Author Topic: WingSUP board with Greenough edges  (Read 10015 times)

kwhilden

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WingSUP board with Greenough edges
« on: April 06, 2022, 03:42:59 PM »
So here's my first SUP foilboard design.  Based on my experience designing my own SUPs and surfboards with Greenough edges. 

My shaper has a blank ready to cut as soon as I finalize the design. 

I'm building my first board before even getting a first foil session. Talk about putting the cart before the horse. But I love designing interesting boards and I've watched a ton of youtube videos on wing foil board design. Given that I've designed and built close to 20 boards in the past 5 years, I feel comfortable making this insane leap.

Feedback on this design welcome.  My stats are as follows: 
- 50yo 6'2 110 kg
- Experienced surfer (SUP, prone)
- No foil experience (yet)
- Windsurf and sailing background
- Goal of wing foiling and foil surfing in the Los Angeles area

Here's the board as modeled in Shape3D.  Note this is just a rough draft, and there are a lot of rough spots in the file. 

Current dims are 6'4 x 30" x 5 1/4" x 133 liters. 

Design goals are to:
1. Get early planing, directional stability and controlled touch-downs from the hard chines
2. Reduce drag similar to a pintail, but with a round tail that adds more stability since I'm not doing any downwinders

Feedback welcome!

Gallery here:   https://imgur.com/a/haQQRJC

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surfcowboy

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Re: WingSUP board with Greenough edges
« Reply #1 on: April 07, 2022, 12:23:35 AM »
Hey man, I like the go for it attitude!

 I'm not familiar enough with foil SUP design to really comment on that part of it. You've got way more experience than me there. The bottom edges are cool. One note, I'd check that with the SUP guys here as to whether those will bounce when you touch down. Directionally is good for paddling but I'm not sure if that would bounce (good) or catch and redirect you (meaning throw you off the board) if you touch the nose. I softened my edges at the nose on my next wing board for that reason based on feedback. But I'm building/designing for prone/wing combo, not SUP.

For winging it's pretty curvy, to my eye but I'm thinking that those rounded rails are good for adding stability and not bashing your ribs, both good points.

Beginner Winging really only requires "a block of foam" so you'll be able to wing any board you can SUP at first. So focus the design on paddling. Literally a few months after you start winging it you love it you'll want to adjust your size down and simplify the design (again way less shaping there than SUP.) So you're good to start here and the size sounds right for learning. I started on 6'4"x28" and I'm smaller than you. Big and easy wins there.

Above all, this board will help you figure out if you like one sport more than the other. Then you can see if one board works for both. I've got buddies who SUP and wing one board. And some who became addicted to winging and immediately split to a wing board too small to paddle (my sad state lol.)

I say check the front rail design and do it! Remember, if you're doing it right it's only on the water part of the time.

jondrums

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Re: WingSUP board with Greenough edges
« Reply #2 on: April 07, 2022, 12:01:28 PM »
I don't think you're going to like the wide flat tail for SUPfoil in waves.  I'm regretting building my latest board that way.  It works fantastic for winging, but taking off on waves, the tail sticks to the water.  The board won't come up off the water during the drop and with waves with any shape, it sticks the nose at the bottom of the wave.  It really just does not work and I went back to my old board 100% now.  I'm considering chopping off the corners of the tail and making the back end more like the latest Kalama SUPfoil boards.

kwhilden

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Re: WingSUP board with Greenough edges
« Reply #3 on: April 10, 2022, 09:08:13 PM »
Jondrums.  Thanks, that's great feedback.  I can see what you mean. A huge bulbous tail cannot sink while catching a wave.

Here's my latest iteration on the design.  I've now put a step in the tail, but from the top.  This will reduce the volume in the tail, while not affecting early wing takeoff.  And therefore enhance wave catching ability.

I also think this will create less drag in displacement mode, for taking off in very light winds.  In contrast to the cutout coming from the bottom of the board.

Please provide critical feedback on those suppositions.

Although I will need to do some bit of work to clean up the tail in the shaping bay. My Shape3D skills can only go so far... 

I'm really happy with the rest of the board. So just need finalize the tail design now. And then Ry Harris gets the challenge of cutting this sucker on his machine.

Gallery here: https://imgur.com/a/AT36V5A













« Last Edit: April 10, 2022, 09:10:01 PM by kwhilden »
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jondrums

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Re: WingSUP board with Greenough edges
« Reply #4 on: April 10, 2022, 10:27:09 PM »
Its a really cool shape!  the tail looks a lot less substantial now, I have no idea how it will work - I guess you will find out

I do think we are seeing a clear divergence of design for foilSUP and wingboards now.  The SUP boards that are catching waves early all have sharp tails and the wing boards that people say are planing up on foil easily have flat tails

burchas

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Re: WingSUP board with Greenough edges
« Reply #5 on: April 11, 2022, 04:47:05 PM »
Nice design 8) good for you taking on this project. I did it twice now and both boards came out as expected. Makes the experience even better especially after testing my boards back to back against leading designs on the market.

Few thoughts. As was mentioned, I would look into the nose section as well.
Having the step rail and hard edge all the way to the end may deliver unexpected results where the nose tend to catch. This may happen during touch downs and going upwind against bumps and chop. Take a look the the attached screen shot.
The design has similar lines with the step rail and hard edges throughout the board but smooth out at the very end for these reasons. This is the SlingShot wing craft, a very good design imo.

As for the wide hips, it might prove more trouble than its worth when leaning the board in cases when taking a hard angle riding upwind, again, hitting bumps and catching rail.
If these are there for stability when standing still on the board waiting for wave, a more parallel but narrower outline might be even more stable but less likely to hit water. My 2 cents and personal preference of course.
in progress...

kwhilden

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Re: WingSUP board with Greenough edges
« Reply #6 on: April 11, 2022, 11:20:04 PM »
Hi Burchas,

Thanks for the comments. Couple of responses:

The wide hips are due to the pulled in tail.  I'm trying to copy a little bit of the Kalama E3 concept, which allows a smooth reconnection of water flows at displacement speed. Which reduces drag. 

I've tried to make surfaces flow really smoothly so it can get moving at low speeds, while keeping some hard edges for planing and bouncing on touchdowns.

The hard edges to the nose is something I've used in my surf SUPs quite effectively.  I think this will enhance planing and bounce over chop.  We shall see...

One other question I'm struggling with is whether to have any tail rocker in the design.  From side profile shots of various manufacturer boards. It looks like there is generally some minimal but continuous rocker.  Additional thoughts are welcome. 
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kwhilden

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Re: WingSUP board with Greenough edges
« Reply #7 on: April 13, 2022, 11:43:33 AM »
I'm getting closer to a final shape.  It's going to get cut this weekend. Just making final tweaks.

Also.. I added a Boston Whaler dingy bow to the board.  I think this is going to work very well.  BW's are made to skip and bounce over chop at planing speeds.  Which is exactly what happens when a touchdown occurs, or when first getting up to foiling speed.

One final question.  How do you determine foil box position?  The current image has it at 15" from the tail. Which seems too far from the tail. 









More images here: https://imgur.com/a/axFd0wO
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JohnnyTsunami

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Re: WingSUP board with Greenough edges
« Reply #8 on: April 13, 2022, 03:47:25 PM »

One final question.  How do you determine foil box position?  The current image has it at 15" from the tail. Which seems too far from the tail. 


I just built a board in the thread "4'6" wing board build". You figure out where you mount the middle of your current foil mast on your board - transfer that distance to the tail to the deck of your current board. They you mark where you put the middle of your feet in relation to the foil - say 55.5cm from the middle of your front foot to the middle of your foil mast. You now can make a template on where to put footstrap inserts in relation to the middle of your foil box - or if no inserts, you know where you will be standing on the board given any foil box location. The relation to the footstraps and the foil box will never change (unless your board weighs 30 lbs you may want to stand closer to your foil).

You move that whole template (box and footstrap location) forwards or backwards in order to get it balanced for the board. You want the board to be nose-buoyant while you are standing in the correct spot to foil. Not too much or you'll be sinking the tail too much, and not too little or you'll be nosediving when you are pumping onto foil. You want to slog in low wind and have the board balanced, and you want to not have to move your feet from that spot when you get on foil. In short, make the point in the middle of your stance BEHIND the point of the center of buoyancy of the board. If you have a naked-shaped foam blank with no cutouts or anything installed, you can hold the board in your hand and figure out the balance point. The balance for the weight of the board will equal the center of bouyancy of the board (I believe). This is not true once you add anything to the board like the box. If you used autocad you can use the function to find the center of mass. I just eyeballed it and it was spot on.

Depending on your foil brand, you can put the box right in the middle of where your foil goes, or you can put it at the front/back of your foil. If you anticipate switching brands, you should know if your foil is more forward or back in relation to other brand foils so you can put the track a bit forward or back (keep your mast in the same place, just make room for adjustment in the tracks one direction or the other). For instance I have axis ART, and they go way back in all boards, but I put my tracks even further back because I use another weird foil that sits further back. I can never use armstrong gear on my board. All of this is to say, my footstraps don't need adjusting and the board is balanced with 3 different foils mounted.

The middle of my axis mast is about 10" from the back of the board. The back of the tuttle is 6" from the back of the board. This is a 4'6" board. My board is balanced and I don't have to move my feet when slogging/foiling - maybe my back foot a little forward if it's a super light slog. If you di d these same numbers for a 7' board you would have to stand way forward to paddle, and jump way back once you were on foil.

So, make the stance/foilbox template, and eyeball it so the center of your stance a few inches behind the center of buoyancy of the board and put your box so your favorite foil will be right in the middle of it.

kwhilden

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Re: WingSUP board with Greenough edges
« Reply #9 on: April 13, 2022, 04:10:16 PM »

So, make the stance/foilbox template, and eyeball it so the center of your stance a few inches behind the center of buoyancy of the board and put your box so your favorite foil will be right in the middle of it.

Thanks for your comments!  Super helpful. This is exactly the advice I was looking for. 

Fortunately, Shape3D makes it stupid easy to get the center of buoyancy.



So would you say the front goes a few inches behind the CB point?

And should I position the Center of Lift of my chosen foil to sit in the middle of my stance?   Then that defines the foilbox location? 

I haven't bought my foil yet, but I'm most likely getting the Starboard S-2000. I can't find the dimensions of the foil online...  but a wild-assed guess looks like the COL is about 10 inches in front of the center of the mast.

Can anyone confirm an average distance for COL from the center of a mast. For a typical low-aspect wing?  Thanks all!


« Last Edit: April 13, 2022, 04:57:05 PM by kwhilden »
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surfcowboy

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Re: WingSUP board with Greenough edges
« Reply #10 on: April 13, 2022, 08:18:48 PM »
Your probably about right with 10". Bigger wings are farthy, smaller, less. My giant beginner foil was 12".

jondrums

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Re: WingSUP board with Greenough edges
« Reply #11 on: April 13, 2022, 10:57:52 PM »
For Axis foils, I've been very happy with the center of the boxes 14-15" back from the center of buoyancy. 
I set my footstrap inserts at 24" width, with the center point of my stance about 2-3" back from center of buoyancy.

JohnnyTsunami

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Re: WingSUP board with Greenough edges
« Reply #12 on: April 14, 2022, 02:01:23 PM »

So, make the stance/foilbox template, and eyeball it so the center of your stance a few inches behind the center of buoyancy of the board and put your box so your favorite foil will be right in the middle of it.

So would you say the front goes a few inches behind the CB point?

...

And should I position the Center of Lift of my chosen foil to sit in the middle of my stance?   Then that defines the foilbox location? 

...
Can anyone confirm an average distance for COL from the center of a mast. For a typical low-aspect wing?  Thanks all!

Sorry, didn't realize you weren't foiling yet on another board yet. I don't know the center of lift of any of my foils. I think that's taking it a step further than necessary. It's easy to measure from the position of the mast and get to the middle of your stance that way. But since you don't already foil, I suppose you should go to a shop and measure some boards.

One other thing I do is if a manufacturer has a clean shot of the bottom of the board, to take a screen shot and measure the pixels in your favorite program. Crop the image to just fit the board, then divide the pixels of the height of the board by the length of the board in inches. I use "preview" for mac for this. Just click and drag on a picture and it will count the pixels for you.

Once you get the number (i.e. 35 pixels per inch) then you can go and look at all the measurements for the box, footstraps, etc.

You can use this to measure a bunch of boards the same length you are shaping from your couch in 30m and average all the measurements to get the box in the right spot.

This is less accurate than just measuring using the board you already have, but it's some objective data of commercial boards.

kwhilden

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Re: WingSUP board with Greenough edges
« Reply #13 on: April 14, 2022, 02:43:33 PM »
Oh yeah. I'm putting the cart way before the horse, by designing a foil board before even learning how to foil or getting the actual gear. 

Yep... that's how I roll.  The design physics problem is just as interesting to me as the actual sport itself. And I've built enough surf SUPs to feel confident.   It's been a really fun project so far.

I will get the specs of my foils from Starboard, which are on order.

Any more thoughts on how to design the COL in relation to the COB are appreciated! 
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kwhilden

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Re: WingSUP board with Greenough edges
« Reply #14 on: April 14, 2022, 05:09:41 PM »
For Axis foils, I've been very happy with the center of the boxes 14-15" back from the center of buoyancy. 
I set my footstrap inserts at 24" width, with the center point of my stance about 2-3" back from center of buoyancy.

Thanks! This is very helpful.  In relation to the spacing between your footstraps, how tall are you? 
« Last Edit: April 14, 2022, 05:11:48 PM by kwhilden »
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