Contact   Imprint   Advertising   Guidelines

DIY bar strength?

forum for kitesurfers


Jyoder
Medium Poster
Posts: 55
Joined: Thu Jul 20, 2017 8:31 pm
Kiting since: 2016
Gear: Stringy Foil and DIY board
Brand Affiliation: None

DIY bar strength?

Postby Jyoder » Wed Jan 17, 2018 7:19 pm

How strong does a bar have to be? If unhooked and boosting, it must me very strong of course, to handle the full force of the kite and rider weight. However, if always hooked in and mostly foiling, how strong does it really need to be to handle the pull of the steering lines?

I’m considering shaping/carving a custom wooden bar and glassing it for novelty and DIY fun, and maybe learning to splice lines, etc. Assuming the CL and safety system is modern and functional, are there any potential problems I may not have considered?

Thanks in advance.
Last edited by Jyoder on Wed Jan 17, 2018 7:30 pm, edited 1 time in total.

User avatar
edt
Very Frequent Poster
Posts: 5046
Joined: Fri Jul 16, 2010 6:27 am
Kiting since: 2010
Local Beach: ford lake Michigan
Gear: slingshot liquid force wainman pansh naish north cwb burton ronix rpm ozone

Re: DIY bar strength?

Postby edt » Wed Jan 17, 2018 7:26 pm

center lines take up to 3 G's but pass through the bar, that can be up to half a ton loaded on the two centers. Steering lines typically take about 1/4 of that at max load, so up to 300 pounds or 140 kg. Remember the center lines pass through the center so there's no force from the centers lines transfered to the bars unless of course there's some sort of death loop. The control bar has to be strong enough that a human's grip will fail before the control bar snaps. You typically want some sort of safety margin so I would design it to take 800 pound or 360 kg. a simple wood bar is strong enough to take this amount of force, the trickiest part is making sure the center of bar is strong despite having a hole in it. Typically bar manufacturers make the center of metal and the bar itself from fiberglass. Not much point in designing a bar that can take much more than 800 pounds / 360 kg that is more than enough to be more than anyone's grip

User avatar
Peter_Frank
Very Frequent Poster
Posts: 8601
Joined: Wed Oct 16, 2002 1:00 am
Kiting since: 0
Brand Affiliation: None
Location: Denmark

Re: DIY bar strength?

Postby Peter_Frank » Wed Jan 17, 2018 10:46 pm

Regarding foiling, it depends on the style you ride - racelike, jumping really powered, or freestyle/waves ?

If the latter, you dont have any significant load on the rear lines really, and I would not worry about it.

The most load then, on the rearlines, will be when you loop the kite, and here you got your hand on the loaded side of the bar, thus no stress on the centre of the bar :rollgrin:

8) PF

Blackrat
Frequent Poster
Posts: 253
Joined: Thu Mar 12, 2015 4:55 pm
Kiting since: 2002
Local Beach: Jeffreys Bay , South Africa
Gear: old
Brand Affiliation: None
Location: Jeffreys Bay South Africa

Re: DIY bar strength?

Postby Blackrat » Thu Jan 18, 2018 7:19 am

Imagine the chaos of a snapped bar 😐

User avatar
rynhardt
Very Frequent Poster
Posts: 810
Joined: Wed Sep 11, 2013 3:51 pm
Kiting since: 2010
Local Beach: Leeupan
Favorite Beaches: Langebaan
Style: Freeride
Gear: GK vSonic 6 & 11
Cloud C2 17
Progeni Mutare
Xelerator door
Hoff DD140
Brand Affiliation: None
Location: Johannesburg, South Africa

Re: DIY bar strength?

Postby rynhardt » Thu Jan 18, 2018 10:02 am

Blackrat wrote:
Thu Jan 18, 2018 7:19 am
Imagine the chaos of a snapped bar 😐
I imagine it will most likely snap in the centre. Which means both steering lines go slack.
Release to single front line and self rescue.
Or did I miss something?

User avatar
Peter_Frank
Very Frequent Poster
Posts: 8601
Joined: Wed Oct 16, 2002 1:00 am
Kiting since: 0
Brand Affiliation: None
Location: Denmark

Re: DIY bar strength?

Postby Peter_Frank » Thu Jan 18, 2018 11:39 am

rynhardt wrote:
Thu Jan 18, 2018 10:02 am
Blackrat wrote:
Thu Jan 18, 2018 7:19 am
Imagine the chaos of a snapped bar 😐
I imagine it will most likely snap in the centre. Which means both steering lines go slack.
Release to single front line and self rescue.
Or did I miss something?

Agree, I see no problem really :wink:

You probably dont even have to release to a line if hydrofoiling, as it is fully depowered now if it snaps and usually very low power for starters, so it will just go in the water without power and you can wait till drifted ashore without risk of tangling in lines :D

But of course, if there is no floaters on the bar, it might get messy if one of the ends tangles into something on the bottom :roll:

8) Peter

User avatar
Peert
Frequent Poster
Posts: 387
Joined: Thu Jun 20, 2013 10:38 am
Kiting since: 2012
Local Beach: Kijkduin, IJmuiden, Schellinkhout, Wijk aan Zee, Marina, Mirns.
Style: Freeride
Gear: Best Roca 4m, Naish Boxer 6 and 9m, GA Pure 8m Naish Trip 10m, Gong strutless 11m Modded Waroo 14m.
Mako 135x38 Mako 140x40 & Mako King 165x45, Crazyfly Bulldozer, T40 Moses Vorace Hydrofoil + Gong Wings
Brand Affiliation: None
Location: Amsterdam

Re: DIY bar strength?

Postby Peert » Thu Jan 18, 2018 12:17 pm

rynhardt wrote:
Thu Jan 18, 2018 10:02 am
Blackrat wrote:
Thu Jan 18, 2018 7:19 am
Imagine the chaos of a snapped bar 😐
I imagine it will most likely snap in the centre. Which means both steering lines go slack.
Release to single front line and self rescue.
Or did I miss something?
I remember a local kitesurfer had his bar (glasfiber one..) break in two and seriously wounded one of his hands in the event. Took him ages to get back on the water, functionality of the hand never got back to 100%.

So chaos due to a snapped bar? Yes...

User avatar
downunder
Very Frequent Poster
Posts: 1478
Joined: Mon Jul 01, 2013 7:16 am
Kiting since: 1970
Gear: building my own
Brand Affiliation: None
Location: Perth, Australia

Re: DIY bar strength?

Postby downunder » Thu Jan 18, 2018 3:47 pm

^
Uhm,that mighthappen to any bar.

I mean, look at Nico, #1 racer and his bar. Just a carbon tube. And man, that guy can jump.

My next bar will be a carbon tube, ultra light. I would rather be hit with an UL bar into my eye than any other bar. As I was.

And, a carbon tube will float if closed right.
Win-win.

D.

User avatar
FLandOBX
Very Frequent Poster
Posts: 919
Joined: Sun May 04, 2014 1:58 am
Kiting since: 2007
Local Beach: Hatteras Island, North Carolina, USA
Central Florida, USA
Style: Freestyle and Airstyle
Gear: Liquid Force NRG, FS Speed 4 Lotus, Pansh Aurora II,
RRD Poison, Axis Ltd, RRD BS45, SS Glide, SS Ankle Biter
Brand Affiliation: None

Re: DIY bar strength?

Postby FLandOBX » Thu Jan 18, 2018 4:10 pm

My only experience with a bar breaking was very chaotic. The bar broke at one end during boosting, so one steering line went slack while the other stayed attached to the bar. Result was the dreaded death loop until I could gather my senses and hit the quick release. I'd like to avoid that experience in the future, if possible.

User avatar
jakemoore
Very Frequent Poster
Posts: 1410
Joined: Tue Jan 20, 2004 3:59 am
Kiting since: 2004
Gear: Foil and 1strut kites.
Brand Affiliation: None
Location: Oleander
Contact:

Re: DIY bar strength?

Postby jakemoore » Thu Jan 18, 2018 6:06 pm

downunder wrote:
Thu Jan 18, 2018 3:47 pm
My next bar will be a carbon tube, ultra light. I would rather be hit with an UL bar into my eye than any other bar. As I was.

And, a carbon tube will float if closed right.
Win-win.

D.
I'm interested in this project as well. I can't stand the integrated puffy EVA bar end floats that are in style today. 20 mm wrapped CF tubes are readily available on eBay. My question is how to address the hole in the bar center with a bushing so the centerline does not prematurely wear. Simple bar end winders might also be nice. I would imagine filling the bar with a polyurethane foam for flotation.


Return to “Kitesurfing”

Who is online

Users browsing this forum: Bing [Bot], cor, ronik and 36 guests