River Roller! Pontoon Boat that Rolls Across the Water!

The craft in the videos has a conventional planning hull which supports the craft while the propulsion is provided by conventional paddlewheels with paddles mounted on open frames. This is fundamentally different than Mr Towne's proposal with the cylindrical Trantoons supporting the craft and the propulsion provided by paddles mounted to the solid cylinder.

 

Nope.

Not even close. A 1:12 scale model means everything on the model is is one twelvth the size of that on the full sized craft. This includes, of course, the trantoons. These will be 1/12th as wide as those on the full size craft as well as 1/12 the diameter. And since the diameter signifies two dimensions, Length and Height, you have to square it. So, what you have here is: 1/12 * 1/12 * 1/12 which gives you 1/1728. If you multiply this by the planned weight of the full sized craft, you end up with 5000 lbs * 1/1728, or 2.89 lbs.

I suggest you build it to 1:8 scale. Your model will then weigh 9.76 lbs, which will probably make it easier to arrange the machinery. With 1/8 scale, every eighth inch is one scale inch, which I find convenient.

 

I'm not afraid to succeed either! Working on the model. 3d printing is a bit of a challenge but I'm getting it. The problem I think I will have with a RC model is that I think the trantoons will need to be operated individually and there will be algorithms for different RPMs at different speeds. Especially to get on plane. Once there I think they can all operate in unison. I'm not sure how I will accomplish that with an RC model.

 

I don't really see this replacing a cargo ship. A traditional pontoon boat is another matter. They are horribly inefficient from my experience.

 

So I assume you think this will make the trantoons less efficient than a traditional paddlewheel. That may be, but will the whole system be less efficient than a prop and displacement hull?

 

Yep thats about what I came up with. Sorry for my poor estimation/memory. Nonetheless my point is still the same. I was surprised to see that a 1/12 scale would result in a buayancy factor much less than 1/12th. This is actually encouraging. I'm pretty sure I can get a 3lb craft on plane.

 

My estimate is your arrangement will be considerably less efficient than a displacement hull and a suitable propeller.

 

As a simple thought experiment, imagine giving a model boat of yours in free wheeling mode a hard shove, your boat will churn and throw water and go nowhere. Imagine giving a long lean displacement boat a shove and it will glide across the pond.

 

I suggest that your first model be a proof of concept one, in which everything but the bare essentials is eliminated. Have your five trantoons, of course, and maybe a motor for each on, so you can control their speed independently. For steering the model, I suggest yo go with rudders, which should work fine. I know this may seem like cheating, but it's not. The test here is to see if you can get this craft to plane with a reasonable power impute. If you are able to do so, the model will have served its purpose. A new, probably much more expensive model, can then be built from usable parts from the first one.

So how much power impute is reasonable?

I know a conventional pontoon boat, not designed to plane, will plane with about 100 hp/ton.

If your craft is to be superior, it must do so with less.

To scale the hp down to model size, it is convenient to convert it to watts. Since the full size craft is supposed to weigh in at about 2.5 tons, it will probably need about 250 hp to plane, if it's to equal a conventional pontoon boat. 1.0 hp = about 740 watts. So 250 hp = 185,000 watts. 185,000/1728 = 107 watts. If your model planes with this much power or less, you will have proved us naysayers wrong.

So how fast is planing for this model?

The model will be 2.0 ft long. The square root of 2.0 is 1.41. That's how many knots it should be moving at, while just loafing around. At about 1.90 kts, it should be at the top of its displacement speed. beyond that, it will be at semi planing speeds, which conventional pontoon boats can do with about just 20 hp/ton.

At about 3.0 kts, it is approaching planing speed. At about 3. 38 kts, it is there.

For convenience sake, it is probably best to break this down into ft/second. One knot is about 1.15 mph. 1.0 mph is about 1.53 ft/second. So 1.0 knot = 1.53 * 1.15, or about 1.76 ft/second. So, to be traveling at planing speed, your model should be moving at about 3.38 * 1.76, or about 5.95 ft/second or about 1.81 meter/second.

Timing its passage between two fixed objects, in seconds, divided by the distance, then divided again by this number this number, should tell you if you have achieved success or not.

 

You are the most effective, and troubling of all contributors. So if i imagine it, yes the slender hull would seem to have the advantage in efficiency.

Let me be clear that i expect this to be more efficient than a traditional pontoon boat. Which coincidentally is two long slender hulls moving through the water.

You may be right. But...... There is more to this. My basis for this design is to regenerate kinetic energy into the batteries when decelerating.

So if you accelerate from 0 to 10mph then decelerate back to zero how much energy has been used? Even then you may be right.

But. . . . There is much more potential here than just efficiency. Which i think is still possible. What if this boat, when on plane is capable of superior control at high speeds?What if the benefits greatly outweigh the drawbacks. What if it's just plane old fun?

Think about the capability of an airboat combined with the comfort of a pontoon boat! Now tell me that wouldn't be fun!

 

There won't be any regeneration taking place, if you get it up to 10mph it will be back to almost zero the instant you back off on the power.

Pontoon boats tend to be very efficient, needing very little power to achieve a reasonable speed. The typical pontoon boat can easily reach 10mph with even a small outboard.

If you can get this craft up to a high speed it could only be maintained on a glass smooth body of water, it has no ability to cut through any type of wave, you will be riding on top of whatever the surface is like. This would probably make it very difficult to control and very uncomfortable.

I'm not saying don't make a scale model, I think it would be interesting to follow the progress.

 

At the very least this thread is most entertaining. Can't wait for the scale model results.

 

Well If I end up with nothing else, at least some of you have found it amusing. Ok, so lets talk about cutting through water. I hadn't really considered that as I see this primarily as a pleasure boat on fresh water. So lets assume that this is only a pleasure boat and will typically be used where waves aren't much more than a foot. In previous posts I have suggested the potential of using an active suspension. This could easily smooth out a ride with waves of a foot or more. In fact it could offer a better ride than any conventional hull. So much for your rough ride.

As far as cutting through bigger waves, well I think the bigger waves would act more like a ramp, perhaps providing some air time? Are we back to the fun aspect again?

 

First of all let me say thanx for taking the time for this analysis! This is the kind of input I was hoping for here. Very constructive. Do you think that since the entire hull is working to move the craft forward, that this will affect your calculations? For example the coordinated rotation of the trantoons will create a higher displacement speed?

 

Never say never. There will be SOME regeneration taking place. The question is how much, not that it will occur.