Kneeboard design for river waves

[Corran]

I've shaped a few surfboards and wave ski's and want to shape a kneeboard, but I have a questions.

1) This is for SLUGISH river waves. Face height of about 3 or 4 feet, and no guts. FAST wave, but gutless. Paddling on is a bitch because you're in the current flying downriver and you have to swim like mad. So I'm figuring thicker and wider. like 23 1/2" wide, and at least 3" thick on a 5'10" fish shape. Any thoughts?

Also a slightly concave hull in the 1st third of its length so it lifts to plane faster. because the wave is so steep and fast, I was also going to give it qwuite a bit of rocker - like 11" in the nose and 5" in the tail. Yeah, I know... thats pretty extreme. But, any thoughts on this line of thinking. The problem is not making sections - there aren't any on a river. The problem is nose diving when you make a mistake, catching the wave, and surfing out the side of the wave (BOARD TOO FAST).

2) about fin placement and angles. How far forward from the tail would the thrusters go (tri fin set-up) go? Or perhaps another way of asking the question is where do the side fins go in relation to the kneeling surfer - under the feet, the toes, the ankles, or the shins? Basically, I've never even seen a kneeboard other than on the net, so I'm having a go at this totally blind.

3) Is everyone riding with knees (legs) parallell, or are some folks riding with knees slightly splayed out?


Thanks. Email me at corran@2imagine.net

CA

[Beeline2.0]

..

[Corran]

Won't the parallel rails and wide tail take away from the boards ability to carve a tight turn?

How about fin placement - how far towards the ncentre from the tail?

Corran

[Beeline2.0]

..

[Beeline2.0]

..

[Corran]

Fast, but gutless.... the water is fast, but so aerated that its usually gutless. There are several waves, and i want to use 1 board only, so its a compromise. One of the waves is about 5 ft and super super fast and hard. Lots of punch to it, but its a pretty flat wave, so the board must be fast or when it surges you'll come off the back side.

Another wave is about 6 ft tall, and very very steep... like when you take off on a breaking 6 ft face in the ocean and you're late... the drop over the pitch falls... well this wave is like that all the time. imagine an environment where you're constantly in the first drop-in over the falls...

A third wave is about 3 feet high, slow and mushy. Totally green face, but slow.

The extreme rocker I talk about is for wave two. Without it you're toast. But, then i run into the issue of speed on the other two waves because of the rocker. So, I need to find a way to generate as much lift and forward push as i can to compensate for this extreme rocker that I really can't do without.

Corran

[Beeline2.0]

..

[Corran]

Thanks... all very usefull. I am actually an experienced shaper... but whitewater kayaks So I understand the complexity of rail foils etc to a fairly high degree. Its jsut I've never done a kneeboard specifically.

Most of what you said made sense. However you refer to design specs on swaylock several times... not sure what you're talking about there.

Incedently, in our invironment, looser is generally better than stiffer. The ability to kick the board sideways and just slide like that for an instant rather than nose diving is a big safety net. Catching the tail in a spin is another problem (hense the tail rocker). The length and width... the board needs to be fast and floaty to CATCH the waves (paddling across very tough currents etc to get out), but once on, smaller is better. You know the drill...

My experience with kayaks has been quad fins, 2" base and 2 1/2" draft each, set tight, lots of toe in to make it hook into the face well on edge. Minimal flair. With boards.. standard tri fin squashtail, slightly thicker than an ocean board, and a slightly wider tail for float when the wave gets flat. Fish's work well as a compromise for getting on the wave, but they just don't turn as well of course (on the rail).

Corran

http://www.2imagine.net/blogger2003/private.html

[stemple]

Once its shaped and in action please post some pictures. Thanks

P.S. Also it seesm that in fresh water you are less bouyant(sp) so thicker is probably better. there is some threads about surfing the great lakes on this site and they talk about board bouyancy. There is shaper from the that area as well may be pm him about the whole float issue.

Good Luck

[Corran]

OK, I will. Actually I've already figured out the bouyency thing... it was more kneelo specific questions that i had.

Corran

[Beeline2.0]

..

[Corran]

Swaylocks? what is this?

Corran

[Beeline2.0]

..

[hart]

Corran,

I have shaped boards (standups) for a river in Munich..a stopper wave. I have also kayacked and matted some pretty big rivers in North Queensland (Tully, near Cairns).

The curve you mention is awesome..particularly over a length of only 5' 8" or so.

Perhaps lifting the rails up from the bottom more with a vee-type forward panel may help with the pearling issue rather than heaps if lift..which of course will then need heaps of (at times 'grippy') concave which I'm not sure that you want.

Can you post any pics of what you're surfing?...doesn't need to have anyone out..just the waves would do.

And Syd..float an egg into a glass of water (fresh) and mark a plimsol line at the watermark. Then add salt and note the added bouyancy.

I understand that professional swimming competitions use a mixture of fresh and salt water in their pools to offset the advantage of fully salt water bouyancy..And of a personal note, I have never been as scared in the Ocean (which I am more used to ) than getting worked on a grade 6 rapid in ice cold water..the rocks are as hard, but rounded (naturally)..it's just so hard to get your head up to catch a breath before you get worked again..and again.

Regards from OZ.

[Beeline2.0]

..