With the lockdown, I've got a bit of extra time on my hands, and I'm thinking of building a wing specific board.
The problem is I'm not sure what kind of board to build. At the moment I have a 5'5" SUP (104L) and I weight 76kg.
It's cool, will do for now, but I can already see how I might want a little smaller, lighter and to shape it slightly differently.
There are things that you care about on a SUP that I don't think matter for a wingboard.

The options are either:
a) Build a board around 80L that can be started kneeling.
b) Build a board for a sinking start of somewhere between 45 and 65 L (I don't know).

I'm happy to build a board I can grow into - i.e. I don't yet have the skills to ride.

I understand there are pros and cons to both - for a sinking start I'd imagine you need quite a bit more wind, which means you need a bigger wing for the same amount of wind. But it's nice to have as small a board as possible. I'm used to kiting on my 82cm pocketboard and really feel the difference of a small board, but it's also nice to be able to ride with less power. At least that's how I feel as a kitefoiler.

What are the optimal volumes?
For kneeling start I imagine you kind of need it to be body weight in kgs or pretty close.
For a submerged start I have no idea. I've seen people start (in videos) with very small prone boards down to 30L. That must be pretty hard.
But if it's too buoyant, maybe it's harder to push the board down and get your feet on it. So what is ideal? And do you need footstraps? - I'm generally a strapless guy.

Thanks in advance for thoughts and tips!

If it was me doing this (and I wish it was but I don't have the skills) I would go for the smaller board. Reason - the difference between an 80ltr and a 104ltr board isn't going to be that big (24 ltrs to be exact), which will reduce further when you go down in size like you say you will do soon, so the difference when that happens will potentially be negligible. The difference between the smaller board (whether 45 or 65ltrs) and whatever size 'big' board you end up with will not only be noticeable, but also will give you a totally different sensation when flying, AND will give you a chance to make the most of different conditions - a light wind board and a board for howling conditions maybe! I don't see the point in having two boards that are so similar in size, even if they are different designs. I know your 'big' board will be SUP specific rather than wing specific, but IMO a good SUP board can wing well, but a wing board isn't necessarily good at SUPing.

I just finished a wingboard about 6 weeks ago. I learned on a 6'6" 115l board and decided I wanted to make something smaller but because I always seem to be out in conditions that are patchy where I need to get in potentially in displacement I mode I decided I was going to go for something in the 90-100l range. I think I nailed the brief pretty well. My next project will be one that is a little less user friendly in  terms of volume.. I went for 5'2" x26". 5" thick to get about 100l volume in the board so that once it was laminated the 6 or so kilos its would weigh would give me about 94l. I think I probably ended up at about 85-90l effective volume. Hard to be sure. It works fine for my 73kg. I learnt a few things that Ill share with you. I decided to use high density polystyrene at 2kg/m3 so that a 100l l blank would weigh 2 kg. I didnt want to skin the whole blank with PU foam -too much hassle for a homer. I also wanted to make it really bomber because I was using a harness and the hook can cause a bit of damage, also Im hard on my gear so I was prepared to sacrifice some weight for durability -cant have it both ways. I decide on a low rocker, essentially flat from midway to tail but using a deck that curved up a bit to keep some nose volume. Some have a flat deck so loose nose volume - a mistake IMHO. I also went for a flat bottom - no concaves blah blah blah. You watch. In 5 years everyone will have ditched the concave idea. At some point it creates derocker and increases your wetted surface area. I dont believe in concaves. I went with rail chines with a straight bevel, not contoured to the rail shape, to decrease drag and also wetted surface on take off. I put a tail kick but I really dont know if this is useful. Looks cool I guess. Usual high density patches for the fin boxes, handle, and a large deck patch for footbeds. Lamination was 2 layers carbon weave plus a uni strip in the middle and extra patches nose and tail and boxes. Handle on the bottom. No footstraps. It came out about 6.5 kg. Its really strong, like really strong. Super happy with it and it works in very light winds through to high winds. A real step up from the 6'6"in terms of performance.
So what would I do different next time?
I would go smaller, maybe aim for 80l to get a board of about 75l effective volume. I would use medium density polystyrene as with a good laminate it will still be strong enough. That should cut the blank weight by maybe half to 1 kg. I would do the same HD foam inserts but I would cover the entire deck with HD foam so that I could then laminate the deck with 1 layer carbon plus reinforcing for footbeds. save a bit more weight. I would laminate the bottom with 2 layers carbon, no uni patches. On the rails i would not overlap so much carbon. All in all I reckon I could save maybe 1-2 kg weight yet still be strong enough. smaller boards have less need of a harness, they are less heavy to fly.
I would put in footstrap plugs because smaller boards lend themselves more to jumping. I would also put 2 handles, one top and one bottom. The bottom one goes well back very close to the front of the boxes to balance with the foil bolted on.
Of course you need to use a vacuum bag. Almost impossible to do a good job without.
One other thing Im not sure about, maybe I'm imagining it. I notice some of the newer boards like mine look like they are riding in a slightly nose-down attitude. I think having the board taper very slightly to the tail, maybe only 2 degrees will mean that the board rides with the nose level with more even leg length. Ive never seen a fone board but the pictures of their boards look like thats what they do. Oh yeah be sure to put a goretex plug in when you have that much volume in your blank.
I have a theory that Im too chicken to try to build in case its a flop: It seems to me that wing boards never come up on foil by reaching planing speed. We wait for enough puff to pump the wing and pump the foil. So why do we use flat rocker? Surely this hinders pumping the board. Maybe we should have a curved rocker so the board pumps up more easily. Then no tail kick required because the rocker does the same thing, just better. I'll wait for someone else to test that theory.Have fun with your project. Its actually pretty easy.

I just finished a wingboard about 6 weeks ago. I learned on a 6'6" 115l board and decided I wanted to make something smaller but because I always seem to be out in conditions that are patchy where I need to get in potentially in displacement I mode I decided I was going to go for something in the 90-100l range. I think I nailed the brief pretty well. My next project will be one that is a little less user friendly in  terms of volume.. I went for 5'2" x26". 5" thick to get about 100l volume in the board so that once it was laminated the 6 or so kilos its would weigh would give me about 94l. I think I probably ended up at about 85-90l effective volume. Hard to be sure. It works fine for my 73kg. I learnt a few things that Ill share with you. I decided to use high density polystyrene at 2kg/m3 so that a 100l l blank would weigh 2 kg. I didnt want to skin the whole blank with PU foam -too much hassle for a homer. I also wanted to make it really bomber because I was using a harness and the hook can cause a bit of damage, also Im hard on my gear so I was prepared to sacrifice some weight for durability -cant have it both ways. I decide on a low rocker, essentially flat from midway to tail but using a deck that curved up a bit to keep some nose volume. Some have a flat deck so loose nose volume - a mistake IMHO. I also went for a flat bottom - no concaves blah blah blah. You watch. In 5 years everyone will have ditched the concave idea. At some point it creates derocker and increases your wetted surface area. I dont believe in concaves. I went with rail chines with a straight bevel, not contoured to the rail shape, to decrease drag and also wetted surface on take off. I put a tail kick but I really dont know if this is useful. Looks cool I guess. Usual high density patches for the fin boxes, handle, and a large deck patch for footbeds. Lamination was 2 layers carbon weave plus a uni strip in the middle and extra patches nose and tail and boxes. Handle on the bottom. No footstraps. It came out about 6.5 kg. Its really strong, like really strong. Super happy with it and it works in very light winds through to high winds. A real step up from the 6'6"in terms of performance.
So what would I do different next time?
I would go smaller, maybe aim for 80l to get a board of about 75l effective volume. I would use medium density polystyrene as with a good laminate it will still be strong enough. That should cut the blank weight by maybe half to 1 kg. I would do the same HD foam inserts but I would cover the entire deck with HD foam so that I could then laminate the deck with 1 layer carbon plus reinforcing for footbeds. save a bit more weight. I would laminate the bottom with 2 layers carbon, no uni patches. On the rails i would not overlap so much carbon. All in all I reckon I could save maybe 1-2 kg weight yet still be strong enough. smaller boards have less need of a harness, they are less heavy to fly.
I would put in footstrap plugs because smaller boards lend themselves more to jumping. I would also put 2 handles, one top and one bottom. The bottom one goes well back very close to the front of the boxes to balance with the foil bolted on.
Of course you need to use a vacuum bag. Almost impossible to do a good job without.
One other thing Im not sure about, maybe I'm imagining it. I notice some of the newer boards like mine look like they are riding in a slightly nose-down attitude. I think having the board taper very slightly to the tail, maybe only 2 degrees will mean that the board rides with the nose level with more even leg length. Ive never seen a fone board but the pictures of their boards look like thats what they do. Oh yeah be sure to put a goretex plug in when you have that much volume in your blank.
I have a theory that Im too chicken to try to build in case its a flop: It seems to me that wing boards never come up on foil by reaching planing speed. We wait for enough puff to pump the wing and pump the foil. So why do we use flat rocker? Surely this hinders pumping the board. Maybe we should have a curved rocker so the board pumps up more easily. Then no tail kick required because the rocker does the same thing, just better. I'll wait for someone else to test that theory.Have fun with your project. Its actually pretty easy.

Hey Slyde. Awesome board, I'm in awe of your board making skills. I completely agree with you about board planing speed. SUP foil boards (and then wing specific foil boards) started off long and (relatively) narrow because designers started off with the idea that a normal SUP board shape would be best, in fact most of the first foil boards were SUP boards with a tuttle or dual US tracks glassed in. As shape design progressed (I'm sure you know all this already) most designs went shorter, wider and thicker - look at Dave Kalama's designs for example. I've just had the good fortune to get Jimmy Lewis to design and make me a foil board (not arrived yet due to f******g travel restrictions!!!!!!!! ) that would be good for SUP foiling (waves but mostly downwinding) AND as a light wind wing board. We had a lot of discussions about hull shape! He is adamant that in foiling, the foil takes over BEFORE the board gets up to planing speed, therefore there is no point in having a hull shape that is designed to plane quickly. Dave Kalama also states that in a few video's and podcasts. The best hull shapes for wing foil boards are designed to break the surface tension of the water when pumping i.e. they release easily. Dave Kalama does this by making hulls that are shaped like race kitefoil boards. Jimmy Lewis achieves this by having a slight 'V' in the hull (hence the name of his SUP foil board, the 'Flying V'. Jimmy also swears that although a tail kick is ok, having a hydrostep (see pic) where the tail kick starts is essential to break the surface tension, while still allowing the benefits of the tail kick when pumping. You've got an interesting point about whether a curved rocker would allow you to ditch the tail kick. The little I know about board or hull design is limited to surfboards, and that the more curved the rocker line is, the less the wetted surface area is, so the slower it picks up speed - the trade off in surfing is that helps performance when planing. God knows how it would affect the performance of a foil board as all the rules seem to be completely different! Granted we don't need to get up to planing speed, but the quicker we can LIFT the board off the water the better. Not sure if a curved rocker would do that. Would be very interesting to find out!

Nothing special. After laminating add a coat of epoxy and microballoons then sand that back with an orbital sander till smooth. Then wet hand sand at 180 grit. Then paint with epoxy undercoat 1 or 2 layers and wet sand by hand to 400 grit. Then paint one or 2 coats epoxy top coat with roller, laying off with a high quality brush. surface preparation is the key. But a 5' board is so small its a pretty simple job. Each coat is maybe 50-100mls total and most gets sanded off so adds very little weight and much more durable than a wet sanded undercoat finish that seems to be so trendy.

Thanks for the great sharings, and awesome builds Slyde and stenninger It's going to take a little time to digest this!

I have very limited board building skills in comparison and also very limited tools and facilities at my disposal, especially during the lockdown.
I'm planning on building hollow with wood (paulownia) with some carbon reinforcements here and there.
This will somewhat limit the sort of shapes that I can build (it's not like I'm a master woodworker either). I believe that you don't need a complex shape for a wingfoil board - it's going to come out pretty boxy and I reckon that's going to be OK.

There are 2 things:
1. one needs a lot of time
2. it is not cheep at all

Totally true! You don't get to save that much money doing this, but you have the priceless satisfaction of riding your own creation.

I've decided there's a lot of room to explore for a board that still floats, can be kneeling started. Maybe a sinker next time!

Here is a draft design. Dimensions are 4'6" x 24" x 5". So it's really short, twintip kiteboard length, and reasonably narrow, but still has 90L volume which should be plenty for my 76kg.
It's really ugly and boxy with square straight rails (though the edges won't be quite this sharp).
Not cutting away the edges and not having beveled rails (which appears to be current generally accepted best practice) maxes the volume and spreads it to the perimeter as much as possible.
There is good rocker / scoop but by starting it further forward also maximises volume - the back 2/3rd is pretty flat. This is a tradeoff.

The main design principle is any part that displaces water as it moves does so by pushing water down.
So any forward speed will push the board up and the water will go underneath.
It should hopefully plane at a very low speed and lift off easily.
Pointing noses mean pushing water to the side, which is a waste of energy for a wingfoil board. Sorry @stenninger  (though your board wins hands down on the looks department!).

One of the nice things about my own build is I get to test out my armchair theories 

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Quote from: stevez on April 05, 2020, 05:43:30 am

I've decided there's a lot of room to explore for a board that still floats, can be kneeling started. Maybe a sinker next time!

Here is a draft design. Dimensions are 4'6" x 24" x 5". So it's really short, twintip kiteboard length, and reasonably narrow, but still has 90L volume which should be plenty for my 76kg.
It's really ugly and boxy with square straight rails (though the edges won't be quite this sharp).
Not cutting away the edges and not having beveled rails (which appears to be current generally accepted best practice) maxes the volume and spreads it to the perimeter as much as possible.
There is good rocker / scoop but by starting it further forward also maximises volume - the back 2/3rd is pretty flat. This is a tradeoff.

The main design principle is any part that displaces water as it moves does so by pushing water down.
So any forward speed will push the board up and the water will go underneath.
It should hopefully plane at a very low speed and lift off easily.
Pointing noses mean pushing water to the side, which is a waste of energy for a wingfoil board. Sorry @stenninger  (though your board wins hands down on the looks department!).

One of the nice things about my own build is I get to test out my armchair theories 

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 Bevels are best known for allowing the board to release from the water easier, BUT, their lesser known characteristic is that they are also very important for providing directional stability - i.e. moving in a straight line. No bevels and a totally flat hull will be very hard to keep moving in a straight line, especially when pumping the board. The end result will be that the board will skew left or right rather than move straight. The greater the angle of the bevels (i.e. the more vertical they are) the more they help with directional stability, but too vertical (100% vertical = no bevel, or, a normal surfboard type rail) and the water wraps around the rail and will prevent release.
But then again, what the hell do I know? If I could build my own boards I would also try to buck the design trends. Respect to you!!!!!!!!!!!!

Hi Dommo,

In my experience, they do the opposite. If the bevel continues all the way to the tail, it will let the board slide sideways, making it harder to track upwind.   

I also don't totally agree with your comment about the water wrapping around the rail and preventing release. If the Rail ends sharp it will release better. 

--
Gunnar