Hello

In the following review www.windfoilen.nl/en/gong-zuma-foil-board-review/ they say a flat underhull takes off later than a complex one like the Starboard. I guess they refer to passive taking off, which I prefer than pumping hard in a narrow board, due to my skill level.

"Compared to the Starboard Wingboard Lite tech, the Gong Zuma boards are less likely to take off. With the same wing and wingfoil we really needed 2 to 3 knots more to get away. And then we even compared it to a board with even less volume (The starboard 5'8" has 88 liters of volume). We can clearly see here that the conventional (or outdated what you want) shape obstruct to get away quickly especially with less wind."

Any comment is appreciated.

We are moving towards what other water sports have known for some time, round is faster. Look at K1 kayaks and ocean surf skis, round displacement bottoms are faster than flats.
We are already moving to longer narrow boards, I'm guessing next will be round displacement bottoms to help get up to foiling speed fast. The faster you can go in displacement mode, the smaller the wing you can use and the faster you will go in foil mode for a given wind strength.

Being in my second winging year, I was on my new bevel'd 5.3 Sky Free now for two days and nevertheless my prior 5.6 was 10l bigger and much wider with flat bottom - what was supposed to be the golden rule for early planning so far at least inhouse Fanatic - the new shape is much better to be pumped onto foil. Used 5.5 and 7.0 with 1250/1500 Frees in perfect testing conditions with decreasing wind on my home lake.

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airsail said..
We are moving towards what other water sports have known for some time, round is faster. Look at K1 kayaks and ocean surf skis, round displacement bottoms are faster than flats.
We are already moving to longer narrow boards, I'm guessing next will be round displacement bottoms to help get up to foiling speed fast. The faster you can go in displacement mode, the smaller the wing you can use and the faster you will go in foil mode for a given wind strength.

You are correct in theory, but stability is a practical issue. doesnt matter how fast a hull you have if you can't stand on it. These displacement hulls can be very unstable, so you find planing features and chines mixed in to add back some stability. most/all the displacement downwind boards have chines in the middle or aft portions of the hull - for release and stability.
I have a displacement hull board and in flat or clean conditions it is definitely faster onto foil. But if it's choppy or if the waves are cross grained to the wind, then I need a lot of power in my sail to add some stability and get onto foil quickly, otherwise it's not useable.

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Sideshore said..
"Compared to the Starboard Wingboard Lite tech, the Gong Zuma boards are less likely to take off. With the same wing and wingfoil we really needed 2 to 3 knots more to get away."

I think the reason is the "magic tail" from Gong. From my experience a flat underwater with clean tail, no cutouts, no curves, is best. Indiana 81L board was the board with the best takeoff I've ever seen from an allround ~5'0 wing board. German review site gleiten.tv came to the same conclusion.

Round rubbish

Nik is correct

The fastest rocker lines on kite and windsurf race boards are the same..... FLAT to about 800mm and square edge water release
A wing board with that rear end and enough width, flies earlier with less wing power and a bunch of testers of a proto and my boards have agreed.

Go put a rounded / belly bottom on your surfboard, kitesurf board or Olympic IQ foil board
There is a reason they are not.

TBF Fanatic/Duotone also said they changed the rocker line to make it easier to pump, which is how wings get on foil. If you aren't pumping then I can believe that a flat bottom with sharp edges will accelerate better to foil.

Of course, Fanatic had the bevels & rocker two years ago, abandoned them for the flat hull last year for a perfect board shape, and then really nailed it this year by putting them back. Test drive if you can.

Agree with Mark. I put a flat rocker on the tail of my board and it made a vast improvement in my ability to get my speed up enough to foil my HA wing. Shoddy craftsmanship by me, but it works a treat. I guess the bevel tails are more suited to large low aspect wings or strong wind.

Unfortunately the bevelled monstrosities have become what people expect to see now

Too short means entry rocker is too steep
Rounded bottom and bevel tails are sucky / draggy

Trouble is, the trendy look is the above and new wingers expect boards to look like a 5ft egg with star wars inspired angular stepped cutouts

Bevel tails are for touchdown in a bowly wave and so it panders to people's desire to feel hardcore. ... i can ride in giant swell herr herr ugh.

I also blame marketing departments and 19 year olds with CAD.... but what actually works is often a little boring

From my experience of using a few board with flat bottoms versus the sophisticated channel bottom on the Starboard WIngboard - the Starboard is by far the fastest/easiest to lift onto the foil either via board speed or pumping.

I want to know why boards with just a flat bottom shape are so expensive when they are just a block of foam and have no channels or cut outs - this must make them much cheaper to design and make?

I windwing this and foil from 8kn with 6.5 dlab and Axis 1030 Spitfire with 300p stab.

Everyone is right in their opinion. The answer varies base on foil ridden.

Guys riding 560 sq cm foils, need different shapes than people riding surf foils and/or riders who mostly do light wind.

A displacement hull and other tricks to improve the release. Allows riding a small foil (631 cm2) and a fairly small 3.6 m2 wing on a quiet day.

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Taavi said..
A displacement hull and other tricks to improve the release. Allows riding a small foil (631 cm2) and a fairly small 3.6 m2 wing on a quiet day.

I am not so sure about the theory of small foils and wings with displacement or longer narrower boards. I find I can get up on a 4'10" x 22 flat bottom board with a foil and wing that need pumping to maintain momentum as the wind is so light. It makes me wonder why anyone would trade the compactness of the board for what, a little less puffing getting onto foil. Obviously missing something. When I downwind with a paddle then different story.

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AnyBoard said..

Taavi said..
A displacement hull and other tricks to improve the release. Allows riding a small foil (631 cm2) and a fairly small 3.6 m2 wing on a quiet day.

I am not so sure about the theory of small foils and wings with displacement or longer narrower boards. I find I can get up on a 4'10" x 22 flat bottom board with a foil and wing that need pumping to maintain momentum as the wind is so light. It makes me wonder why anyone would trade the compactness of the board for what, a little less puffing getting onto foil. Obviously missing something. When I downwind with a paddle then different story.

What kind of foil and how big are you using with your 4'10" x 22 flat bottom board? The displacement hull allows to reach the initial board speed, up to the point where the apparent wind kicks in, so you can truly start pumping a small wing. Of course if you take a big enough foil and a big enough wing that you can start properly pumping right away while standing still, you may not need a more efficient board shape. The shape of the DW board simply allows to build up the speed even with a small foil and small wing.

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Taavi said..
A displacement hull and other tricks to improve the release. Allows riding a small foil (631 cm2) and a fairly small 3.6 m2 wing on a quiet day.

Can you show a picture of the hull of your board? Which are the dimensions? Thanks

I think there may be a difference in what shape is fastest (generating lift from the foil, driving release), and what shape separates most easily from the water at speed...those seem to be different things

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SpokeyDoke said..
I think there may be a difference in what shape is fastest (generating lift from the foil, driving release), and what shape separates most easily from the water at speed...those seem to be different things

A round hull (Olympic kayak or surfski) would paddle fastest but dig itself into the water at planing speed and above.

Add flat bottom section for upwards lift in touchdowns and hard chines for water release.

Barracuda :)

Which shape is best depends - mostly on conditions and rider ability and style.

Looking at windsurfing boards for comparison can be enlightening, since windsurfing has had a few more decades to experiment with board shapes. The rule for early planing seems easy: perfectly flat in the planing area, sharp rails, and wider is better. That led to 1 m wide formula boards that require huge sails most windsurfer's never wanted to use. Many stuck to old, longer shapes, and even modern free-whatever boards tend to have a lot of underwater shape to handle real-world conditions. On the other extreme, you have wave boards for experts and perfect conditions with lots of tail rocker and very little tail volume that are perfect for the intended audience, but somewhere between "unsailable" and and "absolutely no fun" for most sailors and conditions.

The foil adds another level of complication by adding a third dimension. You can get foiling by letting the board to come up to the speed where the foil generates enough lift; or you can pop the board out of the water at a much lower speed, and skillfully use the lower friction and the effective weight reduction from upward pull of the hand wing to increase the speed. Since short foil boards have a hull speed that's lower than the stall speed of most foils, it will usually be something in between - which is a rather large range of different take-off techniques. Which board shapes works best depends on where exactly in this range your take-off technique is.

The "sucking" effect of the underwater shape is a good example. When a board picks up speed and goes from displacement mode to planing mode, star edges let the water tear off cleanly, in effect displacing it horizontally. Any round and angled parts of the bottom will have water follow, giving it upward momentum. That effectively sucks the board down.
But when technique and conditions change, other things may matter a lot more. If you can use chop or waves to get going, a kick tail may play the same role as the rocker in a wave board, and make picking up speed easier rather than harder. When you want to push the tail down and pull the nose up to get the board out of the water, a perfectly flat surface may suddenly be much stickier than one with bevels and concaves or channels.

I use a Starboard Wing board, and the bottom shape looks a bit over-engineered to me. When well powered on flat water, I love it - it lets me plane before taking off, which makes controlled take-offs very easy for my limited skills. But when winging in confused chop, that does not work anymore, I'm not sure the shape offers advantages over other shapes. Of course, how much it matters that a board gets going easily depends on how often you fall. If you nail all your turns and never crash, then you can spend a lot more energy to get going once than if you fall every couple of minutes in every turn.

Bevels vs. tail kicks is another very interesting question. There are multiple reports that tail kick-removal mods like the one Stretchy showed above really help. Theoretically, upward-oriented structures at the tail and at the sides both pull water up, and thereby "suck" the board down. But we got to consider how much of the board shape is in the water. Any upward-angled orientation at the tail will always force water to move upwards, and suck the board down. But the sharp edges that the right board in the OP's picture has only make a difference when the board has risen enough that the sides of the board are above the water - that is, the board is planing. This matters little, because if we have enough speed to plane on a small board, we also have enough speed to foil. Before that, bevels like on the Duotone and Smik boards have the theoretical advantage of reducing the wetted surface area when the board climbs out of the water. It would be interesting to see simulation results on that.

Omen has a longer, narrower approach to their boards. For me at 90kg, their 60L launches stupidly fast even in lighter air. I've not had a chance to look closely at the bottom shape; I've only demoed them a couple of times but they accelerate so quickly. They are almost like mini DW boards with squared off tails but handle touch downs in turns very well.

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Sideshore said..

Taavi said..
A displacement hull and other tricks to improve the release. Allows riding a small foil (631 cm2) and a fairly small 3.6 m2 wing on a quiet day.

Can you show a picture of the hull of your board? Which are the dimensions? Thanks

@Sideshore Mine is 95 L, 6'9'', 18.5'', and I am 72 kg. Wouldn't want a smaller one for winging, or else it would sacrifice the effortless low end. And for using it as a SUP in the waves it's likely too small for me : )

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Taavi said..

AnyBoard said..

Taavi said..
A displacement hull and other tricks to improve the release. Allows riding a small foil (631 cm2) and a fairly small 3.6 m2 wing on a quiet day.

I am not so sure about the theory of small foils and wings with displacement or longer narrower boards. I find I can get up on a 4'10" x 22 flat bottom board with a foil and wing that need pumping to maintain momentum as the wind is so light. It makes me wonder why anyone would trade the compactness of the board for what, a little less puffing getting onto foil. Obviously missing something. When I downwind with a paddle then different story.

What kind of foil and how big are you using with your 4'10" x 22 flat bottom board? The displacement hull allows to reach the initial board speed, up to the point where the apparent wind kicks in, so you can truly start pumping a small wing. Of course if you take a big enough foil and a big enough wing that you can start properly pumping right away while standing still, you may not need a more efficient board shape. The shape of the DW board simply allows to build up the speed even with a small foil and small wing.

I ride RS850 and Eagle 690 and 790 but it is irrelevant really. The point is that once out of the water and foiling the wind is so light that foiling can only be sustained by pumping the wing and foil at times during the lower end. So even though i am on too smaller foil for the wind (maybe 8 knots) the board and technique are still enough to get me going foiling in the first place. So back to the beach grab a larger foil and now flight is sustained without the need to pump board and wing in the lulls while foiling. I always wing a 4m but would use my 5m at this very low end when desperate enough to get wet. Diminishing returns after that with the wing but upsizing the foil to a big glider will get much more consistent results.

For reference board is 75% of my weight in volume.

Depending on ability but maybe a Kalama e3 type board makes sense for those in light wind but not going to Barracuda lengths even though it makes the takeoff stupidly easy. Its already silly easy on the E3.

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boardsurfr said..
Which shape is best depends - mostly on conditions and rider ability and style.

Looking at windsurfing boards for comparison can be enlightening, since windsurfing has had a few more decades to experiment with board shapes. The rule for early planing seems easy: perfectly flat in the planing area, sharp rails, and wider is better. That led to 1 m wide formula boards that require huge sails most windsurfer's never wanted to use. Many stuck to old, longer shapes, and even modern free-whatever boards tend to have a lot of underwater shape to handle real-world conditions. On the other extreme, you have wave boards for experts and perfect conditions with lots of tail rocker and very little tail volume that are perfect for the intended audience, but somewhere between "unsailable" and and "absolutely no fun" for most sailors and conditions.

The foil adds another level of complication by adding a third dimension. You can get foiling by letting the board to come up to the speed where the foil generates enough lift; or you can pop the board out of the water at a much lower speed, and skillfully use the lower friction and the effective weight reduction from upward pull of the hand wing to increase the speed. Since short foil boards have a hull speed that's lower than the stall speed of most foils, it will usually be something in between - which is a rather large range of different take-off techniques. Which board shapes works best depends on where exactly in this range your take-off technique is.

The "sucking" effect of the underwater shape is a good example. When a board picks up speed and goes from displacement mode to planing mode, star edges let the water tear off cleanly, in effect displacing it horizontally. Any round and angled parts of the bottom will have water follow, giving it upward momentum. That effectively sucks the board down.
But when technique and conditions change, other things may matter a lot more. If you can use chop or waves to get going, a kick tail may play the same role as the rocker in a wave board, and make picking up speed easier rather than harder. When you want to push the tail down and pull the nose up to get the board out of the water, a perfectly flat surface may suddenly be much stickier than one with bevels and concaves or channels.

I use a Starboard Wing board, and the bottom shape looks a bit over-engineered to me. When well powered on flat water, I love it - it lets me plane before taking off, which makes controlled take-offs very easy for my limited skills. But when winging in confused chop, that does not work anymore, I'm not sure the shape offers advantages over other shapes. Of course, how much it matters that a board gets going easily depends on how often you fall. If you nail all your turns and never crash, then you can spend a lot more energy to get going once than if you fall every couple of minutes in every turn.

Bevels vs. tail kicks is another very interesting question. There are multiple reports that tail kick-removal mods like the one Stretchy showed above really help. Theoretically, upward-oriented structures at the tail and at the sides both pull water up, and thereby "suck" the board down. But we got to consider how much of the board shape is in the water. Any upward-angled orientation at the tail will always force water to move upwards, and suck the board down. But the sharp edges that the right board in the OP's picture has only make a difference when the board has risen enough that the sides of the board are above the water - that is, the board is planing. This matters little, because if we have enough speed to plane on a small board, we also have enough speed to foil. Before that, bevels like on the Duotone and Smik boards have the theoretical advantage of reducing the wetted surface area when the board climbs out of the water. It would be interesting to see simulation results on that.

Great composition by the way.

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It's really "Which shape is best depends - mostly on conditions and rider ability and style." Look at 2024 starboard. Two totally different shapes.
wingboard.star-board.com/wingboards/wingboard-foil/

TAKE OFF HIGH PERFORMANCE FREESTYLE/WAVE FOIL BOARDS
. FLAT BOTTOM The smooth release with sharp rail edges and the flat bottom give instant takeoff and are more predictable when touching down

WINGBOARD FOIL Olympic windsurfing and thin performance surfboards inspired this design.
. NEW THE "CUTAWAYS"At the tail act as stabilizers while lifting out of the water when the board gains speed, reducing the wetted surface and allowing the board to accelerate smoothly while on water.
.NEW A DEEP VFlows all the way from the nose to the foil, making it easy to get airborne in choppy waters and letting the board skim during touchdowns for easy rebound.



X-15 FOILBOARD PERFORMANCE WING RACING - BUILT FOR SPEED IMHO best for low winds similar to Wingboard but for Olympic racing tutlebox mast
This board is crafted to deliver exceptional early planning capabilities and high-speed performance with low lift foils.

The higher the take off speed of the foil you ride, the better a board with a fast planning shape is. You need to go from 0-10 mph instantly to make these foils work.

The lower the take off speed of the foil you ride, the better board becomes a displacement hull that can accelerate to 5 mph and start lifting. Downwinding, light wind winging, etc.

The displacement hulls show their advantage in confused chop and light wind. A guy on a planning board might have to wait on a clean patch of water to get going.

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DWF said..
The higher the take off speed of the foil you ride, the better a board with a fast planning shape is. You need to go from 0-10 mph instantly to make these foils work.

The lower the take off speed of the foil you ride, the better board becomes a displacement hull that can accelerate to 5 mph and start lifting. Downwinding, light wind winging, etc.

The displacement hulls show their advantage in confused chop and light wind. A guy on a planning board might have to wait on a clean patch of water to get going.

Excellent analysis

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Mark _australia said..
Round rubbish

Nik is correct

The fastest rocker lines on kite and windsurf race boards are the same..... FLAT to about 800mm and square edge water release
A wing board with that rear end and enough width, flies earlier with less wing power and a bunch of testers of a proto and my boards have agreed.

Go put a rounded / belly bottom on your surfboard, kitesurf board or Olympic IQ foil board
There is a reason they are not.

Flat rubbish.

I don't follow these forums much these days, so I have to ask Mark, do you even foil?

Lift off on a foil doesn't come down to just speed, unless we are talking tiny foils but we are talking light wind here so tiny foils are irrelevant.

The fastest rocker lines may be flat, however flat sticks to the surface more than round bottom.
With a bit of pumping a round bottom doesn't need anywhere near as much speed to lift off, ie it doesn't need to be at planning speed.
DWF sums it up pretty good.

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DWF said..
The higher the take off speed of the foil you ride, the better a board with a fast planning shape is. You need to go from 0-10 mph instantly to make these foils work.

The lower the take off speed of the foil you ride, the better board becomes a displacement hull that can accelerate to 5 mph and start lifting. Downwinding, light wind winging, etc.

The displacement hulls show their advantage in confused chop and light wind. A guy on a planning board might have to wait on a clean patch of water to get going.

There is a reason most downwind sup boards are all going longer, skinnier and rounder bottom.

KT's Dragonfly boards (like Taavi's above) are fast becoming one of the most popular boards these days, especially in Hawaii.
You might want to let him know you think he has got it wrong?

www.instagram.com/reel/CxOSTeZvcg7/?igshid=MzRlODBiNWFlZA==

Ok then why do 14ft SUP race boards have a flat bottom and kayaks round?

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warwickl said..
Ok then why do 14ft SUP race boards have a flat bottom and kayaks round?

I'd say that's more to do with stability, standing vs sitting.
Lots of sups are semi round as well.
Round displacement hulls can be fast if they are long and skinny but then they are unstable.

Downwind sup foil boards get their stability from the foil so can be very narrow, some are down to around 15" wide these days.

The thing is what works for sups, kayaks, surfboards, windsurfers, kite boards etc is completely irrelevant compared to a foil board be it for winging, sup downwind foil or whatever, where it just has to reach a speed that can get up on foil and some shapes release heaps earlier.


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Hi
I think everybody must be right. The displacement hull boards must take off earlier in choppy light winds but, as they are quite narrow are unstable and very specialised, so for a one board beginner-intermediate, I guess it should be better to focus in a bit long and wide, flat tail and concaves in the nose board. In this way we've got reasonable early flying and no sticking to the water. Am I right? Could we agree on that?

A couple of questions. Why is there such a big difference for taking off from flat to choppy waters? Apart from the stability. Should we use a bigger, wider board if our conditions are often choppy? How much bigger? any other shape recommendation for choppy waters? I prefer not to pump much.

Has somebody compared real boards with different under hulls and their flying performance in light wind? I've seen some tests but no comparison board to board of similar volume.

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Sideshore said..
Hi
I think everybody must be right. The displacement hull boards must take off earlier in choppy light winds but, as they are quite narrow are unstable and very specialised, so for a one board beginner-intermediate, I guess it should be better to focus in a bit long and wide, flat tail and concaves in the nose board. In this way we've got reasonable early flying and no sticking to the water. Am I right? Could we agree on that?

A couple of questions. Why is there such a big difference for taking off from flat to choppy waters? Apart from the stability. Should we use a bigger, wider board if our conditions are often choppy? How much bigger? any other shape recommendation for choppy waters? I prefer not to pump much.

Has somebody compared real boards with different under hulls and their flying performance in light wind? I've seen some tests but no comparison board to board of similar volume.

I use a 116ltr racing slalom board (for light wind winging). have done for 3yrs. Copped heaps of crap (some smart ass even wanted to donate me his wing board)

I get up in 6knots. Bla bla all the specs.
out there when others are not.

Slalom board. Flat bottom
vt.tiktok.com/ZSNJxxUux/