Wow. My mind is swimming with the possibilities. Kudos for trying something unconventional.
quick question:
Does the water flow that comes out on the top of the board interfere with the surfer’s back foot traction? It seems like this is a pretty critical part of the board. Is it noticable?
Looking forward to hearing more about your progress!
I could also see this as a benefit for noseriding.
Doyle, thanks for the suggestion.
Surffoils, have you tried creating channels or any sort of concave to flow more direction to those ports/ducts? What are they called?
[quote="$1"]
Also, have you experimented with the angle of the flow through the board? If I was starting I would place it at 45 degrees (just as a base model) and then tweak from there. I'm also very curious as to how you came up with the opening shape. One more thing (my head is exploding), have you tweaked the general size of the opening and exit port at all? If yes to any of these questions, could you post your results?I'd like to thank you for posting what you have so far. You are an example of what Sways is about. As a long time lurker here I appreciate the posts you guys put up.
[/quote]
Monkstar1, I think the first thing is to show how we make the molds so people can have a go if they want to.
We started out shaping holes in foam and trying to glass the internal walls but that wasnt the right way.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/August2010007.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/August2010005.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/August2010006.jpg[/IMG]
Now we take a fine grain block of foam draw the induction port (hull) on one side and the exhaust port (deck) on the other. And then sand the wall angles to join the two.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/August2010002.jpg[/IMG]
But the walls arent always a straight plane between the two.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/SeptemberB2010005.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/SeptemberB2010001.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/SeptemberB2010004.jpg[/IMG]
The interesting bit is deciding the shape of the holes and walls of course, youre not shaping something that will be a solid but shaping the water or the way the water will flow, (as you see it,) so its quite an exercise in how you think water travels.
Its a lesson in sorting out your own hydrodynamic theories and putting them up for testing.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010C002SW.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010C001SW.jpg[/IMG]
Boards are about 1.5 in thick where I install the vents so you dont need a big slab of foam just a scrap will do.
I use styrofoam for the mold , glass it in epoxy and then when its polished and has a layer of car wax on it, I then glass around the mold to create the vent using polyester resin. Or swap the resins if Im using a piece of polyurethane foam. I just think that if I use unlike resins then I wont have any trouble seperating the mold from the layers around it. Take into account any undercuts too. Using the different resins I havent had any problems at all with getting the vent off the mold.
To answer your questions, yes we have been trying different angles for the tube, both in the overall direction as well as different wall angles. And we did it pretty much how you suggest, start at 45 deg and go from there.
In the end the wall angles are the greatest challenge and we have found that the walls need to have angles that change along the tube.
At the front, one wall is quite flat ( near horizontal) and then rises to be more vertical. So the wall angles arent a fixed value.
The opening shape came from a lot of theorsing about how water enters a hole..
what range of angles does the water come in at ?
what width will be needed to allow the correct amount of water?
does the hole need to be wider at the front or back ?
do the angles at the hull need to be sharp or rounded to use the coanda effect?
And would the exhaust port need to be the same area as the induction port ?
The general size of both ports has shrunk about 50% from the first prototype.
The water coming on to the deck isnt a worry concerning traction, at times it does shoot straight over the side of the board !
We havent tried 'lead-in' channels or anything more complex, just trying to nail down some basics.
No name for them, but another Sways member did suggest "INFERNALS or INFERNAL FINS... by mixing 'Internal' and 'Fin'... but your suggestions are welcome.
I totally understand, I appreciate what you did show me though, thanks!
I’ve been trying finless surfing on a 5’7" small wave board that I have and have been really enjoying the frictionless speed and feel. If you guys can achieve that in a straight line, with the internal fins engaging when the board starts to turn, now that is pretty exciting.
How does angle of attack effect the hold of the internal fins? I understand they are designed so that water flowing diagonally across the board will run into the ports, but what about the angles of attack commonly used for shortboard turns for example?
Once you get the ports worked out you’ll be able to fabricate inserts which allow you to alter the internal size and angles there-in to customise the flow.
The FCS/probox/futures marketing side of things.
what a great share Surf Foils. we played with some pretty simple round holes going thru from the bottom to the deck a long time ago in my analog days… i had forgotten about it all. but now with my increased computer skills and moulding experiance, you have certainly inspired me to dabble some more. cheers
Hi Dave, its interesting that so many people have had a crack at this type of thing?
We made about a dozen of these tubes in a month and then worked out that we were going the wrong way, we were focussing on the exhaust dims and getting as much water as possible OUT the board.
But we shouldve thought more about resisting the water as it went thru the board.
So the whole shape was reversed...
Now its all about getting as much water IN to the hull port with the wider end of the port at the front.
(The front of the board is at the top)
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E001.jpg[/IMG]
And internally, the new walls didnt lean towards the outside rail but the opposite. So that as the water came in, and was pushed away/ or redirected.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E002.jpg[/IMG]
Now the units were toed in like standard fins and the rail side internal walls had cant similar to a standard fin.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003.jpg[/IMG]
They really were Internal fins now, complete with toe and cant, but inside the board rather than hanging out.
And they worked a lot better too. From the pics on the last page you can see the old designs worked, we'd worked out how the get a lot of volume of water in,
thru,
and out of a board.
SO we had achieved progress with the design in its first shape but we'd missed getting the resistance that a fin applies to the water / wave.
And with the redesign it was now getting the resistance.
More pics to come....
So as a bit of an explanation, I'd like to show what our theories are and how that shaped the design.
The plan was to make a hole thru a board and replicate the effects that fins have on a surfboard.
So the first thing is a hole in the underside of the board.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003lines-1.jpg[/IMG]
Because we wanted to replicate the feel of a side fin we made one side of the hole the 'active' side (red line), it has a straight edge similar in length to the base of a standard fin.
The other side (dotted) is the side of the hole or port where the water comes into the port to interact with the active edge.
Designing a replacement for a side fin instead of a centre fin made more sense because with a tube designed to replace a single fin, you can only have a single fin arrangement but with a side fin you can make twins and quads. So we chose to work on making an Internal version of a side fin.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003activeedge.jpg[/IMG]
The active side is the red line and it sits towards the rail, with the induction area of the port towards the centre of the board.We wanted the hull port to have zero drag when the water flow was going parallel to the stringer so we angled the port towards the middle. Toe-in.
With water running from nose to tail theres no grab / drag / bite with the active edge.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003generalflow.jpg[/IMG]
But when the flow comes from the curved side of the port (running under the board and towards the 'inside ' rail) it has enough angle to meet and interact with the straight edge which is positioned on the rail side of the board.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003activeedgeflow.jpg[/IMG]
The port shape is designed with the biggest part at the front. This allows a high volume of water to come in to the front of the port from various angles.
Theres also a port /hole in the deck to allow water to exit.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003deck.jpg[/IMG]
The deck port is designed larger at the back because we believe that shape allows more water to exit because the angle of the exhaust flow is directed back towards the tail. ( oops I nearly said fins)
In between the hole in the hull and the hole on the deck are angled and curved walls. initially we tried to get the greatest volume of water in and out, but now we have better results by deflecting the flow that comes in thru the hull port. Less quantity, more quality.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003cant.jpg[/IMG]
The two red lines show that the wall on the active side is tilted towards the centre of the board rather than out so it has an angle of 'cant' similar to a standard fin. This gives the water some constant resistance and makes the board feel like it has fins.
So taking the next pic as the inside rail vent on a left hand wave...
The water contacts the board at an angle from the right, rising up the wave across the board and towards the tail and inside rail. ( or some may see that the board is sliding down the wave)
The hull port allows the angled and rising water into the port towards the red line of the active edge,
the active edge and wall resist the flow
and direct it up and out towards the deck port.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010E003reflect.jpg[/IMG]
The board has lateral resistance and it feels a lot like a finned board. I might have the theory wrong but its working well enough so far with plenty of scope to improve.
There are some things we're not showing at the moment.
Fascinating mate, I’m very interested but a bit bemused at such an alien idea!
Is there any chance that you can post a picture showing the whole tail of the board and the placement of the internal fins?
Very keen to see some video as well 
I’d like to congratulate you on what could very well be the most innovative and interesting thread of the year for me. Internal fins… brilliant.
[quote="$1"]
Is there any chance that you can post a picture showing the whole tail of the board and the placement of the internal fins?
Very keen to see some video as well :)
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I dont think I want to show a full pic because some recent changes we are keeping private for a while, but it will all come out at the end. But theres some more research and install pics coming up.
Placement is exactly where the fin marks are under glass-on fins and weve routed out FCS plugs and put the internals in at the same location. The toe-in measurements were there for us to follow. We decided that the placement should be where fins traditionally go and then designed the system to suit that location.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/June2010D013install.jpg[/IMG]
Im not being selfish about revealing progress, you'll understand that we dont want to give it all away after we've spent months working on it every day and into most nights. Might get some video over the next few months of Summer.
I was hoping someone else would chime in and say they were doing something similar...?
Heres a few more pics...
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A040P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A034P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A031P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A027P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A022P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A012P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A008P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A007P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A049P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A047PR.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A045P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A025P.jpg[/IMG]
Hi Cptn, that exactly what is does,
straight line = no drag,
Turn and it bites.
These first two are in trim.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A040P.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A031P.jpg[/IMG]
And this is during a turn.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/July2010A049P.jpg[/IMG]
Or when you trim on a wall and the wave is steep, it hold there too.
I think the greater the angle of attack actually helps them to hold, being right out on the rail helps too. At the extreme end of angles, I dont know yet but for average cutback/ reo surfing theyre fine.
Ive got an old longboard to put one of our latest versions into and see how well they work on cruisier boards.
I think the quad version would stick like shit to a blanket.
This is a great project. The photos really help explain what you’re trying to accomplish. Hope this starts something.
Amazing!
Imagine a high volume planing hull like a mini-simmons or the like, and using internal fins to further reduce drag! My eyes are watering just thinking about how fast it may go…
Dang Surffoils, we’ah dyin’ out he’ah! Get us some action wave riding vid clips when you can. This is cool stuff…
I can’t wait to see people being able to engage and possibly disengage the ports. You could do 360’s and then keep right on riding.
wow, incredible demo. derek hynd going finless-- no induction ports yet, right?
Im still working on the internal / vent fins.
This was the best version with 'as good as' zero drag in a straight line and quick bite in a turn.
2 layers of glass, pretty flimsy, weigh nothing, but they dont need any strength after theyre installed.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/MayJune2010016.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/MayJune2010014.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/MayJune2010013.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/MayJune2010012.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/MayJune2010011.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/SURFFOILS%202010/MayJune2010009.jpg[/IMG]
I just realised that these pics really dont help at all because youre looking at the outside, I forgot to take some pics of them installed in the test board but I'll dig the board out and post some tomorrow.
Has anyone else had a go at making something similar?
I’m going to have a go at it in about two weeks; wife is out of town:). I’m going nuts just thinking about it. Do you sand the inside at all after taking it out of the mold? Before or after install? When creating the actual port on the mold, do you use any sort of lubricant or anti-sticking agent on the epoxy before applying the poly? Also, do you pop the port off while it’s tacky, gelled, fully hard? Thanks, I can’t wait to ride these.