The shots below show longitudinal flex [second shot flexed]. This is not a twist in the tail but flex up each side of the board to the center…& is more dynamic than whole tail flex.
I put masking tape on with marks at every 50mm to give some sense of contour.
I’m not sure you terminology is technically correct but IMHO the type of tail flex you discribe will amplify the vee in the tail and create greater tail rocker on the rail line. This will make the board ride deeper in the water when the rail is loaded and give the board more speed and holding power during turing. Flexibility is a good thing with the right moderation and proper placement in the performance picture.
It’s not a very good photo to really show what the tail is doing. There is a flexible panel in the centre which allows the last two feet of the board to flex down it’s length…on either side…when loaded [on rail in a bottom turn or cut back] only the buried side will flex…giving an increase of up to 1" in tail rocker.
The flexible centre panel allows a shearing action between the two sides of the tail…which in themselves stay flat [in a transverse way]
If you take an old fashioned wooden ruler it has a fantastic resonance of flex…if you placed another by it’s side & glued them together the nature of the flex would change dramatically…the second example I see as a conventional board …my board has simply unglued the rulers to allow them to play a wonderful tune!
The tune can be varied in construction by the power of the built in suspension.
So I have figured out that the deep split in your kneeboard tail as shown in the link is replaced here by a soft section? That would mean less problems for stand-uppers riding that one.
The split works fine on stand-up boards…I will post some photos of one as soon as I can get hold of it…surf is good at the moment & it might be a job getting it off the guy!
I’ve ridden nothing but split tails or boards with the same basic dynamics since making the first one.
“There is a flexible panel in the centre which allows the last two feet
of the board to flex down it’s length…on either side…”
Your words above.
I’m not having difficulty understanding what’s going on with the board. This flexible central panel in the board, how is it accomplished? It may be a trade secret. Knowing John Mel for as many years as I have I’ve asked him a few leading questions over time. Sometimes, understandably, his answer was, “If I tell you I have to kill you.” (-;
Hey speedy… stop thinking start doing… heres one from early 2008 . i have few around the traps being tried. the key is the amount of flex… using a stainless wood screw to move the slit apex back and forward was usefull. i started out with routing a couple tried and proven old favourites. one got better one got worse. then did a few in the shaping process and glassed them then resplit with a blade after glassing… nice for the technical customer to tune himself… and then learning the whens and whys of flex…
