Its snowing here so i thought this would be a nice time to start my cooling similar to @sat_be s Build: Daniels (un)geared inflatable (slowly built) - #72 by sat_be
This solution is much more easy because a water tube could disconnect when the radius is getting to small. The Summer gonna show if the aircooling is enogh 
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So i bought the biggest cooler i could find, around 30010020 and cut it down to 20010020.
After that I trimmed ~8 - 10 mm flat plane around.
Then I made a hole of the size of the cooling fins in the box.
The direction of the fins is going to be in the direction of surf. This should lead to a maximum air cooling.
The heatsink got several screws to hold it in place. Its seals with Silicon all around.
I Placed the VESC directly on the Heatsink with some heatpaste and two screws.
The screws are also seald with silicone.
It looks like its all Waterproof 
Made some Isolation with some rubber from a bike tube. And placed all the components and made some nice cabeling. The placement of the components is pretty nice. If water comes in they stay dry a long time. But the batterys gonna melt 
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The edges of the heatsink are really sharp. If i fall i directly fall over it. So i Made some PETG protection frame around it. There will come an aditional one for the screw of the VESC.
So next steps gonna be:
- Test it
- replace bearings
- replace the old mastmount with the new hydrodynamic improved version.