Carbon Rails: something like a stringer needed?

[AndiHL]

Hey guys,

for my next project (9'6 xps SUP) I want to try a 160 g/mē (5oz) twill carbon rail.
Now I'm in doubt if I need something to make the board stronger. And how.
My Idea is to use a unidrectional carbon tape (160 g/mē (5oz)) on the bottom.
Will that improve strengh without getting too stiff?

Glassing is planned 2*160 g/mē and 1* 160 g/mē on bottom.

Best regards,
Andi

[AndiHL]

Talked to some guxs and it seems that an UD glass tape will be the better choice for a (fake) stringer.
But now i have a new question: I can get 220 gr UD glass tape, 100mm or 60mm wide. Whta setup will be best? 100mm just on bottom or are 60mm enough? Or 60mm on top & bottom? Or Or 100 mm on top & bottom?
Still whant to go with carbon rails...

[supuk]

from my own personnel experience and doing this on your own the time and effort it takes to get the carbon and cut it into strips and then wrap the rails nicely you may as well just do a full carbon bottom. the problems i found was first cutting the carbon in to strips with out it falling to pieces or distorting and that was still using masking tape and the second was trying to get it on to the rails without falling off and lined up nice and then getting it nice and tight. If i was to  try doing just the rails again i would make sure i had a second pair of hands and all so vacuum bag it after.

[Biggreen]

I have a buddy who uses XPS to build his surfboards with no stringer and no extra reinforcement without any problems...I personally don't know.

As for carbon on the rails.  I've purchased some 1/2oz fiberglass, taken some spray glue and given the carbon fiber a light dusting, then rolled the 1/2 oz glass over the carbon and pressed it down.  You can then cut the carbon without it all going to hell...but you still need to tape off your lines. If you don't vacuum bag, you can use Saran (food wrap) and pull it tight over the carbon once you've placed it, tape it down along the edges and wait for your resin to set. The resin doesn't stick to the wrap.  Works pretty slick.  Like Charlie said, an extra pair of hands would be nice.