Timber flex build questions

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llilibel03's picture
Joined: 04/21/2005

Hi.  For the past....10+ years now I've pretty much settled on Greg Leohr's t-flex buld schedule- Stringerless 1.5lb EPS blank, veneer/4oz on the bottom, 4oz/veneer/4oz on the deck. It produces a fairly light, extremely durable board.

This time around I could not find EPS (didn't want Marko) so went with US Blanks polyurethane blank (with basswood strringer).  I've got the a layer of 4oz on the deck, as well as the two veneers bagged on. It  already weighs in at just under 5lbs weight. I'm guessing that's at least a pound more than when I use EPS. Now I'm worried I'm going to have a heavy board.

So questions-

How much weight will 2 more layers of 4 oz and hot coats weigh?  Board is 6-3 x 20-1/4.

or, and this is the big question-

Anybody ever make a t-flex, veneer type board, with no outer glass?

The bottom with just the veneer feels pretty strong. The deck has 4oz (with extra 4oz s-glass patches at the knee and butt - back and front foot) and veneer and feels really solid.  I was thinking to just hotcoat the whole thing (use slow hardener and really let the resin staurate the veneers) and see how it goes. Weak spot are the rails , with just one layer of 4oz.

Anybody do anything similar?  Thoughts?

photo - veneers bagged on, you can see the deck patches telegraphing through the veneer.  These bups were usually taken out by the extra glass on top. Will not be visible once the veneer is  hotcoated.

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McDing's picture
Joined: 05/22/2004

The original veneered boards made by Surftech had no glass over the veneer,  They were spray finished with a Polyurethane clear coat.  They have always held up fairly well.  The few times though that I did ding repair on Surftechs, I used 4oz. to cover the ding..  

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That which can be assorted without evidence was read in an illegal magazine.

lemat's picture
Joined: 04/17/2010

As I said in your other post, no wood on bottom with stringered pu... Now you will have an heavy, stiff, but durable board... If you protect well your wood. Most starboard wood boards and others wood from Cobra (surf, sup, windsurf) have no or light (2oz) fiber on wood (pin or bamboo), they often suffer of water drink of wood. I do many with often same problem, even with saturatef epoxy and 4oz glass over and under. On last I saturate with specific for wood water epoxy, 4oz glass and double hotcoat, no water problem even when dinged. 

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llilibel03's picture
Joined: 04/21/2005

Thanks for the replies. I appreciate it. I'm going ahead with the hotcoated veneer on the bottom.  I did a small test panel comparing just veneer and just 4oz and the veneer was way stronger. Also, I thought, you don't really get dents on the bottom. The wood I chose, walnut, has almost no logitudinal strength.  It was splitting along the grain very easily.  But it was very strong along the grain.  I might have the first board to snap lengthwise!  

I'm not worried about water intrusion. I did a sealer coat yesterday with slow epoxy (about 50ml / 2 oz) so I'm sure the wood is water proof. Now I'll do the actual sanding coat.

I chose wood partially for aesthetics. Having the wood on the deck only (where it gets smothered with wax) has no aesthetic value.

As far as stiffness, I've never been attuned to that.  I have very stiff boards that work great and flexy ones that were dogs. I prefer to get my perfomance from rocker, plan shape, foil, bottom contours and fins- things I have more control over.

So this is an experiment. I hope to try another int hte near future with a proper stringerless 1.5 lb EPS....

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lemat's picture
Joined: 04/17/2010

I am like you most of time I like more my stiffer/harder boards. Even more in winter with boots, they when they feel softer LOL.

At same weight wood epoxy is lower in density than glass epoxy so it's stiffer at flex test, stronger at buckling and impact but it's a Ud so....

I am always scared about water intrusion. See so much wood boards with water problems even if pawlonia. On other hand I work on wood boats with not so much problems so. 

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llilibel03's picture
Joined: 04/21/2005

What is a UD?

I've been making tmber board now for 15 years. Never had a problem. If you get a ding, session over. 

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stoneburner's picture
Joined: 12/30/2007

llilibel03 wrote:

What is a UD? 

I think UD = uni-directional.

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llilibel03's picture
Joined: 04/21/2005

Makes sense because of the grain.  I've never had a timber veneer board fail.  I did have a balsa compsand fail, interestingly right where the vent plug was (1lb EPS).

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gdaddy's picture
Joined: 10/31/2008

I don't think any of the current crop of regulars here has more experience with veneers than you.   

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stoneburner's picture
Joined: 12/30/2007

I think Lemat is saying wood veneer has very good compressive strength (grain running nose to tail).

So, if you want max strength using wood veneer with PU foam, to minimize weight, all you really need is a deck-side veneer.

If wood aesthetics are critical, wax on the deck-veneer will diminish your objective.

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lemat's picture
Joined: 04/17/2010

Yes UD is unidirectional. I make about 50 and repair many of those "Chinese" bamboo and others from "big name". Try all tech from compsand balsa to timberflex veneer. Most water intake problems came from inside, water go is way from fins plugs or other "invisible" holes to the wood. To avoid this i seal my best foam and do a first lam then in second time I bag wood with a good amount of resin, then finish saturated it over before last lam.

Wood is a natural composit with UD cellulose hollow fibers that give a high buckling/weight ratio with nice flexural impact strengh thanks to a good elongation to break. With specific epoxy, high fluidity and match elongation to break, can make good structure stressed by impact flexural strain. Note so good, strengh by weight, for tensil stress. 

Nowadays I work with cork and/or wood in all my projects, not for green washing but because at right use it's best weight/strengh/cost ratio. 

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llilibel03's picture
Joined: 04/21/2005

Thanks for the information Lemat.

I'm trying to understand how the veneer can take on water if it's 1/40 of an inch thick (<1mm) and is coated top and bottom with epoxy ( I used slow cure to try and let it saturate more completely). I have had issues with water intrusion around fins plugs, but not on a timber board.

I put a strip of 2.3 oz glass over the stringer on the deck because that is where the leaves of the bookmatched veneer are. I was worried about that cracking.  THe 2.3 oz is really fine but it came out kind of bumpy. I'm wither going to have to put a heavy hot coat on, or sand intto the weave alot.

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lemat's picture
Joined: 04/17/2010

Wood fiber is hollow, epoxy don't go in otherwise it weight a lot. So if fiber is open, water go in. Need special care for a real watertight layers in and out. Near all used starboard wood i see, 0,6mm pine with thin to no glass over, have wood water intrusion.

Slow cure  is for sure a good idea with wood.

I like your shape, really clean. 

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