1:25 scale Quarter-wheeler river Drogher

[Steven S]

This will be a build blog of a small quarter wheeler river drogher of my own design from information found on the internet.  The prototype would have been used to transport local goods on rivers and small lakes. Full size she would be 75 ft. long with a 22 ft. beam. 

 My 1:25 scale model will be 900x280 (35.4” by 10.9”), it’s a little wide, but I’m a bit worried about stability.  The hull has a displacement of 7.5kg (16.5 pounds).

I will build a non functioning steam boiler, but the twin wheels will turn independently and be directly driven by two Cytron 12V, 150RPM geared motors.  It will use a Sabertooth electronic “robot” control module, controlled by my Spectrum Dx6 G2 transmitter.  I want to use 1 stick for throttle and the other for turning.

I was planning on having angled floats on the wheels as an experiment in steering the boat.  They would be angled to converge about 24 inches astern, but since they will be up against the sides of the boat and not protruding below or behind the hull I don’t think that they would be effective.  I’ll start off by building a set of regular wheels. Any comments on the effectiveness of angled floats on a quarter wheeler or side wheeler would be welcome.

I am well along with the hull build and will start posting my progress shortly.  It’s fall here in Canada so this will be my winter project, ready for spring sailing next April.  Any comments on any of the build would be helpful as this is only my second boat.

https://www.robotshop.com/en/cytron-12v-150rpm-18oz-in-spur-gearmotor.html

https://www.robotshop.com/en/sabertooth-dual-12a-regenerative-motor-driver.html

[DamienG]

Go for it Steven I look forward to your build. 

[derekwarner_decoy]

Steven.......there are some builds here of similar sized pontoon style rear 1/4 wheelers, and also an article with a pair of wheels with angled float

The displacement of 6.5 kg is easiy increased via the flat bottom style...batteries/ballast up FWD

The only initial comment is these motors are listed as 150 RPM but with a no load rating as 103 RPM.......

With the electronic control, it could be worth considering a same frame size motor with ??185 RPM as with scaling....shaft speed is never a clear calculation with the SG of water being constant

The extra speed 'up your sleeve' may be beneficial 

Derek

[Hankwilliams]

Very interesting and promising. With pleasure I will watch your build. I`ve built 2 steam driven sternwheelers - if there will rise any question you will get any  assistance with this blog.

Thomas

[Steven S]

Gentlemen, thanks for your encouragement.  Derick, I used this motor in my first paddler build at the beginning of the Covid shutdown here in Canada.  I used a toothed belt and 1:1 pulleys.  I also bought a couple of alternate pulleys so that I could increase or decrease the wheel speed, but it seemed to operate nicely at just over half throttle.  I've attached a picture of the drivetrain for that boat which is the one in my avatar and in my "Introduce yourself " initial post.  The motors are not too expensive so if I need to change them for this boat they can be here in a week.

Thomas, I will be grateful for any help offered.  I am powering my boat with twin electric motors independently driving the two wheels so my steam boiler will be non functional.  I do want it to look proper though.

Damien, I have built many RC airplanes, but only one boat so I will be looking to learn from yours and others experiences during my build.

[Steven S]

My hull is progressing nicely.  Before I fastened the false deck on I wrapped it in cling film, floated it in the bathtub and added some weights to balance it closer to the waterline.  I have now permanently fastened in 3 pieces of 1/4x4x12 inch steel just forward of centre.  Next I will add a fiberglass layer to the bottom and paint it.

[Hankwilliams]

Looks very good. To the independent wheels: The steering effect through independent stern- or quarterwheels is - in opposition to sidewheels - not very strong. One will see. From my sight of view, it would be more secure, to plan one rudder just behind every wheel. Best solution would be, after my experience, a bow thruster.

Thomas

[Steven S]

Beautiful boat Thomas, it has given me a few ideas for some of the detailing on my boat, like the checkerplate under the boiler and the maybe the arched roofs although I think my type of boat (drogher) was built more "rough and ready", not quite so pleasing to the eye.  I will have lots of questions when I start building my boiler such as how water was added on the real boat.

I am not a boat guy so I spent some time today researching Bow Thrusters.  They are very interesting, I thought that they are external pods under the boat, but I see that they are an internal pump in a tube with the two inlets/outlets cut into the side of the hull with the tube fitted across.  I could fit it up against the front bulkhead if I find that I need it, as long as I am careful on where I add any forward ballast for my final water tests.  I will have a rudder, but I don't think it will be very effective.

I have added a layer of 52 gram fiberglass cloth to the hull and a couple of coats of red paint.  Do you think that they would have painted a waterline on such a boat?

I was going to start thinking of deck planking next, but my motors and controller arrived so I've made the drivetrain mount and am starting on the paddlewheels.  I am very interested if this "Robot" controller will operate as I expect.  All the ponds around here have very hard water (ice) at this time of year so my water trials are a long way off I'm afraid, but I can still bench test the operation.

[Bierjunge]

Looks very good. To the independent wheels: The steering effect through independent stern- or quarterwheels is - in opposition to sidewheels - not very strong. One will see.

With angles/diagonal floats however, the steering effect of a quarter wheeler would be much stronger, as already explained here: http://www.paddleducks.co.uk/smf/index.php?topic=7080.msg42837

Moritz

[Steven S]

Hello Moritz, Do you think angled floats would be on my quarter wheeler?   The wheels are 6mm from the sides of the hull and do not extend below or behind it.  I do not see where the diagonally directed water would go other than hit the side of the boat so I think they would be of minimum usage.  I agree that they may be of greater use in a stern wheeler as shown in the diagram.

I will not be able to use my boat for five or more months as winter is here now so I could make an extra set of wheels for it with the blades angled to converge about 600mm behind the boat.  It would be an easy change to test this theory in a practical way.  Do you think 600 is a good point or should I aim for less?

I hope to have the rest of the electrics in today so that I can bind them to my transmitter and run the basic receiver setup.  Then it's on to planking the false deck.

[Paddlemex]

 Looks great Steven.

But more than the angled or straight paddles I would be concerned about your motor mounts. I can't tell if they are steel or alu, but in either case they look kind of flimsy. There will a considerable stress on these mounts because you don't have any shaft support on the outside.
I would recommend to add some kind of bracket at the end of the motor. Something like what I made for my Morangie Castle.

[Steven S]

An excellent idea Jurgen, I will add a brace like yours to my motor brackets.

[Steven S]

I was able to install and wire up my electronic "Robot" controller yesterday.  It seems to work as expected, Reverse, Neutral, and Forward of both wheels on my throttle stick and both the wheels turn in the appropriate directions when I use the Aileron stick.  I'm about 90% happy with the control and with some more adjusting of the transmitter later on should fine tune it completely.

I will finalize the motor mounting by adding a brace under each motor and make a cover for the robot ESC today.  Then on to deck planking.  I've never done any deck planking before so there will be some research involved.  Any help would be welcomed.

[Steven S]

After some research on the internet I’ve decided on a 3 Butt planking pattern for my deck.  I bought a ¼ inch plank 5” wide by 48” long and cut it into 175 planks with my Proxxon table saw.  I cut them into the various lengths needed for 3 butts and beveled the four top edges.  Now after laying out the pattern on the computer model I’m ready to start gluing.

[DamienG]