Bodysurfing Hydrofoil

Here’s something new for you. Again.

While making the first short board hydrofoil in 2013 there were a lot of foils made with different materials. One of them was this beast made of 1 inch thick XPS but no sooner had the resin dried I realised that this level of buoyancy wouldn’t help with foiling as it would always be trying to pop out of the wave. Ideally a foil should be neutral buoyancy so it goes where you ride it, but this one never made it onto a foil board and sat in the garage with all the others prototypes.

Construction was 1 inch thick XPS with carbon top/4oz glass bottom, vacced with a lazy gloss coat afterwards.

 The next day it was head high and hollow but a bit nasty and and I thought I’ll take it down and see how it performs as a single foil, maybe just by holding it in my hands and see what happens. I thought it might’ve just been ripped out of my grasp by the wave or just been crap but you’ve got to give things a go. Maybe it’ll be great scientific experimentation, or maybe another blood letting experience and sad cautionary tale.

 Paddling out was a bit awkward as there’s a sharpish leading edge and a chunkier trailing edge and it’s designed to ride laterally in the water, sideways rather than lengthwise. But I got out there and figured out the best place for it while waiting for a set was under my butt.  It gives enough buoyancy so that my shoulders are out of the water. Better visibility than normal bodysurfing so that’s a bonus.

 One-arm paddling into a wave, grasping it by one end and quickly grabbed the other end as the wave caught me.

 I’d forgotten to have a morning coffee, shower or make any attempt to wake up before hitting the surf and suddenly I’m dropping into a nasty head high barrel with a newly designed sharp edged carbon blade with no freaking idea of what’s about to happen.

Dropping like a stone, I instinctively push both arms down to distance and protect myself from the sandy bottom of the barrel and the foiling effect kicks in. The width gives lift and instantly the front half of my body is out of the wave, the wave steepens and the outside end of the foil is now out of the water with the inside end stabbed into the face and Im actually moving along the wave with good speed.  In each millisecond I’m waiting for disaster, something hideous to happen to punish me for taunting the wave gods. 

 I shoot out of the tube and it’s over. Done.  I’m adrenalised.

I think…Is this something ? Great new idea or just another unholy bastardisation? 

There’s a bit of adjustment with the inside hand onto the top of the foil to reduce drag but I shoot out of most of the waves I took in the next 30 minutes proving that bodysurfing with a single foil is functional, a bit odd to start with but it works. It’s actually  a new way to ride waves. Handplane, bodysurf, mini bodyboard, bodyfoil…

I wander home stoked in the summer sun, smiling at the experience, constantly turning the foil over in my hands looking for what Magic it contains.

I carefully nestle the foil beside the front door for use that afternoon and the wife asks if I’d like a coffee ?

 Nah I’m fine thanks.

 

I think it’s a great idea !

:slight_smile:

Great story.  I don’t recall seeing a picture of that one. I saved a bunch of pics of your foils thinking I’d do a bit copying and tinkering later.  But never did.

all the best to ya.

WAO, that’s a very cool beast you’ve got there ! How does it go ? what would you do next ? I look at yours and think of making a single piece ‘dynamic ribbon’ with the hand holds shaped like a Manta Rays front flukes.

 Greg, you are welcome to make any of my designs. I was going to bring out a kit but we had two little babies at that time and it just wasn’t possible.

 Still, inventing and riding short board foils from 2009 to 2013 was an achievement.

Currently I keep a few foils at the front door but a hybrid inflatable idea is lurking, inflatables offer little drag but little control.

First I need to tell you that I really enjoyed your hydrofoil threads, they have been very inspiring and motivating.

The bodyfoil works but needs improvement. When designing it I was anxious to have enough lift, and I was wondering if it would work with all the drag of the lower body in the water, so I’ve overdone the wing’s efficiency. It could actually lift a foil board and it’s pilot. But because I wanted the most efficient design I ended up with a high aspect ratio which, for this application, is an obvious mistake now. The next one will have a shorter span with a longer chord instead, also a different airfoil with a rounder lift curve. This one is ultra sensitive to AoA, a very small change of angle results in too big an increase in lift. So if the water is turbulent or especially if you shuttle back to the beach pushed by the white water, it jerks you up and down like a rodeo bull.

On the other hand it is very stable laterally, and has more than enough lift, but you need quite some power from the wave. It is one unit, I wanted to try the idea real quick, so it can’t be taken apart. I need to make an arms-deck/handlebars/mast unit to which I can attach different wings. That will make experimentation easier and faster. I have quite a few projects to work on at the same time, so I won’t be making the next version too soon. I’ve still a lot to learn from this one anyway.

Brett, is that a frame from a video?  Link to the vid?  Would love to see it. Thanks 

all the best

WAO, great feed back from your foils, and I thank you for your praise of my efforts.

 I particularly like the leading edge tuberculosis. If you remember Roy, he was a master of that science.

 If you check out my offerings on Vimeo…

You can see what you already know about low aspect foils, if you make a single foil 12 inches wide by 24 inches long, it’s stable in the tube.

Greg,  back in 2009 before foiling was famous I couldn’t get my kids, friends or anyone to film me. Then in 2013 I got a test rider Alex Budlevski to take the plunge. With me taking water pics, and Ben Chipper on land and the video guy was Adam Rowlison. Everyone went their seperate ways and I’ve tried to contact the video guy but the  best information is that he’s currently on a taxpayer funded break at one of Her Majesty’s hotels.

I never saw the video he took and he only sent me a dozen stills from the video and that was that. There were 4 of us who saw Alex foil 8 or 10 waves in 2013. I don’t know if Ben Chipper has any pics from that day. If I found the video guy I would ask him about any video footage.

It was only in 2016 when Kai Lenny made shortboard foiling famous that everyone said, Oh that was done years ago. Theres even a ’ Surffoils Was First ’ thread here on Swaylocks.

https://www.swaylocks.com/forum/67470/surfoils-was-first

 

  

Thank you, I’ve been working on leading edge tuberculosis for a while, now searching for a cure :slight_smile:

I know of Roy but I don’t find his tubercled fins to be properly designed, at least the elliptic planshape ones that I’ve seen. But I shouldn’t criticise them too much knowing that he can’t post here.

I will have look at all the vids for sure. I agree that foils with an aspect ratio lower than 1 are a thing to explore. I have a few prototypes and some more in the works. As a pilot I got to know about this type of wings through the work of Charles H. Zimmerman who gave his name to the Zimmerman planform. There are a lot of scientific publications on this topic and I think a lot of potential to be explored. 

More diverse foiling ephemera here on IG

WAO, what got me into low aspect foils was that there’s not a sea creature thats wider than it is longer ( Quick Google search)

 By having a <1 aspect ratio, a form is more stable in pitch which makes sense if you’re ‘flying’ under water. You need to be able to control its depth or it becomes a bucking bronco. If we were building something that was unstable in the roll axis then a wide foil makes sense. But foils have shown to be a bit like riding a bike in that as they gain speed they gain lateral stability, they don’t want to fall sideways. Pulling the width in to 12 or 13 inches I got a foil that’s instantly stable and  never ventilates. Apart from varying length and area distribution I’d recommend that width for a single foil attached to any board.

 But for a Bodyfoil a lateral foil is the go. Just starting a new one…

 

Something different. I’ll smooth it out and vac trash bag it with carbon.

Ever thought about putting a skateboard truck pivot system connected to the base of the foil (where it meets the board)? I wonder if there would be any noticeable difference. Or do you want the stiffness that’s already there?

 

It’s the stiffness that gives it stability thru the water.

There’s a lot of swirling inside the wave especially if it’s going over reef or the previous waves smashed everywhere. In my videos on Vimeo you can see the 8 inch vertical mast flexing sideways and torquing by about an inch. It shakes back and forth but still feels smooth. I set the camera facing back and down because it was a mystery how the foil behaved underwater.



Brett,

Enjoyed the FaceTime demonstration of your simple vacuum bagging method.

I look forward to seeing the final glassed foil in this thread.

Bill

Bill, it was good to do a video showing how to vac bag with a shopping bag. For small items like fins and foils the only cost is the resin and glass.

 Looking with a minimalist eye to bodyfoiling, if a single foil can lift the front half of your body out of the water, why not build a double foil setup. It’s a front and rear foil connected with a foam topped body. No need for a ‘board’.



That an extermely interesting idea.Is the mass/density of your foil low enough that dodging it would not be of great concern if you get caught in the spin cycle?

Brett,

As always, your latest concept has inspired me.   Lots of design possibilities.

But my current design/build project has tied up all of my creative time.  

May play with this Body Foiling concept next summer (Northern Hemisphere that is).

Bill

Hi Sam,

Getting slammed by a board is a concern any time you go surfing but the foil is like an oversized handplane or minimalist bodyboard. Sometimes I’ll go over the falls hugging it and sometimes ditch it and dive but I don’t use leashes. I vacbag them so they are generally very light, XPS and 4oz.

 I’ve learnt that if you make a surf item that’s very buoyant it’ll bounce it’s way with the broken wave all the way to the beach.

But if you make it with just slightly positive buoyancy it’ll spear into the depths of the wave and while it’s working its way to the surface, the waves gone by.

So it’s a sunny spring day, perfect for shaping outdoors in the sun.

EPS on 3 ply.

Stack up a few milk crates to shape on and round out the front hand grab and fair the fuselage into where the foil tips will be.



This is going to look awesome.

Thanks for that WAO.

Because it’s the 3rd model and I’m somewhat familiar with foiling theory and practical application, I’m keen to expand the designs elements and incorporate styling and a few ideas.

The overall area is 360 sq in with the fuselage being a basic separator creating distance between the front and rear foil. Using the fuselage to my advantage I’m topping it with EPS for buoyancy and torsional rigidity with a layered glass schedule focussed on the middle of the fuselage. Personally I prefer to layer light glass rather than use a single heavy weight as I can build multiple weave directions. All vacced.

The leading foil edge in the previous model was too thick and I could feel that it was slowing the potential speed  so I’m thinning the leading edges but moving the foil apex further back in the chord.

 And the front hand grip will have rocker under the front edge so that the ‘craft’ will have inherent lift. Add the buoyancy from the foam and the paddle out should be fairly easy. Maximising the foam volume is also a good perk as you can sit on it in the lineup and be higher in the water for better visibility.

 There are a lot of options like internal glassed beams inside the fuselage and staggered foil heights or interchangeble foils but all that can wait for later.

I found out there are people smarter than me already working on their own version of a Body Foil so I’m keen to see what they create.