Rail Structure and Impact Resistance

[Beasho]

My ultralight board has shown its first signs of wear on the rails.

Specifically the Port (Left side) rail.  I was surprised it was ONLY one rail until I realized that was the side I normally crawl on the board.

The board is XPS foam, which means it has a compressive strength significantly higher than EPS foam.  Example 15 psi vs 4 psi. 

Structurally it should be more sound, but I found cracking of a rail that was a combined 6 oz Carbon and 4 oz S-Glass.  Granted my rails were very sharp.  Probably less than 1/4" radius, or half inch diameter (problem #1).

My standard SUP EPS boards have not worn on the rails like this board.   

So is it

1) Simply how hard the rail was?  Make it a 1/2" radius (1" diameter), or 1" radius (2" diameter) curve.

2) Bolster the rails?  I don't think carbon works well on the rounded rails.  I could use 1X 4 oz S-Glass and then a 2" Kevlar strip. 

Other suggestions?

Note:  Because this board is XPS I don't care about dings or water intrusion.  I can also just modify the rail after the fact, use a router and just re-route a larger radius rail, and then re-laminate.  The photo shows cracked rails, sanded down, then modified with 2" Fiberglass strip covered with 1" of Kevlar fabric Gorilla glued on to rail.

[sflinux]

Here is the current build schedule.

I assume you are running the carbon fiber linearly.  For the deck, are you running the S-glass on the bias?  That is what Stretch does for his boards:

Rounding the deck will give you the strength of a round carbon fiber tuber versus a square tube which should definitely help.
I like how Nathan Fletcher has thumb rail indentations on his boards, which adds to their strength.

[Beasho]

. .  are running the carbon fiber linearly.  For the deck, are you running the S-glass on the bias?  That is what Stretch does for his boards:

Stretch definitely knows his stuff.

I am running ALL carbon on the deck, but this makes me realize that running a few layers at different BIAS would add strength per his recommendations.  I had 2 layers on TOP deck, but in parallel. 

I am getting dents but I have discovered that they are exclusively KNEE dents. Knees MUCH harder than feet.  Feet, toes and heels, are soft and squishy.  Knees are probably 1" of area with 100 lbs + each side, or more if your knee is only covering ~ the size of a Quarter.  Putting multiple carbon KNEE patches on the BIAS may help this.