IMO a spiral v is when the v increases towards the tail of the board or fin area making the board have more tail rocker near the rails than the center line and this helps to get the board from rail to rail when turning and may also helps with a clean release of water off the tail going straight and may also help with tracking or giving bite and reducing the tail sliding that some boards tend to do... It's complicated stuff.

DJ

CMC said...

From Swaylocks and the generally accepted design. This is now evolved to become a double concave which is the same thing basically with a concave on each vee panel.

Spiral Vee is a vee that peaks in front of the fins, and flattens going fore and aft.

spiral vee:
a vee in the bottom tail section that has its apex under the back foot, generally in front of the fin/fins.
Attributed to Terry Fitzgerald, circa 1974.

Maybe Fitz and Geoff McCoy could duke it out on the attribution......

I agree with above...

To simplify... This board has Spiral Vee... Single Concave up front, spirally into double concave infront of fin, and spirally out to Vee Double Concave in the tail....

Single Concave


Double Concave


Vee / Double Concave Vee


Extra shots of the board

Adapt said...

and how does it increase and decrease the performance of a board?
Cheers

Concept is;
Front / Water Entry - concave channels the water under the board
Double Concaves - water is channelled into and through, the double concaves
Concave Vee at Tail - The Vee - When you are on your back foot, it allows you roll rail to rail....

In short, "it helps channel water".

"Single to Double" is short hand abbreviation.... Single to Double is a very popular concept on Channel Island Board, for boards built to perform in good clean conditions. Common on the Red Beauty (small waves), the Black Beauty (medium waves), K-StepUp (solid waves), and MBG (Merrick Big Gun - really big waves). (Note, the is a school of thought the Vee component isn't much help in small waves...)...

laceys lane said...

i'll throw an uneducated crackpot opinion'

a double concave is where the the centre 'v' is no higher then the outside rails'

a spiral ' concave' v has the centre 'v' higher then the outside rails.

so there, thats how it is, no correspondence shall be entered.

time go and count how many blades of grass there is in a square metre of turf at percisely 1 am

What kind of turf?

Simondo said...

CMC said...

Is that what he calls his Tri-Plane hull Simon?

Not sure.... That is a MSF - Merrick Single Fin. I haven't sighted a Tri Plane Hull.

I believe this is what Al Merrick calls this bottom. Developed in the 70's.

A bit more complex than a simple Spiral Vee.

laceys lane said...

CMC said...

laceys lane said...

i'll throw an uneducated crackpot opinion'

a double concave is where the the centre 'v' is no higher then the outside rails'

a spiral ' concave' v has the centre 'v' higher then the outside rails.

so there, thats how it is, no correspondence shall be entered.

time go and count how many blades of grass there is in a square metre of turf at percisely 1 am

What kind of turf?

hopefully big leafy bladey turf with some dirt patches in there

Like perhaps a Buffalo with dog pee burn holes??

I had many boards made for me that had spiral v and they were often double concave to v tails and I think when you put a double concave into a normal v'ed tail it seems to lift the rails as it goes back forming the spiral v effect.. I think it's something more used in longer and narrower tailed boards rather than shorter and wider.

DJ