MVG

Reviewed by Sak@ eastcoastsurfer.com

MVG (Multi Vortex Generator)
 
MVGs are based on the caudal finlets (Hint:  search Google images for “caudal finlets”) of tuna, which are among the fastest fish in the sea.  These fish, weighing hundreds to over one-thousand pounds, can not only swim in excess of 40mph in an extremely dense medium (water is approximately 800x denser than air), but are also extremely maneuverable at speed, able to turn on a time to persue prey or elude predators.


 Vortex generation is something that has been used on commercial and fighter jets, submarines, and automobiles for quite some time now.   It only makes sense that they make it to surfboard technology to minimize drag (keep in mind that surfboards are meant to go fast but rather lightweight, so they do not pack a whole lot of momentum, so any “draggy” feature, such as fins and even inefficient foils, can cause rapid deceleration) and reduce “stall” when fins are pushed beyond their limits through turns.
 
The idea behind vortex generators is that they generate micro-vorticies (think of “little tornadoes”) just ahead of a “draggy” features such as flat spots on the foil of an airplane wing, the rear edge of the roof of a car (for example, I believe Subaru uses vortex generators on the rear edge of the roof), the conning tower of a submarine, and the fin(s) of a surfboard. 

The science behind MVGs is pretty complex, so here it is in a nutshell: Specific to surfboards, an MVG is usually placed just ahead of the center fin in order to create just a little turbulence across the base of the fin where it meets the bottom surface of the board.  That right-angle where the fin meets the bottom of the board is an inefficient arrangement and can cause quite a bit of speed-sapping drag.  By managing and minimizing drag in this location, you essentially are making the fin drag less, similar to the advantage of putting in a smaller trailing fin, but the tip of that fin still reaches deeper in the water column, maintaining control.  Additionally, as you pump the board from rail-to-rail and exceed the angle of attack (AOA) appropriate to the foil of that fin, it reduces “stall”, which is when the pressure on one side of the fin becomes too low and destabilizes the flow of water around the curve of the surface of the fin, which can result in side-slip when the board is put on rail.  With an MVG, the fin can be pushed into tighter arcs without “flushing” the fin out.
 
The result is a board that has a bit higher top-end speed but feels free and loose while still maintaining control.  I ride MVGs on all of my boards.  A number ofshapers, pro’s and am’s have ridden ride MVGs with plenty of good things to say; particularily Greg Loehr (who features them on his “TFS” twin fin model), Matt Kechele, Joel Tudor,  and Dean Randazzo (who won the “Anything But Three” contest on MVGs in 2000).
 
For further reading regarding MVGs:
  
http://www.swaylocks.com/forum/gforum.cgi?do=post_view_flat;post=326665;page=1;mh=-1;guest=15830664;sb=post_latest_reply;so=ASC
 
http://www.swaylocks.com/forum/gforum.cgi?post=140274;search_string=MVG;guest=15830664#140274
 
http://www.swaylocks.com/forum/gforum.cgi?post=136069;search_string=MVG;guest=15830664#136069
 
 
Interested in getting yourself an MVG?  Contact me at professorsak@gmail.com .

 

Reviewed by Sak