Surfboard fins: Warp Drive twin fin plus trailer for Futures boxes

Here's the new trailer fin for Futures fin boxes. The foil is E168, and the chord ratio is 14%, with the position of maximum chord thickness at 26.8% aft. E168 has a hollow trailing edge.

The knubster

This is the Knubster pic.twitter.com/xTu5dQgosl
— Roy Stuart (@Roy_Stuart_NZ) March 7, 2014

This foil will handle very high angles of attack, particularly with the AOA enhancing Bumpy Leading Edge. During turns the trailing fin experiences higher angles of attack than the side fins due to side fin toe in. For this reason and the fact that the fin is small we've dialed up the AOA capability. 

The base length has been kept the same as the side fins to keep the Reynolds number in the same zone, this also ensures that the trailer remains powerful even at low speeds and has a lift response which is in harmony with the side fins.   

Warp Drive trailing fin, 89mm deep 80mm base, E168 foil

 Side fins with MH32 foil, chord ratio 8.7% position of maximum thickness at 32%aft.

Ward Drive side fins, asymmetrical MH32 foil, 135mm deep 80mm base

 The complete set of Warp Drive Spitfires for fin size comparison. The cutaway used on larger Spitfires has been removed to keep the base length in the correct Reynolds number range.

Warp Drive twin plus trailer for futures boxes

Fin area:

The Warp Drive side fins each have an area of 13.1 square inches, which is approximately 11% less than the average 'thruster' fin. Given that the Bumpy leading edge increases lift generation by about 8% and that the elliptical planform increases lift by a similar amount the lower area will provide more lift and much less drag than the generic swept back side fin. In fact even if the fins had the same area as a generic thruster fin they would still produce less drag, but would provide far more lift than is needed, so we scale the area down to spread the efficiency advantage of the Warp Drive evenly over both lift and drag.

Used with the trailer fin as shown ( instead of in tri fin configuration) the reduction in area compared with a typical  thruster setup is 26%  giving a large drag reduction and around 10% lower lift than the swept planform tri fins. Thus the twin fin plus trailer setup in the sizes shown is optimised for somewhat higher speed.

Side fin Selector (2 fins) 

Ward Drive side fins

Fin Size

4.75 inch $119.00 NZD 5 inch $123.00 NZD 5.25 inch $128.00 NZD 5.5 inch $132.00 NZD 5.75 inch $139.00 NZD

Colour

Ice clear White Royal Blue Aquamarine Fluoro Green Black

Foil type

MH32 asymmetrical E 168 double foiled NACA 16-012 double foiled

note:
MH32 asymmetrical is the choice for 'single foiled' side fins for thrusters, twin plus trailer, and quad front fins.
E168 double foiled, used typically for quad rear fins in small wave conditions.
NACA 16-012 double foiled, used for quad rear fins and thruster side fins in big waves.

Warp Drive trailing fin

Trailing Fin (one fin, buy two when used as side fins) 

Fin Size

2.5 inch $43.00 NZD 3 inch $46.00 NZD 3.5 inch $49.00 NZD 4 inch $52.00 NZD 4.5 inch $55.00 NZD

Colour

Ice clear White Royal Blue Aquamarine Fluoro Green Black

Foil type

MH32 left (asymmetrical) MH32 right (asymmetrical) NACA 16-012 double foiled E 168 double foiled

note:
MH32 asymmetrical  is the choice for 'single foiled' side fins for thruster, quad or Twinzer front fins.
 NACA 16-012 double foiled, used for quad rear fins, twin plus trailer or thruster rear and/or side fins in bigger wave/faster conditions.
E168 double foiled, used for twin plus trailer rear fin, quad rear fins, twinzer rear fins.

Side Fin set Wide base (2 fins)

Warp Drive wide base side fin

Fin size

5.5 inch $189.00 NZD 5.75 inch $194.00 NZD 6 inch $199.00 NZD

Colour

Ice clear White Royal blue Aquamarine Fluoro Green Black

Foil type

MH32 (asymmetrical) NACA 16-012 double foiled E 168 double foiled

note:
MH32 used for twin fins, side fins for twin plus trailing fin.
NACA 16-012 used for high speed twin/fish keel fins, with or without trailing fin, and twinzer rear fins.
E168 for twin fin/fish keel fins for high maneuverability. 

Or try one of these singlefins, there are 18 different Warp Drive fins to choose from!

In wood the creation of whale bumps is a long involved process: check out how Roy shapes a Dragonboard fin