Jaffa has been brought to his knees !

[jaffa1949]

Time for a new board, A Kneeboard
I have had a lot of design plans in my head for a long time!
I love Bonzers but the state of my knees , my personal plimsoll's line and othe factors make me consider a kneeboard.
I have a good history on kneeboards at some pretty critical breaks that I really have be on top game to ride on my long board.

So a look at all stages of design and shaping a board.

Idea 6ft .... 23 1/2 inch wide diamond tail three fin bonzer set up. FCS bonzer fins Venturi two dimensional concave channels, rail stingers at the point on the rail, where the board ramps up the angle of turn!
A lot of meat in the front section of the board to aid paddling and volume for the steeper take offs a knee board allows ( remember knee boards were the ancestors of short board surfing).

Heavier glass on the deck to counter knee dents.

My shaper is Jed Done of Bushrat Surfboards, he had an ideal blank and a couple of hours discussion got all the ideas in the melting pot!

Here is a picture of the early draw up,

The board could also be a standard short board but it is on the wide side, part of the width will be gained by adding a double stringer the width of the fin box apart, the outer fins will be the FCS Bonzers and can be either the large or small set!
Centre fin will be a Greenough flex fin.

Uncle Jaffa is excited

[dtc]

Was in a line up with a kneeboarder the other day. He was killing us all - zipping up and down like a grom on a grom board.

extra benefit - no longer do you need a station wagon or a roof rack. Indeed there is a kneeboarder I surf with quite often (a different one) who has a postal bike and just putt putts a couple of kms from his house with the board strapped to the side.

[icetime]

I love the idea keep us updated when it's done, I'd love to see it glassed.

[jaffa1949]

Next stage the blank cut in half and a pre rockered tensioned ply and foam sandwich string glued in.
The pre rocker shaped string saves the risk of cutting to rocker in situ . To much risk of sand outs and the curve of the bottom and deck are based on the curve line already established. Tensioning the ply supports the needed flex for longer in the boards life!

You can see the outlines of the planned concaves an rail profile and fine placement and the secret golden mean formulas writ small!

[DreamSurf]

was just lurking how you are doing this. i have all but respect for you. age will come for us all. there are many hungry athletes just to name a few

ken shamrock mma fighter is in fifties. and even tho age has caught him he still wants to fight. he loves what he does.

Royce gracie devouted his life to teach people how to be a smart fighter.

some very old skateboarders from your age. Mark gonzales still skate yeah they dont do rails anymore.

neil unger even started at the age of 60plus. and he is rocking.(never skated before)

you have surfed and surfed. and ofcourse you will not use the kneeboard constantly. im not dumb i know for a fact the urge to stand will remain. but im also happy your trying to make something to kneeboard on when things get unbearable. nothing but respect. please post more so that we may see how it goes from a to z.

we want to see you kneeboard on that thing:)

we follow your example. it would be a waste to sit. getting old is like an old car. you need to keep driving that thing otherwise it wont move anymore.

[icetime]

Kneeboarding isn't really a sign of aging, it's a quite a unique and classic way of surfing, it's perfect when waves get too steep you're not good at airdrop takeoffs you get a kneeboard
Plus you can't fit a longboard in small barrels so there's that too

[DreamSurf]

Kneeboarding isn't really a sign of aging, it's a quite a unique and classic way of surfing, it's perfect when waves get too steep you're not good at airdrop takeoffs you get a kneeboard
Plus you can't fit a longboard in small barrels so there's that too

Yeah i know. And i bet its tricky to. But our old man is going on his knees for a reason.

Small barrels? Now thats a good side of kneeboarding.

[jaffa1949]

Since many don't know and because I'm ancient..... Knee boards descended from paipos and belly boards , which were either made from willi willi wood on Hawaii or marine plywood , (there is a member of the forum who rides traditional ply boards post here).

Early Australian surfers had the ply ones often with kitchen cupboard handles.

About the modern kneeboard , it was the vehicle that showed the wave could be ridden deeper and vertically . Kneeboards are the high functional direct ancestor of the short board .

Investigate Eotge Greenough, Steve Lisse ( fish tail knee boards ) Peter Crawford and many others!

[oldmansurfer]

Next stage the blank cut in half and a pre rockered tensioned ply and foam sandwich string glued in.
The pre rocker shaped string saves the risk of cutting to rocker in situ . To much risk of sand outs and the curve of the bottom and deck are based on the curve line already established. Tensioning the ply supports the needed flex for longer in the boards life!

image.jpeg

You can see the outlines of the planned concaves an rail profile and fine placement and the secret golden mean formulas writ small!

How do you tension the ply stringer?

[saltydog]

Seems like a fun little board for a change of pace. The shape and the eventual concaves look so much like my (kid's) blackball beater but the 2+1 with greenough flex fin would bring a totally different ride than my twin fin. What's the dimensions? I'd love to see more updates.

[jaffa1949]

Ah the questions begin. Tensioning the stringer is done with steam and involves a slightly different process to steam curving flat ply and is done to the planned curve of the rocker, the foam sandwich supports the tension by an immediate glue up. .
The sandwich string is then glued into the halved blank . WWII Mosquito bombers and postwar. Vampire jets were both plywood tensioned planes.

Taking the aerodynamics further the concaves on the bottom owe a big nod to the Campbell Brothers' Bonzer design simply put, a single concave to double however there are tweaks to create both horizontal and vertical Venturi effects . A lot of fluid movement effects on surfboards are responses to Bernoulli's principals.

I have been wanting to play with this set of ideas for years, standing up I am a good average surfer, on my knees I am well above than and able to,exploit the qualities of the board, I certainly couldn't if I used it as a stand up short board.

Dimensions 6' 1" X 24" x 3" minus concave depth domed deck to 60/40 rails to down rails behind the turning point , light stingers to open the arc off turn and give quick release..
Wide diamond tail to give rail bite for high run turns.......... Will the combination of all this work??????? Maybe?????

[RinkyDink]

I would love a kneeboard. I think I'd want a softtop section on the deck for my knees, though. Is that heresy? Would that ruin the board's qualities? I guess I could also request a customized wetsuit to put in some form of knee padding. That would be pricey though.

[RinkyDink]

The more I think about it, Jaffa, I think you're onto something. I'm suddenly very intrigued by the idea of a kneeboard. I'm going to see if I can find a used one out there. I think it would be a blast. I'm not sure about how to size them though.

[icetime]

That knee board is something I could surf standing up How tall are you?

[jaffa1949]

5' 11" and 100kgs, I can surf it standing too but knees won't unfold in time to take the steeper drop I would have to engage in. 67 year old parts are slightly slower in usage.
Now some more progress photos.
Thick board domed deck beveling to rails diamond tail yet to be shaped with15 degrees rolled bevel.

Venturi concaves with curve in both vertical and horizontal plane

Depth of concaves single to double

Progression of rail shape to stinger to provide fulcrum for turn

Side view you can just see the stinger

Final sand to come and an experiment set of side fin systems that allow adjustable toe in and cant so experimental or plain mental only a surf will tell

[dtc]

Lot of skill/thought gone into that design

[jaffa1949]

Lot of skill/thought gone into that design

Still comes down to the fundamental question in design ! How well will it work!

[jaffa1949]

Have designed the logo which will make it go really well, the red cars go faster theory !!!!

[jaffa1949]

The final shape and the first tints applied so it looks like a raspberry icy pole, on the deck in order to support the pounding knee boards get from knees, innegra carbon fibre glass , related to Kevlar. ( so a bullet proof shield for airports.)

Diamond chisel tail bonzer fins yet to be set.

[dtc]

I love those stripe tints. That looks so cool