Electric Surf Board

Very nice. Please try it out soon. Cold or not, I need to know please. ....

Ditto, great work. I didn't realize just how big those Torqueedo's were.

All that beautiful work, but what's with the square tubing below the waterline? Do you have a foil shaped sleeve to go over it?

Nice job Louiss! Where is a good source for planetary gears? The search I did showed some for over 200$.
Still working on water proofing, but after re-reading it seems reduction is a necessity. I do have plenty of belts and gears, but figuring out a way to attach the prop and still have it spin would require more thought.

Very good !
Maybe run 18s lipo with stronger controller to get planing speeds ?

Wonderful to see how that little motor can run so much power, I wonder if the motor and controller can hold that power for a longer time, or if it will run hot.

I also bought torqeedo motor parts with the stock brushless motor and the ISM gearbox, but mine is 1:14 instead of 1:7


How is the noise ?

I know. I just try many things at the same time. Sooner or later I hope to find out what is best. 45 KV motor is for direct drive

It would be interesting to figure the kv of the torqeedo setup. They use a 50mm size motor on the travel 801 motor if that i the unit pictured. Found some interesting info on the belgium torqeedo site while looking for the gearbox. Still no links for me? I can't find a reasonably priced gearbox that would work.

Transmission and gearing

The Torqeedo motor shaft extends into a gear box for a combination of 14:1 gear ratio which reduces the rotation speed significantly increasing power. This is achieved in an oversized propeller, a size identical to that of a 20 hp engine, thus creating an amazing couple and an available power in the early rounds.

Click to expand...

Conventional propeller optimization

Generally, propellers with a large diameter and high pitch, which turn slowly in water, have the highest degree of efficiency. This is because a large propeller diameter results in a high propellant flow, while a high propeller pitch has a positive effect on the additional speed induced by the propeller.

In contrast, increasing rotational speed of the propeller leads to decreasing efficiencies. As a result of their exceptionally high torque, Torqeedo motors are able to drive highly efficient propellers.

In other words, they can rotate large high-pitch
propellers relatively slowly in the water.

Click to expand...

My main problem, which Matthias eluded to, a direct drive doesn't work on a prop designed for 1300 rpms with the motor I am using. Even Torqeedo's 40hp kit maxes at 2600 rpm. The other thought is a jet drive is however made for higher RPMs. If I recall correctly the jetski has a 3-67k rpm range.

Also in regards to the weird prop design, not just being a gimmick:

Multidimensional propeller optimization

Most propellers used in outboard motors today are based on a series of tests carried out in the 1940‘s to 1960‘s in the Wageningen test facilities in the Netherlands and by the US Navy. The results are reflected in general design principles and applied by
rule of thumb.

However, for some years now, large modern ships
have been fitted with propellers designed according to a multidimensional optimization calculation. Unlike standard propellers, they feature pitches and cambers that are not (almost) constant over all the propeller segments. Instead, pitch and camber are
optimized on the basis of a vortex grid calculation method and a stepwise optimization over many thousand iterations for each propeller segment.

With these additional design scopes, Variable- Pitch-Variable-Camber-Propellers achieve additional speed induced by the propeller at top efficiency

Click to expand...

Hey guys I'm doing a university project and looking to build an electric surf rescue board (similar to a surf board)

The main difference to the surf board is that it needs to carry two people (about 150kgs) and is approx. 3 metres in length.
I pretty much have limited knowledge when it comes to motors etc, but from what I can understand a jet drive system is the way to go (good in shallow waters)

So far all I've come up with is using this (possibly 2):
http://www.rcnz.com/Shop/Service/De...itix___50mm_Jet_Unit_with_Reverse_Bucket.html
Does anyone think it could work, and what motor, batteries etc. should I be looking at using.

If anyone could help, that would be awesome!

I tried today my surface piercing props, coupled directly to 6374 BLDC motors. I do NOT have the right combo yet. My theory is that surface piercing or the Thai panga approach allows propulsion and thrust to get to the water, and very importantly eliminates appendages that create underwater drag.

Today I burned up a motor and a controller. They were air cooled with a ducted fan; last measurement of temp was 116F. A large whoomp when I dialed in 80% throttle. I shut off the power and dribbled salt water on the motor.

At this point, I'll shift over and try brushed DC motors, with a panga style drive.

48 volts; port motor burned; never got the power to get on plane, or even near it....

That stinks.. Sorry to hear that.

I've come to the conclusion after doing some more reading from Honks thread and Jeremy's from boatdesign.net that I am obviously using too much prop. As Torqeedo mentioned a large prop at slower RPM is more efficient than a high rpm and small prop. I can't wrap my brain around that though, should work just as well. Kind of like the muscle car vs. the japanese high rpm. They each have their own merits. I know the jet is less efficient, but they use a 4 inch prop (ok impeller) at 3-6k rpm, Why can't we just a 4 inch prop on a direct drive at 3-6k rpm? Does a prop like that exist? My RC boat has a small prop that spins at 28k rpm. That works quite well! I don't get cavitation or efficiency issues. Also, bench testing and water testing these things are totally different and have made me believe things would work better than they did on the water. The props you (blisspacket) were using look similar in size to the Torqeedo - and the Torqeedo was designed for 1300 rpm. Pushing them faster than that is what is going to blow things. I can't recall your kv on the motors though. Just like gearing in your car, you are trying to start out in 5th gear.

I did get some more testing in on today. I was at the lake anyway to try out a new paddle board for the kids. I put on the Machete prop and was using the 80100 motor. This was on a small 8ft board. On 6s I managed to get on plane and ride at a decent clip. The board had too little volume to keep me floating well though. My ghetto mount didn't allow me to try and stand and it was difficult to turn laying down. Motor never seemed to go out of sync, even at full throttle. My wattmeter showed 110a and 2400 watts. Motor was cool and esc was too. I got excited and grabbed another battery to run on 12s. This time the speed was higher, but it would go out of sync sometimes on full throttle. After a short test - I checked the gear. ESC was hot as ever. I didn't want to run it much longer as it would melt everything in the box and I don't want to buy another HV ESC. The meter showed 3600 watts this time at 91 amps.

Again, I'm left with a feeling I can get it worked out, but not quite close enough. Maybe try it on 8s - with the longer board. I still won't be where I need speed wise, but if it was rideable... I'm debating whether to plunk down money on the neugart gearbox, go back to working on the jet unit I have, wait on Aquilla or still monkey with the Machete prop. I'm wondering If I can heat that prop up and give it a higher pitch, or shave some surface area off. Reading Jeremy's thread about using RC airplane props had me looking at what size prop fits on the 80100 motor. I couldn't seem to find any on hobbyking that fit the 12mm shaft. Jeremy mentioned that airplane props are actually the most efficient (I should saw very, not most) in his thread. What size prop was this motor made for? I have some 1045 slow fly props, but they are made for a 3.17mm shaft. I can't imagine the length of something for the 80100 motor. Plus those 1045 props are made for 12k rpm.

Louiss - how did you get a speed measurement? I am sure I way overestimate how fast I'm going.

eekim13 - Good luck on your project. Any new ideas or attempts are appreciated. I did a search for the unit and came up with this:
http://www.ebay.com/itm/RC-Boat-Shi...40-Motor-/271547454999?_trksid=p2054897.l4275
A much cheaper option if you are going to go that route. I think Wavejet uses something similar. They have dual jets - but don't go fast enough - just help you into the wave. Might be good for what you want. I believe the 80100 motor with Machete prop would do something similar speed wise. You don't have the safety and ground clearance of the jet with a prop. I'm curious why the unit says 540 motor - if it is meant for a brushed 540 motor it won't last long. You will be putting way more power into than that.

Last thing, this would already work if I only weighed 100 lbs. Time to start jenny craig

eemkim13 -
This edf unit also looks interesting. I don't know if they work, but I might try one out myself. I've got to do a HK order and have some left over weight.

http://www.hobbyking.com/hobbyking/store/__4235__EDF_Ducted_Fan_Unit_7Blade_5inch_127mm.html

They are only thirty dollars.

Ordered another prop. Should have asked for opinions first, oh well:

Solas Propellar, small horsepower plastic prop with big prop performance. This 3-blade, right hand rotation propeller is 7.3" (7-1/4") in diameter with a 6" Pitch. Solas uses the most advanced design and manufacturing technology to produce the best propellers for portable outboard motors,

Developed to meet the special requirements of small horsepower applications
This propeller fits Tohatsu, Mercury, Mariner, OMC and other engines

Click to expand...

http://www.go2marine.com/product/38...-3-dia-7-1-4-6-pitch-right-hand-rotation.html
At $20 its much cheaper than the torqeedo.

Its made for 3hp motors that spin at 5000rpm. Higher pitch than the Machete and smaller diameter. We will see... The saga continues.

Hello everyone, I'm new to the forum and sorry for my bad English .
Wow guys, this thread is really interesting for my project, kayak with an electric motor.

dirkdiggler said:

Its made for 3hp motors that spin at 5000rpm. We will see... The saga continues

Click to expand...

Dirkdiggler I think you're on the right track with the prop solas (there is also a version with pitch 7 ") recalls, however, that the motor 3,5hp (tohatsu for example) spin at 5000-6000k rpm, but has a gear ratio of 2.15 : 1.
I took the same prop solas that you bought, but not yet proven because I'm still undecided for the motor and kv (c80100 or 6374) and esc (rc model or e-bike controller ??).
These are two photos of the start of work on my kayak.


There is another prop that could be of interest (maybe), it is smaller than the diameter of the solas but I have no idea how much and pitch, it's propeller sevylor sbm 12lbs trolling motor.
Here's a video with very big rc boat.
[youtube]gUdnZhs91uI[/youtube]

eekim13

Check this German shop. http://www.mhz-powerboats.com/category-11/category-22/

They have quite big jet drives (up to 80mm!) for big RC boats. I have planned to build a board using their jet drive but they are quite expensive...

BR
mobius

the aquila board goes pretty fast and is advertised at producing 330n of thrust, So I am using the rcmk K600S Engine (14hp @19000 rpms) with the mhz jet 64 which can produce 400n with around that much power/rpms, but obviously the engine's specs are inflated, and the same goes for the pump, so all in all I am hoping for about low 300s for thrust.

Electric Kite board....



I keep waiting to see someone out on a paddle board being towed by a small RC boat but it has yet to happen on my watch.

-mmmethods

Me too, an inflatable paddle board with and RC motor and a model boat jetpump would be so cool !

This aquila board looks great, I just wonder about the noise it will make. If it will sound like a gasoline jetski than it would be less cool.

I am willing to accept LOUD and INEFFICIENT as a starting point for my (fantasy) project.

The way I figure it... if we just get 10 or 100 of them buzzing around.... eventually we will attract some crusty old barnacle who abandoned some ultra awesome project in his garage 20 years ago (due to fussing over internal combustion engine specific issues)... and maybe we will jump the gap and get lucky.

Or maybe we will just inspire someone else to work out the mechanical issues (there are many who are experts)

Proof of concept is all I am interested in
Even if it sounds like a horrible, screaming, retching, monster... so long as it has pure electric power (with a generator backup).

-methods

Since you guys want speed, it's time to start working on a board with hydrofoils. At the other end of the spectrum I'm surprised no one is working toward a lightweight board + jet drive + smallish motor + smallish battery pack + solar panels on the board recharging the batteries. We're still quite a way off from a fun to ride board unless you're doing it for small kids, because of battery limitations.

OTOH a board used for surf school, or some assist getting through the break and/or catching waves easily as well as further out than possible by paddling, is readily possible now. Every serious surfer I've talked to down here whose native language is English, has hated the idea. They seem to want everyone paying their dues and no making it easy, though reminding them of jetskis giving people a tow into big surf mutes the objections. The Spanish speaking guys see the merits right away and are much more open to the idea.

The kiteboard would suck, they aren't designed to go straight, just sideways. If you mean wakeboard, then yeah. Radin already made a board close to that size. I do not know how they get up with full boots though. If you are strapped into the board - how are you going to stand on power? One of the reasons the board has to be large enough to lay on is in order for you to stand-up. You could hold onto something while you start, but what happens when you fall over out in the water? Take the board off and paddle into shore?

Proof of concept has already been done by Radin, Waterwolf, Aquilla, Wavejet, Lampuga and Matthias from here has a working board. Matthias has a video and is using a 80-100 on 48v with a Neugart 5:1 reduction. Plenty of other videos in this thread and on Youtube if you want to see footage. Looks like Louiss is close. Plenty of design options already out there. Most are commercial versions that come with a high price tag. Surf-jet has a working gas version and then there are the old style ones that have been around since the 80's.

As for noise, my prop attempts are quiet as can be. You only hear the sound of the water. Jet drive is likely the same. The water muffles the noise. Even the loss of sync noise is barely audible.

John - Wavejet already has a system like you described. Its actually a decent price. I am surprised that surf schools and old folks haven't taken to it. Pretty neat deal for someone like me who tries to surf every few years. For waves I'd been all for that. Helps to get out and no paddling to catch the wave. I'm landlocked though, so I want something that goes faster than its 5mph or so top speed. The surf crowd is a different group. Have to pay your dues for sure. The ticos probably don't care as the sport is fairly new to them and they haven't had the territorial issues like the Californians. Plus there are still plenty of uncrowded spots in Costa Rica. The Californians have that mentality beat into them for the past 70 years!

The Solas prop arrived today. I had to drill and cut out the prop to fit on the 80100 motor. The I.D. is 12mm and I had to remove the back side to thread a nut onto the motor shaft. It is much smaller than even the Machete 3 blade prop. I should have a chance again tomorrow to try it out.

Also found some Neugart gearboxes on ebay for about $100. Might be my next purchase if the Solas prop has issues.

methods said:

I am willing to accept LOUD and INEFFICIENT as a starting point for my (fantasy) project.

Click to expand...

Hey, as long as you're fantasizing, why not go big?

http://en.wikipedia.org/wiki/Magnetohydrodynamic_drive

Let me know if you get one working so I can share credit.

Dirkdiggler! Do you have a link for that Radin board? I am making a wakeboard that will have the undercarriage from a 15 hp yamaha with brushless power on top. Havent desided on esc or motor yet. By the way I dont have any issues going straight on a kiteboard (downwind) so that would probably work too. But I will rather chop up my wakebord. I reckon with enough power and thrust I could get out of the water without beeing towed by a boat.

All I need is a wake board
A 200' rope
and a sick-ass 3D plane with a 20 minute fly time and... 200lbs of thrust.



-methods

pure electric power (with a generator backup).

-methods