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questions about building a custom board

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Joined: 08 Aug 2008
Posts: 73

PostPosted: Sun Mar 28, 2021 12:54 am    Post subject: questions about building a custom board Reply with quote

I have plans to build a light weight custom freestyle board
a few questions :

Divinycell, I am buying from fiberglassupply in WA, they told me most board builders have the 4x8 sheets cut up on 3 pieces in order to save on shipping. You would then "glue " the pieces together to fit your projects. Thoughts on how this would possible compromise the structural integrity ?

Glassing: Vaccum bag after glassing for better bond or just squeegee out excess resin without vacuum ( I've seen it done both ways )

paint: Any disadvantage to mix a dye or colored powder into your top fairing resin ( versus using paint that ads weight and chips )

mast track and foot strap inserts: cassettes made of high density polyurethane foam or multiple layers of glass ? (

any other suggestions to keep my project light weight. Goal is under 13.5 ibs for a 92l board. Anything over 14.0 ibs and I won't sail it.
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Joined: 25 Jun 2007
Posts: 798
Location: Corpus Christi

PostPosted: Sun Mar 28, 2021 3:59 pm    Post subject: Reply with quote

So far, you probably won't get to your desired weight. I'm going to make a few suggestions.....take them or leave them is up to you. Styrofoam comes in different densities. You should use the 1 lb. density. There are a number of high density urethane foam cores available, for a freestyle board corecell is a best choice due to it's "toughness" by a big margin. Having joints between pieces of corecell or any other core material is not a problem and will substantially reduce the shipping cost of the high density foam. For the layer of reinforcement between the styrofoam and the high density, since weight is critical, I would use 2 to 3 ounce carbon, with two layers in the standing/walking/footstrap area. Resin is going to be one of the components which will contribute lots of weight. You will want to set up a 8' long banquet table to work on when wetting out the carbon cloth. When mixing the resin add microballoons until the resin has the consistency of somewhat thick syrup. This will reduce the weight of resin per square foot. Cover the table with a layer of heavy visqueen. Place you precut pieces of carbon cloth on the table, wet them out keeping the cloth wet with the least amount of resin possible, then lift the pieces of carbon off the visqueen and place them on the prepared styrofoam core. A lot of resin will be left behind on the visqueen. This will really help keep the board light. Cover the wet carbon cloth on the board with the corecell, Cover with a bleeder ply then an absorption ply then inside the vacuum bag and then pull a vacuum until resin sets. On the outside, I would use 5 oz carbon against the corecell and apply a layer of 2 to 3 oz carbon or S-glass on top the carbon. Again, use the banquet table/visqueen when wetting out the carbon/s-glass. S-glass should have a tight weave and should minimize pinholes. When mixing the resin for the outside reinforcement, add come color tint to match your outside of board final paint color. This will reduce the amount of paint it will take to cover the outside of the board. When it comes to the mast track and the finbox, when making the styrofoam core, cut the styrofoam out where the corecell boxed mast track will go to a distance 1" farther than the boxed mast track perimeter. remove that styrofoam and pour 2 lb. density expanding urethane foam in it's place. This expanding foam has about twice the compressive strength of the styrofoam and can take the abuse a freestyle board gets and especially a freestyle board's mast track. I will assume you know how to apply the exterior carbon/s-glass. Do some research on the Board Lady and follow her guidance in boxing mast tracks, fin boxes, and footstrap inserts. Before you paint, flock the outside....mix up some epoxy with lots of microballoons and squeegee that on to the board, filling pinholes and other imperfections. Let dry then very carefully sand. When it comes to paint, I suggest using Awlgrip polyester based urethane paint and get some urethane paint tints to get the color finish you seek. You can get tints from US Composites. This paint can be applied with a foam roller then tipped with a brush to achieve very attractive durable non yellowing finishes. Follow with color sanding and machine polish using Mequires Ultimate polish. I will assume you have the non-skid down. Good Luck.
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Joined: 10 Apr 2006
Posts: 2517
Location: Killer Sturgeon Cove

PostPosted: Sun Mar 28, 2021 4:37 pm    Post subject: Reply with quote

Well, that definitely covers it from a high level. This has to be a labor of
love, right? I mean, it's a joy for you, and something you want to
spend your time doing. If it's something else, you'd do well to buy a board
with the specs you want (or have one made). Getting a 93 lt board to 14lbs
(or less) is a trick not easily accomplished on your 1st (or second) board.

I also say, Good luck.

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Joined: 08 Aug 2008
Posts: 73

PostPosted: Mon Mar 29, 2021 12:00 am    Post subject: Reply with quote

Thombiz, thanks for your in depth explanation and expertise
It follows pretty closely what Iíve watched in various videos. Exception would be carbonart YouTube channel where they only use one top layer of carbon.
For epoxy tinting Iíve seen two different methods: dye or colored powder ( mica powder ) Any suggestion what might work better ?
There are also at least 5 different methods of applying non skid, any preferred way youíd suggest
Thx again
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Joined: 25 Jun 2007
Posts: 798
Location: Corpus Christi

PostPosted: Mon Mar 29, 2021 9:02 am    Post subject: Reply with quote

I've found that a second layer of fabric which is tightly woven is important to reduce the number of pinholes and to give some toughness to the outer skin, which s-glass provides. Carbon is strong and light, but s-glass is tough while carbon can be brittle. The s-glass is to protect the carbon fiber cloth. I have only used the tints from US Composites and they come in small glass jars and have the consistency of slighly runny peanut butter. They work very well with epoxies as well as polyester based urethane paints (Awlgrip). As for non-skid, I use the acrylic dust from Fiberglass Hawaii fine texture matches OEM non-skid while medium is a little more aggressive. I use medium and lightly sand it if it is too harsh. For Non-skid, I mask off the area to receive non-skid, I lightly sand to a matt appearance. This gives the nonskid paint something to attach to. I do not put non-skid on the nose of the board....only where a foot might be placed. Non-skid on the nose will damage the sail. Once masked and sanded, I use the same Awlgrip to make non-skid (Fiberglass Hawaii does sell a clear non-yellowing epoxy which works well). I use one of those small foam rollers West System Epoxy makes to roll one light layer of Awlgrip on the area to receive non-skid, then I immediately roll on a second coat at about medium layer. then I immediately sprinkle on the non-skid dust using a salt shaker. Hold the shaker about 12" above the deck and try to sprinkle to produce a very smooth even spread of the non-skid dust. The shiny paint will take on a matt finish as the dust lands in the paint and bonds to it. Try to make the dust have a nice smooth even finish. Once the dusting is done, immediately remove the masking and set the board aside to cure.
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Joined: 06 Nov 2008
Posts: 499
Location: Cedar Falls, IA

PostPosted: Sun Apr 25, 2021 4:45 pm    Post subject: Reply with quote

Thombiz; you are a windsurfing treasure.

Surfalex: I wish you luck. I hope you will feel good enough about your work you will sail any board you make no matter how much it weighs.\

Weight is only one design parameter. There might be other design changes that fit your usual conditions so well you could build a board that is heavier than standard that would still be a better than standard board for your conditions.

Or a really lightweight 92 liter board might fit your conditions less than one third of the time. Maybe you would get more pleausre from, be able to use more often, and be more likely to be successful at creating a really lightweight 140 liter board or whatever size fits a significant portion of the other two thirds of your conditions. (I know nothing about your conditions, I'm just hoping you will pick a board to build you will use.) Decades ago in the open class there were partisans who believed the best course racing board was a Mistral Equipe, others said Fanatic MegaCat, others said F2 Lightning. I would guess materials science has progressed enough you could make a copy of my '93 MegaCat that is lighter than its 28lbs, though its 380cm length poses additional challenges.
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Joined: 03 Jul 2009
Posts: 5194
Location: East Bay

PostPosted: Sun Apr 25, 2021 7:38 pm    Post subject: Reply with quote

Hand spackle with squeegee after lam and again after sanding.
Exact mix can vary from oily to barely pourable.
13 lbs. 92 liters is possible, but not for your 1st board.
K glass soaks least epoxy.
Avoid carbon except under heels.
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Joined: 18 Oct 2009
Posts: 348

PostPosted: Sun Jun 06, 2021 7:58 am    Post subject: Reply with quote

I would start with a clark foam blank before you get too fancy with hi tech materials. Jp
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