![emot-4.jpg](https://modelboatblog.tedatum.com/wp-content/gallery/jmotors/emot-4.jpg "The shaft is a rather small 1/8\\" diameter. There are splines to help hold whatever is installed on the shaft.")
The Dauntless
This is the Primary Category for the Dauntless construction.
Motor Mount Ideas
I have a machine shop and engineering project for the Dauntless boat project.
I have done a fair amount of research on the motor mount of scale model boats that use electric motors. One thing that totally astonishes me is the casual use of cheap universal or “ball” joint between the motor and the drive shaft. What is typically displayed in the Dumas (boat kit manufacture) and other brands is a fairly noticeable angle between the motor and the drive shaft. Many times a crude plastic “dog-bone” connector is in use between the yokes.
Of course I have seen a lot of very good installs. The racers usually have found out the secret to best running is with straight shaft alignment. The modeler shouldn’t always follow prototype with a waterline level engine mount fastened to an angled drive shaft. Even if there are quality parts available to do it.
This is not a problem for an automobile and other low RPM drive-shafts that have no slop roller bearings built into the cross and yoke design. In my experience and opinion, slop is one heck of a problem for very high speed drives like are used in fast running model boats. I am talking 5000 to 10,000+ RPM. Would anyone build and run a dragster with the bearings removed from the U-Joint? Model boat builders seem to do it all the time. This is where a lot of the vibration noise is coming from.
I have installed hundreds of powerful motor and pump systems in commercial central plant HVAC system with a precision drive coupling between the pump and the motor. There are especially trained technicians with very expensive test equipment who do the alignment job correctly. For highest efficiency and lowest wear and noise (power loss) the two shafts and the coupling must be perfectly aligned. I believe no less care should be taken with the high RPM model boat drive line.
Yes, the quality model u-joints are made for a small angle but it is probably not wise to run anything more than a few 1000 RPM for short periods with that set-up.
So my design goal is to build a motor mount system with coupling and engine room drive shaft alignment built in. This includes the HQ stuffing tube mount through the hull. The prop end mount will have to be carefully designed if the boat design requires an exceptionally long drive shaft. I may even use ball bearings on the shaft and stuffing tube if I can figure a way to do it. However, I have read that BB’s are somewhat overkill as flanged Oilite bearings work great and are easy to replace.
A lot of time getting this part of the build right will pay big dividends when running out on the pond. I have read a lot of stories where the motor was installed (for the first time) the night before the big outing with a couple of straps to hull blocks and the u-joint expected to take care of all the alignment.
That’s not for me.
Kit Dauntless
Got my delivery today. Here is the starting point on the Dauntless build. The box of wood that will eventually get glued together in the shape of a rather large model boat called the Dauntless. There is a date on the box 5/2/2011 so this is a fresh kit at a very good price. Not much more I can say at this point. I’ve got a building board I need to make from a luaun door panel. Enjoy the pics.
The Dauntless Chosen
The choice has been made. I selected the boat that will house the RCS control system. I did a LOT of internet searching and found out the Dumas Dauntless does have a long and fairly loyal following. Here is a link to a forum with lots of Dumas Dauntless builders.
There are quite a few kits that died on the vine, started but not finished. Also some very poorly built and finished examples. That’s just how it is. The kit build is a serious undertaking and is not a well documented build from Dumas. I bought the plans a few months ago and I can see why some builders struggle.
From what I can determine, the kit has been around (produced by Dumas) for almost 35-40 years. I’ll post the true length of production when I find out for sure.
As plans go, the Dumas Dauntless plans are minimal as far as step by step instruction. What a kit provides is a box of wood and some almost scratch builder plans. There are some details in the plans but Dumas says quite clearly that the plans are not suitable for scratch building. For example there are no full size hull formers (frames) drawn. I am sure that is intentional. Since the kit wood is already die cut, little measurement is provided. The plans do look to scale but there is nothing confirming that.
All in all I believe I am capable of the Dauntless construction task having built many wood models in my life including several smaller Dumas boat and many aircraft kits. Let’s say I am not intimidated of doing something incorrectly.
I did the same research on the Dumas American Enterprise. It’s an older kit than the Dauntless. I saw some pictures of the kit being built “right side up” from the keel and it looked like the builders were having a very serious problem keeping it straight. I also read a lot of complaints that the wood supplied was of dubious quality with some plywood delaminating. No idea how long ago that was. The Dauntless is built upside down on a flat building board as were the other Dumas boats (Deep V’s) that I have constructed.
I think the American Enterprise is a beautiful boat and would like to build one someday. I have seen some well constructed examples and they are exotic. The models on the internet have model jet drives but I read no reports on how they run.
In any case I am committed to the Dauntless on this project. I ordered the Dumas kit through Amazon and it will be shipped from Best Service Stores for a total cost of $130.95 including shipping. Not bad since Dumas direct wants $210.00 plus shipping.
Since I have access to a complete modeler sized machine shop I am anticipating making most if not all the operating hardware myself. I think the Dumas running gear is minimal design and far too expensive. There other much nicer commercial model boat driveline vendors on the internet. Their product looks very good but also higher priced than the Dumas. There appears to be much higher value in the “after market” gear. I think I can do as well.
Stay tuned. This is a major project. Much more to come on the Dauntless build.
Johnson Motors
I am not sure if these motors are keepers yet. Well, I will keep them but not sure if they will get installed in this project. The specifications seem good (see below) but the motors, well… they seem so small. I did find some two inch diameter motors but I don’t think they are as plentiful as these Johnson brand motors. The price for the two Johnson’s was about $7.00 each. I have seen a conflicting price on the larger motors but all I see now is about $10.00. At that price it is worth experimenting .
I purchased these Johnson 9167AK from a seller on Ebay. There are quite a few sellers with this motor so it must be widely available. I didn’t see it listed under this number on the Johnson Motor web site. I assume it may be some kind of overstock for someone needing a small motor of these specification.
Johnson Electric 12VDC Motor (6 to 18V) – Model 9167AK
Extreme Torque of 2.2 in-lbs
Super Grip Serrated Shaft
This motor is quite a bit larger than most hobby types. It’s suitable for any model or experimental use where high shaft power and torque are needed. Please note that there are a couple of different Johnson model 9167 motors. The 9167AK is the biggest one with the highest power.
Runs very smoothly over the range of 3VDC to 18VDC.
Light load Medium Load Heavy Load
3VDC: 1,400 RPM 850 RPM n/a
6VDC: 3,150 RPM 2,100 RPM 750 RPM
12VDC: 6,560 RPM 4,900 RPM 3,400 RPM
18VDC: 9,800 RPM 7,350 RPM 5,100 RPM
At 12VDC the motor has very impressive torque.
Starting torque is 2570 gm-cm = 36 oz-in = 2.2 inch-pounds, at 14 amps.
Operating torque at medium load is 440 gm-cm = 6.1 oz-in at 2.8 amps.
As the load is increased, the torque and current will increase correspondingly. Please check that the case temperature stays below about 100 deg C, in order to maintain long life.
On a dynamometer, the motor was able to generate a continuous 31 watts of mechanical shaft power, with a peak value of 46 watts (temperature limited). A typical small hobby motor can only produce 2-3 watts and a medium-size motor about 10-12 watts, usually not continuously.
Overall length is 3-1/2″ including terminals and shaft.
The body is 2-5/8″ long, 1-1/2″ diameter. Or 65 mm by 38 mm if you prefer metric.
The shaft is 3/4″ long. It’s 1/8″ (.125″) dia with a .130″ serrated end section that grips tightly to a suitable hub, pulley or shaft coupler.
The heavy duty self-aligning front and rear bearings are lifetime lubricated oilite bronze.
The brushes are low-friction and long-life graphite carbon, NOT just copper spring arms as in many small motors.
The armature is 5 pole and the spin is reversible by reversing the power wires.
A Pretty Face
Dauntless
American Enterprise
This thought is being generated from trying to decide what should be the water borne operations platform for the Roboboat project. I have been wishy-washy on my decision on how big and fancy the boat needs to be. The robot competition boats for autonomous operation built by students are almost always ugly looking floating boxes. No classic marine hull designs at all. Many look like pontoon houseboat platforms.
My intention from the start was realistic boat hull design. To that desire, my urge at this writing is to skip the ugly test platform stage I have briefly considered (the pointy box) and go back to my large hull original conception.
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I want to get there (real hull design) anyway.
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Saves the cost and time of “ugly duck hull”, as a “just get it on the water”, intermediate stage.
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Kit boat saves all marine design work. Just build it. This takes hull design and performance out of the variable list.
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The onboard electronics are very small so require little space. Access for experiments and alterations will not be an issue using a large hull.
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Most experiments will be in software control functions.
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Did I say reduces overall development costs?
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Standard boat design has retained value if controls project is ever abandoned or sold as finished design.
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Larger, heavier model boat projects perform much better in a wider range of water conditions than small, light, non marine designs.
So with all that considered, I have two prospect boat designs in mind. Both are made by Dumas. My top of the list is the Dauntless Kit #1211. Also considered is the American Enterprise Kit #1213. Both use the same running hardware, but I am considering sourcing the electric motors from other than Dumas.
The Dauntless is about 2.5 inches shorter than the 52 inch American Enterprise but is two inches wider in beam at 14 inches. It is also more expensive than the American Enterprise. However, the Dauntless looks a lot roomier due to its much larger freeboard.
Yet, the American Enterprise is sexier and faster looking. I’d take either but which one first? Ha!
This means I will soon be putting a face on this project. I’ll let you know when I decide.