Author Topic: Ultralight Board Designs  (Read 18922 times)

Dwight (DW)

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Re: Ultralight Board Designs
« Reply #15 on: January 10, 2023, 03:48:42 PM »

BTW- Is anybody using Innegra?  I love it! It's a very light weight fiber with exceptional strength for ding resistance. 1, 4 oz layer of Innegra cloth covered by 1, 4 oz layer of glass is far more ding resistant than 1 layer of carbon cloth.


Yes, everything I build is the same as yours.

jondrums

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Re: Ultralight Board Designs
« Reply #16 on: January 10, 2023, 04:34:50 PM »
I no longer finish my boards with hot coats. I use Peter's slurry method. They still get sealed. They are light as hell. They don't delam. Sanding isn't a pain. Try it guys.

What's the ratio of epoxy to micro-balloons?  Or perhaps you could just describe the consistency of the resulting mixture - more like honey, creamy peanut butter, or spackling compound?

surfcowboy

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Re: Ultralight Board Designs
« Reply #17 on: January 10, 2023, 08:39:57 PM »
I go peanut butter now. Not runny. I do squeegee one fill coat on first and then sand it all off/flat.

Squeegee the microballoons and then sand with 220 or even 320 between applications. When I think I've got the pinholes all full I do one more application and then I spray it with primer which shows any last pinholes. Fill em and go, or paint.

If you don't wanna primer it you can rub some resin on it with a gloved hand. When Peter says lean he means lean.

By the second application there's almost no material going on. I can do the whole board with like an ounce of material.

I'm digging my results.

JohnnyTsunami

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Re: Ultralight Board Designs
« Reply #18 on: January 10, 2023, 10:16:05 PM »
When I made my last board (4í1Ē prone) I was thinking of ways to do closed cell foam skins. Iíve done Dcell on 1lb eps but the trouble is how much epoxy it needs to stick, even as a thickened mix. I was thinking gorilla glue would be good except that I canít really spread it thin evenly on the board quickly, itís pretty viscous especially for 1lb eps. Pour foam or pour epoxy was my answer and I started a thread on it.

Well after talking to a few crissy guys they just go 1lb eps and do 4 layers of carbon on the deck and one on the nose and wrap rails. Seems like itís less durable but you will have no problems with dings or delams or boxes coming out of you do it well and avoid hard objects. If anyone can show me how to make it lighter Iím all ears but they are putting out sub 8lb 75L boards including the pads. I think even a 100l 7í3Ē DW sup under 10 lbs. Iíve done deck sandwiches, standing area sandwich and full board sandwich. Next is just carbon on eps and a patchy white finish job using textreme.

SUPeter

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Re: Ultralight Board Designs
« Reply #19 on: January 11, 2023, 04:21:48 AM »
I've made several boards using XPS and have only ever found delamination issues when using paint over the foam. Thats not to say I am not suspicious of the bond between skin and foam.  All the talk of "outgassing" and "oils" from production keeps me somewhat cautious.  I have always coated the foam surface with epoxy and micro balloons.  Seems to work as far as I can tell, though I would appreciate a lighter weight filler. Maybe just spreading a fine layer of Gorilla Glue over a finely water misted surface (let harden and sand afterwards). Epoxy resin bonds well to PU foam and PU foam bonds well to anything.

On another note, I've got this massive sheet of green, high density XPS (unsure of exact density) from a recent project. I'm going to enlist the help of a 3D CAD modeler friend to help me loft the ribs of a DW board so that I can cut them out, lay them down on a foam stringer, and skin with high density XPS 3/4" sheets, just like the hollow wood board builders do (using Gorilla Glue to bond), only thicker than wood skin.  Of course, the box area will be almost solid as well as foot strap insert areas.  My theory is if going with far less foam, make sure its dense and strong.  Eliminates the need for 1/8" Divinicell and maybe even carbon cloth.  This should be a fun project.

Just noticed a question regarding consistency of Micro balloon paste- I like it like All-Natural Peanut butter, it flows if you tip the container, somewhat runny. I also make sure the board is good and warm (for a long time) when squeegeeing it on, and the bring the board out in the cold. This way the resin gets sucked into the pinholes.
« Last Edit: January 11, 2023, 04:39:02 AM by SUPeter »

jondrums

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Re: Ultralight Board Designs
« Reply #20 on: January 11, 2023, 12:59:22 PM »
Next is just carbon on eps and a patchy white finish job using textreme.

What's textreme?

JohnnyTsunami

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Re: Ultralight Board Designs
« Reply #21 on: January 11, 2023, 10:58:37 PM »
A brand name for spread tow carbon. The same weight and strength fabric will be ~20% lighter or so using that instead of other weaves because the epoxy doesnít have to fill as many kinks in the carbon weave.

tarquin

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Re: Ultralight Board Designs
« Reply #22 on: January 12, 2023, 03:59:54 AM »
SUPeter, maybe you have looked but people have built kayaks and SUPs like this before. If you google foam strip kayak there are a few build threads.
 As far as the forms you can do it on Shape3D if you have it or know someone with the paid version. There is a hollow board function. Mine expired sorry.
 I used a free program called kayak foundry a long time ago. Pretty basic but allowed you to print out forms on A4 paper and glue them onto ply or whatever.
 Or maybe your computer skills are better than mine(not difficult) and you have it under control.

SUPeter

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Re: Ultralight Board Designs
« Reply #23 on: January 12, 2023, 09:37:02 AM »
SUPeter, maybe you have looked but people have built kayaks and SUPs like this before. If you google foam strip kayak there are a few build threads.
 As far as the forms you can do it on Shape3D if you have it or know someone with the paid version. There is a hollow board function. Mine expired sorry.
 I used a free program called kayak foundry a long time ago. Pretty basic but allowed you to print out forms on A4 paper and glue them onto ply or whatever.
 Or maybe your computer skills are better than mine(not difficult) and you have it under control.

Thanks Tarqiuin, I have seen this function back when I was thinking of building a hollow wood board.  This "foam skin" design has a few idiosyncrasies which need accepting but I don't think it'll be any more difficult than similar builds. 

tarquin

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Re: Ultralight Board Designs
« Reply #24 on: January 12, 2023, 01:09:19 PM »
Well after mentioning kayak foundry I thought I would have a look and see if it still exists! Yes it does. Tried to download one of my old files and it opens up Navionics on my phone and says file to large to import?
 I remember the problem with kayak foundry was .yak files and nothing would recognise it. Oh nightmares coming back!

Beasho

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Re: Ultralight Board Designs
« Reply #25 on: January 14, 2023, 08:57:23 AM »
The 'Dowels' method looks like this

I got a new board but knew that it had EPS foam ONLY between the tracks and the top deck so I added wooden dowels to transfer the load from Deck-to-Deck.

SUPeter did a similar thing with Carbon Rods. I would have preferred carbon but did not have an affordable source.

The idea is to create a table structure.  2 layers of 6 ounce Carbon over the tracks, then dowels through the board, then 2 more layers of 6 ounce carbon on the deck.  What results is a structure that carries the load from the bottom of your back foot directly to the Mast Plate.  The tracks at this point are just keeping the foil from falling off the board, but are not necessarily carrying the load.

I used 1/4" dowels on the outside of the tracks.  Then 1/2" dowels in the center biased towards the front of the tracks because TRACKS ALWAYS FAIL UP FRONT from the compressive load created by the front wing cantilevered forward.  I measured the distance from the tail using the template shown and drilled from the BOTTOM and from the TOP.  Then had to meet in the middle.  I cut the dowels ~ 1" too long.  Fortunately the dowels loaded with Gorilla glue filled any internal voids and locked tightly into the BOTTOM and TOP decks. 
« Last Edit: January 14, 2023, 09:49:56 AM by Beasho »

Beasho

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Re: Ultralight Board Designs
« Reply #26 on: January 14, 2023, 09:06:56 AM »
Top Deck:

There was a Single track on the top deck: In theory to attach straps.   You can see the dowels that were routed flush with the deck.  Then capped with 2 layers of 6 ounce carbon fiber.  I then routed out the track.

Note:  When I lay up the carbon fiber I do it on a separate sheet of plastic.  Boeing makes aircraft grade Carbon : 70% Carbon Fiber to 30% Epoxy resin.  I target 60% Carbon Fiber to 40% resin.  I then weigh the Carbon, say 30 grams, and calculate the ideal ratio of resin (60:40 means 20 grams of resin so I'll mix 25 grams.
 
When you lay it on plastic, and weigh the ingredients, there is NO dripping of resin.  What this means is that I don't need to fill my tracks.  I can apply vacuum, let dry and route out the tracks without any infringement of Epoxy into the tracks.
« Last Edit: January 14, 2023, 09:09:16 AM by Beasho »

JonathanC

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Re: Ultralight Board Designs
« Reply #27 on: January 14, 2023, 12:03:38 PM »
Fantastic explanation Beasho, thanks for taking the time

Fishman

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Re: Ultralight Board Designs
« Reply #28 on: January 14, 2023, 03:58:14 PM »
Nice track reinforcement idea. I wonder if 3/4" Home Depot PVC board could work instead of a track for the top deck.

I have a board that can use this modification/ repair.
« Last Edit: January 14, 2023, 04:00:18 PM by Fishman »
SupSurfMachine 9'9" longboard
SupSurfMachine  8'2" funboard

sflinux

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Re: Ultralight Board Designs
« Reply #29 on: January 15, 2023, 12:42:08 AM »
The Dowel method looks killer, thanks for sharing.

PVC is heavy (density = 1.4 g/cc).  I would use Paulonia wood instead (density = 0.26 g/cc and does not absorb water. [for reference xps has a density of 0.04 g/cc]

Ryan Burch rode a finless unglassed chunk of foam with a specific aspect ratio, which he called the Lord Board.

The board was fast, but fragile.  Glassing the deck should keep it from snapping.  I wonder if flexseal could be used on the rails.  I repaired a catchsurf softboard with gorilla glue foam, then sprayed several layers of flexseal to give a pretty decent waterproof seal.
https://www.youtube.com/watch?v=K63S4KFk9Tw
I wonder how much cardboard surfboards weigh:
https://www.youtube.com/watch?v=BrIidL34rfw
« Last Edit: January 15, 2023, 12:56:19 AM by sflinux »
Quiver Shaped by: Joe Blair, Blane Chambers, Jimmy Lewis, Kirk McGinty, and Bob Pearson.
Me: 200#, 6'2"

 


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