I’ve had a few guys aproach me with modular board concepts. The most interesting had interchangable rails for the length of the board, combined with various tail sections. The designer (I can’t remember who at the moment) talked about varying the flex, weight, shape… all around a common center section. It was really thought out… and very complicated.
I’d rather just have a garage full of boards.
Ok so lets say you slice the board in two nose to tail, then various inserts can be added, inclusing trailngular ones… . put the wide part of the triangle forward to bring the widepoint forward, put it aft to bring it aft and widen the tail, or use parallel inserts of different widths. . . . many different baords with the same rail line.
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I’m not too sure I could disagree with the notion that the whole has to come together in the end.
Nevertheless, parsing out the paddleboard from the surfboard is an interesting idea and one I believe, can potentially lead to innovation.
Anyway, a final diagram.
Here a 70A is (sort of) turned into something approaching a 67A. Sure it’s not exactly the same board (heck, they’re just close-tolerance blanks), but its probably close enough for most. I can’t imagine the engineering required to pull this off would be all that difficult.
On Pro Boards
Pro boards should be dedicated to the pro and the conditions - just from a structural standpoint.
kc
from aviso descriptions fo how there hollow boards work iam going to say that they claim to have an adjustable deck/ bottom area going. what happens is as the board get compressed in a turn it widens creating a curvier rail line and a ther fore can go through tighter turns. where as berts flex theory is based on rocker flex they seem to be try to work with outline flex.
Uhmmm- wow, they’d have to be awfully thick for that to make any real, significant. difference in area of the bottom segment that was immersed. Almost initially circular in cross section, I’d guess.
Plus, if the board is going along at speed V and keeping a constant area A immersed, would it make much difference just what the outline shape is?? Especially if the difference was something on the order of 1%.
Interestingly, you can treat a hollow board as something with a cross section of constant circumference, that is it isn’t likely to be expanding or contracting like a balloon but rather like a beer can. Call it an ellipse. For a change in thickness, the change in width can be calculated - see http://en.wikipedia.org/wiki/Ellipse#Circumference for a not-especially-easy set of formulas to play with.
However, if we treat a hollow board as something with a flexible curved deck and flat bottom but thick rails that won’t change much, then the possibilities change somewhat. Both bottom curve and rocker might be changed, far more than the outline shape.
interesting possibilities here - starts to remind me of Wright vs. Curtiss in a way.
doc…
In my humble opinion (okay that’s a lie, change that to self-inflated) you can’t count on flex. Outrageous? Perhaps, but unless you strap yourself to the board, the board will do what the board needs to do - your control over its response is close to zip. Okay, maybe you might moderate its response or redirect it in some manner, but a flexed thing will likely want to unflex at the earliest possible opportunity once the load is removed. In surfing I don’t see why this would be desirable – ancients or otherwise?
For a long time people thought in order to fly you had to build something that looked like a bird. The bird solution surely works – for birds.
Stiffness works in surfing. A rigid stiff surface area harvests the force of the flowing water of the wave (gee… that’s almost prose like.) Flexible structures yield to stress, they yield in such a way as to minimize the surface area presented to the flow –i.e. reducing the load – which in this case reduces that ‘harvestable’ force.
Then someone figured out it wasn’t looking like a bird that makes you fly.
Some flex is inevitable – all things give a little (except for my current employer.) But as a major design element in stand-up surfing vehicles, that is, an element which is actively used by the surfer – I’ve yet to see a workable implementation. If you can bring more of your body to bare on controlling the characteristics of the craft, as in mat surfing or flexible kneeboards, etc. that’s a different matter – flex can have a big role.
It’s about control and flex puts you in the back seat.
How about a beak, if you had a beak, maybe then you could fly?
kc
PS
This reply might have been too harsh, nothing personal. I woke up too early and couldn’t get back to sleep.
(chuckling )
yeah, I agree - flex that works on a stand-up board has to be done just right to work, or else it’s a happy accident. When the board flexes/distorts, is it gonna do it the right way? Plus the single small point of contact doesn’t help.
Although - mebbe a little ‘give’ built in might be of some use, as shock absorber or to moderate other effects. Kinda like working on a wooden floor versus working on poured concrete.
For those of us in the ‘other forms’, of course, it’s another story. Multiple points of contact and control.
Like the illustration- puts me in mind of E. H. Shepard , which I remembered with pleasure.
And on that note, my current employer (me) is being a bit unyielding too. Been slacking these last few days while healing up, and now I’m healed enough that I have to get back at it. Boat shoes just are not all that good against sharp objects, alas.
doc…
Flex in standup surfboards is very effective, and with longboards it is very easy to get it right, in fact it’s almost impossible to get it wrong.
The physics which explain why flex works in a surfboard is very simple and is well known, but if you expect to “see” it working, don’t hold your breath, it’s too subtle . . . . you can’t actually see the board bending when watching it being ridden. . . the way to find out is to ride them and feel the difference.
Actually, given that flex is able to transfer rider energy into forwards motion, a standup surfer is much better placed, because he can weight and unweight much more powerfully than a kneeling or prone rider.
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riffraff wrote:
I designed a modular board system a couple of years ago but never built any of it… basicly the concept was to split the board into three segments - tail, mid, nose and have inter connectable pieces so you can mix and match your boards. i.e. you could buy 3 noses, three tails and the mids and have a 27 board quiver. I thought of using a dowl system to connect the peices which whould mean that dufferen dowls could be used for different flex properties (ie, more in tail less in nose. Same all over. etc etc)
the reason I didnt bother is I thought… its just surfing :o)
would still be fun to play with if there was time and money avaiable to prototype…
rif.
kendal wrote:
I’ve had a few guys aproach me with modular board concepts. The most interesting had interchangable rails for the length of the board, combined with various tail sections. The designer (I can’t remember who at the moment) talked about varying the flex, weight, shape… all around a common center section. It was really thought out… and very complicated.
A few perhaps related patents (and some perhaps not, depending on your point of view):
USPTO #
6,656,005 (2003)
7,121,909 (2006)
3,879,782 (1975)
3.409,920 (1968)
(There are more, but they relate more to flex and being able to disassemble, rather than customize the shape)
mtb
I understand your point(s). And on that uncharacteristic note, I also liked your suggestion regarding other ways to manipulate the surface area, in particular with respect to width.
Anyway, thanks.
kc
PS
The idea for the cartoon below came to me the last time I understood a point you made. Thought I’d finish it up and get it out of the way.
Flex in standup surfboards is very effective, and with longboards it is very easy to get it right, in fact it's almost impossible to get it wrong.
I’ve ridden some boards that got it wrong… at least for me. The first time I really noticed board flex was on a friend’s Bic popout. That thing would flex into turns, then it wouldn’t unflex to let you change direction. I felt like the board robbed my input by sucking up the energy I put into it and not returning later. What a pile. After that experience, it took some convincing for me to think of flex as a good thing. The flex testing we did at Hydro Epic opened my eyes to what’s possible.
Oh sorry Roy… you said longboard… the Bic was only 9’6" 
There is a modular board from the early 60’s on display at the Surfing Heritage Museum in San Clemente. It is called the 1963 Hobie Two Piece (Suitcase board).
http://www.surfingheritage.com/reg60.html#board61
It was designed so that you could ship your 9’11" board on a plane with a small cargo bay.
Hi Kendall,
I have only used wood, and wood is pretty much gumby proof when it comes to flex, it’s hard to get too much, flex with wood not so with foam apparently.
Flex is a basic concept, easily applied, and excellent for standup boards. . . . all WCT shortboards flex don’t they ?
OOPs we are OT
Nice. Also, if you haven’t already, take a peak at some of the patents that MTB listed. Splitting a board is not a new idea - I opened the thread with that.
My notion was motivated by an attempt to pull out the paddleboard from the surfboard. I’m not much of a gizmo guy - wish I was.
In terms of design, I’m actually inclined to drop most of the foam in the tail section, almost to the point of making it a stiff rigid sheet. (Basically a composite sheet or very thin hollow structure with a few supports. I was thinking of using that honeycomb stuff in a half-sandwich with a thin sheet of EPS, which by the way has also been used in board construction circa 60s something, the honeycomb stuff that is.) I’ll finish up some diagrams and post them later this evening.
kc
Here it is…
Below is just a minor change to the previous 70A to 67A diagram. Hopefully the idea is clear enough – whether it is workable is another matter.
The forward section is constant and can be customized for a given customer. The interchangeable tails are minimal, at least their point of attachment would be standardized and the only concern being structural, rather than floatation –i.e. volume is not a concern, in that the less the better.
How to do this is a big question. I’ve illustrated a sort of hollow chambered section and in my initial reply, I also thought it might be a nice application for a plastic honeycomb material (I’ve forgotten the proprietary name of the stuff.)
Anyway,
kc
An Attachment Mechanism Strategy
Given that the main point of the idea of an adjustable or replaceable tail-section is not motivated by transport -i.e. a convenient fold-up for shipment kind of product – why bother with it. That is, say it’s not a issue. Then given that to be the case, and given that simple is best the diagram below is sort of what I see as a possible solution.
The forward-section has some permanent ‘male’ pipes, the different tail-sections having the same ‘female’ slots. Hopefully, how this would work is clear in the diagram.
Construction The Tail-Section
The diagram gives the impression that the tail-section would pretty much be a solid form with tubes etc. (In the diagram the square areas are for the inserts.) Perhaps in the end that would be required, but even if it does require that kind of structural treatment, there is always the honeycomb material that I referred to in the prior post.
My preference would be a minimal rigid sheet with the structural tubes solidly attached to the sheet. There would have to be some consideration for fins, and rear and forward foot placement. A solution to the rear-foot placement problem might be a bridge across the tail at some point, and the fins, by some other localized additional support. Forward foot placement could be solved in a similar manner.
The tail-section could be held tightly on the tubes with large plastic bolts, flush with the deck, but large enough to be turnable by hand – like a sunken dial for instance.
In the end, you would potentially have a board that potentially ranged from 6’ 6" to 7’ something with a number of different tails. The volume of the forward-section (the floaty bit or paddleboard component) purchased once, its characteristics determined by the surfer preferences for volume etc., the choice of tail-section determined by conditions.
Also, there would be a matter of correct balance, which could be solved by having small compartments in the tail section which the surfer could fill with a bit of sand or water or something (spare change?).
Workable? Still don’t know.
kc
Added as edit
Adjustable Tail-Section cont…
In the diagram below, both rear and forward foot platforms have been added, as have some ‘tightening’ screws, here either a slot head bolt or a raised dial, both assumed to be plastic.
The extended front-foot panel is sort of interesting - it adds some additional support.
Anyway, a slow Saturday, … just completing a thought.
kc
Very interesting pictures but far to complicated for me otherwise. Core fusion in Australia is already doing something like this. Their EPS blanks are variable density throughout the length of the blank. So softer in the tail and then harder through the middle.
Agreed. In addition, changing the fin setup has a far larger affect than changing tail dimensions. Tail feels too wide and unruly? Put in larger fins.
Complicated?
Gee… I thought the idea was pretty simple? Also thought the mechanism for attachment was pretty simple too.
Also, I didn’t pick up anything similar from my cursory peek at the Core Fusion site. A variable density EPS does sound exciting though. However, I’m not sure its going after the same thing. This idea started as a desire to separate the ‘paddleboard’ from the ‘surfboard’ - the paddleboard (forward section) remaining constant, the surfboard (tail-section) being somewhat interchangeable. In the above examples (spanning a few posts) the replaceable tail allows for a change of about 6 in. which can be a pretty significant difference, particularly when the shorter tail is moving the board in the direction of something ‘fishy’.
But with respect to your ‘complicated’ comment - simple is always best - complicated can be a real negative all by itself. I’ll give it some more thought, thanks.
kc
Sure, but I’d be amazed if you didn’t agree that most of the time in surfboard design, there is usually more than one solution, and the rest of the design usually dictates which of those is likely to be best.
In my opinion, playing with the fin setup will only get you so far, particularly if you what to move towards something more fishy, or move from something fishy to something ‘not so fishy’. Fin configurations could definitely be used to tweak either case, but there is a sure way of getting from one to the other - screw with length and width.
Interesting thought though.
kc
