building a SUP how do you strengthen it for kiteboarding?

[edt]

Can I drill holes thru the blank and let epoxy go thru to fix the top and bottom deck together? maybe double layers of glass, or corecork? kiting is a lot harder on a SUP than paddling or surfing, I know I will slam it.

[zfennell]

you may be right.
but unless you figure a way to jump with it, i doubt the damage will be that severe.

SUPS are thick, with padding?
and not much bending.

assuming you do damage it, i would wait to find out what the specifics are.
then make repairs

....something like a section of sheet foam to beef up the skin.
the eva pad can be tailored to dress up the repair.

just a thought

[plummet]

Hmmm..

Ok my ideas.

For a start use epoxy resin and not polyester.
you could simply add extra layers. I'm assuming it has a wood stringer like a surfboard. Adding an extra couple of these would help.

Carbon at the foot placements to prevent denting.

Check out bro kite kiteboard construction videos. it would be pretty easy to band saw your blank into 1/4's and laminate several "I Beams" into the core.

[not annonymous]

If you want strong but still reasonably lightweight, then you need sandwich construction.

Corecork might work great but I have no experience with it. Balsa wood, corecell, and divinycell are also great choices for sandwich cores.

With a sandwich build you can use the lightest possible eps foam for the core. there is no point having a stringer.

Trent

[edt]

tks for the tip not, I'll try making it a sandwhich, didn't realize it added so much strength that's just what I was looking for.

[mattthieu]

sandwich and reverse drop stitch !

what ?

chech out inflatable sups, then think reverse :

you want the deck and bottom to stay at equal distance, but, pressure is not comming from inside but outside.

so drill holes between top and bottom, but, for more then one third of inch, only resin inside wont work.

so, take fibers of glass, or better, carbon fibers and put them thought the holes. glue them on top and bottom, only, you can do that one hole at the time or easyer stich them throug mutiple holes in a continus pass, just stick them to botto and top, dont put resin in the holes.

then, once you do your vacuum laminate, IF you do it bottom first, the resin is going to flow throug the holes and you'l end up heaving carbon fiber mini rods betwin top and bottom.

this way, you can use lighter foam and have an enormus strenght between top and bottom sheets.

[FrederikS]

tks for the tip not, I'll try making it a sandwhich, didn't realize it added so much strength that's just what I was looking for.

That is incredibly bad advice. A sandwich structure does not add any strength, it adds bending stiffness!

In fact what you are looking for is impact resistance, toughness and strength. The easiest way to accomplish this is to add more layers of carbon or glass fiber (assuming equal strength layups where you have to add ~1.5x the weight with glass). Fracture toughness and fracture energy is roughly the same for both well made CFRP and GFRP.

Furthermore you could add EVA pads where you stand as this soft medium will help disperse some of the impact energy.

Since the a SUP is used in very low winds I would just add four layers of 150ish gsm glass fiber and epoxy to the deck stand area and then let that taper down toward the front and back of the board where you do not stand.

You could also buy pre-fabricated GFRP plates if the stand area on the SUP is completely flat.

[edt]

Since the a SUP is used in very low winds

I am using my SUP as a boat to move my kite gear across the lake, should be reaching speeds of 20+ mph in big waves, anticipate quite a few heavy crashes in these conditions. The only time I will paddle is if the wind dies or line snaps and I have to get back to the launch.

[FrederikS]

Since the a SUP is used in very low winds

I am using my SUP as a boat to move my kite gear across the lake, should be reaching speeds of 20+ mph in big waves, anticipate quite a few heavy crashes in these conditions. The only time I will paddle is if the wind dies or line snaps and I have to get back to the launch.

Then it is probably best to give it a thin layer of glass fiber all the way around and then double up where you stand.

[BWD]

Stitch through idea or many stringers might be too heavy and stiff for sup I think. I would just do a sandwich deck of 2-3mm high density foam (corecell or d-cell etc) or thin okume plywood, veneer etc.

Frederiks idea is correct in a way but only partly.
Its right mainly IF he means having a sandwich deck AND sandwich bottom. But many board builders have known for many years a sandwich deck helps against impact and heel dents.
By making the laminate thicker it is stiffer and resists impact. The recipe is different to maximize stiffness and light weight.
For example:
stiff and light = eps core, 2 oz glass, core cell, then 4-6oz glass on top. This sandwich can wrap the rails and deck
Impact resistant = eps core, 4-6 oz glass, THIN corecell or ply or veneer ( or even just a thick hot coat), then 6-8 oz glass on top.
Or you can just add a few glass layers on deck!