9.25″, 30.6″ sq. fin Longboards & SUP, the WG2, now in clear



  • Total area: 30.6 sq. inches
  • Rake/sweepback: 15 degrees
  • Height/depth: 9 inches
  • Stiffness: Semi-flex or stiff
  • Colors: Glossy black, orange, blue, or matte black
  • Fits Fins Unlimited and Bahne fin boxes
SKU: FSI-05-1 Categories: , Tags: ,


WG2 fin for longboards and SUP

The WG2 fin for longboards and SUP is our latest fin, designed for excellent turning and speed. Our fins with winglets produce a lot of hold and drive (lift–see article), so we can make them smaller than the average fin–by 20 to 30 percent.  Basically we take a “regular” fin, chop off about 30 percent of its area, then add back in about 5 percent in the form of winglets–just like what airplane designers do with airplane wings these days.  The result is a fin that produces the same amount of hold and drive (aka lift–see post) as other fins, but with a smaller surface area.

Because our fins are smaller–they have less surface area–they have less drag.  And less drag means quicker acceleration, easier paddling, and longer sessions. These fins  don’t stall like a typical fin–because of the foil section we chose.

Less drag, more fun! Faster fin, better acceleration, better turning, longer sessions! That’s what these fins are about!

Like our Wavegrinder Classic fin, the new WG2 fin is just over 30 square inches.  We moved the winglets to the end of the fin to increase overall performance.  We decreased the size of the winglets a bit to decrease drag even more.  And we added a bit more sweepback, or rake, to help shed kelp, while still maintaining a very high aspect ratio and low taper ratio–in other words, it provides excellent hold, good drive, accelerates quickly, and paddles easily.

  • Ever miss that perfect wave by half a stroke?  If your fin had less drag,  you’d have caught it!
  • Ever lose a wave to somebody who paddled in just a bit faster than you?  If you’d been able to accelerate faster, it would have been your wave!
  • Ever feel like conditions are great, but you’ve been out so long your arms have turned into limp spaghetti noodles?  With less drag, you would have lasted longer and caught more waves!
  • Ever make a sharp cutback, or even a sharp right or left when trying to catch a wave, only to stall out and lose it?  A better turning fin that doesn’t stall so easily would help.
  • Ever wish you could ride the small waves in marginal conditions?  Less drag makes it easier to catch them!
  • Ever wish you could go faster to get to part of a wave that looks a little better?  A faster fin would make it happen!

Winglets have been used on aircraft for quite awhile now, people are used to seeing them on the end of airplane wings. But winglets also are used on submarines, on some rotor blades, on the ends of race car spoilers or air dams, and on boat keels. Winglets, or a version of them, were conceived decades ago, but not put into use until after Richard Whitcomb of NASA and Boeing studied their ability to reduce fuel costs by decreasing induced drag. Whitcomb found that [highlight]winglets reduce induced drag by about 20 percent, while improving the lift-to-drag ratio by about 6 percent, findings that Boeing confirmed.[/highlight]

[toggle title_open=”More about winglets, how they help fin efficiency, and why we use them on surfboard fins and SUP fins” title_closed=”More about winglets, how they help fin efficiency, and why we use them on surfboard fins and SUP fins” hide=”yes” border=”yes” style=”default” excerpt_length=”0″ read_more_text=”Read More” read_less_text=”Read Less” include_excerpt_html=”no”]

Check out this article about Richard Whitcomb, NASA, and Boeing’s research on winglets–or try doing some of your own research on the topic–we don’t make this stuff up.

The purpose of winglets on a surfboard fin is to inhibit the migration of water from the high-pressure to the low-pressure side of the fin, as when turning or exerting side pressure, in order to increase the efficiency of the fin overall. If you’re a paddler–whether you’re into SUP, kayaks, or canoes–you’ve seen the top of a vortex in two dimensions at the water surface with each stroke of your paddle. Water sneaks around the paddle’s edges, moving from the high-pressure to the low-pressure side. The same water movement from one side to the other occurs with surfboard fins when you put pressure on one side or the other. As the fin and board move through the water, the swirl elongates into a vortex, evidence of the water movement from the high- to the low-pressure side of the fin.

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In fin design we could make up for inefficiency by adding surface area. Many fins are designed this way–they’re big. In other words, if the fin doesn’t produce lift real well, just add more area, that’ll get the turning force or hold that you need. In the ’50s, ’60s, and early ’70s, engine design in cars followed a similar thought process. “Just make the engine bigger.” Few cared much about efficiency then, so powerful engines were large, sucked lots of gas, and the cars to support them were heavy. Then came the energy crisis of the ’70s, and folks started thinking in terms of efficiency.

Why do we care about fin efficiency or whether we add more area to surfboard fins or SUP fins?

Because adding more area adds drag. Every square inch of fin is skin-friction drag. Bigger fin, more drag. Drag slows you down, makes it harder to paddle, slower to accelerate, and causes you to burn more energy to catch a wave–meaning shorter surf sessions before your arms give out. So if we can get the hold and drive we want, why not have the smallest fin you can get away with? Read more about fin sizing on our FAQs page.

Any by the way, the winglets are not intended as hyrdofoils–they are WAY too small to lift you out of the water . . . and they are not designed to hold down the tail while you walk to the nose. Winglets aren’t magic–just science.[/toggle]

This Wavegrinder 2 fin for longboards and SUP has several features designed to maximize fin efficiency.

  • A high-aspect-ratio shape (tall and thin)
  • A low taper ratio
  • A short base
  • A cutaway
  • A bulbous forefoot
  • A NACA double-zero foil section
  • Winglets


  • Height/depth:  9 inches
  • Total area (with winglets): 30.6 sq. inches
  • Planform area alone: 28.5 sq. inches
  • Winglets surface area: 1.6 sq. inches (about the size of a US quarter)
  • Rake/sweepback angle: 15 degrees
  • Fits Fins Unlimited and Bahne Boxes


$75.00Select options



Additional information

Weight 13.1 oz
Dimensions 9 × 5 × 1.2 in
Select a stiffness-and-color combo, then ADD TO CART

Stiff, matte black, Semi-flex, clear, Semi-flex, orange, Semi-flex, gloss black, Semi-flex, translucent blue


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