Electric Surf Board

Boats, Jet Skis, Kayaks etc., including hovercrafts
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bigbore   10 kW

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Re: Electric Surf Board

Post by bigbore » Aug 01 2019 1:50pm

It is strange that the capacitors burn, I think you will know that all the old Lampuga surfboards were equipped with MGM controllers

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 02 2019 4:59am

yeah, well they must have figured out a way to stop them exploding.
maybe they went with external watercooled caps banks also, or maybe they just tuned the resonance out of the caps with specific wire lengths and battery configs, and esc settings.

through a combination of increased motor timing to max, a large external watercooled caps bank, and temp monitoring, i managed to stop the caps exploding in the end. but mgm were literally useless, they had no tech insight to offer, rarely replied to my emails, and refused to offer any kind of warranty, despite the claims that their esc's are guaranteed.

even the chinese companies i bought esc's from had way better customer service than MGM.

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bigbore   10 kW

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Re: Electric Surf Board

Post by bigbore » Aug 02 2019 10:27am

chris_kline wrote:
Aug 02 2019 4:59am
yeah, well they must have figured out a way to stop them exploding.
maybe they went with external watercooled caps banks also,
I personally saw two of the old Lampuga surf boards opened and there was anything like that
chris_kline wrote:
Aug 02 2019 4:59am

mgm were literally useless, they had no tech insight to offer, rarely replied to my emails, and refused to offer any kind of warranty, despite the claims that their esc's are guaranteed.

even the chinese companies i bought esc's from had way better customer service than MGM.
This is very bad and useful info about MGM.
Did you noticed the bike controller that Vasilisk is developing? I thought the 24 fets with a Maximum power of 20kW and a Nominal power of 10kW could be good to drive a surf board out-runner motor. What do you think about it?
They also can be potted to protect them from corrosion.
viewtopic.php?f=31&t=75494

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 02 2019 2:00pm

looks well made, would be interesting to know what the max erpm is on that.
im thinking it would need a watercooling heat exchanger on those fets for a surfboard application though. thing is on watercraft you are operating at a high load constantly, its like gong uphill all the time.

about mgm, maybe i had a bad experience, i was dealing with one sales guy, who then handed me over to an apprentice sales staff, who then left, and was replaced by another apprentice who didnt ever reply. all in all the experience was pretty terrible

fabianpusch   10 mW

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Re: Electric Surf Board

Post by fabianpusch » Aug 02 2019 2:02pm

Yes MGM is really good in selling the controllers but if you have a problem, it is always the battery or e.g. the lengths of the cables.
I have solved this by putting two additional banks of caps shortly before the ESC.
And still the battery can be an issue....I am now using military specs cells from Kokam.
Nice run with the gasoline powered board.
Are you using molds?
By Fabian

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 02 2019 3:00pm

mould for the board? no this one was hand made, from expanded polystyrene foam and wet lay carbon like the last one, i just got a bit better at doing it this time :D

the motor compartment was made with a mould though, and prepreg carbon, but i dont have a big enough autoclave for the main board to fit

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madin88   100 MW

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Re: Electric Surf Board

Post by madin88 » Aug 03 2019 8:57am

Has anybody thought about using a VESC 6 300, or SLS (sinusleistungssteller.de)?
Lehner Torqstar has sinusoidal BEMF so it would be even more efficient if driven with a sine wave controller.


http://www.sinusleistungssteller.de/FuriaOne2012.html

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 03 2019 9:01am

yeah i contacted them when i was in the middle of my troubles with mgm.
they said they werent really able to get the erpm needed

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Bazaki   10 kW

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Re: Electric Surf Board

Post by Bazaki » Aug 03 2019 5:37pm

The gasoline jetboard makes almost the same sound as the electric version in your video's :mrgreen:

I can imagine that trouble after trouble is demotivating you.

I also stopped for the same reason with my electric jetboard, but now my electric hydrofoil is almost finished. It has so many benifits, only need about 900 watts to Foil, more silent, easier, cheaper and it is the feeling of flying and surfing.

Maybe i will build a prop driven surfboard, like the waterwolf for shallow water.

https://www.esurf.com/ did you see this?

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madin88   100 MW

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Re: Electric Surf Board

Post by madin88 » Aug 04 2019 5:53am

chris_kline wrote:
Aug 03 2019 9:01am
yeah i contacted them when i was in the middle of my troubles with mgm.
they said they werent really able to get the erpm needed
Yes most controllers struggle to do high RPM in FOC mode, even the mentioned Nucular controller does not like RC motors that much.

If 16s and 300/450A are high enough for your setup i would give the VESC6 75/300 a try 8)
In terms of ERPM in FOC it should be one of the best controller available out there.

Silixcon controllers also seem to be a good choice for RC motors check them out:

http://silixcon.com/products/

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 05 2019 7:26am

yeah, those Esurf boards look very well made, next gen stuff.
but they cost like 20'000 so for that money, you would expect the best!

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bigbore   10 kW

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Re: Electric Surf Board

Post by bigbore » Aug 05 2019 12:17pm

chris_kline wrote:
Aug 05 2019 7:26am
yeah, those Esurf boards look very well made, next gen stuff.
but they cost like 20'000 so for that money, you would expect the best!
Yesss 20k + VAT .... around 24k€ but based on the video they posted at the end last year they seems to be the most powerful and reliable jet boards and I would love to have a test ride one day on one of them...

srn   10 W

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Re: Electric Surf Board

Post by srn » Aug 07 2019 2:40pm

Did some water tests.

Two major problems:

1. Sealing of my polycarbonate glasses is not good. Had water in my board, thats why I had to stop testing.

2. I am too heavy :oops:
In my design phase I thought that it will produce enough lift when accelerating. So I designed 100l of volume. The board weight is 30kg + my 85kg.
Result is, that I push it completely under water and it cannot accelerate. Now I am thinking of two wings to get more uplift.

How much volume do your boards have ?

Here short a video which shows 10.000rpm @ 4kW:

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 08 2019 12:32pm

my electric jetsurfer has about 150l of volume
my gas jetsurfer has about 90l of volume.
my gas jetsurfer sinks if im not moving, but i wanted it smaller to be more maneuverable.

if you decrease your nozzle diameter at the small end, you will get a lot more thrust, and will get on the plane almost immediately.

looks great though! now its the time for endless fine tuning to get everything sweet. i spent ages fine tuning pretty much every aspect of mine over the course of a year to get it working well.

do you have any video of it with you on it at full throttle? :)

Alexandre   1 µW

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Re: Electric Surf Board

Post by Alexandre » Aug 08 2019 5:06pm

i am using the vesc6 75/300 on my efoil, running 100A (battery) continious with no cooling at max 70°c, above you will need to add a watercooling system for a esurf, i think your board is to small to acheive planning speed, mine (efoil) is 90L and it takes this power and the wing to take off and it needs the same power to go about 35km/h (big wing and propeller duct)

the vesc6 75/300 is very nice and let you do all kind of setting but it s expensive... , a bit overkill for a efoil, but nice for a esurf

battery cables are about 25cm long (2x10awg)
motor cables are about 200cm long (10awg , cooled by water)
no capacitors
no amp pics above max settings 100A battery and 130A for the motor, no heat problem beside the battery pack: running 12s8p 30Q, above 7.5A/cell the battery starts to heat to the manufacter specification @60°C , the battery is too small (i knew that just trying to save some weight...)

srn   10 W

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Re: Electric Surf Board

Post by srn » Aug 09 2019 1:40am

chris_kline wrote:
Aug 08 2019 12:32pm
my electric jetsurfer has about 150l of volume
my gas jetsurfer has about 90l of volume.
my gas jetsurfer sinks if im not moving, but i wanted it smaller to be more maneuverable.

if you decrease your nozzle diameter at the small end, you will get a lot more thrust, and will get on the plane almost immediately.

looks great though! now its the time for endless fine tuning to get everything sweet. i spent ages fine tuning pretty much every aspect of mine over the course of a year to get it working well.

do you have any video of it with you on it at full throttle? :)
I was not surfing on it at full throttle yet. When I sit down on it, it is more like a submarine and cannot accelerate :confused:
My nozzle has 50mm at the end. How about yours ?

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 09 2019 2:59am

45mm nozzle, 76 diameter prop, with 70mm pitch

srn   10 W

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Re: Electric Surf Board

Post by srn » Aug 09 2019 3:50am

chris_kline wrote:
Aug 09 2019 2:59am
45mm nozzle, 76 diameter prop, with 70mm pitch
how about your water inlet ? My prop is 60mm. This could be too small :idea:

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 09 2019 4:39am

inlet is equivalent to about 80mm diameter.

i think the 60mm prop should be fine, whats the pitch of it?
just reduce the nozzle size to get more thrust, it will make a huge diference.

4kw @ 10000 rpm is very low power for that rpm. mine consumes about 10kw at 10'000rpm
ive found, going over 14000 rpm tends to cavitate on both my boards

srn   10 W

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Re: Electric Surf Board

Post by srn » Aug 09 2019 6:20am

chris_kline wrote:
Aug 09 2019 4:39am
inlet is equivalent to about 80mm diameter.

i think the 60mm prop should be fine, whats the pitch of it?
just reduce the nozzle size to get more thrust, it will make a huge diference.

4kw @ 10000 rpm is very low power for that rpm. mine consumes about 10kw at 10'000rpm
ive found, going over 14000 rpm tends to cavitate on both my boards
Pitch is 60mm.


My biggest issue is the sealing of service hatches. Do you guys have good solutions for that ?

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 09 2019 10:51am

ill post a photo tomorrow of what i did with my hatches.

basically i just had a rubber gasket cut for me by a company who cnc cuts gaskets for plumbing and oil industry etc

60mm pitch is a little low, especially for a 60mm diameter prop, you would need to get that nozzle pretty small to create enough thrust for planing, something like 40mm. but with a small enough nozzle, it will be fine

chris_kline   10 W

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Re: Electric Surf Board

Post by chris_kline » Aug 11 2019 10:10am

heres a photo of my hatch, aluminium flange, with a rubber gasket, and thumb nuts for fastening it down
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fabianpusch   10 mW

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Re: Electric Surf Board

Post by fabianpusch » Aug 13 2019 11:24am

My board has around 110l.
@10000 rpm I also need about 10kW, so it seems that your jet has a lot of cavity issues.
To seal your compartements use a soft tape made of Pvc....I have bought this from a reseller of RC controlled boats.
It is a quick and easy solution.

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