Jan 11, 2012

Mat Geek Design Forum: Flanges, Flanges, And More Flanges!!!

A wide variety of mat flanges all in one place...JJ's back yard breezeway! I'm tempted to say it doesn't get any more exciting than this.

OK, I'll say it...it doesn't get any more exciting that this!
(My inner mat geek...stoked!)

Of all the design elements of the surf mat, none is less important than the width of the flanges...

...and yet, the flange width, if it's extremely narrow or extremely wide, can ruin a mat. A flange that's too narrow (or non-existent) allows water to wrap around the rail in low velocity situations...which is when you most need the water to shear off the rail. A flange that's too wide will "buzz" at high speeds -- slowing the mat down, and interfering its ability to hold in.

Below is one of the earliest known photographs of a surf mat, published in 1935. It would appear that there were no flanges on this design. At first blush, it's logical...a cleaner shape should work better, right? But in practice, surf mats perform better with flanges than without. That little bit of fabric running around the perimeter of a mat cleans up the water flow immeasurably. I've made mats with the flange bonded flush to the mat's outer pontoon, creating a truly round rail...and none of them worked particularly well. Very boggy in slow/bumpy waves.

A 50's era shot of English school boys on holiday in Australia. The surfoplane-style mats they were riding had narrow flanges.

60's Hodgmans sported narrow flanges.

Two shots of 70's era surf mats...look how wide the flanges were!

Two recent eras of 4GF mats. Surf Sister on the right with a thin deck mat with patches. Val with a later canvas deck mat. The stiffer material of the canvas deck allows the flanges to be narrower and still shear off the right amount of water, without buzzing at high speed. There's a sweet spot in every mat design that allows both those elements to be in balance.

Kendog on a Neumatic. Lean flanges, but still plenty of width to allow for shearing water off the rail.

Art imitates life. JJ's inflatable hand plane mat with nicely proportioned flanges...

...while his figurine-sized mat has flanges you could land a Piper Cub on. Break out the scissors, JJ!

Tom T's surf mat art features a fastidious depiction of the flange...

..as does the work of John C.  :)

The flange of an air mattress is simply the result of bonding the top and bottom layers of fabric together along the perimeter. So in truth, it's a design element born out of manufacturing need. But, as we've learned over the years, the flange is essential to a mat's performance.

Flanges Rule!!! :) :) :)


Okemah said...

Picture 1 looks like a definite fire code violation to me!

daniel said...

i had no idea that there was so much to it. really awesome thanks for the info. my first mat was one of those blue and red ones and i thought the only reason there was that long edge was for the rope which might be correct with those mats. love the small secretes im finding on mats this was cool thanks

9N78W said...

agreed. that was a good bit of info, as i myself often wondered why the mats weren't made in a fashion that would eliminate that "flap". Makes sense, now that you put it that way.

thanks - Jason

GRAYMAN said...

I cut mine to 5/8". Seems to work just nice. Went 1/4" on my first one and you could feel the drag. I think they play a role in releasing on turns too.


PS I call them "edge laps". In the UK "flange" is a slang word for lady-parts! :-0

Piskian said...

Cor!I thought they were talking about their blancmange flans.You live and learn.

misterdirk said...

What are the implications if it tapers, or varies in width? Like, short in front to long in the back. I can't do the thought experiment.

GRAYMAN said...

Half way along its width it'd be just so!


You want a straight, even edge. I would suspect variation in the size of the edge lap would lead to different pressures and, thus, a distorted rail line.


PG said...

I like as much "flange" as is possible without the material buzzing on bigger waves. (Flanges is in quotes to acknowledge the double-entendre nature of the term!)

The reason is simple...I like having material to hang onto. So, as wide as possible without the buzz effect.

I haven't tried tapered flanges, as Dirk suggested, but I have tried a wide (like 3") flange right at the nose to hang onto, then quickly tapering down to a normal width. Didn't work too well.

The traditional "even" amount nose-to-tail seems to be a good solution. I guess there could be a bit more up front...maybe I'll have to try that!

GRAYMAN said...

"I like as much "flange" as is possible"

You old fox you!



pranaglider said...

Thanks Gman. I was thinking that but didn't have the flanges to post it.

juz said...

bring back the 70s
-thanks for the info too.