Kneeboard Surfing USA Community Forum

My tri fin/ thruster has this curve at the point of entry, at the drop, that seems to avoid the need to lean back in steep situations - it feels a bit like a boat - but the ability to keep the weight foward allows one to keep speed and direction

Looking at the quad I cant detect too much obvious difference other than its set to ride a few inches further foward than the three finner - yet in the ride it is more likely to bury the nose on a very late or very steep drop - i have to lean back which can mean losing control and thus the section

can punters discuss as I would appreciate understanding theory and practice as this feature will be an important element when my tin can money box is full - that maybe a while but ive started


cheers

good points Wax

however

im yet to find that same feel in experimentation on position

the thing is i have been getting to far foward on the tri which produces a tight ride but still the feel of the curve hitting the water and keeping the nose up and out of the way is there - ive got back on the tri over time

both boards are pre loved so im aware im not 100% sure of the intentions of rider and shaper - though i suspect the tri was made for more specific conditions than the quad - the quad seems to be for all seasons whilst the tri likes it good and clean - i tend to ride the tri when its bigger due to the feel of the foward curve (and narrower outline) however, im still unsure about fin set up as a preference

Put a ruler at 90 degrees to the stringer on both boards.
Check differences to 18" back.
Also look at rail shape (eggy or down) differences
Also look at volume in the front 18" on both boards.

Some boards actively "suck in" because of the nose (rail) shape (i.e. once water comes over the front rail the dynamics change and dive dive dive becomes more efficient than pull up pull up pull up). You have to pay a price for building speed in and this is often it.

could be thickness, thick tails don't bury on take off nose dive

at least one board I made was too thick in the tail and liked to make friends with the sandbank on steep takeoffs....

see article by John ware here

viewtopic.php?p=26315#26315

I saw that comment by John Ware.
Interesting - I'm building in a bit more thickness in my tail because I think it helps with paddle in. Tail lifts and board starts sliding down the face earlier.
Of course I am holding my rails thin at the tail by doming the deck, so I don't have 'thick tail' syndrome in turns.

I've also learnt to hold both rails when getting pitched by the lip, forcing the board to land flatter, so not pearling. I had to do this because that board would not paddle into waves early enough owing to excessive vee and rocker. Another thing to think about, Dorje

Im just going to the shed with my ruler

back soon

Yeah, yeah this is what I want to know...what determines 'best' knee position. Long ago I had stand-up boards w/ "progressive" rocker which I think is what Hart uses and what it seems is on classic fish per some old plans from swaylocks. Single fin. Found that by moving the fin I moved the sweet spot forward or back. But there must be more to it than that???

Recently rode K-man's Flashpoint (tri). Swapping for my Mandala fish (turbo quad). They have similar rocker curves, just the Flashie has more. Both have the rocker effectively flattened in the middle w/ concave. K-man's wide point near center, Fish's forward nearly 4 inches. Flashpoint rides w/ knees just behind center, fish as far back as you can get w/out falling off the back.

So what is/are the determining variables that dictate where you kneel? Any takers???

Man, I'd really like someone to post about 20 pics with labels showing exactly what are "hard rails", "down rails" "Spiral Vee" "reverse Vee", "progressive rocker", etc etc etc. Mind boggling

Mr. Wax you have outdone yourself. Thank you! So really everything about the board determines knee point except maybe what material stringer is made of...

Sorry to interfere but there you go,

had the best late this afternoon, paddled out at 6, sat through a scary thunderstorm, got out at 8.oo, and am 2 kilos lighter cause of the mossies


http://img226.imageshack.us/img226/3253 ... ils9bk.jpg

rail pics for strudle