You should put the screw propellers in a tube and see if you get more thrust

I've been working on my own BLDC motor controller for a while now, and it's astonishing the ESC worked with two motors attached. The way they work is by listening for the back EMF from the phase that is not energized to know where the position of the motor is in order to advance to the next phase. If you have two motors, you also have two back EMF signals mixed together. It probably works because the motors are the same size, therefore they can get into lock-step with each other. It's really fascinating! If you would have asked me before seeing this video if you could drive two motors from the same ESC I would have said no way!

Tips: *(from a former naval architect)* 1. *Put the propellers on the opposite sides:* Currently, they throw thrust outward when trying to go forward. a lot of that pressure is wasted. Swapping the screw directions will push the water toward the center, making a more consistent centered thrust. Also, if you think about the screws applying torque to tip the boat, currently the low side wants to flip the boat! Once your high side screw got too high in the water, the lower screw quickly flipped the boat. Swapping the screws will make the low side try to correct/stabilize the boat instead. 2. With screws like that, you can *counter drive the thrust directions to intentionally crab-walk sideways.* (conceptually, imagine the screws are wheels. Since they normally spin opposite directions, if you spin them the same direction, they cancel forward/rev thrust, but "roll" sideways.) (if your controls will allow you to do that) 3. *use a balanced rudder:* whether you use a wing/foil shape or a simple flat sheet as a rudder, a balanced rudder will perform much better and significantly reduce the torque on your motor. What is meant by "a balanced rudder" is this: look down from the top. You have a centerline/pivot. *Imagine it's a teeter-totter:* All the area of the rudder behind that pivot = force pushing torque against your steering (fighting your motor) but also is trying to self center/stabilize All the area ahead of the pivot point is _trying to turn the rudder_ and makes it more bitey/turn inclined. ... In your design, you actually have extra lever arm increasing the negative effects of an unbalanced rudder. *You **_don't_** want a 50/50 balanced rudder for 2 reasons:* 1 it's not self centering/stabilizing (boat would want to slew and dart too much vs drive straight). 2 it's actually _overbalanced,_ because the front actually loads more (runs in higher pressure). *A good rule of thumb for a (from a side view) D-shaped rudder is 1/3 of the area in front of the pivot 2/3 behind.* You don't have to be exact, but if you do this, it will work better and you can actually put a larger rudder size for the same turning motor and it will flex your lever arms less. (ps the curved side of the D-shape goes in front, the square side aft) (note: concentrating the thrust in the middle by swapping screws will also help your steering, because the rudder will be in the pressurized thrust, especially so if you use a balanced rudder design)

Screws going the length of the vessle seem like the ultimate land/water propulsion system if you have an insane power to weight ratio

Your boat is undriveable because your steering is right in the wake of your 2 screws in very turbulent water, especially at high speed. If it capsizes when you go full throttle, it's not because of the speed, it's because of the acceleration and the torque. If you were accelerating more progressively, it would probably work better, although the water wall would always end up making the rear faster than the bow and make it capsize in a way or another anyways. One obvious solution for the steering is to have 2 rudders each side of your boat (even ouside of it) and drive them from your 9g servo with arms. When you drive your boat backwards, the rudder is before the turbulence of the screws so it has authority. You're then in the position of a trolley, with caster wheels at the front and push at the back, but it's not ideal because the camber of your rudder is reversed, the attack side of your hull if flat against the flow and thus is a huge brake... it's less bad, not better. However, it proves the point. Now, if you want to keep only 1 rudder at the back, you may think of putting your screws in a duct to to protect your rudder from the wake, and make your rudder a lot deeper. A common thing as well is to put a fin fixed to the hull before the rudder. Ducting your screw is simply going to put you in the situation of a "water jet", which is pretty powerful, probably too powerful for your styrofoam hull (too much torque). Also, one of the big advantages of a single-hull boat is to be able to lean on one side or the other to take advantage of the wind. To increase the amount of force you can take, you can use dedicated long fins (sometimes multiple ones) and/or a keel with a big weight. On a motor boat, unless you intend to surf, you want fins in front of your motors and probably a keel as deep as possible to enjoy the lever effect at the level of the floating line. It's usually unproductive to have mutiple keels because of geometry. Now, in RC world, you probably want to put floats on the sides to get roll+yaw stability. They don't have to be big, they just need to be as far as possible from the "main" hull, at some cost of maneuverability (spin). It doesn't mean screw propellers are wrong, well to the contrary, it just means you need to do things differently after observing what goes wrong depending on your actions. Put food colouring in your bath to make things easier to see, no need to have a degree in fluid dynamics to figure most things out. For the rest, you have thousands of years of solutions found by engineers at different eras in history... In terms of experimenting "unusual" methods, kinda related to the screw propeller, you may try to figure out what are those "caterpillar" propellers from "Hunt for Red October" (the book, the movie sucks). One of the reason you may want to go for screw propellers would be the noise/thrust ratio... and thus look for a solution that provides a little bit less thrust but with a lot less noise, or a solution that makes a lot more noise for a lot less power consumed for a similar level of thrust (I think of "propfans", here). Most problems already have solutions, just make your own blend, solve the interactions, don't rush to the goal: the enjoyable part is the path, not the destination.

Duct the screw. The Archimedes screw works better when enclosed. You can the use it like an impeller and also duct the outflow to provide steering or put larger rudder fixed just at the outflow. You could also put hydrofoil at front to reduce drag too! This will also ease the ability to turn and provide stability in the water

Your boat is missing some sort of Keel to keep it moving straight. As for steering your propellers are creating so much turbulence behind the boat, the rudder wont work, the reason it works in reverse is because the rudder is actually doing something. I believe many ships like this had a rudder behind each screw like a sub to control the direction of the water flow coming off the props. These small changes could help solve your troubles

The two blades are creating a downward flow between the blades, lifting the back of the boat, and pushing the front down, if you swap the over the motors and screws over, left to right and right to left, the flow will be upwards towards the centre of the hull.

I think one of your motors is losing sync and causing the thing to turn and capsize. you can hear the motor start "screaming" when this happens - the faster one is what the esc is locked to (more voltage from the faster motor), and the slower one is vibrating randomly

This invention will surely push the whole civilization. Possibly we can even generate electricity the new ways. You deserve a Nobel prize.

Scrolled a long way and didn't see many people saying.. You *really* need an ESC per motor, you can't run brushless motors in parallel, it's amazing they're working together at all! That's why they keep doing weird s**t like starting backwards or going out of sync.

Nice video! The comments are only made of suggestions, so heres mine: Battery is way to far in the front and threatens to sink the tip, making it hard to controll, easy fix, move battery back :)

1st thought "those electronics are damn close to the water", 2nd "why not a catamaran or trimaran?" - thanks for proving me right 😉 😆

in the future you can increase stability of small boats with a keel(hydrodynamic or weight), outriggers, or a catamaran design. to increase rudder authority you need a larger control surface. alternatively with a dual thrust system you should consider using thrust steering at least at low speed where the rudder will have least effect

"The motors will spin for fun"😂

So, you've discovered why we don't use multi-rotation screws. 1. You're moving the same water with every additional rotation rather than move a water unit just once. Sure lifting water on land with an Archimedes screw makes sense, but on a boat, you only want to move the unit of water once. 2. The forward 360° rotation will induce turbulence for the following screw rotations ending up in each additional screw cavitating -- spinning without inducing thrust. So, say, you would take the 10 360° screw rotations, cut each one out making them singular (a normal propeller), and mount them side by side. You can imagine that each now moves its own independent unit of water, no leading cavitation exists and you'd get 10x the thrust.

I've been using hobby $ESC's and brushless motors for a long, long time. I've never once seen anyone wire two motors in parallel to one ESC before. That's uncanny..

Archimedes would be proud!

Cool that we get to see failures in your projects, too. This might help some people not having to make them again by their own and save humanity some time for more important things...

The reason the boat keeps going on its side is because both propellers are producing torque in the same direction. They need to be going in opposite directions just like the props on a twin engine motor boat, with the top of both props rotating outwards.

Lots of fun playing with boat designs, there was a successful version of screw drive where the screws were mounted up into the hull with only half below the hull surface and independent motor control for steering.

hehe...when you put that comically small rudder on the boat XD

Id like to see an attempt at making an Air-Bubble Anti-Drag system. You would alter the Bottom of the boat, with length-wise "channels".. about a cm of depth. Then you drill holes at a +45 degree angle... about every inch, in the center of these channels. (The boat itself, would have an inner and outter hull.. thus, preventing it from sinking) These drilled holes, would release Air Bubbles... which would add "Lift" under the boat.. as well as potentially act like "Bearings".. helping it glide through the water, much easier and faster. You would either have to force air from front collected scoops... or... use some sort of air compressor system. That said... it might also be worth trying with low-pressure water, instead of air... I just think that the airs buoyancy, might help greatly in helping with something like a huge, heavy, Cargo Ship. Helping to reduce the weight to a certain degree... and again, to potentially act like an anti-frictional bearing. To test this, you probably want to use a boat large enough to sit in, and piolet. As anything smaller, would be hard to tell if there was any notable effect, due to scaling issues. Even a modified Canoe, might be fine. I will say that a lot of small boats pop up for FREE, on craigslist. The most simplified version, could just be having the air going under the boat from frontal feed pipes... and the Channels would allow all trapped air, to run from the front of the boat, to the rear. You would just need to make a way to equally divide the air, and guide it to each of the channels.

"It might blowup, but im 20% sure it will not." I like those odds! Let the testing begin!!

a fin keel will stop it rolling, also very simple to add on that hull

I'm surprised that putting the motors underwater doesn't seem to be a problem. Are they waterproof?

For the best result make a left-handed screw on one side and a right handed screw on the other side due to you having 2 screws of the same direction as soon as you rev up the motors the Torque produced tryes to rotate the boatwith different direction screws they will cancel out the oposite direction torque.

try the hunt for red october version. put the screw propellers in their own tubes and see if it's easier to propel. maybe quieter.

The Arimedian screws are way more efficient at low rotational speed. When using this kind of Propeller for porpulsion you should use low Speed and big Props to get the best effect or you duct them.

Those bearings at the prop ends are it's death. Gotta be losing more than half the thrust right there. Wouldn't a simple needle suffice as a bearing there?

If you're looking for suggestions, a larger rudder and another esc so you control each screw independently. That may allow you to ditch the rudder, it seemed to have decent power in your tub before the wiring correction.

exactly what i was thinking. Then direct flow right or left for direction using a variable nozzle

Very cool concept and I'm glad someone tried it. Here is why I think your performance was not as good as you may have hoped. When the screws turn, they grab water and push it backwards, but because the flow is not constrained it ejects the water out sideways. Some of the flow hits the hull, pushing the back up slightly along with the escaping flow downwards cause the nose of the craft to push downwards. (Left and right escaping flow cancel eachother out. Two suggestions, constrain the screws in a tube or box to prevent escaping flow, and make a progressive pitch screw thread, (aka small thread gap at inlet and a large thread gap at outlet). Doing this you'll convert your screw drive into a jet drive and the progressive thread pitch allows the water to reach higher output speed as it gets sped up more gradually.

You have a LOT of drag where the motors mount. You need to put some really long and sharp cones. Otherwise, the faster it goes the more drag and the more unstable. This is why the fastest boats have surface drives so when at maximum speed the only thing in the water is the bottom half of the propeller. The screw drive will work at lower speeds, but not at high speeds. In fact, you would do better running that thing in snow. LOL

The reason why the rudder worked better bakewards is that its no longer in a turbulent flow, pretty sure the water behind the boat ended up being quite low pressure. Think the reason why it might want to capsize in one direction was maybe related to something being misalgined, maybe inertia but it shouldnt be an issue due to the different directions of the motors

Try to build the Propellers in a housing like a screwcrompressor, with a outgoing nossel for stering

The problem is that the water is being pushed away from the screws in all directions. Put the screws in the hull of the boat with an ingest and exhaust port for each so that the water only goes backwards and then the boat will really move forwards.

incredible ) now i understand why it so difficult to create some product

With all your experience printing pumps, can't wait for you to do something like this with a pump for jet propulsion like a jet-ski. I hear they usually use impeller pumps but not entirely sure. Prolly depends on the jet-ski. Slapping a super heavy (like steel or brass or something) thick fin, aka a "keel", under the boat would make it a million times more stable I'd think.

Compressor pumps, makin a tube for them to sit inside and slowly taper it down in size

You need to put some winglets or outriggers on that hull, so it don't flip while turning under full power.

The boat needs to be wider and maybe use pontoons or Catamaran style boat? Also surely you would either 1 screw plus rudder or if you use dual screws then you would stear with the screws going in the opposite direction, lot more stuff you could play with and test here - you have most of the stuff already so you might as well dig deeper!

Fantastic, 👌 👏 Amazing 👌 👏..

Very interesting and Educational video!

great humor while doing great tests

Fantastic work, dude! Nicely done! 😃 Stay safe there with your family! 🖖😊

Interesting use of an Archimedes screw. If you made them wider apart and the full length you could probably crawl out of the water on to land. Always good to see people trying out things and being a little inventive.

A duct would help a lot, although tough to design properly. The other thing is the speed of your screws is way too fast for your screw pitch. At that speed you should only have 1 pitch. Multiple pitches at that speed will only trap air instead of pull water. That's where the duct comes in....

You could use an oscillating multi tool to cut the hull of the boat.

You need a tube over screws because opposing screws force water out and mostly down. That's why boat flips over. Better yet, you only need one turn on screw to reduce drag. A screw in a tube produces more power.

You should make the boat as a double haul.

Have the screws both spin towards the center and move them out to the edges.

All of that crap hanging in the water is killing it with drag. Put it all inside the boat with either the props as the only part outside or put them in a duct like a jetski.

I love your projects, they are very informative and fun to watch. Thanks :)

A keel will give you better handling and if you make it from something like lead it will stabilize from rollover

The trouble you had with the bad rudder control and capsizing is because you printed the rudder back to front. The foil shape was nice, but the thin edge shouild be at the back! Also if you made it less deep and a bit wider it would be less likely to tip the boat.

As with dual propeller propeller boats, the props have to spin in opposite directions and the tiller controls the steering. This being a test, I'd switch to jet drive which is basically a screw encased within a tube. But that'd defeat one of the purposes of long torpedo screw drives. If they were buoyant, a vessel utilizing this system could be good for swamp expeditions because these screw drives would crawl over the muck like a tank.

Screw propellers are suitable only for propulsion of solid or cement with high density,not for water with much lower density.

video idea: make feathering paddle wheel kit boat

Dude, you need to cowl the upstream side of the screws. The leading wall is like big water brakes.

With regards to set screws in plastic, I've found diameter is most important for holding power. If you are limited in diameter then you need length. If you don't have either you're in trouble. Hole size also matters, you want to have it as tight a fit as you can without it being to difficult to screw in. Sometimes a larger diameter lead-in can ease installing into very tight holes. Lately I've been using M5 set screws with an undersized 4.7mm hole with at least 4mm thread depth in the plastic. This has worked fine for securing D-shaft motors to gears and as set screws for holding PVC pipes in place. The material I'm using is PETG. Also you might try slowing down one screw to create drag on one side as a means of steering.

The boat must be large enough to counteract turning or toppling because the propeller take a large space of boat section making an large unstable end

Switch the screws and reverse the direction and maybe they will fight each other less and gain stability

You need a longer or deeper rudder. Right now it's just sitting in turbulence so it isn't going to do much.

Make reciprocating paddles!

Reason because of your rudder is not working when moving forward is that it needs laminar flow to work properly, and your propellers are making the flow turbulent when spinning fast. Indeed, your boat is steering better when slow and when moving in reverse. You might try to move the propellers more towards the bow.

You should add a "regulator" system to adjust the inclination of the screw propellers if you get more thrust. The problem is that the propeller running parallel to your boat will maintain a larger area of contact with the water, making it more frictional and therefore slower and even sinking (Coanda effect). To avoid this, it is necessary to slightly adjust the pitch so that the bow of the boat rises as the acceleration increases. For each type of vessel, an angle is required, so a way of adjusting your propeller is required.

The steering issue is down to a single, narrow rudder (more appropriate to a sailing rig than a power boat...) sitting between two highly cavitated prop-streams. Thus very little water-pressure enacting upon the narrow rudder surfaces. A broader aspect ratio, twin-rudder assembly centred on the prop axis would have been more efficient; or differential 'screw' steering might be another way to go; though the torque of those motors might require some careful tiller/joystick handling. The hull form isn't really suited to the prop design/torque/screw pitch, especially compounded by aforementioned zero-helm rudder design. I would have enclosed the Archimedean screws in a tube - making essentially a hydro jet, with twin-nozzle servo-steering and placed the battery pack further aft, to bring the bow up, that way, it might just plane...

It looks like the prop wash runs to either side of the rudder, so it struggles to redirect the water to turn. You could try a double rudder mechanism placing each rudder surface in the middle of the prop output perhaps?

great project my friend, keep going to the perfect result

You should make the screws turn in opposite directions.

youre very brave, leaving battery exposed over water xD

I suggest redesigning the support at the end of the screw to be more hydrodynamic. It is blocking off a lot of the thrust.

. maybe you need tube outside the propeler, than the propeler will works like pump, moving water from front to back, i think you will have more thrust

Use twin ducts and differential motor control for each side with a heading reference. Add a NACA scoop to draw the intake, stream line the rear bracket and try to get rid of the rudder which is why the stern was pushing the bow down. Also a hydroplane step on the bottom, Air drones got their start a long time ago when some military officer who happened to watch R/C models. You have a great attitude -- lead, follow, of get the hell out of the way. Kind of Elon-like.

These screw propellers were first made in 1790 ish and they were later competition to paddle steamers

make them inside a trusthertube whit a conical inlet , allot more focused propulsion and make rudder bigger en longer. and more weight to the back.

After many years with RC jetboat design there is so much here that shocks me😂The streamlining interruptions, the extremely high drag low pitch options, unprotected motor bearings and ESC, I am truly shocked. I suppose it's an excuse to have a streaming channel though! I'm 57 so I've had plenty time to learn from my mistakes. Seeing as you are pimping out PCBWAY, I suppose I should see if your SW or HW design compensates 😉

Put a propeller behind the screws. water will be supercharged flowing past propeller

you should try putting the screws on two really long arms that make the boat wide so you can do tank steering

Oh boy, you have a strong Hungarian accent! :D

Put the propellers down the entire length of the boat. And have each motor wired like a zero turn. Then you become amphibious.

I think you would get more stability if you swapped the screws so that if one screw gets out of the water the torqe from the other one will push it down again.

I do love your videos bud please make more. Your wacky inventions are bloody great 👍.

I love this channel. Seriously one of my favorites. I like seeing you go through the troubles and figuring out solutions. Nice job with this one!

This is such a great experiment! Didn't know this was the birth of water impellers. I believe aa Soviet inventor built a tractor on that principle. Really enjoy your videos!

Nice project. Definitely need a keel with some weight for pitch. Weight distribution (battery high and forward) is causing the front to submerge. Maybe consider a single step hydroplane design or tri-hull for stability. 🙂🙂

You should arrange your motors to work in opposite turning direction. When you speed up, moment of inertia causes to ship flip over. When you arranged the motors, you should arrange your propellers like the motors. Otherwise your propellers would act one forward one backward. Besides, loved it.

8:07 best wiring diagram ever

Move the battery like 5sm back or mor. And get a bigger stearing thin

2escs and differential steering is the way

The boat rocking must be caused by torque - perhaps you should let the screws rotate opposite directions. I.e. one turning clockwise and one counterclockwise

you dont have any pontoons to stabilize, the hull is very narrow for the amount of rotational force the screw props will create. If you add pontoons on the sides of the hull is wont tip over so easy. also counter rotating props when using two at the same time is important.

Try designing the screws so they're progressively deeper in pitch, like I've once seen in a blurb about making a more efficient water propulsion in Popular Mechanics.

I feel like this is a spin off of the Voith Schneider Propeller system only on a waaaaay simpler scale hahaha and not vertical.

A duct would add control and can be designed to hold it in the water.

love the idea but way way to narrow design. also 2 smaller rudders one each screw might help? do you think spreading the screws out and rpm change on each screw , could help steering? also the bow is diving which won't allow steering.

Nice work. Try 2 rudders with a linkage bar and you'll have more fun

I suggest side thrust cuz this boat unstable asf 😂 or just remove the 2nd thruster and use one thruster for directional thrust

Hello, haven't you considered why you can control the vehicle backwards and not forwards? Your rudder is built upside down. Build it again and this time the cross section should be rotated 180 degrees. The surface of the rudder must also be adjusted. Maybe a little bigger.