Boards for eFoil

15C should be fine as long as the epoxy isn’t too thick at that temp. A rule of thumb I’ve heard is the pot time and cure time doubles for every decrease by 10-15F (6-10C). So if 75F/24C is the speced time, you could have roughly twice as long of pot time to work with, but twice as long of full cure time as well. Dropping another 10-15F (6-10C) you’d be at 4 times as long.

I’ve laid up a kiteboard in the garage in the winter at like 5C, but put foam around it with small heater so I didn’t have to wait until spring until it was fully hard…

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My garage is about 35F when I turn the heaters on, It comes up to 60 F very quickly. Its a big garage full of metal things so as soon a I shut off the heaters it starts to quickly cool. The week end is not long enough to get the garage to stabilize. Also putting that much heat in to the garage that quickly raises the humidity.

Another problem I am seeing is any time I leave water sitting on the cured carbon fiber/epoxy it turns white cloudy. I think its because the epoxy is not fully cured when exposed to water.

The Epoxy has very little smell to it, I wear a respirator when I use it. I don’t know if you would want those vapors in a closed up house basement.

With my first board I had that problem, the epoxy turns white after touching water, that epoxy also took a while to cure compared to the epoxy I use now. With my other boards I used a different ‘surfset’ epoxy that set very fast, maybe workable for 15 mins, and had no issues with discolouration when in contact with water. The board with the epoxy that turns white also tends to get soft and flexible if left in the sun while the surfset epoxy stays rock solid.

I have also observed that the the epoxy gets soft when I warm it. I really can not blame it on the epoxy.

I read that epoxy works best at least 75F. And Moisture will make it cloudy. I heat my garage very quickly with a large kerosene non vented salamander heater. They put tons of water in the air. When I open the door clouds billow out the door. Plus the garage never gets or stays much warmer than 50F.
Unfortunately winter is the time of the year I want to be in the garage working on a project. Warm weather is for fun.

If you vacuum bag, you can use an [Electric blanket](CHF 50.31 40% Off | 35-55 Degree Electric Blanket Heater Double Size Body Warmer Heated Blanket Thermostat Electric Heating Blanket Electric Heating https://a.aliexpress.com/_sMpXYx) to cure.
Just wrap your blanket around your bag and turn the heat on full. The advantages are that you use slow curing epoxy and take your time but once you turn on the blanket it will cure fast and when cured it will be harder under the sun.

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I really like the electric blanket idea. I would not even need to actually apply Vacuum. Will need to take steps to keep the blanket from sticking to things. I like the fact that I can take as much time as I need and then get a good great cure. Also to improve my results even more, I usually heat the garage very quickly with a un-vented kerosene heater. I can switch over to a the slightly slower method using a normal vented heater. That will reduce the moisture in the air.

excellent work jake! How many liters?

Thanks! I don’t know exactly. It can keep my roughly 80kg above the waterline pretty well when stationary.

Im thinking about making my own board. Any tips regarding adding multiple layers of glass? Do you do both at the same time or do you let one cure first? Are both layers the same size or should the top layer be larger? Hit me with your best tips!

Thanks

All at once, if you do one by one, you’ll probably end up using more resin so the board will be heaving and not necessarily stronger.
Don’t make them the same size to avoid having a big step to sand down to get a smooth surface. Usually, the top layer is the biggest, not sure the reason why, from my point of view, it helps as you only have to deal with 1 edge and not 2.
and… better to have 2 much resin than not enough. i usually mix 1.5 time the weight of the cloth.

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This guy made a good video on the subject of building a surf board. Its very long. From what I recall he did 2 layers on top, and one layer on the bottom. https://www.youtube.com/watch?v=GnT82s0wkxc

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How much buoyancy is enough buoyancy for a 190 pounder like me?

Is there an equation or rule of thumb, like volume_board x density_water > me+foam+batteries+mast x 1.1 or 1.2 or something?

It all comes down to experience. I am 200lb and ride a 70L board happily. In fact I prefer it to my other board which is around 120L because it’s smaller and lighter and way less wind resistant. If you don’t have a lot of experience though you might struggle getting up at first on a small board.
If you can surf and are used to getting up then go for something in the 80L range.

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I am pretty new… 100L maybe? My outline dimensions will be 1.57m X .762m. Does that seem right? Is that a little wide or sounds good?

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The big thing to remember is that you are only a beginner for about 30 minutes! Once you have figured out how to stand up the smaller the board the better. I wouldn’t go wider than 65cm, the added width doesn’t really add any value. A board size of about 157cm x 65cm (same width as Lifts cruiser model) is pretty decent and should cater for you from beginner to experienced.

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My mast mount (gonna use axis foils system) needs to be bolted onto the bottom. I was thinking that I would cover the bottom of the electronics cavity cutout with a piece of 6mm G10. Will that be stiff enough? Or should I put an aluminum plate in there? Aluminum has corrosion problems. Stainless is very heavy.

6mm g10 is also very heavy!!! Especially when compared to carbon.

The axis system is nice. I have an axis mast that I designed an adaptor for so that I can use unifoil wings with behind the boat.

Do you have a picture or drawing of how you attach the mast mount?

Or, do you recommend stainless vs the g10?

I used Chinook longboard fin boxes, but if I were to do it again I’d design a custom carbon fibre system.
The way Eduard did his is also really clever of you are looking for another alternative. In fact his whole build is a great example to follow.

Thanks Jeremy, that is an amazing build. Germans, amirite?