I was afraid the steps were going to be difficult to align.  You will see in later pictures how it looks with the steps in place.  I'm not sure this was a good method.  It worked well and came out fine, but I don't think it was worth the extra time.  If I were building the model again I would do it without the spaces. 

[kno3]

Thanks!

[mjt60a]

I'm following this build with just as much interest as all the others - including my own 

[Eddy Matthews]

I'm following this build with just as much interest as all the others - including my own 

I always enjoy the build threads, to me it's the most interesting part of the forum. I only wish that more people would take the time to do it! We can all learn from the methods used by others....

Regards
Eddy

[Don]

December 2010:  OK, the bulwarks and sponsons are finished.  Now on to the turtleback. "Turtlebacks" were fitted to many blockade runners to help them cope with the large waves they encountered in the open Atlantic.  Presto's bow was covered with a wooden turtleback.  It looks like the turtleback probably made it more difficult for the crew to enter the forward hatch to get to the forecastle.  But, this is a blockade runner, they were made for speed, not comfort.  In the third picture you can see I finished with the turtleback and moved on to the pilothouse and cabins.  You can also see the framing for the widows that looked down on the engine.  One of these days I want to see one of the surviving direct acting steam engines like on PS Waverly.  I'll have to plan on making a trip to Glasgow!

[Don]

PDs,

I borrowed a poor quality video camera and took a quick shot of Presto making a high speed pass.  At the end of the run I put the helm all the way to starboard and you can see how she responds. 

http://www.youtube.com/watch?v=Qjx1yKMhOlY&feature=feedwll