tombloke,
It seems that your agrument is that longboards cannot use rider energy in order to accelerate because they have hull shapes which are not suitable for the purpose. . . . . . if so your theory has more to do with shape than length.
Longboard riders can use kinetic and torque, or as you describe it, “rider energy” to accelerate, however talented shortboard riders can generate rider energy more efficiently.
High performance modern shortboards like the board ridden by the young surfer in the story of my earlier post are stripped down to the bare bones; all excess foam is redundant leaving a hull that reflects the basic elements of ALL efficient modern surfboards, I’ll come back to that later.
All surfers utilize kinetic energy by emphasis of energy transfer to the front or back foot.
In the case of the young surfer in my story the bottom was a typical concave, deepest just at the leading edge of the front fins and if viewed sliced at that point flat across the bottom then cupped close to the rail.
The plan shape was typical with the widest point just aft of center allowing the entry rocker to set into the wave face as he drove off the front foot. The exit rocker accelerated off the tail balancing a wide squash to take advantage of the back foot energy transfer.
The basic elements….
Plan shape -Stringer rocker – Rail rocker - Entry rocker – Exit rocker
As noted above the plan shape is widest center or just aft creating a pivot point at the same spot the front foot sits, the entry curve also comes to this same point or just aft.
The plan shape pulls in just forward of the front fin cluster the same point the toes of the rear foot sits. The concave being deepest here effects the rail rocker causing it to be more accelerated in the exit on the rail (at the leading edge of the fins) than the stringer creating another pivot point at the back foot (in conjunction with the plan shape )
Note; the surfer does not have to move his feet enabling him to being more responsive to the energy transfer between front and back foot and therefore more efficient tapping into the rider energy.
The trick is to start by balancing the entry curve with the exit curve for the style of the surfer waves they want to ride.
Doesn’t matter short or long, vee or concave wide tail, narrow the elements start with the rocker, the entry curve – exit curve
TomBloke,
OK then forget it just go for it surfboard design makes no difference at all I didn’t realise that now but I have seen the light thanks very much for helping me to realise what a waste of time it is thinking about tail area most surfboard builders don’t so they must be right next time I will nail a rubbish bin lid to my tail as penance for having thought about it too much in the past or better still take the whole tail away completely no point in being logical hey?
Tom, welcome to the stunned mullet club
According to “the Dinkum Dictionary” A ripper guide to Aussie English,
Like a stunned mullet:… bewildered; surprised; astonished.
Nik
The more I learn, the less I realize I know!