MOONRAKERR 7.0 Twin Tab
You want extra Drive and Hold? This fin is a must have in your quiver. The combination of the swept back rake along with our patented dimple technology creates incredible drive, quick release through turns and great hold in bottom turns. This size is great for bigger, more powerful waves and people.
The MOONRAKERR™ is Josh Kerr’s signature fin, with patented dimple technology. It has been designed to give extra speed and drive, both down the line and through critical turns. Independent tests have proven the dimples on the MOONRAKERR surf fin increase lift and drive by up to 15%. This gives a surfer the ability to gain more speed, and with more speed comes the opportunity for more advanced manoeuvres.
The MOONRAKERR fin uses dimples located on the fin’s curved surfaces to create a turbulent flow. This turbulent flow draws the fluid back over the foil surface, reducing cavitation and drag during extreme changes of direction (high angles of attack) and at high speeds. A foil with dimples allows the surfer to create more drive and to maintain speed and hold through turns. This then increases the overall performance of the surfboard.
- Size: Large
- Fins in set: 3
- Mount: FCS
- Base: 4.64 in, 118 mm
- Height: 4.72 in, 120 mm
- Area: 16.16 sq in, 10426 sq mm
- Sweep: 36.6°
- Foil: Flat
- Base: 4.64 in, 117.9 mm
- Height: 4.49 in, 114 mm
- Area: 15.32 sq in, 9884 sq mm
- Sweep: 36.6°
As we all now know, a golf ball with dimples will fly further than a golf ball without. What most of us don’t know is why? There are two main reasons:
- The Dimpled Surface reduces drag.
- The Dimpled Surface improves lift.
First a quick lesson in hydrodynamics (aerodynamics).
There are two types of flow around an object: laminar and turbulent. Laminar flow has less drag, but it is also prone to a phenomenon called “separation.” Once separation of a laminar boundary layer occurs, drag rises dramatically because of eddies that form in the gap. Turbulent flow has more drag initially but also better adhesion, and therefore is less prone to separation. Therefore, if the shape of an object is such that separation occurs easily, it is better to turbulate the boundary layer in order to increase adhesion and reduce eddies (which means a significant reduction in drag) Dimples on golf balls turbulate the boundary layer.
So we at 3DFINSCIENCE decided to test these principles and apply them to a surfboard fin. With advanced Computer Flow Dynamic testing 3DFINSCIENCE compared two identical fins: the MOONRAKERR dimpled fin and the same fin without dimples. The tests were conducted by flow dynamics expert Darrin Stephens (formally of CSIRO) and the results were surprising. A surfboard fin with a smooth surface is much like a golf ball with a smooth surface, it has a lamina flow over the surface. This works quite well when going straight and at lower speeds, but when you start to turn and reach higher speeds the fluid starts to separate from the foil or fins surface.
A surfboard fin with dimples creates a turbulent flow. Turbulent flow has more adhesion so when you start to turn, the dimpled fin surface delays the flow separation, reducing cavitations (the separation bubble) allowing the foil to maintain performance. When the surfer is turning at high speeds, the turbulent boundary layer helps the flow overcome an adverse pressure gradient and allows the fin to remain attached to the surface longer than it would otherwise. This reduces drag, increases lift and improves overall performance of the fin design.
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