okpTow - Jatem's style

[okp]

Hey,

I’ve taken some delay on the building of my eFoil so I decided to start another build in parallel. A much easier one but with a lot of uncertainty. I’m going for a Tow build, @Jatem 's style.

For the electronics:

• remote : maytech v2
• battery : NESE modules and I’ll put some 21700 cells. 14S8P.
• ESC is a Maker X HI200/HV200
• Batterie BOX : Pelican 1470
• Motor : Flipsky 65161 120kv

For the mast, I’ve bought a cheap gong 55cm mast that I will chop to 20/30 cms (TBD).

Quick 3D custom motor mount prints. I’ll keep the mast base to attach the motor to the board.

I plan to use US BOX rails so I can move the mast on the board (more to the front or to the back) as I decided to simplify and put the motor just after the mast. I’ll likely use some risers to have the motor slightly a bit nose down (to lock the board on the water). My plan is to start by having the propeller at the vertical of the rear of the board to have a good weight balance.

Now the challenge is the board design. I plan to go composites (carbon/gf) like my dock start board but with a more “yatch” look on the front. I’m still wondering how to attach the bungie cord and which one to get. Some ideas I’m thinking about.

Any insights ?!

[Alexandre]

Nice ! Just make sure that the nese module are really attached between themselves , no play at all and take in account the cells temp building up to the discharge rate wanted

[okp]

happy new year builders!

I’m getting the cells today and in the meanwhile, been working on the mast/motor pod. Of course, the mast will be shortened; probably to 25cm.

I’ve used my dockstart board to see the scale of things and get inspired to build a new board.

[okp]

moving on. 14S8P almost done. few photos of the assembly.

It’s tight fit on the 1470 case. Enough and good space but challenging for the ESC. Maybe a vertical fit could do the job.

I’ll shrink-wrap the battery when it’s done and make sure it sits very well in the battery box. Maybe 3M velcro can make it happen.

[SoEFoil]

Looking really good ! Would yo have a link for these soldereless NESE modules with tin tabs ?

[okp]

thanks. here you go

https://18650.lt

If you want to print the modules yourself, you’ll find the STLs here : All the 3D models of 18650・Cults

And all the guidance here : Resources – AMtech

I’m searching for the STL of a 3D printed enclosure for the HI200 @makerX-david is this something you got ?

[okp]

For the ESC, I’m going for the FESC. 75200 with water-cooling included.

Does anyone knows the specs/size of the inlet/outlet tubes?

To ensure it’s a super tight assembly and no leaks occur in the inside of the pelicase, I’ll sikaflex the inlets/outlets.

[okp]

moving on. I received the FS 75002. Overall quality is great but the tubing is very poor quality. I would trust this water tubing. I’ve removed and replace the tubing with a stronger one.

I’m still wondering if I keep the water connectors or replace them with something else. This 3D printer like connectors don’t inspire me too much confidence. I can also put Sikaflex F11C to make the connector/tubing zone waterproof.

[okp]

I’m launching the 3D print of the modified nose cone with the 8mm water tube intake

[okp]

moving on to finish the battery (14S8P) with NESE modules. I added loctite on the nuts and decided to solder the balance wires to the strips (thank you Mark!).

I will use an external BMS so I can share it between my upcoming eFoil and this project. AWG10 & QS8-S connectors will be used.

[okp]

battery is done and the placement seems good.

[Jatem]

Keep a close eye on the bolts remaining tight, or your battery will melt the NESE battery holders. Tow boogies get bounced around a lot.

[okp]

yes brother! loctite all the way; I’ve also tighten them pretty hard. that’s also one of the reasons I didn’t put some connectors to attach the balancing wires and soldered them on the strip.

[okp]

big step to finish the battery… charging works using the external BMS. I’ll be also using this method for my upcoming eFoil.

[okp]

Big news ! I got my imaginary shape cut down in CNC.

[okp]

moving forward and very quick sanding. It’s cool but put so much dirty particles everywhere!

I will need to round some stuff and angles to make the vacuum exercise a bit easier.

[Foilguy]

I am awaiting delivery of some FLIPSKY components to start my “case” on top of board build. I also chose the 75200 VESC from FLIPSKY and am curious about more detail on how you enhanced the original product.
I would appreciate some additional photos and detailed description of what you did to reduce the leak risk.

Thanks

[Jatem]

It’ll be interesting to see how the narrow tail on the board handles the torque twist of the motor. Running a bigger/wider boogie board significantly improves usability in tricky conditions, because the wide tail resists flipping to one side from all the prop twist when you’re giving it lots of throttle.

[okp]

thanks brother! I plan to put the mast in the middle of the board with USBOX to move it and tune it over time until I get the right balance.

I’ve moved forward on building the USBOX & Airex combo. It’s overkill I know, but I’m not going to lower the standards! I’m using Silice cells because it’s mechanical property vs glass cells.

50 grams of resin / 25 grams of hardener and some silice powder. A good mix and then I through this in one USBOX rail holder. Same for the other one. Sanding the USBOX rails is super important for a good bond.

Checking alignment

Here we go with some weights

I will also dig a rail between the two USBOX to enable the 3 motors cable and the water tubing that will escape on top of the mast baseplate … to move freely when moving the mast on the USBOXes.

[okp]

definitely. I will keep you posted. I’m going to do some work on the board before to progress slowly but surely!