I have clients who have ordered stringerless boards (short boards) but a few have snapped off the noses of those boards. The rate is far more egregious for the stringerless boards versus boards with wood stringers. I used carbon fiber x 2 inch full length strips, typically two, where a stringer would normally be. I put them on the bottom for some boards and the deck of others and one on top and one on the bottom on other boards. Still, nose snapping off seems to not follow any pattern; nose snapping has been an equal opportunity destructor.
The glassing schedules have been what I consider normal for recreational surfers: 6,6/4 or 4,6/4.
Any hints for the more experienced builders, aside from using a stringer, that might help this situation?
Carbon Fiber the rail all the way around. A glue line is stronger than stringerless foam. Vector Net top and bottom. Vector Net @ the bottom. Or combine Vector Net and Carbon Fiber with a glue line.
I’ve given up on stringerless after snapping every one I made - a half dozen at least (some more than once) including perimiter stringers and carbon, veneered and compsands. 12oz min on rails but usually 16oz or more. Edit: All were epoxy/EPS.
As a comparison, my stringered boards (typically 6mm redwood ply) with 12oz cloth over the rails have taken equal or more punishment and thrived.
I love the idea of stringerless. Just can’t seem to get it to work for me.
it’s a question of overall bending stiffness. vertical stiff stringer increase drastically overall stiffness. with stringer less, for same effect you need to increase a lot skin stiffness with benefits of local buckling strength increase and denting strength increase, which is good for deck durability. Or you can increase locally flexible skin with stiffeners but a strip of carbon is not suffisant, need T or Omega stiffeners. Increase rails strength can be a good way on many aspect but because of deck dome not really effective against deck buckling where stiffener need to be at top of dome. I made big guns that experiments really big conditions for some years in stringerless eps epoxy with no problems : omega stiffeners top and bottom + strong skins (20oz total multiaxial glass epoxy foam), boards need to be heavy.
It seems as though the stringer is quite a nifty design.
If it was the other way around, if we had been building boards for 50 years with all sorts of extra cloths and processes only to get marginal results and some dude came along and slapped an 1/8 wood stringer in the board and said “hey guys you can now shape and glass your boards in a day, and only use 3 pieces of glass and your good” we’d all think he’s a genius, the fact he did it over 50 years ago some how makes him out dated.
What about rail channels on the deck? Drew Bagget does those on his carbon/cork boards and Hickman did them on his boards (as well as others). Do they work? Do they help minimize snapping?
For sure stringer is really effective way to build surfboards. It help customing rocker when build blank, stiffen it when shaping reduce distortion when polyester resin take, then increase overall stiffness and so strengh. That’s way it’s use.
For eps époxy boards, because of properties of materials you can go in other way that don’t need stringer. It’s a différent build that give différent boards, some like others don’t.
As a mechanical teacher i learn, and like it, studdents how to calculate and build systems. I like do the same with my hobby, building surfboards.
Deck channel like all corrugation increase bending stiffness of skin so improve buckling strengh. Look at Vulcan surfboards they patented it.
Funny that you mention this. I have a Varial blank (stringerless) in the shop that I got off a guy who was selling off his board shop last year. You got me excited. I’ll have to give this a shot. Thanks.