Edge vs flyers

[red]

This is tricky to explain, but I'll do the best I can

As you know most boards have a hard edge on the rails in the tail that gradually softens in the rails towards the nose. Frequently this edge ramains pretty hard until in front of the fins and the transition to no edge is gradual.

There's an (old) idea that, instead of gradual transition of the rail edge it can be discontinued at a single point and the rails changed to non-edge down rails.

The idea is that the transition point acts as a pivot point or change of area and so might replace flyers (changes in the plane shape).

Does anyone remember this idea? Why did people stop using it?

[Headwax.]

RED

post deleted

will pppppppm you

cheers

andrew

[K-man]

'' arggh : apathy (which is why you have had 75 lookers and no replies) ''

Interesting choice of words......99.9 % of surfers could care less about these threads dealing with design.They're interesting as far as I'm concerned yet I/we]don't have the couriousity of board design of others.For instance,Part of my bread comes from being a naturalist.That's my curiousity......
Might suggest you temper your judgements of our surfing community

thanks

[Beeline2.0]

..

[Headwax.]

K-man, thank you for providing evidence for my observations. I will delete the offending post forwith.

And yet apathy was meant to be a "happy" word.

After all,

ignorance is bliss....

err

isn't it?

'happy' surfing.

[K-man]

OK... One more time for posterity.
It wasn't the post,it was that little blurb,the design threads are good,and they do stimulate the though processes.Good stuff.



''ignorance is bliss? Ignorance is ignorance...bliss is bliss


And good surfing to you also..cheers

[KenM]

Red, I have never seen a board with the type of abrupt edge transition you describe but I'm wondering if the "pivot point" might create a catch point as opposed to a flyer that creates a release point. Just wondering out loud.

[red]

Sorry, I missed the drama. I can only comment in general terms.

Re design threads:
I could experiment independently and keep my findings to myself. If I made a living out of board design that might be exactly what i'd do (which is what makes participation by professional shapers such as Hart, John and Bud in these forums all the more impressive and a credit to their commitment to the sport beyond $$ in their pockets).

But I learnt a long time ago not to reinvent the wheel but to understand its principles, why its good and what disadvantages there are to the concept. (think solid wheel vs spoked wheel, for instance).

Hence the questions here and elsewhere.
Discussion is good.
Constructive disagreement is excellent

In my view board design has stagnated over the past 10 years (maybe it's 15 or 20 years?). Improvements have been there, but they have been incremental (refined rocker, rails, tails, etc.), rather than revolutionary. Maybe there are not any revolutionary concepts left within the current materials paradigm, but I'm of the mind that computer aided design could provide a major breakthrough if we are able to interpret the results of our research (i.e. have surfers savvy enough to provide relevant input on board performance to drive the feedback into the design cycle).

I don't think that my questions have anything to do with revolution - I'm just trying to figure out how to make a decent board for myself and possibly learn from board design history in some way. If what I learn can help other kneeboarders, too, all the better.

It's easy enough for me to not post the questions. I have a pool of shapers who can answer the questions, but I'm think that the questions may be of interest to some people in the kneeboard community, in much the same way that posts about surf conditions at a local surf break on a given day might be considered interesting and relevant. That's what the site is about.

No comment to a post is ample comment 1) people don't care 2) it's not relevant to them 3) they haven't thought about the subject and don't want to 4) they scared of being seen as ignorant 5) they don't see a benefit to themselves in responding, etc. etc.

Come one, come all.
Or to paraphrase that wonderful Rabbit advertisment of the 80's
"If you don't surf, don't fucin come!"

[frankfqr]

I can,t wrap my head around the pivot point on the rail. Flyers and hard edges for release and speed, but a specific point of pivot seems it would have to be so dialed in, in relation to rocker and fin placement. But at that point, which is the most relevent factor and how would you be able to discern. Pivot point? Please expound. P.S. I deleted 2 pages of response, if anything on this site I enjoy the discussions on the evolution of toys!!! Headwax---do you save copies of your deletes? Bring it on!! At least it garnered a response and kept this thread alive. So many good threads die due to idle banter.

[skansand]

so the board ive made and been testing for 2 months has soft rails all the way cause i never put the effort into sanding it........but its my favorite board guaranteed.....holds nice....what are the sharp edges supposed to do for performance???

[Headwax.]

hi frankfqr

as an example: one instance of a pivot point in planshape can be seen in Kyle Bryants tails (his kneeboard tail) where there is a sudden change in curve where you might find a wing would have been.

beautifully drawn image to illustrate. you can imagine that the sudden chnage in curve could act as a pivot point, depending on other design variables:, especially when coming off the top in a snap turn,...



the apex of a vee might be another pivot point, as might a flyer, a step in the rocker, old fashioned tail lift ...... and certainly a fin. A fins rake means that the effect it has on pivot point varies during the turn.


pivot point is probably the wrong description, as when everything is combined, it is, of course, more like an area.

eg in quads the size of the pivot area/fulcrum point varies on how close the fins are

the idea is to get everything happening in unity. One of the reasons that some tris have such a small back fin is that the fins are too seperated and the back fin is not working in unison with the front ones. It is in fact a "rudder" rather than a driving point. This is an example of the fulcrum area being too spread out..

(apathetic surfers will never discover that moving the outside fins further back slightly and the back fin further forward will result in a much drivier turn but still keeps the looseness that they crave. Nor will they discover that increasing the rake of the front fins slightly yet moving them forwads slightly will give a similar effect. ie adding drive while keeping looseness.]

the area and pivot 'point' will change depending on for example wether the rider is leaning forward, or applying body torque. Because the pressure points during the turn vary, we need a number of points to press against, not just one. EG when we begin a turn we might lock in the rail in front of the outside fins. But at th end of the turn we are pushing hard on our back fins to get more rail out of the water in prerperation for our next turn, or to compensate for change in the wave shape.

Should we have for example a single fin with no rake (ie very upright) then we won't be able to change our weighting from front to back during the turn. We would produce a very pivotty undrivey turn which would feel s*&^ house.

It follows we need to be able to spread our pivot area or points out to compesnate for our weight chnages and needs during the turn.

as red points out, these pivot points can be tuned by using the edge of the rail.. Idea: hard edge gives crisper turn, (with possible sudden release) soft edge gives more forgiving, easy, turn more prone to gradual slide

why? possibly: because of the differences in meniscus tension at the rail edge between the two designs, also differences in ability to bury rail because of foam crossection

and it can also be tuned by using rail profile.

eg how easy is the rail buried at a certain point in relation to the rail around it. How can we use this to mimic a board with a smaller rail line and produce a more refined fulcrum area/point..

eg a blocky rail going into an easy to bury down rail without a gradual transition can produce a pivot point

some of these ideas were explored in the quintessential stinger..

eg radical change in planshape at the sting, change in rail profile at the sting, change in bottom contour at the sting, utilisng the combined fuclrum point of sting and fin by moving the single fin up to 18 inches from the tail

other egs: kneeboard twinfin fish the pivot points are influenced by, among
other things, the fins placement and shape, the fishtail apexes, any tail vee, the tail lift, the rail just in front of the fins. To get a twinnie on its rail you might have to use the rail and the fins at the expense of the other points.. In standup fish you rarely see the board its rail cause the rider doesn't understand this and is using the fish tail and the fins (which are usually too far back because it is a retro board and that is why he/she is riding it) to work from.. he usually also has the disadvantage of having keel fins with minmial rake so that his chance of locking in the front rail and actually getting the board on the rail is also miminized - because his fulcrum area is concentrated in his fishtail.

having no rake in the fins means that you also do not 'lead' the water off the back of the fin. Means (among other things) that you need to place the fins further back to get the same drive. Means that if you are a kneelo with keel fins you probably grab the rail to turn cause your board is so stiff, because your pivot area is concentrated in exactly the wrong place for a kneelo and you cannot lean forward to properly engage the rail, because this would be spreading out the fulcrum point too far and creating drag (see rudder effect in tris)....


etc etc

cheers

great surf here today, another 3 hours in the water, ho hum

[red]

Thanks for the comments.

KenM
You're right, the abrupt transition might cause drag. I guess the transition needs to be phased in over 1/2" or so.

what are the sharp edges supposed to do for performance?

- see this thread
viewtopic.php?t=2223
After wou've surfed the board with no edge, glass one on. I think you'll like where it takes you.

Headwax certainly got me thinking about how playing with the edge might be done effectively and combined with variable rail profiles.

In my understanding of the physical shaping process, most shapers stay away from mucking with rail profiles too much because it's just too bloody hard. The have to figure out how to cut a rectangular lump of foam into a flowing edge while maintaining balance in foam volume front to rear. Often they use the same curve that they used for the board outline to mark out how much foam to cut out of the rail. You can imagine how hard this gets if you're trying to cut 2" out of the top deck at the tail, 1" at the centre and 1.5" at the nose; and then put a different set of measures for cutting the bottom deck/rail - the curves of the top deck and rails are much harder to match up (where does the rail midpoint end up?).

I don't have that limitation because I don't think in terms of the physical process (I don't know shaping, only design (and not too much of that, either!)). I work with machine generated bezier curves and the design software ensures smooth flow between points. I do, however have to be very careful how I define those points so that I don't put wobbles in the rail profile.

More importantly, I also get 100 or more attempts at designing the rails before I cut them. While it's not so easy to envision how the on-screen board will look in real life, it is possible to see when it looks wrong and edit the design - a lot easier than glueing back foam!
I also have a record of what I did so when I ride the board I can look at the design and try to see how the board shape might be adjusted to manage certain characteristics.

For instance: I have a board where I worked to get the rail foiling forwards, so that the board would accelerate when on edge. Now the board goes like the dickens, but it tracks somewhat (the volume of foam at the front 'pulls" the board in the direction it is going - it's a wierd feeling - like being stoned and towed behind a boat (I guess ).
I went back to the design and saw that I took it too far, wasn't concentrating when I finished the board and ended up with the centre of mass about 50mm too far forward. I've adjusted the design to be more neutral while retaining the essential aspects of rail foil that I wanted in the first place and expect an even better board next time around.

Edge is a lot easier to deal with - glass it on, sand it off. Cheap, quick and effective.

[KenM]

Red, you could use a resin bead to put on the hard edge and pivot point. If it's "sticky" you can blend it a little at a time, even take a sanding block to the beach for tuning it.

[weirdo]

Red and Head of wax..... another thought provoking discussion...

I've read the whole thread 5 times and think a bit of it has gone in!!

I have a few questions to throw in the pot...

If the pivot point (as you call it headwax) is a flyer, is there any advantage in having a double flyer?
Im supposing to the pivot point of a board dictates where the rider generally positions himself on a board? and any thoughts on the weight of a rider (i.e skinny v heavy) on board length and rail thickness?

Headwax: I have a mate that makes standup fishs.... and your observations are spot on I reckon (he puts No rake fins in way up the back of the board)! Not to mention the fact that peoples are always giving them back to get the fins put back in as they snap out from so much pressure on them...

Keep it coming gents...

W

[Headwax.]

Hya weirdo,

well just had a three hour session at the local (great waves last few days and an old guy (about my age) was out there ripping on a fish. Like flying! He had the keels slightly forward of normal,. His board was about five eight. The thing that stood out was he had his weight forwarrd most of the time and did use the rails. I think cause the board was so short and his stance was wide but not ugly he could control the back and the front simultaneously. One of the few

as far as double flyers, I think that they would encourage a fulcrum point somewhere betewwn them, rather than on either flyer. Depending on wether you could bury the buggers. EG whether they are fluted on top/ bottom/ both.

But I guess their real advantage is keeping a bit of area under the rider while letting you have a fairly pinnnie tail eg old steve artis board

album_showpage.php?pic_id=590

Im supposing to the pivot point of a board dictates where the rider generally positions himself on a board? a

well almost. I reckon the rocker determines that. Too far forward you eg nose dive. Too far backward you push water. The fulcrum area would determine where you place the most pressure during different parts of the turn.

album_showpage.php?pic_id=5784

in above pic left hand board you can see how Parsey's located the first flyer to work with the forward fin.. he's also done some other things with the rails

this pic cause I like it album_showpage.php?pic_id=5602