Holland board build

Nice drawing! Let me know of jou need some more prints;)

As hiorth mentions above, I’m also curious about your cable connection trough your board. I’m struggling with mine all the time when I’m attaching/detaching the mast. Already had to tape a naked cable:(

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I took your advise about a solid connection, want to have it strong :smile:
I am not quite sure if I follow you. my plan is to make a hole in the mast connection plate and guide the cables down and have an exit there to guide them into the torpedo. In the board I am planning a pipe for the cables. At the end, above the mast connection, I want a custom plastic pipe (3d print) which is same width as the pipe but longer in the longitudinal plane (sort of triangle shape) for me to adjust the mast position of necessary. This should also give some flexibility to unscrew the mast for transport. So far the thought. Have to figure out if this will work.

Sounds good, my thought is just that you need some additional cable length somewhere in case you want to detach your mast from the board when transporting.(Or you could detach the cables from the esc every time you transport it.)

Yess, the plan is to have some over-length somewhere. Have to find out a suitable place once building it up. I think I will try to avoid the disconnecting. Perhaps when you finish some connectors are still wet and you might have short-circuit?

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Update 2

It has been a while but making small steps forward.

Cut up the old windsurf board i bought on the cheap. Thought this would make my life easier but it doesn’t. Lots and lots of work, starting from a foam block would have been half the work. Upshot is it already has a lot of strength by itself and I will add another two other layers of glass (test piece on a cut off part worked fine).
The bottom has several slots where I will add 6 90cm strips of wood to compensate for the large hole.

The large chamber is for the electrics. THe small recess is for my metal cover plate where the studs of the fin box securing will end. Will be covered with foam and glassed shut (see my sketch above of mast connection).

Pouring a high density foam section to which the mast will be secured. Will glass this into the cavity in bottom of board.

Setup of my electrics (4 12 Ah 6s batteries). The white paper is same size as the E-box in the board. Will make a divide between the batteries and the rest of the box. Got a Littel mega fuse, Seaking 130A ESC, dual SBEC and a small frame I printed to hold the water pump and raise the display so I can read it through a plexiglass section of the cover.

Do you guys have any thoughts or suggestions on the setup??

Below the frame which I came up with. Inspired by @rogjalon. I printed a profile which I will epoxy the hell out of to make it water tight. In the bottom picture you see the test piece with the rubber seals which, with some additional grease and a bolt every 6cm, should seal it from water, I hope.
Still need to use the router to remove the section in the board to fit this frame. Will also add a royal amount of bostik superfix for additional measure. The threads are stainless steel threads with the bend section made straight again and inserted in the recesses in the bottom of the profile.

Any thought on the workability perhaps? Have to test it still.

Today was also early christmas. After 18 weeks of waiting the Neugart gearbox arrived :smiley: :smiley:
But, but, but, the clamp which should fit on the 10mm shaft of the electric motor is only 9mm … :frowning:
Will call them tomorrow, but don’t want to wait another 18weeks for a redelivery.

What do you guys think is the way forward, to drill out the clamp to 10mm, or lathe the shaft of the motor (on the right below) to 9mm?

Hope to be ready for spring weather, but still lots and lots to do

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Nice job!
For lathing down the shaft you could go for the ‘rough’ method, though it worked fine for me;)


UPdate 3,

I cut the alu pipe to length today. I don’t want to cut the motor cables so, to compensate for the extra length I printed this support. On the forum I saw somebody drilling a hole in the fuselage to mount a similar support. I did not feel so comfortable with that idea so I took a photo of the cross section of the fuselage and after a few prints I had a very tight fit, so it is can take some lateral loads in addition to the vertical loads.

The prop is originally from @tunnelvision, THanks! I adjusted it so it will fit on the PM setup. The parametric duct by @pacificmeister & @Taylor is adjust to fit the prop. I beefed up the struts a bit and tilted them further back (I have this space available with this prop).

All but 1 hole are drilled in the mast for the wires + water cooling.

The mast clamp and seal mount are epoxied to ensure water tightness.

Do you guys recommend to epoxy the prop and duct as well?
And how many layers do I have to apply, just 1?

So next up is assembling the pod and pull the wires through. I am just waiting for a re-delivery of the shaft seals.

The epoxy foam mould which I inserted the other day cured nicely, feels quite solid. I used the router to make 2 recesses for the fin boxes. Next time I will epoxy these in place.

Do you guys have any tips/recommendations for this part??
Do I have to later place epoxy+glass over these boxes (except for the slot) as well, or should I work just directly around them?

My biggest worry is the box hatch. Really hope it will be water tight. I started to assembly the (red) frame (made up of 8 parts, 4 corners + 4 straights). The corner sections and short straights are epoxied together and curing. Later they will make up 1 frame as per below, but fully coated with epoxy. Finally I will place, from the bottom up, the stainless steel inserts with thread, so I can secure the cover with 30 bolts. In between the frame and cover will are 2 strips of rubber, as a seal.

The big hole is where a 3d printed part (coated with epoxy) will be placed, to route the cables from the box to the mast.
I prepared the e-box first with a layer of epoxy+wood fibres and later with another thin layer of epoxy+filler to make it level. Next, after sanding it smooth, will be a layer of glass.

The shallow recess is where a metal counter plate will be placed to give additional strength to the mast connection (see sketch further above).

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Looks great. You’ll be surprised how well your hatch seals. Are you using marine plywood for the hatch lid?

hello, the project is advancing, concerning the box for the US rails it is good to make a liner fiberglass epoxy resin micro balloon and then actually several layers of fiberglass resin on the upper part. we can not imagine the force generated by the mast at this place.

Thanks Roger! Good outlook, hope it will work out nice. Yes I am, 5,5mm thickness. WIll epoxy this as well. Did you every had any issues with leaks around the holes of the plywood cover?

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Thanks Manu. Trying to follow your proposal. Do you mean to place the liner of fibreglass epoxy resin between the box and the foam of the board? And than additional layers on top of the box, covering the board+fin box, is that what you mean with “resin on upper part”? Thank you.
I agree with you that the loads will be very high, so that why I want to make this as strong as feasible.

I’ve never had more than a few drops get though. I’m still not sure if it came from my water pump or incorrect lid tension.

@Marc87 ,


Thanks Manu, will study this!

It’s been quite for a while, but I have been working plenty of hours on the project. Especially the board, close to a never ending story of sand paper, epoxy and filler, and again and more. But the last 2 weeks the board took some shape.

I epoxied my hatch frame into the board, using a mixture of epoxy and a small cotton fibres, to thicken the paste. The wooden hatch was placed on top to create an even pressure on the 3d printed frame. The small gap between the frame and the board was filled with more epoxy. Really hope this is properly water tight.

The steel counter plate with long studs fixed to the fin boxes was also installed and tightened securely. I used metal pipes around the studs between the metal plate and the fin box in order to avoid compression/denting the foam board. It feels quite sturdy. I used a polyurethane foam to fill the hole. So can’t access it anymore.

I left the original glass fibre structure intact wherever I could, but in order to compensate for the Ebox hole I added a layer of fibre glass in the E-box and on the top+bottom of the board. Wooden strips + fibre class were epoxied into the bottom of the board earlier.

Against the backside of the box you see a 3d printed plate+frame. This “collector” is where the motor wires + waterline come from the mast. The collector is epoxied for water tightness and then heavily gloed into the board, to avoid leeks. I will place the cable glands into the red cover plate once the cables are pulled and finally epoxy this into place as well.

I am quite afraid that the box might not be fully water tight so I designed a polycarbonate box to go inside the box. All the electrics will be installed into the polycarbonate box and some additional cable glands will wire the cables outside this box.
Unfortunately the company did not provide all the parts, so could only glue half the box together.
I guess apart from designing, fabricating parts, overcoming challenges, etc waiting is big part of this project :smiley:

But it is all slowly coming together. Yesterday night if secured the efoil to my custom board for the first time. It does all get quite heavy, have to check the weight, very curious.

Next step is to paint the board. Unfortunately for me 1m above my head here I have neighbours, and poorly insulated floors, who complained about me painting before. So I have to make a paint booth in my guest bedroom.
I soldered all the electrics together and powered the prop with 12S, feels very powerful. So soon I can assemble the motor pod and pull the wires into the board.
Then finalising the poly carbonate box + some other small bits in pieces.
Half May is the target for first testing. Keeping my fingers crossed


I have almost the same shape of board. Mine is only 135cm long and 77cm wide but it works very well. My weight is 73kg.

Cool, sounds promising for me. My weight is about 70 with roughly same volume of the board.

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Last couple of weeks I tried to finalize the Propellor pod design. Really afraid that seals will leak because of the mismatch between propshaft and coupler.
Tried a few designs and printed a few new sealmounts to test. Below proposal is based upon a Hiorth setup using jaw type coupler. But I had some issues to make the custom shaft or having it made turned out very expensive.

Next option was with a much larger clamp coupler and redesigning the PM sealmount so it would fit this coupler. Thought it would be good to add a second (dry) bearing and have quite a big gap between seals which I will fill with grease. I also increased the length a bit so a grub screw can be placed before the O-rings. My solidworks skills improve because of all this quite a bit :slight_smile:

Today the coupler finally came, and it is quite a unit, 40mm long with two clamping screws per shaft.
So an important moment, would the shaft (by now 130mm) fit properly and will er be less to no wobble during operation. I did not add the second dry bearing yet but what a difference! Below current setup in a nutshell.

I probably will tried the jaw coupler eventually as well, but I’m building for 9months now and want to get onto the water :smiley:

Board and Electric box are pretty much finished. Just need final positioning of the ESC and pump/display mount.
The E-box is a box in a box. So a bit weird, but have 2 lines of glands to get cables into the board. Water tightness test 1 was positive and increased it a bit further with the rubber seals ontop of the box (visible below).
The batteries a secured with Velcro and this seems to work very nicely. A rubber strip is mounted to the inner polycarbonate box side walls. So hope the lid seals even better now.
I plan to assemble the Prop pod this weekend and pull the wires in. Lets see how it goes.


Congrats on the build, looks good. Your big coupler looks similir to mine, Ruland stainless, quite big. Mine has a slot for a key which prevents slip (a common problem when using a coupler). Due to the lenght of the coupler, the shaft alligns quite well, 5/100 untrue at the pod exit of the shaft in my case. I don‘t know how much wobble other builders have, would be interresting to see if you have a dial gauge.The coupler should be balanced to reduce vibration. I removed matrrial with an angle grinder until it was balanced.

Thanks @sat_be Daniel. I have a non branded one, but think will work same as yours. I haven’t measured the untrue value for my setup, as I don’t have a dial gauge. Might ask around if somebody has this laying around. Eye balling it so far and looks promising. Leaks at the seals are one of my big worries.
Good point regarding the balancing, will check it out. How did you test this?