> So, I am a fairly new surfer and I have been watching this group fo a
> month or so now. I am getting confused with all these fin sizes and
> shapes. It took me a while to figure out board size, sail size,
> getting in the straps etc. Now I have to worry about my fin being the
> correct size and shape. Can somebody break it down in basic
> terminology the diffs between size of fins in relationship to the
> performance of my surfing. Oh and by the way, why the heck is a small
> piece of plastic so expensive.
A very useful article on fins was written by Greg Fenton in Windsport #
62, 1993 and as I think is still very relevent today. Essentially it
The greater the area (not neccessarily length) of the fin, the greater
is the lift produced. Higher aspect fins (blades) usually produce
somewhat less low-end lift but better top speed and control. Older,
heavier boards and beginners often gain from having a wider base,
lower-aspect fin to help planing.
By surveying many sailors, using a wide variety of equipment and
collecting data on the size (area) of fin that they used with different
sizes of sails, a consistent "magic number" was found. For sail sizes
from 4.5 to 6.0, the number is 41 and for sails 6.5 to 7.5 the number is
45. So by multiplying the sail size by this number you will get a close
approximation to the optimum fin size in square centimeters for allround
use. For example 6.5m sail - 6.5 x 45 = 292.5 sq cm. so a suitable fin
would be say a 14.5 inch, True Ames Series II of area 290.3.
What about the weight of the sailor? That factor is eliminated because
heavier sailors will usually be on a larger sail for a given wind
Other tips included:
For those who have trouble planing in marginal winds add 1 to the number
and for most of us it is better to have a fin a little too big than one
too small. Its a good starting point - not the final word!
My only advice is don't waste your money on very expensive fins until
you are ready for them.