Olo! Jingo! Gloria In Excelsis Deo! The video "LeviO

[gulfsurfer]

Theres no hope....

[babyboarder89]

thankyou! that made a lot of sense actually, the bit i didnt understand is if you cut it in half the rocker is only 2cm, so im, drawing a model (17 'feet' long, with 18" of rocker at each end) on a piece of paper and cutting it in half ...... ok im back, it worked, the rocker at each end of the two 8.5 'foot' sections was 6",
is rocker measured like a 10" rocker is a board which is raised 10" at both the nose and the tail, or is it 10" of rocker in total?

[Roy Stewart]

When we are talking about 10 inches of rocker in a seventeen footer, we mean that each end is raised 10 inches.
The conventional way to describe rocker is to quote a nose rocker and a tail rocker (and these are often quite different). This method can be misleading because it doesn't tell you what the overall rocker in a board is. Also, if there are differing nose and tail measurements, then it shows that the nose and tail have not been established as the sections of the board which are fore and aft (respectively) of the rocker apex.
Defining the nose and tail of the board as those sections fore and aft of the rocker apex is the system we use to measure rocker for Power Surfboards, and it gives a single overall rocker measurement for the board.
To find the rocker apex on a board, take a line from the nose to the tail of the board . . .the rocker apex is the point on the bottom which is furthest away from the line.
Using a single rocker measurement, and defining the nose and tail of the board as the sections in front of and behind the rocker apex, we are then able to adjust the relative proportion of the rate of curvature in the nose and tail simply by moving the rocker apex fore and aft.

It is easier to see with a straight edge and a ruler than it is to explain!

Thanks for your interest

Roy

[babyboarder89]

thankyou for your help.

[gulfsurfer]

Heres some more advice for your shaping babyboarder. DO NOT, i repeat DO NOT do anything Roy tells you.

[k mac]

i gotta disagree with you there whatever you may think roy is a very clever skilled craftsman of a bygone sub sector of a very skilled trade and he knows what hes talking about, yes he may come across as a bit of a twat sometimes but atleast listen to him when hes talking about boarddesign offering some help .

[Roy Stewart]

About the rocker apex. . . it is (In my opinion) a very good idea to keep the rocker apex in the same fore and aft position as the planshape curve apex. This ensures a predictable and smooth rail to rail transition and a useful sweetspot.

Regarding tail rockers. . . we prefer to use circular arc tail rockers, for much the same reason that most fins are foiled using circular arcs through the trailing section. Circular arc tail rockers are fast and smooth to ride.

Another interesting aspect of rocker design is flexibility. . . a flexible board which is able to change its rocker has a great advantage . .particularly if the energy which is stored when the board bends is able to be efficiently transfered into drive. This can be done using horizontal fin area ( fin systems which utilise horizontal fin area include bonzers, Starfins, some quads and fish setups, 'turbo' tunnels, tunnel fins, butterfly or V fins, and even thrusters.) Any board which has horizontal fin area will benefit from having some flexibility through the board.

[gulfsurfer]

i gotta disagree with you there whatever you may think roy is a very clever skilled craftsman of a bygone sub sector of a very skilled trade and he knows what hes talking about, yes he may come across as a bit of a twat sometimes but atleast listen to him when hes talking about boarddesign offering some help .

I know, i just like to give roy a hard time.
There'd be no way i'd ever have the patience to shape a board.

[Roy Stewart]

Regarding the fin, there are no big secrets, it is just a big wide based cutaway fin with an efficient upright planshape. The fin is 14 inches deep. A common mistake with wide based fins is to make them proportionally too thin. This fin is 21mm thick . .which gives it approximately the same proportion in cross section (although slightly thicker proportionally in the base) as a typical narrow Greenough fin.

Singlefins benefit greatly from plenty of rail curve (rail convergence) in the fin area . . this helps to generate lift through turns by presenting the fin at a positive angle of lift.





There's more if you want it.