Rail Rods

General Discussion
1

Hi all

I am building a 6’2" x 21.5 x 3" quad fin biscuit and have read a fair bit about rail grooves and rail rods.

My previous 2 boards (6ft pin tail and 5’7" fish) both creased on the base. Both were building depot EPS/Epoxy with central stringers. The 6ft pintail had a kevlar/glass ‘I’ beam central stringer running all the way through the blank, but  it broke at the rail. Construction was: Deck-  6oz, then 4oz cloth, then 0.6mm Walnut/Beech veneer, then 4oz over veneer.

Base was 6oz then 4oz, no veneer.

In fairness both creased when using them for kitesurfing  when crashing out through some pretty heavy waves and landing heavily. Both are now repaired.

I intend to use the Biscuit mainly for normal surfing, but may occasionally want to use it with a kite.

So, I have used building depot EPS, no central stringer, but have routed,Deck and base, a semi-circular groove about 1/8" deep, 1.5" in from the rail, all around the outline, also 2 grooves further in board.

Into these grooves I have epoxied carbon fibre tows until flush with the surface. All carbon is joined so there should be no stress points.

Carbon deck patches, 6oz cloth onto deck and base, tack glue 4oz cloth onto back of 0.6mm veneer, then vacuum veneer skins (deck and base) onto board. Finally 4oz cloth over veneer.

Does this sound about right/any comments?

Biscuit

 

 

 

2

Hey garyb…

Have you considerd using core-cell rails as your stringer/ strengthener, based on where you said the boards failed…?

I use 5/8" A550 Core-Cell rails on my kite -surfboards… I also skin the eps with 3mm 1/8"  A 400 to  A500 corecell skins…

Do you jump these boards when kiting?? If so you 'll unfortunately have to beef them up a little more…

The carbon tow will stiffen things up ok, and should help the board last, but the reinforcement is localized to  one thin strip…

Hard foam deck skins or the veneer with the 4oz. glass on the underside spread the  load impact of smashing out through the waves better…

Core cell skinned bottoms will not crease like your boards did…  Sandwich boards are stronger , but stiffer , and slightly heavier… I’m working on these  last 2 items by trying different materials,resins and lay-up’s…

I use carbon patches for my foot areas, but I pre-fab them.  Don’t let the carbon patches have any straight edges, like shown in your photo… You can also eliminate the strands of carbon coming off the patches if you pre-feb them first…

I use a large  hour glass ,( figure 8, peanut )  shaped template for my carbon patches, no straight edges for the board to brake along…  I wet out a large enough piece of carbon on a sheet of tempered glass then sandwich it with another piece of glass… Then I pile on weights, as many as will fit, like a home made press… Make sure you place something non-stick on the press halves !

After the carbon has cured enough to handle, I trace the figure 8 pattern onto the patch with the template and cut out the shape… I lay the patches on the board where I want them and trace their shape onto the foam… I usually rout or sand down inside this area the thickness of the patch, but this is my  anal  attention to detail, and is not necessary  ,lol…  .It just stops any bumps under the finished glass showing…