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first foil build advice

Posted: Sat Jul 08, 2017 7:07 am
by ragzilla
My enthusiasm and knowledge on foiling is non-existent.
Just figured id give myself a little hobby over the winter, and can make something half decent and bring it along for all the local crew to have a flop around on.

ive made a few boards, mostly twinny's and a wakeskate, so ive a little shaping & glassing experience. Im no expert, but im patient & meticulous and enjoy giving it a crack.

my plan is to make a small directional.... 150cm should be enough.
nothing too fancy. but something i can take the foil & straps off and whip around on.
Probably do the glued plank , shape, and cut. Not a huge fan of the plywood decks.
No rails- but a nice concave or channel. (again.... trying to make it useable without a foil.

preff, id like to build something with a shortish mast. Something around the middle size of the slingshot flight school range.
I think a very short mast will get boring quickly, but something too long will make it annoyingly difficult.... remembering it will be a home made build without an R&D team. Our local spots are generally big surf beaches or shallow lagoons, so i think a short mast is the way to go too.
The whole idea of building and having a foil will be to use it as a communal board for everybody so that we can laugh and throw beer bottles at them while they screw around. We need to make this thing invincible.... or close to it. ........ I'd be expecting (and looking forward to) some super high speed crashed into the sand bars.
its gunna be great!

Question time.......
Ive read plenty of build articles stating that i need to use carbon or al for the mast to stop any flex.
If i build a shorter mast, do you think i can get away with using good quality fibreglass?

Bigger wings = more stability , right ?? (im gunna make them bad boys so fricken tiny)

what do i need to know about the angle of the fuselage?
I can only guess that it changes the lift?
For the sake of build simplicity..... can i just make it at 90degrees to the board, or does it need the angle to create the lift?
I dunno..... explain it to me like im an idiot please.

can somebody explain the difference between having the foil placed too far forward / back ?
whats the difference?
whats better for learning?

Building will start this week.
more to follow.

Re: first foil build advice

Posted: Sat Jul 08, 2017 9:46 am
by plummet
I can probably provide some direction as I did exactly what you are considering last winter. Tootled away in the garage and made myself a foil.

To answer your questions.

Fuse 90 mast and parallel with board.
Front wing at 0 and rear wind start at -3 deg aoa relative to front wing.

Make the rear stabaliser adjustable! This is very important. The difference between a stable easy to ride foil and a twitchy unridable monster can be only a couple of degress of rear stab aoa.

DO NOT make a short mast if you plan to only have one mast. Go at a minimum of 90cm.
Short masts are only uselfull for a month or so. It is perfectly possible to learn on a normal mast height.
It just takes a little longer.

Choose a mid aspect design. I modelled my wings off a moses Fluente.

If you are making a board, Search hydrofoil boards and make one with chines and reasonable nose rocker. Not too much volume.

Re: first foil build advice

Posted: Sat Jul 08, 2017 10:03 am
by TomW
I started making a 70cm mast last winter after struggling with 91cm mast in 3 sessions before winter break. Then, mid winter went on holiday in Mexico and in 2x2 hrs private lessons learned to get up on the 91cm mast.
The 70cm mast is 80% done, but it's been a lot of work and super dirty if you use carbon. My entire shop got covered in fine black dust.
I still have a bit of grinding to do and then a final layer of glass or carbon, but im dreading doing it...I think you need a small dust room to do any grinding.
I built the mast with a homemade Uni directional plywood Core, shaped it then v-Bagged on carbon.

Knowing what I know now, I'd get a used foil set up. Then build a board for it. That's easier way to save some money and have maker fun. Learn to ride the thing. Then you'll have more understanding when you build your out foil setup. You could just make some wings for that fuse and mast too.

Plummet did the whole thing, very impressive, but I got a feeling he's in the 98th percentile...

Re: first foil build advice

Posted: Sat Jul 08, 2017 12:20 pm
by downunder
I'm quite the opposite, no dust anywhere, doing only water sanding. for the mast, it wasn't that much work either, maybe wood profiling about 2-3hrs. Front wing, maybe 3 hrs.

But the process to get there, hmmm. I was struggling with a first mast carbon wrap, and binned the complete carbon. Than made this simple jig (sorry if repeating):

The main problem for me is precision drilling. I have no fixed drill or something so to get everything square is, well, difficult for me.

This is what I mean:
Mast should be perfectly aligned with a fuselage, and I can see my mast is not. This is more because the mast screws were not done perfectly. So, you need a jig for the screws as well. Which adds up to the build time. I also needed a jig for the wing screws, but ignored this and guess what? not 100% aligned again.

I would go with a fixed mast/plate/fuselage next time but this problem still remains. If you built a mast/plate connection first, you won't be able to see if the mast is aligned properly.

And, as I see the LF mast (this is the plate), is way smaller than Manta on which I based my profile:
At least, I can use this plate as an example for my build. Im also surprised how heavy this plate is (inc. a rubber): 579 grams
Manta mast is 1821 gram

My carbon mast and a fuselage now is 978g. The target is way less than 1.8kg for a foil. Plus board.

So to answer, no FG anywhere. Only carbon and a wood core for mast. Carbon 22mm tube for a fuselage, reinforced with heaps of carbon. All of that to have it light coz I do not want to be axed with a 2kg mast.

And knowing myself, will jump with it on a first occasion :) I also think a wing size is very subjective, there is no way to find the perfect size if not trying heaps wing sizes, which again depends on conditions.

I recon your short mast idea is not bad but very limited usage.

Re: first foil build advice

Posted: Sat Jul 08, 2017 9:32 pm
by plummet
Tom and downunder all have valid and usefull info.

Yes the Mast to fuse to plat to mounting bolt angles are all critical!
Mine are not perfect!. Close but points of degrees out here and there.
I went for fixed, fuse, mast plate. Mainly for strength. I located and laid that up in several goes.
At the time I only had a level. And set that angles with a standard builders level. To be honest, A builders level is not good enough.

Later on I discovered this video an digit level gauge. Dammit I wish I had that tool from the start.

If I could have afforded it at the time I would have purchased a second hand foil and learnt first then built my own after knowing how to foil and what I didn't like.

The biggest challenged with building before you know how to foil is not know what is good and bad and even not knowing what style of foil you would enjoy most.
My biggest regret Is not making the mast longer. Its 90cm and in my lumpy choppy ocean that makes it real difficult not to vent a wing. I would have been better off with a 100cm past.

Re: first foil build advice

Posted: Mon Jul 10, 2017 6:45 am
by mopman365
plummet wrote:
Sat Jul 08, 2017 9:32 pm
My biggest regret Is not making the mast longer. Its 90cm and in my lumpy choppy ocean that makes it real difficult not to vent a wing. I would have been better off with a 100cm past.
And I just cut my 100cm mast down to 65cm hoping to learn quicker. :duh:

Re: first foil build advice

Posted: Mon Jul 10, 2017 6:54 am
by downunder
I see my buddies not really making any progress on a short(er) mast. One should have more time to react on a longer mast. So up to now I still did not see the evidence for short mast, just the opposite, a guy with longer mast progressed a bit quicker.
Duno, never tried so only a theory.

Re: first foil build advice

Posted: Mon Jul 10, 2017 4:28 pm
by gmb13
A short learning mast is not longer than 50cm. 60 is too long for the very first rides.

You will have the same issues with the 60cm mast as with 90.

If you want to start from scratch start with a 40.

Re: first foil build advice

Posted: Mon Jul 10, 2017 4:36 pm
by socommk23
Can be and has been done with just fibreglass. But carbon may offer the better strength to weight. Just not cost. Based mine on clearwaterhydrofoil design. Built the board from a flexi foil pirate chopped up n glasses with inserts for foil mount. Cheap and it works. Just need more time on it.
I'd advise go for a 90cm mast unless your fine with making more than one.
0 degrees for front wing, can be flat bottomed and no need for anhedral or dihedral. -3 degrees for rear.make it adjustable if possible as mentioned before by others. Mine is not adjustable. But it works just fine luckily.

Re: first foil build advice

Posted: Mon Jul 10, 2017 7:25 pm
by Benicia Wind
My first homemade foil uses a 24" birch mast and fuselage. Only a small bit of carbon fiber on the fuselage to reduce twisting flex between mast and wing. The wing is 1/2" plywood approx 7"x17" shaped and coated with resin to make water proof. This is attached to an old Cabinha double agent twin-tip/surfboard. It is very slow. But it is also lots of fun. I ride it all the time even though I have a faster foil. It has a really low stall speed and it turns quickly. I tried to learn on a full length mast but just couldn't get it. I was up first try on the short mast.