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 Post subject: Critique My Design...Pretty Please
PostPosted: Thu Sep 22, 2011 2:59 pm 
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Joined: Thu Jan 14, 2010 1:28 pm
Posts: 453
Location: Cottonwood, UT
So I'm designing a board that I want to try out. I started by roughly modeling it after a Hovercraft/Fish as you can see by the tail geometry. Except that's really the only thing that remained since manufacturers don't give you enough information to replicate it exactly (Things like rocker shape & length, tip/tail height, tip curvature, etc. Also each manufacturer has a different definition of effective edge and some use it interchangeably with running length). Anyway, I'm a taller guy so I customized it to a length I felt more appropriate.

What I'm hoping to get from you all is your thoughts on the rocker/tip length, tip height, tail length, etc. I've never really tried rocker but I really want to see how it affects my riding. To set the context, I'm 190 lbf & 6'3". Primarily, I ride in Utah. This prototype will be a solid but I'd like to make a split eventually if I can get the flex profile, and design right.

Is my tip tall enough? Rocker long enough? Setback enough (Hovercraft has 20mm/Fish has 75)? More or less taper? Etc.

Image

I appreciate any help. Thanks


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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Thu Sep 22, 2011 4:09 pm 
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Joined: Mon Sep 19, 2011 6:37 pm
Posts: 167
Location: Calgary
from the looks you still have camber board here. are you wanting the rocker between your feet? for ideas check out the lib tech birdman, directional rocker pow board, built like a 156 with 12" added to the nose

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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Thu Sep 22, 2011 6:08 pm 
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Location: UT
PROS: Looks like a solid design. If your going for mostly trees, lots of turning and resort/side country this design looks really, really fun.

CONS: On hard pack steeps the small side-cut radius (e.g., deeply curved) and bulbous tail section will likely hook up on you and toss you around.
Personally I don't get the rear notch on these style boards. :scratch:
Since these designs are generally turned up at the tail there is very little contact with the snow unless you are weighting your back leg, and that defeats the purpose of having a notch. Seriously, at your height I doubt you'll gain anything from the faux swallowtail.

Definitely not my style, but I'd probably love it on mellow resort terrain on a so, so pow day...

Happy building :thumpsup:

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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Thu Sep 22, 2011 6:28 pm 
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Doesn't the cut out tail reduce surface area allowing the tail to sink while riding pow? I assume reduced swing weight is also a benefit.

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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Thu Sep 22, 2011 6:53 pm 
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wjb wrote:
Doesn't the cut out tail reduce surface area allowing the tail to sink while riding pow? I assume reduced swing weight is also a benefit.
True, if the cut goes into the base, but in these designs the tail is typically upturned like a twin tip board, so getting the very small cutout into the snow requires leaning back. The purpose of having the cut-out is so the tail sinks on its own, while maintaining a neutral stance over the middle of the board.

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Experts tell me I'm not a serious rider; riding boards that are too long with the incorrect boot and binding setup and I'm not having fun...


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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Fri Sep 23, 2011 10:22 am 
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Joined: Thu Jan 14, 2010 1:28 pm
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Location: Cottonwood, UT
Thanks for the responses so far. I forgot to post that the sidecut radius was set at 9.5 meters.
Snurfer - I have every intention of building a true swallowtail at somepoint but I want to start with an easier shape. I imagine the torsional rigidity of the forked tail can be tricky.

You really think the tail is bulbous and will hook up? I was thinking it wouldn't because of how short it was. Perhaps if I moved the widest point of the tail closer to the tail contact point it would prevent that. I'm thinking I should pay a visit to my local board shop with a notepad and measuring tape.


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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Fri Sep 23, 2011 10:53 am 
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Joined: Thu Feb 04, 2010 9:55 pm
Posts: 291
Location: Whistler, Coast Mtns
Ok Phil I'm 6'3 just under 190 too.

Looks fairly good, I have something slightly similar.
With a nose that big(really long) I don't think you have to be setback any more than 20mm.Stance can be centered over the sidecut. The running length seems fairly short for 9.5m, maybe bring it up around 125.I wouldn't go with any more than 11mm of taper. The widest point of your tail should be the end of your running length, I wouldn't be worried about hooking up.
Personally I would add a couple mm's to the tail and take a couple off the nose.


PM and I could get in to it further, here's what I have
http://splitboard.com/talk/viewtopic.php?f=2&t=11071

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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Fri Sep 23, 2011 11:27 am 
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Posts: 453
Location: Cottonwood, UT
Mav - I like your setup, I imaging that the benefits of the squared tail are great for a splitboard. I would imagine the tail shape in this design behaves similarly except without the ease of attaching skin clips. For this "solid", I'd imagine it's more of an aesthetic feature (Depending on how short you make the tail at least). Did you have Prior custom build this for you?

I initially designed the sidecut radius on this board at 10m but I backed it off a little since 9.5 is still be bigger than the largest sidecut board I own. I mainly wanted this to be a test board to see the affects of rocker.

Mav - you said I should move the widest point of the tail to the end of my running length but I see boards all the time whose wide points are well beyond the running length (For reference, the definition of running length I'm using is distance between nose and tail contact points when laying on ground). Especially now with the widespread use of rocker. On your green Prior, where does your rocker start? Is it at the same point as the widest point of the nose?


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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Fri Sep 23, 2011 2:48 pm 
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Joined: Fri Jan 15, 2010 2:01 pm
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Location: Colorado
Maybe some more taper in the tail...

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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Fri Sep 23, 2011 11:56 pm 
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Joined: Thu Feb 04, 2010 9:55 pm
Posts: 291
Location: Whistler, Coast Mtns
Yeah of course, I haven't looked at a board in a while.
The widest part of the tail is further is behind the running length.(About 2cm's on mine)
Rocker on the nose starts 7cm's before the widest part of the nose.
As for radius, I still don't know why they haven't gotten bigger, it's so easy to move around a board with rocker.

I had this done as a custom after talking to Chris Prior and Dean(Prior). Chris built me a template first which I went down to the factory and checked out first before it went to press.

I don't know if you have any builder's down there(Chimera??) but if you can talk directly to whoever is building your board and bounce reasons/ideas off them.

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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Sat Sep 24, 2011 7:27 am 
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Location: UT
WhitePine wrote:
Snurfer - I have every intention of building a true swallowtail at somepoint but I want to start with an easier shape. I imagine the torsional rigidity of the forked tail can be tricky.

You really think the tail is bulbous and will hook up? I was thinking it wouldn't because of how short it was. Perhaps if I moved the widest point of the tail closer to the tail contact point it would prevent that. I'm thinking I should pay a visit to my local board shop with a notepad and measuring tape.
No worries man I didn't mean to come across like swallowtail or die sort of vibe. I just don't understand putting in a mini notch in an upturned tail. If you read the descriptions of most of these designs they claim to do the faux ST so one can ride switch. If you can ride switch it means the tail is upturned and the only way that notch is sinking is if you lean back. Again, just my opinion based on having ridden real ST's for a while.
As for the tail hooking up, I was mostly citing the two prominent knobs where the side cut drastically transitions into the tail, however this may be inconsequential as well due to the upturn of the tail. I think Pedro is on the mark with tapering that tail a wee bit.
Lastly, I second Whistlermaverick's point about why radii haven't gotten bigger. The boards I'm designing have compound radii of 13 to 15m, but to each they're own, snurfing has always been about individuality and I hope it stays that way... In any event, sorry if I wasn't clear about the cut-out.

Cheers!

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Experts tell me I'm not a serious rider; riding boards that are too long with the incorrect boot and binding setup and I'm not having fun...


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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Sat Sep 24, 2011 12:00 pm 
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Joined: Mon Dec 21, 2009 12:03 pm
Posts: 51
has anyone ever tried a down turned or flat tail, would be horrible from a drag perspective but if the tail had a very pronounced rocker just before the down turn, would this create a huge pivot point?


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 Post subject: Re: Critique My Design...Pretty Please
PostPosted: Sat Sep 24, 2011 12:51 pm 
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Joined: Thu Jan 14, 2010 1:28 pm
Posts: 453
Location: Cottonwood, UT
dafu wrote:
has anyone ever tried a down turned or flat tail, would be horrible from a drag perspective but if the tail had a very pronounced rocker just before the down turn, would this create a huge pivot point?

I need an illustration of what you mean. My brain is having trouble wrapping around that concept.


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