design question

willli · Post by **willli** » Sat Jan 03, 2004 3:23 pm

was watching a Nova episode on the development of the fighter plane of the 21 century and they made a curious point.. that by building in aerodynamic instability they increased agility. so I started wondering about the way "wings" are used on rails to get rid of width (thanks mr. hart) and wondered why the same techinque isn't used to add width from a narrower nose. if drag is the only a factor couldn't it be harnessed to make the board more agile? has anyone ever tried this?

Beeline2.0 · Post by **Beeline2.0** » Sun Jan 04, 2004 12:28 am

Beeline2.0 · Post by **Beeline2.0** » Sun Jan 04, 2004 1:18 am

willli · Post by **willli** » Sun Jan 04, 2004 6:30 am

Terrific link beeline. voila, a pic of a little girl holding a board with exactly the concept I had in mind, and if you lop off about 3 feet of nose, the kneeboard I was imagining. as far as breaking water tension, back in the 70's wasn't there a spray-on bottom application that supposedly made the board faster, possibly even marketed by slipcheck?

Steeno · Post by **Steeno** » Sun Jan 04, 2004 3:12 pm

I remember the spray, it was used on yachts ect to increase water flow of the surface, was it called slippery seal or something like that. We used to use it in the early eighties, mind you I could not feel the difference..

geetee · Post by **geetee** » Sun Jan 04, 2004 6:37 pm

I've still got an old board shaped about 12 years ago in my garage by Bear (P Burridge) with a 1-2 concave 4 channels and a step in the tail for a hydrofoil effect. The board is 5'7'' and about 24'' wide and flat, very flat. The board is the fastest board I have ever ridden. I currently ride a Parkes 3 fin 6' board and am more than happy with it and even though it is not as fast as Bear's design it turns more smoothly. Over the years I have had many boards shaped by Craig McDonald, Bear and David Parkes and kneeboards have evolved greatly but I have noticed that a lot of the old ideas are being thrown up again like the ski tails by Dale Ponsford and other interesting snippets published in these forums. This only shows that we are advancing without losing sight of the once radical designs of the past. I look at other guys boards and some of the pictures on this site and the range of board shapes is mind blowing.

crox · Post by **crox** » Mon Jan 05, 2004 1:22 am

Steeno - wasn't there something called Ultra Glide?

doc · Post by **doc** » Mon Jan 05, 2004 5:27 am

Ultra glide is the name they sold it under here in the States...never really worked especially well. Memory's a mite vague, but I seem to recall it being a kind of silicone spray lube of some sort.

Between those that're trying to get the bottom as smooth - or lubed up - as possible for good laminar flow and those that are tring steps and airscoops and such for boundary layers...it do get a little confusin'...

doc.............

DavidW · Post by **DavidW** » Mon Jan 05, 2004 8:50 am

I used to surf with a guy that swore by Turtle Wax when the waves were small. I tried it once and could not tell any real difference. I think the offshore texture on the waves eliminated any supposed benefits.
The Willis Bros. promoted the dimple concept in the late 80's through the early 90's. A lot of guys in Monterey were riding them at that time. Have not seen many since.

Steeno · Post by **Steeno** » Tue Jan 06, 2004 2:30 pm

Hi Crox
It was called "shiny seal" here, maybe just marketed under a different name.

I had a dimple bottom kneelo in the eighties for about 6 months, could not notice the difference and the shaper hated doing them and the glasser aswell, and the sander lol. I love trying new board ideas and find it a challenge to ride each board to its potential.

Beeline2.0 · Post by **Beeline2.0** » Tue Jan 06, 2004 2:58 pm

hart · Post by **hart** » Tue Jan 06, 2004 2:59 pm

geetee,

Just a minor correction..hope you don't mind.

Dale rode and shaped his 'Screwdrivers' which were adapted from Rodney Ball's Skitails.

Rod was a bullshit snow skiier AND shaper and based his outlines on the 'waist' of a snow ski. Predating twinfins..Rod did this to increase the angle of attack, between the fin and the rail..just like twinnies did some time later by adjusting the fin angle..not the outline of your tail.

Rod stopped shaping because he was commissioned by the US Collegiens (?) Downhill Racing Team to teach and train the students in America.

I rode a number of true skitails (late 70's)..unbelievable in walls..like 5 foot Currumbin Alley with the best Rollercoaster ride you could imagine..turn after turn.

Regards,

Bruce.

geetee · Post by **geetee** » Tue Jan 06, 2004 5:41 pm

thanks Hart you're right he calls them screwdrivers. he still shapes, rides and loves them. we surf a fair bit with Dale at Avoca and he goes great on them. they look a bit wierd for me though. I'll stick to Parkesy's boards.

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