New (jet board) build discussion thread

[Kian]

Guys (girls?).

I’ve just received 2 brand new jets… So… It is time to start building version 2 of my jet board.
This time instead of converting an original surfboard into a jet board I am going to build a board around the needed parts.

My 1st idea was to build a board from wood, but this is on hold for now… I’m going to use foam.

For the blank I will be using EPS blocks in combination of Styrodur and fiberglass. (The styrodur will be used to make a sandwich construction). The plan is to keep the blank below the 3 kg!

The board will be 160 cm long, wide 60 cm and thick 16 cm.

As this is a jet board, it needs 2 watertight compartments.
1 for the battery’s, and 1 for the motors/jets/ESC’s

The battery’s and ESC’s will be in a water tight box, but the motors/jets not

I might consider making 1 big hatch covering both battery and motor compartment. (any thought on this from you guys?)

I’ve seen many differente ways on the forum of watertight hatches, but unfortunately no how to’s…

Anyone here who might know of a how to on hatches / compartments?

Also… Any input is welcome!

[Alexandre]

Just take 2 waterproof cases and mold the board around those cases , a lot easier at the end and it will waterproof for sure

[Kian]

That is what I am doing for the battery box.

The jets need to be on a 2 mm aluminium plate, and need to touch the water at the bottom (water intake for the jets). I need to be able to access the jets from the top, and all this needs to be waterproof.

In version one I have the jets in an aluminium box, but am till now unable to make it 100% waterproof

[Sliman_O]

What’s your jets specs ? I know Onean use 64mm impeller to get you to 30kmh with a single 5kw motor. Are you done with your battery case ? Ever thought of using the same system as Onean does ?

[Kian]

53mm impeller pushing water through a 44mm nozzle (board has 2 jets)
Motors used are Surpass hobby 56102 600KV
Running on two 6S3P (22…2 volt)
Max current per motor 110 Amps. (so 220 amps total)
Speed in this config: Just under 30 km/h

Just tested this setup (static) today with my new 12S12P
Max current 271 amps @ 11490 watts!
Speed. TO FAST!

[Sliman_O]

600kv @12s seems a lot (26640 rpm) !

I guess 11,5kw is your total power ? So half per motor 5,75kw) ?

When do you think you will be able to test the speed ? I wonder how it compares to 2x64mm jets from Onean carver X (10kw too)

[Kian]

Correct. 5,75kw per motor.
And yes. The motors are rated to max 30.000 rpm at 50 volts. So the 26640 RPM is about correct.
At this moment we (my dad and I) are still working on the blank (shaping it).
After this we will glass it, and start putting in the jet box and battery box.
It’s going to take some time. We do not want to rush things.

I’m sure 50km/h will be doable with this rpm. If it will be safe to do so I am not sure.

We are going to do some load testing soon.

[Sliman_O]

I don’t know about this rpm. The problem is the impeller diameter vs power. Lampuga boards have even a higher impeller diameter and are barely able to maintain 50kmh. Onean have 2x64mm jets with 2x5kw motors for their carver X and is « only » able to reach 45kmh with a 75kg rider.

Am I missing something ?

FYI, I would go for at least 12S14p with your configuration or you will run your pack warm. The problem doing this is that you have the BMS inside and might get hotter than the pack itself. Take care, there is a reason Onean runs 12S16P pack

[Kian]

During testing we monitored the pack, and it did go up to 55 Celsius.

One thing we noticed with our 1st build was that it got faster when we made the board shorter!
Strange but true.
We started with a 9ft surfboard. We are now down to 5 1/2 foot.

The problem with the Onean and Lampuga is (we think) that the boards are way to long!
Yes. It is nice when learning to ride and user friendly, but really not needed when you get better!

Our board will be just under 190 cm, and a little bit more concaved.
I’m a light rider. 60kg (for now)

The 12S14P or even more is an option we might consider in a later stage. That is if the cells do get to hot!

We have set the BMS to cutoff at 65 Celsius and we will monitor the temperatures very closely during testing.

Thank you for your input! Any help is appreciated.

[Sliman_O]

How long did your static tests took place ? Don’t forget that if you are already hitting 55ºC within let’s say 5 mins, you’ll have a problem when riding after a session or even a half session.

Lampuga and Onean boards are long, that’s true. I have a carver (first generation, 1 Nozzle and 5kw motor) and the board is huge, 2,4m. What a pain to put it in a car… that being said, even like this it is not easy to learn riding it or even stand on it (might be different for other people, but let’s consider newbies like me). Another point to consider is how the water will hit the impeller. And also where you place the nozzle on the board. Too deep and this won’t be good. Too high and you’ll end up with same problem. This also has a big incidence on performance.

Any chance you share some pictures of your jets ? Lemme know if you wan me to share a picture of a specific part of the board too.

[Kian]

The test was about 10 minutes (not WOT all the time), and here are some pictures of what I’m using now.
Please note that it’s not the most beautiful build.

[tacktun]

Hey guys, great topic with great input.
I’m in the planning face of building my own jetboard and right now I’m trying to figure out what jets to use.
I see the trend in DIY Jetboards is to use two smaller jets.
The problem is, I already have a board I want to convert to jet drive and I don’t think two jets will fit in there (besides the fact that you would need two motors and two ESCs instead of one).
I thought about using an 80mm jet with an SSS 56123 500kv motor. At 12s and with 150 amps the motor would have approximately 7500 watts.
I’m not sure if that is enough for such a big jet. But I haven’t found a better suited motor jet.
Any ideas, suggestions and help is appreciated.

[Kian]

Finding a good board to fit everything in nice and flush is hard.

The board I am using is a soft top surfboard. It was a long board (9 ft) as they are thicker than a normal surfboard.

Another nice thing of using a soft top board is that you can easily make the needed cuts to fit everything.

The one I used is 10 cm thick and has 3 stringers inside. You will need to cut the stringers in the middle of the board as this will be the place for the batteries. We reinforced that area with glasfiber again.

Now we are going to make our own board for the 2nd version. One of the reasons being is that we need a little bit more room (thickness) in the middle as we are now using a bigger battery pack.

We are also going to make the board a little bit wider at the back as this is needed to eliminate (not sure what it is called in english) the added weight of the motors and jets.

[Alexandre]

what you are looking for is more like a maytech MTI85165, C80100 watercooled, or a TP100 (best) with custom KV
maytech, alienpowersystem, tp-europe, tp-usa…

[e-Jetter]

For an impeller that’s any bigger than 60mm impeller I would buy a water-cooled outrunner.
I’m thinking about this guy:
IMG_20200905_120636|488x500

[Kian]

is that an outrunner?

[tacktun]

It’s hard to find bigger motors with a suitable KV rating (around 500kv).
TP100:
would be perfect, but way to expensive

Alien Power Systems 80100:
350 KV is the highest KV I could find

Maytech 85165:
Expensive and only 200KV

Flipsky:
Same as Maytech. Only 200KV

When talking about KV ratings… I assumed the target KV for a jet drive should around 500 KV. But now that so many motors with a significantly lower KV rating are suggested, I am not sure anymore.

[Kian]

Did you have a look at the rocket motors?
The Rocket 56112 is a 520KV motor.

[tacktun]

I think the Rocket 56112 would be comparable with the SSS 56123. They have nearly similar specs apart from the SSS being twice the price.
The question remains, if those motors will be powerful enough to drive a single, bigger jet (around 80mm).

[Alexandre]

that is why it would be easier to built a 2 or 3 jets board, and you can not go cheap with 1 jet: big motor and big esc ,like tp100 and vesc 75/300 : 1400€ would be the price you will pay but only one time instead of keep buying cheaper that would fail

TP100

but you can always ask alienpowersystem if they can order you a custom aps83100 at 350kv

i think the main reason that we don’t find high kv big outrunner is that they don’t like “high” rpm.

Scorpion HK-7455-320KV