I attached a BOGA Grip, 260 Version, with an IGFA Certified Fish scale good to 60 lbs on the Tow Rope.

The GoPro was attached to the BOGA at an angle to film both the rider and the metered scale at the same time. On a crappy iPhone this is hard to read but its clear at full 1080P resolution.

You can see the drag for the Foil fluctuating between ~ 4 lbs up to 18 lbs. I pegged the average DRAG to be 12 lbs

The drag on the Surfboard from ~14 lbs to 30+ lbs - See next.

It's nearly 2:1 Surboard Drag vs. Foil Drag:

Foilboard ~ 12 lbs

Surfboard ~ 22 lbs

Ratio: 55% of Drag on Foil vs. Surfboard

I set up a test using:

My 5 HP boat
My 118 lbs Daughter - Had to teach her to foil but this is incredibly easy - Stunt Foiler
Home-Made Foil-Board - Weighs ~ 20 lbs
Sunova 9' 1" Acid SUP Surfboard - Weighs ~ 20 lbs
BOGA 260 IGFA Certified Fishing Scale measures to 60 lbs
GoPro - Filming at 2.7K

The Videos speak for themselves.

Boga Grip and my daughter on the shortest Foil Foil Board in the World - 3' 3" (with soft ends)

If anybody challenges this I swear I will cut the board down

My daughter weighed 118 lbs. The foil with the board weighed 20 lbs.

Call it a total of 144 lbs with Life Jacket . . . .

This would put the Lift to Drag Ratio of 12 : 1 for the GoFoil Maliko 200 flying at 10 mph.

That's pretty cool Beasho , thought about it but never did it well done.

Interesting test Beasho. When I'm foiling on a wave it feels like there is almost no drag at all and going back to a regular SUP surf board it feels so SLOW in comparison. A 45% reduction of drag is substantial but I thought it would be even more.

Beasho, I would argue that on your videos the surfboard is not planing, and thus has much more drag than on a real wave.

Robert, And even if a SUP had 45% more drag than a foil, it is very easy in good waves to position a surf or SUP in a wave section that is at least 45% more powerful than the ones manageable with a foil. I definitely feel more power and speed in hossegor beach breaks with a SUP, where I can lock in the power of hollow waves, even small, on shallow sandbars where I would be afraid to destroy the foiling gear. And I guess a shortboarder could say also that his sinking shortboard feels faster than my SUP.
The foil shines when you cannot find proper waves, either because of the conditions or the crowds, where any drag reduction is extremely significant.

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colas said..
Beasho, I would argue that on your videos the surfboard is not planing, and thus has much more drag than on a real wave.

Prove it!

The test identified approximately how much drag is reduced by a 120 lbs rider going 10 mph on a foil and a 'surfboard'. The size of the surfboard matters. A 'Shortboard' would likely have still been sinking and 2X the drag at 10 mph.

To plane a surfboard requires speed. From my 'Speedwatch' days a windsurfer would plane at 17 mph. Good luck finding any wave going 17 mph that is less than 8 feet. What this suggests is that the majority of people surfing in smaller waves ARE NOT PLANNING on their surfboards but PLOWING their PLANKS.

Speed is measured as distance over time. Because of the reduced drag a foil can 'fly down the line' to places no surfboard can go. This increases the distance and the cosine of the angle down the line. This is the only way to go faster than the wave is progressing towards shore.

When I look at surfers in small waves I actually feel sorry for them GLUED to the Whitewater. Why because they are stuck in the 'energy' pocket the only place where their toy will work. But it is true that as that energy pocket grows it can be its own unique source of fun.

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Beasho said..

To plane a surfboard requires speed. From my 'Speedwatch' days a windsurfer would plane at 17 mph. Good luck finding any wave going 17 mph that is less than 8 feet.

You know that surfing is not going straight to the beach anymore? With a surfboard you go faster than the wave by surfing at an angle and "rollercoasting", to trade back and forth potential energy with cinetic energy.

You can go much faster than 17mph on a 1' wave if it breaks on a shallow sandbar. This is why I love beachbreaks, btw.

And shorter boards will plane at a lower speed, their planing speed depends on the hull length. A 10' will be in displacement mode a lot of the time, but a 6'8" will be at full planing.

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Beasho said..

Speed is measured as distance over time. Because of the reduced drag a foil can 'fly down the line' to places no surfboard can go. This increases the distance and the cosine of the angle down the line. This is the only way to go faster than the wave is progressing towards shore.

When I look at surfers in small waves I actually feel sorry for them GLUED to the Whitewater. Why because they are stuck in the 'energy' pocket the only place where their toy will work. But it is true that as that energy pocket grows it can be its own unique source of fun.

Hey!!!! That's what I said.

This is the beauty of the FOIL vs the Surfboard. Some people might say "DUH!" The foil's lower drag allows you to fly further and therefore FASTER.

I have done extensive testing of Surfboard speed on a wave more than anyone. With 400+ TRACE sessions and 25,000 data points per session measuring Latitude, Longitude, Speed and Direction 5 times per second. 10 million data points. Typically 1/20 of these data points are actually wave rides which would pare it down to just 1/2 million data points of pure wave speed. Almost 6,000 waves measured everything from 2 ft to 30+ feet. The lowest speeds being ~ 6 mph the fastest 35 mph on a 30 ft wave at Mavericks.

I am in the process of putting it all together but concluded 2 years ago while testing fins that the Wave Energy in the Pocket is so great that whether you are riding a SHORTBOARD or a VOLKSWAGON's hood you will go the same speed. The only way to go faster is to tighten the angle "Down the Line" pump, shoot whatever. At 45 degrees this increases Board speed vs. Wave propagation speed by 1.4X.

At 60 degreess your speed could DOUBLE 2X the speed of the wave but this is highly unlikely for any sustained amount of time. At 90 degrees you would go down the line at the speed of light.

However when the speed is limited by drag, and the surf craft maxes out, the wave will just pass underneath your feet. This happens much, much later on foils than surfboards. And in small waves the comparison is absurd.

Low Drag = More Speed = More Fun

The last wave in this video highlights the low drag advantage of the foil. I take off 10 meters from the guy. The guy on the long board is STUCK and can not escape the whitewater meanwhile I am flying 80 meters further down the line and come back.

Lower drag = More speed = More distance = Need to Carve and Cutback = Fun, Fun, Fun!

I was flying 14 mph on this wave. It looks like a 45 degree angle so the wave was probably moving forward 10 mph.

The longboard wasn't planning and neither would a shortboard. Everyone GLUED to the whitewater looking silly.

Advantage FOIL:

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Beasho said..
The last wave in this video highlights the low drag advantage of the foil. I take off 10 meters from the guy. The guy on the long board is STUCK and can not escape the whitewater meanwhile I am flying 80 meters further down the line and come back.

Lower drag = More speed = More distance = Need to Carve and Cutback = Fun, Fun, Fun!

I was flying 14 mph on this wave. It looks like a 45 degree angle so the wave was probably moving forward 10 mph.

The longboard wasn't planning and neither would a shortboard. Everyone GLUED to the whitewater looking silly.

Advantage FOIL:

In the last wave the board rider was stuck in the wash - he would not have been planing and probably had very little angle to the wave. But that's not what I (or you) do on a surf sup on a proper wave - we stay on the clean face and make the best angle to maximize the speed. We might (should) cut back to the pocket if we get into the fat part of the wave, but if the wave stays steep then we zip along the wave. I have no idea if I am making 45 degrees to the wave (it feels like it is greater than 45 degrees, but you have to take the movement of the wave into account) but I am maximizing the angle.

I have no doubt at all that foils create less drag. (I have 1% of the experience you have, but I have experienced it enough to know how it feels - and have been towed behind a small boat and every time I lifted on the foil the boat sped up due to the reduction in load).

Do you know how fast the boat was traveling? The acid looked like it was plowing, not planing. I regularly get up faster than 20 kph/12mph (according to my Rip Curl watch) and it does not feel like plowing - the boat did not 'look' like it was traveling that fast.

(Also, it would depend on the water conditions behind the boat - turbulence and aeration from the prop may stop the board from achieving hydrodynamic flow under the board, necessary for planing.)

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Beasho said..
The only way to go faster is to tighten the angle

No, not the only way. Basically, if the wave curl goes from point A to point B, the more turns you perform, the more you lengthen your travelled distance. But you still get from A to B at the same times. By turning you are lengthening the travelled distance while keeping the time constant, hence enhancing the speed. Tightening the angle only pushes B farther away, but turning adds more.

But I guess since you foil big waves you are used to going rather straight to the beash, so are more used to travel at the speed of the wave, when looking at the GPS traces you posted:


Whereas, as a small wave surfer, I cannot go straight, I wouldn't have the speed to even plane on a 4s period wave. This is why I actually do not enjoy bigger waves, I get the feeling of being "stuck" to the wave (I go faster but slower relative to the wave) and not have the freedom brought by going (much) faster than the wave. But I must admit that foiling in bigger waves lifts this frustrating speed limit of a planing hull.

I do not have a GPS watch, but here are typical surfing tracks:


On your New England video, with a proper SUP (and Quobba fins :-) ), I guess I could have worked a lot of turns in the nice curl just in front of you on the waves, instead of going straight to the beach with a foil. Granted, I would have got out of the wave earlier. But personally I would have had more fun "milking" speed with turns in the curl than just gliding straight. But it is personal, to each his own.

Being located inland, supfoiling only happens in my holidays, but our local river now spoiled my search for a new playground. I recently found a stretch of dock allong the river where i could get pulled by a e-bike (big thanx to wifey ).
Towing me on the Slingshot Infinity 84 on a 7'11" SUP she read on her speedo 14 km/h / 9 mph for liftoff while pumping, followed by a sudden reduction of pull on her, so she could accelerate to 18 km/h / 11 mph with the same power.

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AlexF said..
. . .Towing me on the Slingshot Infinity 84 on a 7'11" SUP she read on her speedo 14 km/h / 9 mph for liftoff while pumping, followed by a sudden reduction of pull on her, so she could accelerate to 18 km/h / 11 mph with the same power.

Interesting. Similar experience to us in our boat. I estimated it was cruising at 10 mph. This was plenty for the Maliko 200 wing but a bit slow for the GoFoil IWA.

I also assume that your eBike can go 20 mph. Does this mean that the drag was limiting top speed to 11 mph or were you able to go faster?

Either way the data is in the ballpark. Foils start to fly ~ 9 mph. Comfortable from 11 to 13 mph. 14 mph and up the surf foils get to be a handful. You can fly them at 20 mph but it will take some practice.

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Beasho said..

AlexF said..
. . .Towing me on the Slingshot Infinity 84 on a 7'11" SUP she read on her speedo 14 km/h / 9 mph for liftoff while pumping, followed by a sudden reduction of pull on her, so she could accelerate to 18 km/h / 11 mph with the same power.

Interesting. Similar experience to us in our boat. I estimated it was cruising at 10 mph. This was plenty for the Maliko 200 wing but a bit slow for the GoFoil IWA.

I also assume that your eBike can go 20 mph. Does this mean that the drag was limiting top speed to 11 mph or were you able to go faster?

Either way the data is in the ballpark. Foils start to fly ~ 9 mph. Comfortable from 11 to 13 mph. 14 mph and up the surf foils get to be a handful. You can fly them at 20 mph but it will take some practice.

She could've gone faster but that would've exausted her more.
She gave me some runs and so it was a real workout for her, esp. bringing me and my 90 kg up to speed from standstill.

Now i'm looking for a small boat, 10 hp should be enough, or an add-on efoil kit.
The guys of Elevate efoils are located on my side of the planet, only a 2h drive away to test their stuff, and seem to have a Slingshot compatible system under construction.

In this video they found 7-8 mph as the liftoff speed, but they had the wake of the ski as a support

Hi Beasho, wait until you try flat plate foils with very low volume. The form drag is almost zero . The acceleration is instant and the top speed can't be reached onsmaller waves.

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surffoils said..
Hi Beasho, wait until you try flat plate foils with very low volume. The form drag is almost zero . The acceleration is instant and the top speed can't be reached onsmaller waves.

SurfFoils: Love It!

Can't wait to see how they perform. I'll put a scale on it if I can.

Thanks for your support. You know the 2nd generation of foils is coming soon.
The Fanatic foil is just the start of new designs and once they grab the single foil concept as shown in your video, it will be a new world of design. The single foils are so much faster and easier to ride. You'll be able to foil Mavs. A foil for Mavs will be long, slender and with minimal area. If you've got an average speed figure for Mavs I can work out a foil for it ?