Don’t bother about a price, I’m happy to help and I’m sure Dave Tomasetti will too.
Collaboration sounds great, start a new thread probably…
No doubt. I don’t want to sidetrack this discussion.
faced with shoulder surgery I took a break of several months to pretend surfing doesn’t exist, to look for other avenues to a fulfilling life. I tried family, community and religion but they were all dead ends.
So it’s back to surfing !
And I’ve built a modular version of the multi level foil from 2013.
The 2013 foil was a single piece of aluminium with a planing area divided between 2 levels so as the speed increased the foil automatically adjusted the area to the speed.
Here’s the old foil then a few pics showing how it adjusts to speed and the shape of the wave.
And then the new version.
You can see the whole foil is submerged but as speed and the face steepens the foil rises and pierces the surface. Design wise the total area gives plenty of lift at low speed but instantly transitions onto one side foil, I kept the foil arms wide for stability so it acts like the inside rail of a board.
The modular design is connected by folded aluminium so I can adjust the distance between foil and board and seperate foil sections. There’s room to experiment with using the board rails for extra drive in cutbacks and tubes. Currently it works as well as the original multi level foil but there’s always room to sharpen the design and look for better performance.
The foil width is down to 13 inches so it all fits under the footprint of a normal shortboard.
The length is still 24 in.
The foil depth is around 8 inches and the board flies 6 inches off the surface allows for better control. The whole foil is no deeper than a longboard fin when paddling and riding only site a few inches under the surface.
IMHO, The easiest way to glass these components without touching resin is basic 3 ply in a glass sandwich and vac-bagged with epoxy.
Apart from the resin the only consumables are the plastic bag and a strip of fabric ( from an old bed sheet) that I use to draw the resin away.
When set its light, rigid, smooth and just needs an outline trim.
The retail foil guys have been doing the twin wing aeroplane look, but it doesn’t lend itself to riding hollow surfing waves. The wide tips pierce the surface and the foil ventilates losing lift. Rather than redesign they just turned the tips down, which reduces lift during a turn.
The simplest foild design is the low aspect flat plate but the best design for real surfing is the Inverted V Foil with multiple foiling areas.
Fig 1. From the front, all 3 foiling surfaces are submerged, there’s not a lot of need for balance with the craft hull in the water. Total foil area is around 300 sq inches.
Fig 2. As the speed increases the lift value does too, the foil can become unpredictable with so much lift so having the central area A lift out of the water reduces the lift keeping it stable. Balanced on the 2 sides foils of around 200 sq inches. At speed a foil is like a surfboard or a bicycle, it creates lateral stability and you don’t need a setup wider than 16 inches.
Fig 3. As the wave gets steeper there’s a massive increase in the lift from the wave, now it all about shedding lift by reducing area to a single foil of around 100 sq inches. A submerged surface has much more lift because it’s embedded in the flow and keeping the side foils close under the riders centre of gravity makes it feel a lot like riding a board.
The transition from paddling to top speed/minimal area can be very quick as you can see in the photo of taking off on a pitching wave. The transition is almost instant. This transition works in reverse too so that when you go over a flat spot or pull off the foil automatically gives the maximum lift and you can glide a long way on the back of a wave.
A wide foil is fine for flat water foiling like kite, tow, sailboard, sailing or downwind.
But in the surf the wide foils ventilate and stall so the tips are turned down and the mast needs to be longer and that creates structural problems with the mast flex and connection to the board with a Tuttle box or large adhesive plate. As long as the foil is wide it has to stay a long way from the board.
An Inverted Vee Foil sits no deeper than 8 inches, it fits under the outline of a standard shortboard, the connection to the board can be done with FCS plugs and there’s better control.
Now I’m back in the surf after shoulder surgery I’ll work on the modular foil design to find the best ride height and foil positions.
This is why a variable lift foil is essential… when you buy a thousand dollar foil it’s good for a small slice of wave energy. If the wave gets bigger or smaller you need to buy a new foil and have them all on hand to change as the surf changes.
It also hilights the ventilation problem with wide foils breaking the surface and stalling.
Clay does a great job riding and sharing his experience but every foil system on the market is the same. No one has a variable lift system so you have to buy a new foil to suit each surf condition.
Thanks for sharing, it’s most interesting!
Is the transition between ‘gears’ difficult to handle?
I cannot help but ponder how the lift can be made ‘continuously variable’, maybe by using 5 or 7 panels in an arched configuration to fill the gaps between the three foils you currently use.
But that might be totally unnecessary, no idea, because I have never foiled yet.
Hi Mik, I know you’re not the person to do things without great detail but having the 3 Foils over 2 levels is all that’s needed. Because of the slope and curves of the wave it’s more a slide than a step between foils.
There’s 2 measurements that control the flight, the vertical distance ‘x’ between the board and the top foil A.
And the vertical distance ‘y’ between the Top and lower foils.
‘X’ is the minimum foiling height and ‘y’ is the maximum so you can control how high you Foil and the smooth transition to high speed foiling. Ive had the whole setup as low as 6 inches to the hull but around 8 inches is very easy to ride. (x + y)
Do you think it would be possible to paddle (prone) a foil board to lift-off speed on flat water? And stay close enough to the waters surface to keep on paddling?
It’s possible to foil on flat water using paddle power but it’s not ideal. Theres a physical energy requirement that’s going to make it very difficult.
The best thing about foiling in the surf is that there’s unlimited energy available from the wave to play with, It’s not about looking For the energy, it’s all about trying to release / filter the rising force of the wave through the foil with control.
The area of the foil regulates the amount of lift, the arrangement of the foil position regulates how you can control it.
Having a single or split foil that sits in-line at the same depth is fine for flatwater or shoulder hopping but on a steep face it makes sense to have a deeper front foil so both parts are submerged on a sloping face.
I think some kinda Meccano / IKEA design that’s easy to build but covers the best range of waves. I remember building balsa planes from flat cutouts and they created great shapes.
There’s some theory behind the design.
ROFL same here! Even the religious bit
The science of foil design is just like fin design, vertical fins/ foils are quick to lift but poor at drive.
Long base fins/ foil have great drive and poor lift, but on a Hydrofoil the vertical lift isn’t important as the drive. There’s only so high you need to go to clear the surface and there’s tons of lift anyway.
When designing, my first interest is making it easy to ride, if it’s impossible to learn the basics there’s going to be a very small market of people dedicated to learning how. Making it easy to learn is the first priority so every punter can get a quick positive reward. Currently there’s a lot of second hand foils for sale and that’s probabaly because it’s not easy to learn.
All the commercial makers have gone from high aspect foils on long masts to lower aspect foils on shorter masts but are yet to embrace a single foil design rather than the twin blade design or even look outside the box for a hybrid design.
I started with the twin lateral foils like theirs but when I moved to longer low aspect foils, the control is amazing. It’s very stable to learn on but for a while I’ve been looking for a balance that’s more manouverable.
The only issue with long foils is that they don’t like going down a closeout. I think it’s becasue the length of the foil makes it stall.
A better variation is to combine the quick lift of a lateral foil with the drive of the long foils. A wide lateral front foil sticks partly into a steep face providing quick control yet good balance.
Adding long foils at the back gives it drive from the tail to stabilise the jumpy front foil.
The separation between front and rear foils allows the rider to balance between the lift and drive much the way we already do on a shortboard. There no need to reinvent how to surf, a new concept should incorporate the skills surfers already have.
Here’s the latest setup. It’s easier to comprehend how it works by seeing it upside down. You can see the front foil is set lower than the rear foils so it stays submerged in a steep wave.
It’s sill technically a basic design, the depth and length of the foils will need to change but overall the quick lift of the front foil and the drive of the rear foils is a better setup.
Here’s a few early versions over the years and then the best version in red.
The gaps and spaces between the foils are like the spaces between surfboard fins and are just as important as the foil design itself.
Splitting the lifts area between foils means that the foils can be more specific in purpose rather than just lifting. The front foil is only 18 inches wide so it tilts lift a surfboard hull, the rear foil has a simlair wetted length as an inside rail so it responds to drive like a surfboard.
Foiling has got all the media hype but it’s still not spreading into the surfing community.
3 obvious reasons are that commercial foils are massively expensive, dangerous and difficult to learn. Looking at any business model the first thing towards making a profit would be that a product should be cheap, safe and easy to learn.
My foils are about $20 to make , as safe as possible and every person who has tried my foils can ride on the first wave. The exception being one guy who took his first foil wave on a head high backhand beach wave.
This new multi- level version is unapologetically a pool toy in appearance. Cut from a flat ply sheet, but it does explore the possibility of a CNC kit being available for sale, it tests variations of multiple planing areas, different planing levels and the balance of mixing lateral and long foil design.
I know that commercial foils makers would dearly love to have a foil that actually pulls into a tube but so far only Terry Hendricks and I have done that.
Spot on observation.
What would I do if I was selling the current high aspect foils ?
I’d swap the rear foil for a long foil. Keep the highly tuned front foil that they all use for lift and put a low aspect foil at the back for stability. It wouldn’t lose any lift from the front foil but it would stabilise the quick AOA change that makes these foils difficult to learn.
Hey man, been quietly watching this one. I like this new design. It hits a lot of the right spots. As you know I’m building a more traditional foil right now, Mainly so I can compare the experience and have a place to start. Your hybrid idea is right on, I think.
I’m anxious to try the higher flying foil though I know the learning curve will be steep. But I still want to build a full scale lower masted foil like you are showing. I think the experience will be totally different but both should be fun, in different ways. I’ll post up when I finally get this thing ready to fly. Winter has been slow going for me but I’m in the home stretch.
The two foils at different heights is a great design and making it CNC cuttable is a great idea as well.
Hi SCB, I’m sure you’re not the only one lurking…
When surfing hydrofoils became a big thing a few years ago I thought Oh shit here we go, thai’ll be great !!
I picked it up from Terry Hendricks who was doing it in the 70’s but I thought these new millennium guys are going to wipe the floor with their massive hydro tech knowledge, they’ll have a foil out that’s cheap, easy to ride and putting every surfer on Earth into the fastest tubes on foils. And I held back waiting to see how good they would be but as it turns out, theyre no competition.
They went with the high aspect main foil thats so twitchy and ventilates and they stuck with it, I thought they must’ve tried low aspect and moved forward but it’s clear they never made that effort. I reckon they looked at Lairds foil and chose to make theirs look like a glider plane for stability without doing the real Surf R and D. How cool would that have been to do ?
In some ways it’s a disservice to the market because the punters who’ve recently spent $2000 won’t be impressed to know there’s a simple, cheaper system that rides easily in real waves. Even my amateur Vimeo vids show more tube time than all their commercial footage put together.
Sure you can get a surf wizard to ride your product for the hype factor but few of us are at that level, so it wasn’t really fair to market such an expensive and unstable ride, but I guess ‘First To Market’ was an important goal.
I was very happy to see foiling get attention but In many ways I’d prefer that the foil market dried up.
They priced it Bugatti when they should’ve gone IKEA. You got to accept the New World business concept, put out an App with the Surf Foil CNC program for $2.99 and move on to the next idea. The dream of one surf idea making you a billionaire is dead. It’s a pool toy, move on.