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Fins come in four
materials
(from top to bottom)
l
pre-preg carbon/
fibreglass
composite
l
carbon
l
G10
l
plastic composite
Fin calculator
My CarveIQ 114 freemove board comes with a single freeride
38cm fin yet the fin that comes with a board will only go so
far in balancing the power from a range of sail sizes. I run
four fins on this board: K4 Fang freeride 34, 36, 38 and
40cm. This board has a massive range of use but only if you
match the fins to the sails you use.
As a rule of thumb for single fins, take your sail size and
multiply it by five then add 4cm (for boards above 110 litres)
or add two (for boards below 110 litres). Then tune up or
down as follows:
• Increase fin length by 1-4cm for lower ability or heavier
sailors or when marginally powered or underpowered or
to help with planing upwind.
• Reduce fin length by 1-4cm for higher ability or lighter
sailors or when solidly powered or overpowered
• Increase fin length by up to 10cm for pottering about in
non-planing conditions to help to stay upwind.
So, as a 76kg sailor, the sails I use on the 114 and their
corresponding fin sizes are:
• 5.3 Blade = 5.3 x 5 = 26.5 + 4 = 30.5 (I use 34cm*)
• 6.0 Gator = 6.0 x 5 = 30 + 4 = 34 (I use 34cm or 36cm)
• 7.0 Turbo or NCX = 7.0 x 5 = 35 + 4 = 39 (I use 38cm)
• 8.1 Turbo = 8.1 x 5 = 40.5 + 4 = 44.5 (I use 40cm)
*This works perfectly for well-powered coaching yet, when
sailing for myself, I would usually be sailing my Kode Freewave
103 when it’s windy enough for a 5.3. I cannot really get away
with shorter than a 34cm fin on the CarveIQ as it is 76cm
wide so I am happy to sail with the extra lift from the fin. When
I use the 5.3 on the 103 and use a single fin then I would use
a 28 or 30. For better carving (and higher winds) on the 103
then I would swap to a thruster setup with a 22 and two 12s
or a 20 and two 11’s. Don’t worry that a 20 plus two 11’s
equals a total length of 42cm. The area of the fin is more
important than length. One fin is more effective than three
fins. One fin has less drag. The advantage of a thruster setup
is manoeuvrability and not performance,
Further up the scale of board sizes the CarveIQ 141 comes
with a 46cm fin and can take a 9.5 sail. Now imagine that, on
Plastic progression: (from left to right) Hifly older-style
intermediate, Drake Shallow beginner (two lengths),
K4 freeride/freewave single/freestyle
a day when some people are out at your local spot planing on
100-110 litre boards on 5.0m sails, you also want to go out
and play yet you have not progressed beyond a 141 litre board
yet. So you take the 141 out with a 5.0m sail (below the
minimum recommended sail size of 6.5 but it’s what you need
to support your progression at this time) and the stock 46cm
fin. Do the calculation: 5.0 x 5 = 25 + 4 = 29cm required.
Yes, that is too small for a 141 but the 46cm fin is going to
make your board feel like a ride on a wild horse. So a step
down fin is needed to enable you to stay in control. So a 36-
40cm fin, whilst not fitting perfectly into the standard equation
should help to bring your board back under control.
Fin materials
There are a number of different materials that fins are made
of. Considerations when choosing the fin material include
price, durability, stiffness/flex and weight.
G10 fins
G10 is fine-weave fibreglass matting with epoxy resin, laid up
and pressed under weight to produce a dense, durable
laminate. CNC (computer numerically control) machines
shape the blanks into one-piece fins. G10 has high impact
resistance, is one of the most common materials used in fins
yet is relatively heavy.
uk
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SURFING