For the quad setup, I think, and it seems Erik of twitter.com/erik_antonson found out the same thing, that we need on SUPs to oversize a bit the front fins, and undersize the rears, compared to what would work for our weight on a prone shortboard.

Also, oversize them on short ( 8'6" +) boards, and undersize on short (7'6" -) boards. It seems related to rail thickness: the more volume in the rail, the bigger the front fins.

So, basically take what a size chart would advise you for surfing fins for your weight, and undersize/oversize accordingly.

C-Drives are an excellent solution for front fins, to oversize the grip while keeping looseness at speed.

colas said..
Also, oversize them on short ( 8'6" +) boards, and undersize on short (7'6" -) boards.

Sorry, I meant oversize them on short ( 7'6" -) boards, and undersize on short (8'6" +) boards.

IF YOUR BOARD IS WIDE IN THE TAIL A QUAD SET UP IS THE GO . e.g....x32 Hokua .

SPECIALLY with 7 foot wide boards ,

A set of STANDARD medium size is good ,I Brought a large set but found them to big on most boards .
two sets... to play around ,1 small 1 medium ...set for life .

Thanks guys on the input! Will have a play around with it , otherwise I will stick to what I know. Trusted Thruster! Happy surfing.????

Tardy said..
IF YOUR BOARD IS WIDE IN THE TAIL A QUAD SET UP IS THE GO . e.g....x32 Hokua .

SPECIALLY with 7 foot wide boards ,

A set of STANDARD medium size is good ,I Brought a large set but found them to big on most boards .
two sets... to play around ,1 small 1 medium ...set for life .

Boards 8.1 x 28 103 litres