Electric Surf Board

[chris_kline]

That's an amazing job!
Did you seal the edges with epoxy? How thick are the blades?

cheers

no, i didnt seal the edges. i didnt really have any need for it. the prop pretty much came out of the mould like that. then i just broke of the thin film excess of epoxy that was kind of like webbing between the blades, and did some light sanding with "wet and dry".

the blades are not really a constant thickness so its hard to say. theyre kinda wedge shaped, with a lot of variable surface geometry. the thickest point near the center is around 4.5 mm, and near the edges the thinest points are around 2.5mm. but thats ignoring the fillets etc on center shaft and blade ends

[chris_kline]

here you go. i just put a nut in the mould prior to injecting epoxy

[srn]

here you go. i just put a nut in the mould prior to injecting epoxy

Our shape is nearly the same, but I think I will mill a new mould with same system of screw & nut.
Have not thought about this before, very good idea

[ropower86]

All my photos are massive in size so I had to reduce it multiple time just to get it under 512kb.

[ropower86]

[eFr3ak]

Merry Christmas !

[shefler]

Hi everyone,

Any suggestions to where and how I can buy lipo batteries via international shipping?


Thanks a lot.

[chris_kline]

Hi everyone,

Any suggestions to where and how I can buy lipo batteries via international shipping?


Thanks a lot.

not sure if they will do international shipping, but this is where i got my batteries from. https://www.fogstar.co.uk/

[chris_kline]

Merry Christmas !

this is completely awesome!

good job!

[chris_kline]

board progress

[chris_kline]

happy new years to all!

i need some advice. kinda new to this electric motors thing.

ok so my motor is 8kw, 48v, which i suppose would make it 166 amps peak current.

the battery was about to make, is a 14s8p battery made from panasonic NCR18650B https://www.fogstar.co.uk/collections/b ... 00mah-6-4a

apparently their rated at 6.4A continuous current. which would give me 51.2A.

obviously this is nowhere near the 166 amps i need for full torque. im guessing maybe the cells could give 10a for short bursts which puts me at 80A.

so would i need a 14s16p battery to make this work at full rpm and torque? or is there some subtleties to this that im not aware of?

thanks in advance

[Frizzo]

Happy New year!

Chris, You may find some infos in this thread:

viewtopic.php?f=14&t=26621

Cheers

[chris_kline]

Happy New year!

Chris, You may find some infos in this thread:

viewtopic.php?f=14&t=26621

Cheers

thanks

i think to answer my own question, i should have bought these https://www.fogstar.co.uk/collections/b ... 000mah-19a

then i would have a 160A discharge rate

[srn]

Did you think about something like this ?
https://hobbyking.com/en_us/turnigy-nan ... -xt90.html

with a 2s3p setup you will have more power, less price, less weight and less work compared to 114pcs of small batteries.

just 300$ compared to 725$

[chris_kline]

Did you think about something like this ?
https://hobbyking.com/en_us/turnigy-nan ... -xt90.html

with a 2s3p setup you will have more power, less price, less weight and less work compared to 114pcs of small batteries.

just 300$ compared to 725$

yeah, that would have been a good option. i looked at ready made hobby packs before, but couldnt find anything this cheap with this kind of power.

i ended up buying this https://wholesale.fogstar.co.uk/collect ... box-of-100

cost 255 pounds. oh well, at least i get to learn how to make batteries from hundreds of little cells!

[luca]

hello everyone, I'm new on this forum.. I finished to read all 20 pages of that thread.. I write from italy so I apologize in advance for my bad english.

I'm building a jet kayak with the following components:

kayak Ouassou bic sport
jet unit Graupner Jet 5
motor Tp power 5870 400 kv 9 kw at 12 s ( I mesured the rpm unload and I see 24500 rpm..so around 490 kv effective)
Esc Flier 16s 380A
I'm going to use a series/parallel pack of multistar 6s 20000mah by hobbyking.. (the cheapest one..110 eur pack)

I know the jet unit is undersized among the motor but mhz is too expensive and the jet 5 has been a gift..so I bet everything to the best motor possible.
I will post some pics..

thanks

[srn]

My jet unit is making progress

[chris_kline]

looking great! nice machining work!

[chris_kline]

some progress.

turns out, custom building a carbon fiber surfboard from eps is pretty difficult.

making batteries next!

[Frizzo]

That's an amazing work!
Looks like you have choosen a really big volume for your board. Did you run some calculations for that or did you just follow your feeling?

[chris_kline]

That's an amazing work!
Looks like you have choosen a really big volume for your board. Did you run some calculations for that or did you just follow your feeling?

thanks frizzo.

its a little rough in places. i may sand it down smooth, and apply a final hot coat of resin. but for now, the planing surface is smooth, and its water tight, i hope!

yeah its big. about 140 liters of volume, 2.2 meters long, 600mm wide at the middle. i used to windsurf and standup surf a lot, so i kinda drew from those experiences. 140l should be pretty buoyant, and the 600mm wide should mean i get a slower planing speed, so im hoping it will give the board the best chance of getting on the plane.

i guess i'll find out soon, maybe this weekend if everything comes together i can test it on a lake

[Frizzo]

Well, let's hope for the best!

It also seems to me that your jet unit is kinda going underwater. Doesn't that lead to thrust losses?

Cheers

[AMM118]

Did someone add this one already?

https://newatlas.com/radinn-g2x-electri ... ard/53160/

[srn]

Well, let's hope for the best!

It also seems to me that your jet unit is kinda going underwater. Doesn't that lead to thrust losses?

Cheers

I think the same.

[chris_kline]

water seperation happens below the body of the jet. so the actual jet outlet will be out of the water.
this way water doesn't have to be sucked upwards into the jet, and it reduces the inertia at the inlet sucking the board down, and preventing it from planing.

well, ill see if it works tomorrow.

seems like onean had the same idea