Foiling Surfski?

Hello,
can I expect 2021 to see some foiling surfski on the water?
All is foiling today.
I would be even happy for some semi-foiling. The DNA F1 high-performance sailing in soft wind, will come up if some waves roll in (wheely style, the rear is still in the water). The same effect would be quite nice to see it at the surfski. Also the foils can stabilize the ski. Perfect would be some hybrid ski (foiling and classical adaption for the actual conditions).
I have seen only the Flyak, but it is not comercial available on the market.
Cheers

What would you expect to get out of foils on a surfski?

Charivari wrote: Hello,
All is foiling today.

Odd

I've never seen a foil, in a shop or in use. Plenty of surfskis and sea kayaks.

Might be because I live in a cool and wild area. (how good are foils for heading upwind in wind gusting at 30knots or higher?

> I've never seen a foil, in a shop or in use. Plenty of surfskis and sea kayaks.

I think Charivari means that everyone that has a board puts foils under it: kit foiling, windsurf foiling, wing foiling, SUP foiling, surf foiling. The sailboats too: Moth, Waspz, etc. Not to mention AC45's, AC72's, etc.

I do have "foil envy" when I pass by the beach where everyone else is on a foil. I have some ideas about what I'd like to get out of a foil on a surfski, but I'm wondering what others imagine...

I think the primary issues would be -
1. how do you control front to back angle of attack? On a foiling surfboard your front to back angle is critical. Also you cannot 'pump' a ski
2. how do you paddle when you are 12" off the water? you would either need a paddle that is way too long or short depending if you're in the water or foiling
3. how stable is the wing, side to side? is it stable enough that a non-elite could use it?

I like the idea of a front foil. Get the front 2/3 of the boat out of the water. That would help with resistance, angle of attack would not be variable, paddle length/height is less affected.

Foils kick ass but im struggling to see how they work on a ski.

Want I really want is a Lithium battery powered propeller that adds like 1hp of power for a few seconds to boost me onto groundswell. I only need it a few seconds at a time to accelerate. Once im on the wave I could probably stay on it. That would be great!

MCImes wrote: I think the primary issues would be -
1. how do you control front to back angle of attack? On a foiling surfboard your front to back angle is critical. Also you cannot 'pump' a ski
2. how do you paddle when you are 12" off the water? you would either need a paddle that is way too long or short depending if you're in the water or foiling
3. how stable is the wing, side to side? is it stable enough that a non-elite could use it?

1: I don't know how much weight shifting can work and whether it's practical to paddle and control front-back weight. I know that I can shift my COG forward/backward by 8"-10". But realistically, a 1-mast set-up doesn't work on a surfski because you need something to counteract the yaw forces of paddling. So you need a front and a rear daggerboard mast. There's some footage of the Flyak from directly behind and you can see how it snakes along.

You're correct that you can't pump, but I paddled next to a friend who took off on a wing board making an effort not to pump and he was not going much more than 6mph.

Getting the angle of attack is easy, what's difficult is to increase the AOA for take-off and then decrease it at speed...

2: paddling 12" up is a good question, if you're going down a wave on foils, maybe you don't really need to paddle that much? It's a good question.

3: stability doesn't seem to be an issue from what I've been seeing and hearing.

MCImes wrote: Want I really want is a Lithium battery powered propeller that adds like 1hp of power for a few seconds to boost me onto groundswell. I only need it a few seconds at a time to accelerate. Once im on the wave I could probably stay on it. That would be great!

Wouldn't it be nicer if you could get on the foil and accelerate on your own to the required speed? That's actually my #1 use-case for foils.

There's a kickstarter, I believe, that promises a motor with a prop that folds up when the motor is off. This is for e-foiling to go up-wind. That's probably close to what you're talking about. Shouldn't be difficult to mount that under a surfski

People have tried to get surfskis to foil but it hasnt worked. I think controlling AOA is the biggest issue but I don’t know that with certainty. 

Downwind foil sup looks so much better than downwind surfski, which is already amazing and my favorite thing to do. The speed, the glide, the ability to surf at extreme angles to the wave, the way they deviate hundreds of yards in either direction instantly and effortlessly. They have a really high vantage point from which to read the waves. It’s a sport I will never do, but I enjoy dreaming about it. 

zachhandler wrote: People have tried to get surfskis to foil but it hasnt worked. I think controlling AOA is the biggest issue but I don’t know that with certainty. 

Got any links, references, names? I only know of the Flyak and a few copies, all flatwater kayak based. 

Downwind foil sup looks so much better than downwind surfski

Yes & no, it depends on whether you include the hospital trips to get stitched up from an encounter with the foil...

A few years ago I did a bunch of downwind runs in the Columbia Gorge, on 3 different boats, and a bunch of different wing / wing configurations.  I was hopeful that a typical foil configuration (borrowed from kite/sail/SUP) would work on a ski, but it doesn't.  I did achieve regular, brief flights, and speed while not flying wasn't terrible - I could "hang" with other surfskis.  The stability gained from the wing is tremendous.  It slows any roll to ridiculously low levels.  That said, it's also difficult to counteract any roll, but adding knee straps (like a waveski) helped.  It was possible to extend flights by "pumping" - throwing ones torso forward and back - but very strenuous (like doing crunches as fast as possible with a bunch of extra resistance!)  The fundamental problem is that when a ski is in position to achieve lift-off, the wing is in the wrong position relative to the wave, and/or you can't maneuver to maintain the correct position (due to the ski's length and "swing weight")  You can pop up, but either fall right back down pretty quickly, or zoom down into the trough and crash that way.

I think "sit down downwind foiling" may be possible, but probably not a typical surfski platform.   Look at how SUP boards have evolved, from slightly modified boards, so now being un-recognizable from regular SUP boards (just a "patch" of material big enough to stand on).  It may take some out of the box thinking, and some resources (time, $$).

Flatwater foiling (yawn) is a completely different problem, and I suspect there are viable solutions.

Thanks for the info, Don. Do you have any photos of the foil configurations? I'm thinking of having a main foil pretty much under the bum and a small one at the tip to steer and control height. Did you get away with just a single mast under the COG with a fuselage and two foils? I assumed that such a config doesn't work due to the yaw forces of paddling and would turn the surfski into a helicopter propeller at the first paddle stroke...

I also wonder whether the Gorge is a good place for surfski foiling due to the typically short waves (at least in my understanding). In my very limited experience in the Gorge you're pretty much going at wave speed in a surfski and look to jump over the waves ahead. That seems tough to improve on, at least with something as long as a surfski...

I don't think a bow-mounted foil works in a downwind scenario.  (It may be great or even necessary for flatwater foiling, as shown by the Flyak.)  At the point where you're able to take off, the bow is out of the water, and once you pop up the bow is way out of the water.  You wouldn't want anything there - weight especially, or anything to catch the water. 

Yaw didn't seem to be a problem... I wasn't really worrying about it, and certainly don't recall yawing all over the place.

Every other foiling craft works in the Gorge.  Once you're up on foil, the exact nature of the waves isn't a big issue.  It's just a matter of positioning (maneuvering) and timing.  The SUP foilers are going faster than surfskis, which shows that foiling is a completely different mode than displacement (you don't have to push a hull up / over / through anything).  The skilled SUPs aren't even using a paddle any more (SUs?) - either stashing it, or using it as an action cam extension.  Here's a good, recent example:

This article here talks about Revo's attempts at this

www.surfski.info/latest-news/story/1665/...tow-tests-video.html

waterbornewarrior wrote: I don't think a bow-mounted foil works in a downwind scenario.  (It may be great or even necessary for flatwater foiling, as shown by the Flyak.)  At the point where you're able to take off, the bow is out of the water, and once you pop up the bow is way out of the water.  You wouldn't want anything there - weight especially, or anything to catch the water. 

Interesting! Thanks for the explanation. Did you just use a foilmount stick-on mast mount or lay up a bit of a pressure diffusion plate under the surfski (also to flatten the area)?

tve wrote: Interesting! Thanks for the explanation. Did you just use a foilmount stick-on mast mount or lay up a bit of a pressure diffusion plate under the surfski (also to flatten the area)?

I built a carbon plate (20 layers!), molded to hull on one side, and flat on the other for the pedestal mount of the mast.  Good enough for testing, but a flush or recessed mount would be much better.  You can kind of make it out in this pic.

Is that a forked rudder on the back of the foil ski? 

zachhandler wrote: Is that a forked rudder on the back of the foil ski? 

Haha, good eye, Zach.  It had nothing to do with foiling, just happened to be on that boat.  Like nearly everything I've tried, it worked.  But not better than a standard rudder.

waterbornewarrior wrote: I built a carbon plate (20 layers!), molded to hull on one side, and flat on the other for the pedestal mount of the mast.  Good enough for testing, but a flush or recessed mount would be much better.  You can kind of make it out in this pic.

Very nice, that's a lot of layers! I just ordered materials to make a ~42" long plate with ~36" long rails so I can really experiment with different foil configurations. I know you say that a foil in the front wouldn't work but I'm not sure that's true for ocean swell, and I think in the end there's only one way to find out...

Any recommendations for which types of foils to try/avoid? I'm eyeing either a 2450cm^2 low aspect or a 1800-2000 cm^2 high aspect.

You're right - only one way to find out!  

Just a gut feeling: get the biggest, lowest aspect foil you can.

The first issue I thought of for my location is shallow water.

By myself I foil the Trampofoil and the DNA F1 A-Cat and for cross training I use the coastal rowing boat Volans (and soon my first surfski for a better rotation training).

With the Trampofoil I feel it take really a lot of energy, to get on the foils with human power. And some waterstart is not possible with the Trampofoil - never ever (you start from the peer). But it is a perfect explosive power training (a friend wins always after our trainings his tennis matches).

On my perspectives the Surfski is the slowest vehicle, so a foiling surfski would be fun!
If I could by the Flyak, I would be the first. For me it's a cross training, so I can do it also for two times 1000 m.

The idear with a starter engine is quite clever.
Hier some jetkayak:
www.gadgetking.com/2017/08/18/jet-angler...elled-fishing-kayak/

My experience with the the A-Cat, hat any wave hits the boat (75 kg!!) quite hard.
Now with the same soft wind and the F1, I jump over the rolling in waves.
So my conclusion, why a Foiling Surfski would be cool:
+ more stability (assumptions the Foils are broader than the surfski)
+ more speed (less water resistance, even in the semi-foiling mode, like the F1)
+ better in jumping over the rolling in waves (the water-speed defines the uplift nothing else)
+ better downwind foiling, more water speed lifts the boat, less resistance and higher speed
+ more fun = more speed

If you study the F1 Foils, you see:
www.sail-world.com/news/198017/A-Class-C...rlds-in-Poland-day-3
+ that the angle of attack is adjustable is key
+ the foils must be designed for the purpose (any spill of energy ends up in a non-foiling mode)

If I would design it, I would use two foils like the F1 in the front (you can lift them for the surfski classical mode).
And one in the back, the rudder foil.
I expected to see 2021 more foiling surfskis....