Technical discussion around jet surf board

Boats, Jet Skis, Kayaks etc., including hovercrafts
Post Reply
User avatar
Ratking
10 kW
10 kW
Posts: 519
Joined: May 20, 2010 5:27 am
Location: Norway

Technical discussion around jet surf board

Post by Ratking » Aug 27, 2015 9:43 am

Hello guys,

I am about to use a bit of money on trying to make a electric jet board. But I am afraid that I am too optimistic of what is possible without wasting a lot of money.
From what I have gathered of information is that there are boards with a two stroke single cylinder with 35hp with a top speed of 65km\h.
Others have a 100c singe cylinder with a top speed of 55km\h, Lampuga with 15hp has a top speed of 54km\h.

In other words, I would need a least 13kw of power to get things going like I want. I don't need a board that barely moves, I want speed and acceleration.
Getting a motor and controller for an application like this is not hard, I want to use two good old 80-100 turnigy outrunners with my custom winds. They should be able to make 12-14kw for a short burst here and there. What keeps me from doing this is the axial pump with an impeller. I don't have any data on thrust compared to watts and size needed for the power I have. All such data is kept secret as far as I have seen. The cheapest and most reliable pump would be an old pump from a Kawasaki JS 300/440/550 stand up. They are 120mm in diameter and cheap.

A JS300 has a 26hp engine capable of making 100kg of thrust with a dry weight of 110kg. Since I have a board with half the water resistance and one third of the weight I guess I can get away with a bit less power. But I have no numbers of torque needed to drive the pump. Will it work good enough? And what kind of pump is the Lampuga using? I guess a bit smaller pump, maybe 90-100mm.

Please give me some input if you have any thoughts that can help me in any direction.

Preliminary part list:
Motor: 80-100 turnigy 160kv x2
Controller: CC HV 160 2x
Battery: Enerdel 12s2p (50v, 35Ah, will be increased to 3p or 4p if weight is not an issue)
Pump: JS 300 or 440 with a 15.5 pitch impeller
Board: Any surf board over 6 feet
Drivetrain: HTD aluminum pulleys with belt
Throttle: Would like a waterproof transmitter

User avatar
Ratking
10 kW
10 kW
Posts: 519
Joined: May 20, 2010 5:27 am
Location: Norway

Re: Technical discussion around jet surf board

Post by Ratking » Sep 17, 2015 8:44 am

I've been sourcing three motors and got them a couple of days ago. I will wind them as 133kv since that is the best compromise for 12s pack.
Only two of the motors will be used of course, one extra is if two is not enough ;)
Attachments
IMG_1117 (Small).JPG
IMG_1117 (Small).JPG (54.79 KiB) Viewed 1527 times
IMG_1118 (Small).JPG
IMG_1118 (Small).JPG (52.76 KiB) Viewed 1527 times

galo_ivi
1 µW
1 µW
Posts: 3
Joined: Sep 02, 2011 10:27 pm

Re: Technical discussion around jet surf board

Post by galo_ivi » Sep 17, 2015 10:46 am

Hi
In the pump jet is very difficult to get efficiency.
Basically we can calculate the power we need to obtain velocity. But have other things that influence in the efficiency, like the design stator, length impeller, design of hub impeller, design bottom board.

I will try to do with just one motor 80100 130kv and Lipo 12s.

Good luck.
Attachments
Jetspeed_Single_Stage_Unit-(English).xlsx
Calculator power
(12.37 KiB) Downloaded 216 times

User avatar
Ratking
10 kW
10 kW
Posts: 519
Joined: May 20, 2010 5:27 am
Location: Norway

Re: Technical discussion around jet surf board

Post by Ratking » Sep 18, 2015 6:33 am

Thank you for the calculator, the problem is that impellers used in jet skis are calculated in degree and inches. I have not found a way to convert it to standard pitch as I am used to in the aircraft field. I am after fairly good acceleration, so I think two motors is the minimal for my requirement.

Good luck yourself, feel free to post progress pictures :)

ropower86
1 W
1 W
Posts: 52
Joined: Dec 05, 2016 7:50 pm

Re: Technical discussion around jet surf board

Post by ropower86 » Dec 05, 2016 11:01 pm

Hello (Ratking), I know this post is very old but I wanted to know any updates on your project with your electric surfboard build. Hope to hear from you.

Post Reply