Jet Kayak RC components

mikebikerad said:
I got one of these http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=19111 and played with it in the bath tub hooked up direct to a 3'' boat prop and it created a monsoon on 2s! The RPM seem perfect but the cheap 20c Hobbyking cells I was using made the esc cut out after a few seconds. Fun stuff.
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How do you figure it was the battery that made the ESC cut out ?..Low voltage ?
Or did the ESC overheat ?
 
The 2s pack was sagging to around 5.9x volts when the prop was loading for a few seconds, causing the esc to think it was a low voltage situation. The esc was slightly over ambient temp because I only ran it for a few bursts.
 
Hi All,

Finally completed our work on the updated version of this project. Please shoot me any tech related questions on here! Thanks for checking it out as always ES community!

[youtube]oVSvbFtiIbg [/youtube]
 
Looks good. Kind of like the ebike kits that fit the bottom brackets. Great idea to use the fin box. Any thoughts on doing a faster version for shortboards? Could it be retrofitted for a larger motor/prop?
Hope it sells well.
 
grindz145 said:
OK Mr. Tesla...
Click to expand...

You know, sending meaningful energy to a boat on water should be way less lossy than a plane, and you can send RF energy to a toy plane in a meaningful enough amount to keep it flying.

From a energy usage perspective it would be more lossy than a wire obviously, but actually possible to achieve, perhaps even in remotely practical way/cost with CREEs new SiC RF powerfets IMHO. :).
 
Fantastic video! In SC, we have an absurd surfing population with myself among it. I want to see what your motor does when mounted to a modern fiberglass (reinforced) board with one of my local surfing pros on it.

Does it provide more thrust than a human paddler can burst? I think it could be a clip-in attachment to a board that gives you a serious wave catching advantage. People practically battle for waves these days with hundreds of surfers on each prime break.

PM me. :)
 
@dirtdiggler Thanks!

We are staying out of the shortboard market for the time being, I have too many surf friends who don't want to see these in the lineup......but want to use them for cruising, fishing, and general water fun. That being said, we have already made some progress on preparing a faster 2-3kw brushless gear reduction version of the ElectraFin, which we don't see as a mass market product, but part of our product offering for people that will pay a premium and have a need for such fun!

The ElectraFin is sort of like the Bafang BBS02 bottom bracket drive of the electric watersports market.... simple, low cost, efficient, and easy install (but ours installs in 1 minute vs 20!)
 
@liveforphysics: ElectraFin would get you some serious enemies at Steamer probabaly! It feels like about double the thrust a surfer puts down when charging to catch a wave. If we do decide to offer a surf focused package we could use one of the folding props we have to reduce drag once inside. Ill send you a P.M now :twisted:
 
@sk8norcal That was our thought as well, Wavejet's look killer and they have put in a lot of work to streamlining the product, webpage, marketing, etc but it seems like their target market of surfers is difficult to capture and can be somewhat temperamental around the theme of electrically propelling yourself past the competition and stealing waves but using a wavejet is probably a lot like e-bike riding on a bike path.....as long as you are respectful everyone gets along :mrgreen:
 
I'm in Utah so, not going to snake anyone in the lineup. I know of a few companies producing both gas and electric shortboards, but they come with a price. Being on a DIY forum, explains either my cheapness or the mindset of I can make that myself for half the price. I'd personally rather pay a bit extra to have everything work correctly and look professionally done. Like your BMS and waterproofing. I don't know if you saw the waterwolf surfboard, but they also have an open prop similar to your setup, but with a 5kw? motor or so. I was going to try and use a jetdrive setup for my DIY board, but it seems that prop drive must pass the mustard and not be as dangerous as I think. It would be simpler to build around a prop driven board. Did you ever get anywhere near the prop falling off the board while testing? Any advice on props if I want to setup a shortboard using an 80/100 motor on 12s? Also if I remember right you were using an exposed motor underwater - that could have been someone else - did you ever end up with issues due to the water?
 
@dirtdiggler The out runner lasted fine for a few underwater runs in fresh water, but I would think it would get ruined very quickly in a few salt water runs!
 
I'm strictly in freshwater, so it might be easier on the motor. Long term, I think you'd better enclose it. Any recommendations on props if I use the 80-100 motor? I'm still antsy about an open prop, so definitely no metal blades.

Since this is ES, if I did purchase the electra fin and did a few of the ES tricks, ie over-volted, new controller, would I get enough rpms to hit the 20mph mark? Hopefully that keeps things vague enough. How fast are you going on 2-3kw?

Also congrats on making your goal on Indiegogo.
 
@dirtdiggler Lots of options on props, might be best to reference the thread about prop sizing in the boat thread.

Electrafin is designed with some safety margins, and we would definitely not warranty any mods, that being said, we expect the ES type folks to have fun with any products they have in their garages. The 20mph mark is definitely not possible unless you were going down a waterfall!
 
The music in your video cracks me up!! Props for building an rc kayak.
 
New vid showing some of the new features we added over the past 6 months: [youtube]yjOoUe4CKBQ[/youtube]

We just made another change to the winding for a bit more speed and had the manufacturer pack as much copper in as would fit. Pretty fun and really reliable now. To conquer the challenges of wireless communication on the water we added a pretty significant antenna that sits inside the plastic enclosure, but outside of the aluminum motor controller housing. Thanks for checking it out.
 
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