stevelebanni said..
Hi, l can't open that . Could you write the name of your board please .

Simmer style 3xs 116

I think there's a number of people with different skills and abilities which allow a different array of shapes to work best for them, I've used traditional flat wing boards for the past 4 years and have enjoyed them immensely. The very first one was very flat. The second one was still flat through the middle but had a rounded bottom from the nose to the mid which seemed to assist with take off (I think it displaced rather than 'barged' through the water to assist with early take off). The rounded nose was also good on touch downs. I've since moved to a 7ft x 23 inch wind DW foil board for winging, and in my experience it's definitely taken my minimum take off wind speed lower by a knot (around 9 knots). Cpmpromise is a touch harder to turn - swing weight) and a little less stable while on water.
Surfboards and windsurfers require flat shapes to maximise getting planing. But as boardsurfr says, if you want wave orientated windsurfing, the shape may change. What we wingers seem to be searching for is getting flying as early as possible. This depends on your foil (as well as a bunch of other things). If you have a super lifty foil (which will often mean its compromised for manouverability and higher speed control), then it will closer approach the threshold of the boards sub planing speed. This may mean you can get away with a flatter "bargier" design that might be wider and more stable and suit the type of winging you want to do and the conditions you're learning in. However, if you're looking to fly foils that are lower profile, faster and generally have more glide, then these usually require faster speed to get flying. To do that, you want a board that moves through the water faster with minimum effort. The new downwind boards do that for me without question. Yes they are a little less stable, but the force required to get the board and foil up and going is less than a 'traditional' squarer shape.
I think comparing windsurfing and surfboard shapes with what wingfoilers require in a board is not the same. I think there are elements of different water sports that we can look at and learn from.

Similar kind of stories and developments with surf boards, the channels were really big in Oz at one time, and the brothers out in Hawaii had their mind bending Phazer balls (I used to own one haha), but the small crappy wave boards tend to be wideish, and have little rocker. Starboard windsurf have always maintained that the flat planing hull was the fastest shape but like everybody says and each has his own experiences different shapes do different jobs.
Last week I was winging on a Gong Lethal 4.6 and came in because there was no wind. A fellow winger, older than me I might add, had a downwindish shaped board and a beefy 7.0 wing, the tiniest tiniest breeze came by and he got up and rode about 30 meters. So absolutely no doubt the downwindy shape is the light wind early take off machine - I've seen it with my own eyes, lol

I got a little illustration about different take-off techniques yesterday. Just switching the tail wing required a surprisingly large adjustment in technique. With a smaller stab, a bit of back foot pressure would pop the board out right away, and off it goes. That did nothing at all with the larger (362 vs. 196 cm2) tail wing. I could not get the board to fly at all with the larger stab for a while, until I eventually figured out that I just needed to be patient, and let the board come up gradually.

At the same spot, a custom narrow shape is quite popular. Looking at the underwater shape, I would think that the pronounced V in the tail would create a sucking effect that makes take-off harder. But everyone on these boards definitely gets up quite easily. I think the technique may be quite different from small, short boards, too: more of an all-out pump on the tiny boards, more of a gradual speed pickup and rise on the narrow boards. I'll have to go and ask some of these guys if/how they changed their take-off technique.

Pacey said..
I'll give a simple objective illustration of the difference between the two styles of boards. I have a foil drive assist plus which when I put it on my current wing board, 5'8" x 27 1/2", and using my gofoil 1770 front foil, I cant get the board up on foil in dead flat water (i.e. no waves, no wind) without a few strokes from a SUP paddle.

If I switch to a Kalama 6'5" x 23 1/2" downwind style board, with exactly the same foil and stabiliser, I can get up on foil in a few seconds without a paddle.

In other words, the difference in drag between the two boards is significant. A longer, narrower downwind style board would have even less drag.

For those that are arguing that a rounder hull will get stuck to the water and won't release easily, consider the shape of the SailGP catamarans that evolved from the catamarans used in the 2013 Americas Cup. These use round underwater hull shapes to minimise drag, as form stability is not an issue. The sailors don't seem too concerned about them being too sticky on takeoff or needing planing area to assist the foil.

Not sure that is an apples to apples comparison...

And speaking of apples...Apple Tree, in talking about their Apple Skipper boards, says that the rounded hull makes it harder to get to planing speed, but releases better...so round and round we go, and I don't see any end in sight to the back and forth arguments about hull shape, speed, and release...

Pacey said..

SpokeyDoke said..

Pacey said..
I'll give a simple objective illustration of the difference between the two styles of boards. I have a foil drive assist plus which when I put it on my current wing board, 5'8" x 27 1/2", and using my gofoil 1770 front foil, I cant get the board up on foil in dead flat water (i.e. no waves, no wind) without a few strokes from a SUP paddle.

If I switch to a Kalama 6'5" x 23 1/2" downwind style board, with exactly the same foil and stabiliser, I can get up on foil in a few seconds without a paddle.

In other words, the difference in drag between the two boards is significant. A longer, narrower downwind style board would have even less drag.

For those that are arguing that a rounder hull will get stuck to the water and won't release easily, consider the shape of the SailGP catamarans that evolved from the catamarans used in the 2013 Americas Cup. These use round underwater hull shapes to minimise drag, as form stability is not an issue. The sailors don't seem too concerned about them being too sticky on takeoff or needing planing area to assist the foil.

Not sure that is an apples to apples comparison...

And speaking of apples...Apple Tree, in talking about their Apple Skipper boards, says that the rounded hull makes it harder to get to planing speed, but releases better...so round and round we go, and I don't see any end in sight to the back and forth arguments about hull shape, speed, and release...

If a board is short and flat, it needs to go through a stage where it is planing prior to liftoff on foil to reduce its wetted surface area and drag. If a hull shape is long and slender enough it can go straight from displacement mode to foiling without needing any dynamic lift from the hull shape. Racing catamaran hull shapes are usually long and slender enough, and recent foiling Moth hull shapes (11 feet long) have been shown to favour round hull shapes over more boxy ones, but not by a big margin. Whether wing boards can be long enough and can be made narrow enough to benefit from a more rounded hullshape given the stability issues, we wont know until someone tries it.

I agree with all of this, but the caveat is that the displacement hull needs sufficient volume. Otherwise the efficiency kind of works against you. You cant speak in generalities about hull shape without considering volume.

My $0.02, but from my own experience this is the case.

ArthurAlston said..
Dave West's recent video is worth watching.

He rides a long Amos Bullet and sings its praises over the Sultan. The former has a rounded hull compared to the latter.

But the only difference he discusses is length...not saying hull shape doesn't play a part, but if there is a clear message in all the discussions, length has a significant influence on hull speed

Lots of different arguments for what works and what doesnt.

It's fun to see all the same things happening to wing and foil boards that windsurfing boards and surfboards before them went through as the shapes became more refined .

"Same old, same old " is the phrase that springs to mind..

Flat, sharp and straight is fast. Curves , rounds and bends slower. Blending them all together to get the performance you want for what you need the board to do is the shapers super power.

I'm learning to wing foil on a 5'8" inflatable that is allegedly sticky - Don't feel that - or much of anything at my low standard. It gets up on the foil as easily as I fall off it. My next board will be a long downwind board.

The short kicked up tail / chopped, stepped tail funny bottom wing boards I see look like they have been shaped by people who didn't do their surf board shape history homework - or by some marketing man.

BTW, my long Division 2 very round bottom displacement windsurfing board from 1982/83 got up on the plane easily enough..

wully said..
Lots of different arguments for what works and what doesnt.

It's fun to see all the same things happening to wing and foil boards that windsurfing boards and surfboards before them went through as the shapes became more refined .

"Same old, same old " is the phrase that springs to mind..

but the point is that it is not the same old, same old. Windsurfing boards and surfboard are planing craft, not foil craft. If a hull is sufficiently long and slender, and the foil is sized appropriately, the foil never needs dynamic planing lift from the hull.

wully said..
"If a hull is".
The point I was trying to make is all this hull shape designing has been done before.
For fun I worked out the displacement hull speed of 2 foil boards folk were arguing over. One short, fat typical foil board, one long slim DW type, can't remember the dimensions but the difference in max displacement speed possible was less than 1 knot. There was some discussion about climbing over the bow wave which both would need to do to get to planing speed.
I know next to nothing about foiling but would expect the critical speed to get onto the foil would be the speed the foil needs to be able to generate enough lift to overcome the load of the board, rider and wing? Displacement speed is a function of waterline length so if that speed is more than your foil needs then your laughing, no need to plane Longer IS faster but how long do you need for that displacement speed to get you up?

So an optimised foil might give you more get up bang for your buck than the board will - within limits, what they are I have no idea.

Yes it has been done before, it's called Slender Ship Theory. The standard equation for the hull speed limit of a displacement hull (roughly 1.3 * SQRT(WLlength in feet)) does not apply to sufficiently slender vessels. That's why a 20 ft catamaran can go faster than 6 knots.

Same applies to long skinny boards, particularly when the foil starts to contribute lift even at very low speeds.

Pacey said..
I'll give a simple objective illustration of the difference between the two styles of boards. I have a foil drive assist plus which when I put it on my current wing board, 5'8" x 27 1/2", and using my gofoil 1770 front foil, I cant get the board up on foil in dead flat water (i.e. no waves, no wind) without a few strokes from a SUP paddle.

If I switch to a Kalama 6'5" x 23 1/2" downwind style board, with exactly the same foil and stabiliser, I can get up on foil in a few seconds without a paddle.

In other words, the difference in drag between the two boards is significant. A longer, narrower downwind style board would have even less drag.

For those that are arguing that a rounder hull will get stuck to the water and won't release easily, consider the shape of the SailGP catamarans that evolved from the catamarans used in the 2013 Americas Cup. These use round underwater hull shapes to minimise drag, as form stability is not an issue. The sailors don't seem too concerned about them being too sticky on takeoff or needing planing area to assist the foil.

I totally agree with this. My experience (and not necessarily that of others) with the fatter traditional board I have is it requires more effort (and wind) to get up on foil compared to my DW board which has a thinner more rounded shape. I also feel that there is no need for the board to plane before the foil gets it to lift. So I dont look for a flat planing shape as it's not required. I think it's better to get a shape that cuts through the water as efficiently as possible til it gets to foil take off speed. Those Sail GP cats do that really well. As does my rounded underhull DW board - for me.

Pacey said..
I'll give a simple objective illustration of the difference between the two styles of boards. I have a foil drive assist plus which when I put it on my current wing board, 5'8" x 27 1/2", and using my gofoil 1770 front foil, I cant get the board up on foil in dead flat water (i.e. no waves, no wind) without a few strokes from a SUP paddle.

If I switch to a Kalama 6'5" x 23 1/2" downwind style board, with exactly the same foil and stabiliser, I can get up on foil in a few seconds without a paddle.

That's an interesting data point, even if the results are not surprising. Sounds to me that you arealmostable to get up on your27 1/2" wide board, since you're talking about a few paddle strokes, not all-out "super athlete" paddling. So a relatively small amount in drag reduction should be sufficient to get going. What we really need is someone with an endless pool to measure the drag of these boards.

Pacey said..
For those that are arguing that a rounder hull will get stuck to the water and won't release easily, consider the shape of the SailGP catamarans that evolved from the catamarans used in the 2013 Americas Cup. These use round underwater hull shapes to minimise drag, as form stability is not an issue. The sailors don't seem too concerned about them being too sticky on takeoff or needing planing area to assist the foil.

Interesting argument. The picture also shows the wave-piercing hull very nicely, which is one key component to getting around the simplistic "hull speed" limitations (piercing through the bow wave eliminates the need to climb up on it). I have been somewhat surprised to see narrow boards with V-type tails perform rather well recently; water release on sharp edge to facilitate planing is clearly just one factor, and one that may not play a role for some board shapes at all.

think "stickiness" comes into play when you whip the board into the air to get going. That's definitely the case for small boards that are too small to get anywhere near planing speed on the water. My wife complains about it every time she's on a board larger than her 50 l Armstrong. I've even noticed it on the huge boards I prefer. I can whip my 115l Starboard wing board out easily, but not the longer and heavier 140 l Stingray, which requires more patience and at least semi-planing speeds (or a ton of power in the hand wing).

ArthurAlston said..
Dave West's recent video is worth watching.

He rides a long Amos Bullet and sings its praises over the Sultan. The former has a rounded hull compared to the latter.

Interesting boards. The > 8 ft boards seem to turn very nicely for these guys. Translating the board shape to wing boards for flat water, though, has to consider the the board shape seems to mimic the water shape. I'd love to know how the boards paddle up on flat water, compared to boards with a similar outline and underwater shape but a lot less rocker in front and back.

All this makes me want to make a board - probably 8 ft, round nose, pintail shape, foil near the center, around 22-24 inches wide, and then put a total beginner on it for the first flights.

NordRoi said..

FranP said..
Most of us, wing-foilers are caming from surf, windsurf or kite and we think a wing board enters into planning before releasing the water.... I believe this is not the case, so a flat bottom is not necessary, although it helps with stability:

Keep in mind reduced drag equals to laminar water flow, no hull corners, minimal board surface touching water


I see different stages before releasing the board:

- phase 1: Before standing up. No speed. A flat bottom is more stable and helps a lot compared to a belly-rounded-shape.

- phase 2: Low speed 0-2 knt: start pumping but still no planning and minimal foil effect --> displacement hull (rounded belly shapes) makes the difference

- phase 3: foil starts to push up (aprox 2-4knt) but no planning yet --> keep pumping to accelerate, but speed is still too low for true planning, so displacement hull with reduced drag keeps helping, while a flat bottom is stickier. Bottoms with

-phase 4: At aprox 3-5 knt foil flies. Board releases, so board shape doesn't matter.


... conclusion, a full displacement hull, rounded bottom, like a kayak with minimal flat sides, corners and planning shape, might be the most efficient board shape. if you can stand up and manage board balance

I like that thinking. I never tried a DW board so I cannot comment on them, however on shorter board, you will engage the foil and will pump the foil and this will accelerate. I'm not sure a flat bottom is sticky...I know a double concave is..when I try a deep double concave vs a mini double concave in a very minimal wind where everything matters, you need an extra effort to unstick the board with the deep double concave. I guess with a dw board you reach the speed of the foil sooner and you can reduce the foil for same wind...does it pump as well as a shorterboard?

- DW boards and/or pure displacement hulls are easy to pump and they keep speed when your wing pumps

while

- Traditional boards ( wider, shorter, flatter) accelerate when you pull the wing and they decelerate when you move the wing forward when pumping.

I think the idea of "stickyness" is a bit of a myth, or at least a misnomer. When a board feels sticky, it's actually drag that's preventing you from accelerating to the speed the foil needs to lift off, not the board trying to stick to the water. The speed required to take off is generally between 6-9 knots depending on how big a foil wing you have and this puts us squarely in the transitional zone between displacement and planing speed.

Another thing that can make takeoff feel sticky is if the board cannot pitch up enough to get the foil to a good takeoff AOA, pretty sure this is what Appletree is talking about with their rounded tail sections aiding release, they are giving up lift near the tail so that the board can pitch up for takeoff. Kalama accomplishes the same thing by pulling the planing surface down to a narrow pintail with very little surface area.

The graph below shows drag curves for boats in the transition to planing range with different slenderness ratios (short/fat wing board would be 3-ish and a long/narrow DW board would be 6-ish). You can see the curve labeled 4.0 (approximating a mid-length, Sunova Carver etc) has a big drag hump compared to 5.0 and 6.0 (8'+ DW board).

the upshot is that length is the primary factor for reducing drag near takeoff speed and all the other stuff is about handling characteristics like how the board pitches up, stability etc.

JonahL said..
I think the idea of "stickyness" is a bit of a myth, or at least a misnomer. When a board feels sticky, it's actually drag that's preventing you from accelerating to the speed the foil needs to lift off, not the board trying to stick to the water. The speed required to take off is generally between 6-9 knots depending on how big a foil wing you have and this puts us squarely in the transitional zone between displacement and planing speed.

In low wind you want to generate a burst of power with the wing unstick the board with you feet/pumping action and pumping the foil to accelerate up to the foiling speed, like you would do on a beach/dock start. It's where i feel the stickyness, just make sure it's not the rake of your mast that is making your plane pointing down.that is also a case of stickyness.