## ”The barge” efoil build

Boats, Jet Skis, Kayaks etc., including hovercrafts
larsb   100 MW

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Location: Gothenburg, Sweden

### ”The barge” efoil build

Building a foil board, first attempt. How hard can it be?
I have very limited time so i’ll build quickly and to learn more than to do a beautiful design, it’s now called ”the barge build”

Took about an hour to build a hot wire foam cutter so i am off to a flying start.
25A656DC-199E-43BE-A764-A948F05D1D83.jpeg (117.5 KiB) Viewed 8866 times
I found Gong surfs/foils on the web and have ordered this xxl size foil after some emailing back and forth:
3D20B64C-E2EC-45E9-905B-606EC7D04CE8.png (30.42 KiB) Viewed 8866 times
It will be powered by a c80100 motor setup so i’ll have to waterproof one of my motors, coming soon
Last edited by larsb on Jun 24 2020 4:47am, edited 1 time in total.

DogDipstick   1 MW

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### Re: ”The barge” efoil build

larsb wrote:
Jun 24 2020 12:03am
Building a foil board, first attempt. How hard can it be?
I have a lot of experience in building boats, rc motors, batteries and the like. Got a good foam cutter, lol. Look forward to seeing how you go. I have been entertaining the idea of the same thing, .
84v of Ironhorse XC.. by Chevy You call .. that.. a "glitch:" ? (...No Mom. The formula is Kaw > 1(Hr) = Impounded. The math checks out. I'll be fine. ).. Broke20Horsies! 17,830w !! 1 (pound / second) Hp = 338.24 M^2 Kg^2 / Sec^4 ) isn't 13" x 27".. Oh nvrmnd 4+25% = 5 ; 5-20% = 4... 5(1-20%) = 4.. so, to correct the incorrect reading, of 4 ... 4(1+25%) = 5 Fabricator @BSECo. God. Damn. Slugs.

larsb   100 MW

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Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

The barge foam design:
foil_board.jpg (35.18 KiB) Viewed 8851 times
Basic dimensions 1700x580x150mm, 120 L

larsb   100 MW

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Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

First foam glue and cutting done, i got some issues. Three stacked foam sheets of 50mm hardly works as their tolerances are too large. There will be gaps - i have used 3m 77 spray adhesive which is not gap filling and instantly tacks so repositioning is not possible. I’ll try a foaming PUR adhesive instead but i have doubts it will work well while sanding and hotwire cutting.

I might try also to also find thicker xps foam sheets to solve the stacking gap issue, should be better with only two sheets stacked
7FDC534C-224F-415E-87CC-063C4C41D9E7.jpeg (48.7 KiB) Viewed 8823 times
Last edited by larsb on Jun 27 2020 9:37am, edited 1 time in total.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Got new xps sheets and sikabond-545 (ordinary PUR) glue. Hopes are high.

Will make a new attempt at gluing the slabs on sunday when it’s raining.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Made a smaller hot wire bow for shorter cut depths, this is about 30cm/12” wide and can do 30cm deep cuts. It turns the wire red hot.. dimmer does not affect either voltage or current.

Seems the dimmer cannot regulate the power supply. Guess they’re not compatible. Why?
A7FCDD2D-F17F-4513-98A8-2954CCB920AC.jpeg (116.21 KiB) Viewed 8776 times
Cutting with the longer bow is slow, the power i've got is struggling with 75cm/30” wire, cuts are slow through the foam even though they burn the wood guides i made. I guess the melting/gassing of the foam cools too much over too long width. Power is 19V*3.9A so 74W. Maybe i’ll have to use metal cutting guides and more power. but that requires another power supply or a battery.
Last edited by larsb on Jun 28 2020 4:15pm, edited 2 times in total.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Testing cuts on ordinary EPS80. It’s a lot easier than cutting XPS300 due to the lower density.
B47CB29E-FB1C-43E7-89E1-16DA1491DB17.jpeg (76.03 KiB) Viewed 8759 times
I think the hot wire calculator i used is not for XPS as it gives out too low power values.
(https://jacobs-online.biz/nichrome/NichromeCalc.html)
I guess more like 150w is needed to take a full width cut through 24”/600mm XPS300 sheets.
Last edited by larsb on Jun 28 2020 6:28am, edited 1 time in total.

larsb   100 MW

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Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Well, temperature of the short bow really is too high, i started a fire when cutting I got no pictures of that though, had to save the board
F56B9AFF-EF55-475E-9E3D-CC2508CF3FE6.jpeg (55.16 KiB) Viewed 8744 times
I made some guide rails with metal strapping fixed with hot glue dots. Worked remarkably well!
Last edited by larsb on Jun 28 2020 6:24am, edited 1 time in total.

larsb   100 MW

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Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

I couldn’t wait for the PUR glue to set in 24 hours and the new XPS sheets (jackofoam XPS250) turned out to be a lot better in the dimensions so i decided to give the super 77 adhesive another chance bonding time is then reduced to 30 minutes which is nice.
I sanded hairlines and small ridges created during the manufacturing of the sheets to get better flatness, took about 2 minutes per sheet
28A846A5-4F13-428B-8485-58508E4DBF14.jpeg (31.31 KiB) Viewed 8732 times
The slabs are bonding as we speak and i’m already happy with the result. Cowabunga!

I think i’ll scrap the CAD designing and just freebase with the hotwire bow and metal strapping, it was quick and a lot more fun.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Since dimmer doesn’t work i’ll need to solve it with longer wire. Hacked up a new 50cm bow which gives the thread a really dark cherry color. I’d guess max temperature is around 450-500 deg C. No more fires
Incandescent color vs temperature
FD977A8B-5435-4720-8F98-1739BB0E9B79.jpeg (32.31 KiB) Viewed 8722 times
Mid size / 500mm bow
E36241FE-E302-4903-9C26-1A010EE8EBC1.jpeg (89.51 KiB) Viewed 8722 times
Last edited by larsb on Jun 28 2020 4:17pm, edited 1 time in total.

larsb   100 MW

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Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

All the hotwire cuts are now done, just some rounding of the corners is needed before glassing. I had a lot of fun with it!

The gluing turned out to be sh*t (again), i sprayed heavier coats than before with the super 77 and it seems the foam melted a bit. Aaargh! The sheets are now only partially glued - It’ll have to do anyway though far from optimal. Tomorrow is sanding time.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Sanding halfway completed. Not going for the gold just barely OK looks
I wonder how to fill small voids in the foam.. best would be something that sands as easy as the foam itself. it’ll have to be a quick solution. Maybe epoxy putty if result doesn't need sanding at all, or some other ultralight sandable filler.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

I've ordered some heavy glass fibre cloth: https://shop1.r-g.de/en/art/190156
600g cloth.JPG (20.46 KiB) Viewed 8666 times
It's 600g/m2, goal is to do 1 reinforcement layer + 1 top layer with this and glass it in one layup only.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Got an IP67 electronics enclosure. A bit lazy to not build it but making a DIY 100% waterproof seal is not easy.
208FEAC7-7970-4471-802C-0828EF7F8BB0.jpeg (85.95 KiB) Viewed 8659 times
Last edited by larsb on Jun 30 2020 9:30am, edited 1 time in total.

larsb   100 MW

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Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

This guy knows what he's doing, love to see a pro do his work.
Last edited by larsb on Jul 19 2021 11:56pm, edited 2 times in total.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

I couldn't open the enclosure for the life of me, then i saw the lid bulged inwards by half an inch, there was so high vacuum in it that i had to heat it for five minutes with a hairdryer before the suction let go

I guess tightness is proven so that's good
Last edited by larsb on Jul 01 2020 1:33pm, edited 1 time in total.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Got the foil today it’s humongous
Came packaged in a super nice bag with separate foam sheets for the fuselage, mast, front and rear wing. Build quality is good - way better than my expectations.
1018B0EA-6C4F-4601-B668-58ACB29E7486.jpeg (173.03 KiB) Viewed 8614 times
One thing to improve: The fuselage is 30x30 solid alu, weighs a ton and could easily be replaced. Carbon variant of this or even a drilled out one would shed a pound or two.

larsb   100 MW

Posts: 2657
Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

I am thinking about how to connect the phase wires, there’s plenty of space inside the mast even for 8AWG wires but not for connectors. I also want to be able to separate the mast and board with no connectors in the water.
99BB7317-499B-4E7E-8EDA-C77EA6C42841.jpeg (65.34 KiB) Viewed 8579 times
Guess i’ll do a larger through hole from the top of the board and a small recess in the bottom to get into the mast somehow. I want to keep the flow as good as possible around the mast.

larsb   100 MW

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Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

First prop on the way.
DE36DE0C-A4E8-4020-AC8B-4D806D0CFE27.jpeg (106.35 KiB) Viewed 8572 times
Don’t know yet if the support structure can be removed

larsb   100 MW

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Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Support material was sticking so it looks a bit rough, i’ll try to finish it with carbon and epoxy. It’s still quite strong!
D96F54F2-6BF5-4A96-8FB4-DDBD5665940D.jpeg (106.74 KiB) Viewed 8566 times
Later on i’ll print some other props also, that’s the big question for the drive system.

amberwolf   100 GW

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### Re: ”The barge” efoil build

larsb wrote:
Jun 28 2020 2:54pm

The gluing turned out to be sh*t (again), i sprayed heavier coats than before with the super 77 and it seems the foam melted a bit.
I have found with Super77 and similar spray glues that it works best if you spray it on boht surfaces, let it dry just to tacky, and *then* stick them together.

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larsb   100 MW

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Joined: Dec 10 2014 5:12am
Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Yep, that’s what i did. The confusing thing is that 3m77 spray was foam safe historically but now exists in two variants due to california environmental regulations, one with acetone in it (that can barely be used on foam if very careful) and then the old formula.

There’s also 3m78 that’s specific for foams but i don’t find anyone who sells it.

The foam melted in the middle of the sheets, i think it might have been ok if i let them air even more before assembling. You live, you learn

larsb   100 MW

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Location: Gothenburg, Sweden

### Re: ”The barge” efoil build

Battery doesn’t fit in the box height or width in the way i wanted as the lid protrudes inside the wall of the bottom part. It doesn’t matter, i have some room to spare, i’ll rotate it and cut away part of the lid. I planned an alu plate lid for better heat exchange anyway
AF05ACFC-8120-4C4D-931F-3A4A86DA8416.jpeg (62.29 KiB) Viewed 8517 times
Last edited by larsb on Jul 05 2020 12:40pm, edited 1 time in total.

amberwolf   100 GW

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### Re: ”The barge” efoil build

larsb wrote:
Jul 05 2020 2:00am
Yep, that’s what i did. The confusing thing is that 3m77 spray was foam safe historically but now exists in two variants due to california environmental regulations, one with acetone in it (that can barely be used on foam if very careful) and then the old formula.
Ah...I've never run into the acetone variant. :/ The old formula always worked fine on everything, though getting it off of *you* was a huge PITA if overspray got beyond your gloves/etc.

I used to use it on a lot of sci-fi props and such, most especially to put printed labels on things, whcih I could then clearcoat with Krylon to ensure they didn't wear away easily, where necessary. But also useful just for securing things like foam layers for cores and molds together prior to sculpting.

There’s also 3m78 that’s specific for foams but i don’t find anyone who sells it.
https://www.amazon.com/3M-78-Polystyren ... B001EUOAGK
Terrible price, but at least they have it, as long as you're not on Catalina Island.

Beginning of a New Life

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(More here, including experimental)
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larsb   100 MW

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### Re: ”The barge” efoil build

”Unavailable” to me in sweden..