im aware that stringers do not provide the majority of a surfboard’s strength. why not let it provide more strength by using different materials, different types of metals or plastics? anything with strength, even carbon fiber which is very light. ya know?
anything stronger than wood just will delam off the foam
metal and carbon stringers would create shaping problems unless added to the blank after shaping.
Then that would require the stringer insertion process be perfect.
seems problematic at best.
would seem like better cores would make more sence than working on better stringers.
This may blasphemy, but cores need not be shaped with a planer or even a sander.
I’m sure there are folks out there that are working with cores other than foam and wood.
I’ve thought about hollow frame core similar to Paul Jensen’s hollows, but out of other materials,
such as prepreg carbon panels. Much lighter than 1/8" ply and stronger and stiffer. Might be
tough to get a good bond to such a thin frame when laminating the deck and bottom panel though.
This is similar in concept to Paul’s thoughts on a carbon re-enforced cardboard frame, buts removes
the need for the cardboard as well. Also thought about honeycomb cores. But I don’t know where to
get 3-4" deep honeycomb cells in suitable sizes for longboards (at reasonable cost). This is how
trick skis (water skis) are made. Also how slalom water skis used to be made. Some wake boards
are honeycomb core laminates.
S-core seems to be along the right track, but does not enable custom shaping, at least not to the
same extent as the clark catalog.
just my $0.02
–4est
good answers, good answers
If you preshaped your stringer to its final size, and had it glued up in eps before cutting the rocker, it could actually be helpfull in shaping the board, as a guide for the hotwire built into the board, between the stringer and a nice set of rocker templates on the outside, you could get an almost perfect rocker cut. This would get rid of having to shave the stringer. Still the metal stringer probably wouldn’t bond well, either to the foam or glass, but this would work for thicker carbon stringers, or anything else you wouldn’t neccesarrily want to plane. Not sure if a stronger center stringer is what you really want though, the logic behind perimeter stringers sounds good to me. Metal stringers would definately be cool as far as looks go, put in three platinum stringers and you’d have the most expensive blank ever made, but there would be a lot of bonding issues.
Fly shapes in NJ makes EPS blanks with Carbon fiber
The stiffness of the stringer cannot be substantially greater than the stiffness of the glass, or else the board will delam easily and break.
The stringer is there to provide I-beam support for the glass on either side of it. The stringer/glass stiffness is a cubic function of the stringer thickness, and the strength is a square function of the thickness.
For example, a board with a stringer 2.25" thick will be 80% as strong as a board with a 2.5" stringer, and 73% as stiff.
If you take it to a 2" stringer (compared to 2.5), the stiffness is halved, and the strength is 65% of the thicker board.
Using the composite I-beam model, if you want to double the strength, you can increase stringer thickness by 40% (ie: 2.5" to 3.5"), or double the stringer width.
The arguments for perimeter stringers are that the load is highest on the rail, the rail fails before the center fails, and you should put the strongest design element where the load is highest to maximize efficiency. You still need to consider the thickness when you do this, and its relation to flex and strength.