Page 1 of 3

DIY dropstitch Inflatable foil boards? We can do this!

Posted: Wed Jan 06, 2021 7:32 am
by fluidity
Hi all,
Most of us on here are likely quite familiar with composite lamination processes using fibreglass, kevlar, basalt, innegra carbon fibre etc. Those are great for planing hull applications.

For foiling though, the board is only in the water to start. Most of us are familiar with the traditional inflatable SUP shapes, no hard chines, rails to split off the flow of water at the back and sides. It's easy enough to glue extruded, 3D printed etc strips onto those regions of an inflatable SUP though to get a similar performance. I'm very used to making a lot of what I use in the water. I'm daunted by the idea of making kites, hand wings and sails, there are a lot of stitches that should be done with industrial sewing machines.

I don't believe this is the case for inflatable SUPS. I think we are about to see a revolution in DIY design of these because the manufacturers are not fast enough or inovative enough in bringing out the features that we want. A couple of manufacturer's have some half-baked fitted rail extrusions but nothing yet to give similar performance close to hard boards.
So I have been searching for drop stitch fabrics but having diffuculty with finding low minimum order quantities per square meter. I'm sure that there are manufacturers prepared to sell small rolls but the smallest quantity I could find on alibaba was 500 sq M. :o

We don't want knitted fabrics! Too stretchy! Kevlar- thick polyester, great. Extra thick rip-stop, great.

I've attached a pic of my F-One. I learned to foil on it and when I finally got around to checking the pressure on it, it had dropped from 18psi to 12psi over about 5 months. Still foilable but a little bit wobbly.
Yo can see my 3D printed Coanda disruptors on it in blue, I printed them in TPU filament and glued them on with flexible superglue. Two at the back of the sides, several underneath at the back and some to the sides underneath as well, these last ones let water peel off side ways when I dig the back of the board down instead of letting the water run higher around curved sides.
My F-one has unfilled internal foil mounting box void space that is hard to drain water out of. There is maybe a couple degrees max flex of the mast from my foot position at proper board pressure, it's insignificant and just adds slightly to the flex I feel pumping my 1200mm wingspan diy glass fibre coated plywood core foil.

I reckon we can do better! :) Who can find a good source for small quantities of suitable dropstitch fabric, say 5 to 20 meter lengths, ideally around 150mm pumped height?
Like this: http://www.henshaw.co.uk/products/388-d ... -hen003097 or this: https://www.alibaba.com/showroom/drop-s ... ric_1.html or https://www.trelleborg.com/en/engineere ... s/about-us

Graham

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Wed Jan 06, 2021 9:14 am
by nixmatters
Try Haytex, they might have some leftover short runs
https://heytex.com/en/portfolio-item/te ... l-heytrax/

Your other option for starters is a cheap or even FOC warranty SUP. Plenty of such due to failed glued seams.

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Thu Jan 07, 2021 10:08 am
by fluidity
nixmatters wrote:
Wed Jan 06, 2021 9:14 am
Try Haytex, they might have some leftover short runs
https://heytex.com/en/portfolio-item/te ... l-heytrax/

Your other option for starters is a cheap or even FOC warranty SUP. Plenty of such due to failed glued seams.
I was considering your second suggestion, or buy and old SUP and trim off the front, re-glue.

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Thu Mar 25, 2021 7:42 pm
by RTL78901
fluidity, I like you idea of making rail attachments with a 3-d printer. I modified an Isup (for use with my Iwings) by adding an Air-7 finbox and some rails made from a material I found at Home Depot. I used 3m 5200 Marine Adhesive to attach them. I could stay upwind quite easily, with just the center fin, but I think the rails to help with upwind and speed.

Does it take a very expensive 3-d printer to make the attachments you printed for your f-one?

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Thu Mar 25, 2021 8:48 pm
by nixmatters
RTL78901 wrote:
Thu Mar 25, 2021 7:42 pm
fluidity, I like you idea of making rail attachments with a 3-d printer. I modified an Isup (for use with my Iwings) by adding an Air-7 finbox and some rails made from a material I found at Home Depot. I used 3m 5200 Marine Adhesive to attach them. I could stay upwind quite easily, with just the center fin, but I think the rails to help with upwind and speed.

Does it take a very expensive 3-d printer to make the attachments you printed for your f-one?
Cool! What fin size do you use in the new finbox? And what's the longest one you've come across?

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Fri Mar 26, 2021 12:04 am
by RTL78901
Thanks. It doesn't need very long fins to keep upwind. The one I normally used is only 23 cm. I've used some some a little smaller. I don't recall the largest, but probably 34 CM. Here is a video of my 10 ft Isup with the fin box before I put the rails on it.


Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Fri Mar 26, 2021 6:22 am
by fluidity
RTL78901 wrote:
Thu Mar 25, 2021 7:42 pm
Does it take a very expensive 3-d printer to make the attachments you printed for your f-one?
Answer is no. I used TPU filament and most 3D printers will work so long as the path from the filament drive wheel is within a couple mm maximum of the feed hole for the filament otherwise it will bend and bunch up.

My design is here if you want to find someone to print them for you:
https://pinshape.com/items/103319-3d-pr ... laning-kit

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Sat Jun 19, 2021 7:34 pm
by RTL78901
@fluidity, I found a service that printed the file for me. I'm finding the layout seems a bit different from the pictures in this and the other thread so I am wondering about the layout. The pcitures below show two options that have occurred to me: One one side I would just trim the small wedge to a v shape to create a smooth shape. On the other side I trim the longer slanted shape so it matches smoothly with the rectangular wedge. My board is the larger size if that mattes.

Also there are 4 of the curved wedges, while the pictures posted show only 2. Are these just spares?

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Sun Jun 20, 2021 9:48 am
by fluidity
RTL78901 wrote:
Sat Jun 19, 2021 7:34 pm
Also there are 4 of the curved wedges, while the pictures posted show only 2. Are these just spares?
The curved wedges are for the sides. I only needed one each side but depending on the outline at the back you could have a gain from a second set further back. I tried to account for different stern board shapes with the little joiners and angled pieces but you can also chop them at an angle to flow them around the tail.
I also found there was quite a big gain from the ones at the bottom/side, as you pick us speed with more weight at the back of the board they help water to split cleanly off the board from the tendency of water to want to eescape to the side.

Re: DIY dropstitch Inflatable foil boards? We can do this!

Posted: Tue Jun 29, 2021 2:08 pm
by RTL78901
Here is a video showing the effect of adding the disruptors. Does show release is cleaner and occurs at a lower speed than w/o the disruptors.