Donek Web Site, 2nd Board recommendation

Very good Arvin.
Just think how much time we could have saved if you'd emphasised at the
beginning that your original comment was a joke rather than continuing
to take pot shots at my posts. You'll notice that throughout my
responses I resisted taking any shots at you - and it wouldn't have been
hard!
I look forward to meeting you at Kirkwood and I hope the face-to-face
impression is better than the one I have right now!
Iain



lonerider wrote:
id wrote:

This is wierd. I seem to have got myself in the position of defending

my

right to spend my time as I please and to post on rss!


This exactly the reason why I wanted to stay out of you subthread - I
could just tell it was going to lead into a quagmire debate. Hence why
I was reply to Mike T's posts and not yours directly because I knew you
would want to debate the point and I didn't really feel like debating
points that I felt were "moot". Before I start, this will be my last
post on this matter. You are free to reply as you want, I just don't
feel like spending more time on explaining why I didn't want to spend
time discussing a moot point with you in the first place.

I think this is mostly a misunderstanding. As I mentioned before, I
don't think your calculations are clearly incorrect (as you first
assumed), and even if I don't think their are particularly helpful, I
do not believe that you shouldn't have posted them at all (as you also
just assumed). You can post to the newgroups as much as you want (I
mean Mike T and I spend more time here than you, so it's not like we
have a right to say anything about spending too much time on RSS).
However, in the same way, I am free to have my own opinions about
whether posts were helpful or not (like like on Amazon), these are
personal opinions and do not claim to speak for the group as a whole.

Let's go back to the original comment I made.

lonerider wrote: ========================

P.S. IMHO, with a 9.5 boot, the Wide is as good a choice as the

Incline on

average, better for some, worse for others. The last time Iain and I
engaged in a calculation-intensive thread, it was on this very topic




I'm am not getting anywhere near Iain's pseudo-physics subthread!
================================================

See the smiley face? The comment was made in a light-hearted joking
manner. But you took it fully serious and became very defensive
immediately.

id wrote :========================
Ouch!
My first degree is in engineering (admittedly some time ago)... I
recall you have a technical background? In my experience, anything
pseudo can be quickly demolished by the genuine expert. If you think
that's you, I invite you to bring it on! If what I've proposed is
right, then great. If it's wrong and we can improve it, then that's
great too
================================================

I try to explain how this was a misunderstanding on my choice of words
and I also mentioned how you we taking things to seriously.

lonerider wrote: ========================
I think I shouldn't have chosen, the term "pseudo" as it have a
different connotation than what I was looking for (not the fake science
definition that I should have realized it would be interpreted as). I
was thinking of like pseudo-code, where the basic solution is correct,
but just the exact details are left out.

[from another post]
ok I think you took my comment a little too literally
================================================

You start seeing what I mean, but still are looking for a fight

id wrote :========================
...
If you want antisocial, take a look at this:
...
I'm a little disappointed no-one challenged it! Care to defend it
while I shoot it down?
...
so maybe we get to argue
face to face :-)
================================================

You can see while, still light-hearted, you are still looking for a
heated (but civil) debate - and keep encouraging me to challenge you on
any of the previously "discussed" points - after I said three times
that I wasn't going to. And this was precisely what I wanted to avoid.
I suspect no one else wanted to challenge you for similar reasons. I
made the mistake of making even a side comment to Mike about it... and
look at how much time I've had to spend at once explaining my opinion
and yet still saying I don't want to spend time debating/arguing with
you about it... can you see the irony of the whole situation.

Ok, I think that should explain my position pretty clearly... and
that's all I'm going to write on this topic.

Hello Robert,


I find it interesting that your board damage made it past the
PVC/Sidewall! I have damaged boards much like you have, but they where
full cap construction. I have found full cap to be pretty brittle.

Just an idea, (only if you have dealt with composites) I would soak the
damaged area in CA, allowing the wood to soak up as much as possible,
and press it for the cure. The press could be as simple as a clamp with
wood blocks with wax paper as a release area/barrier.


Thanks for the reply,

Chris

Robert Stevahn wrote:
On Sat, 13 Nov 2004 00:14:47 GMT, Christopher Cox
wrote:


Could you embellish on this? How long have you owned the board? What
kind of delamination?


I think this will be year 4 for the board, with about 90 days on it so
far. I think the tail was initially injured by trying to sink it in
some hard snow to stand it up! This is not a manufacturing defect, and
since it's right at the tail the board works just fine. I've had it
repaired once, and will have it repaired again, but eventually the
injury is going to spread due to water penetration.

-- Robert

Mike T wrote:

I actually did enjoy the FRS 165 on open powder bowls of moderate pitch,
where gaining too much speed was never an issue. However I scared the crap
out of myself whenever I took it into the trees or down an extremely steep
powder run where I wanted to make some turns to keep from going Ludicrous
Speed. (Think, The Wall at Kirkwood. After dropping in off the
cornice, I liked to make a couple of quick turns to shave off the momentum
of dropping in... )

Thanks for the vivid example! I'm making good progress on an analysis
and explanation. A few more baths should do it :-)

Iain

Neil Gendzwill wrote:

Fernie's great if it's not raining.

Yes I've heard people say that. How often is it a problem there?
I remember a 'powder' day 2 years ago at Red Mountain. It had been
snowing heavily all afternoon and evening and was forecast to continue
overnight. There was a real excitement in Rossland with the prospect of
a big powder day.
The next morning I was in the lift line 45 mins before opening. With 30
mins to go there was a mass of excited people queued up. Then the ski
patrol made an announcement "Exercise extreme caution on the mountain.
There is an ice crust from top to bottom". People didn't really believe
it, convinced there was powder to be had - so we were still excited on
the lifts. As I neared the top, the first people were coming down. The
noise was incredible, like 50 snowboarders sideslipping on ice. But
these people looked like they were riding normally.
It was a wierd day (actually my first day on a Fish). As the ski patrol
had said, there was a 1 cm ice crust on everything (even in the trees)
which shattered and then rattled down the hill in small pieces as you
rode it. Turning required real commitment otherwise you just kept
tracking in the same direction. The Fish did ok but I've had better days!
The snow had turned to rain at the end of the storm and then frozen...

Iain

id wrote:
Neil Gendzwill wrote:

Fernie's great if it's not raining.

Yes I've heard people say that. How often is it a problem there?

I'm not a regular there but from what I've heard, lots. Not Whistler
lots, but still quite a bit. It's the price they pay for the loads of
snow they get.

Neil

weight the Incline 160 is probably quite stiff. (Jason Watkins - any
comments? You're lighter and ride a 161W...). If the board is stiffer

Someone paged? The only Incline I've ridden is MikeT's older model
167. And I've only ridden it in hardboots, and only ridden my wide in
softboots... so I'm not so confident of my ability to compare. If I
had to though, I'd say that overall they're really similar, but the
old incline is perhaps a bit more 'springy' than the wide, the terrain
bumps and whatnot push back a touch more. I'd be willing to bet that a
current incline and wide would only differ in how the width felt, not
the flex.

But for myself, technique matters a lot. I think MikeT can probibly
recall a storm we got early last year with a lot of dry loose powder,
and I was just submarining everywhere. Horribly frustrating day. But,
by the next storm, I'd gotten the balance figured out, and by the end
of the season, keeping on top of the powder was automatic.

And then I switched to the incline on hardboots, and I've only ridden
that setup once in poweder. It definately required more care to float
at the right angle... but I strongly suspect that had more to do with
the boots than the board itself.

I think the advice here is spot on. If you're in the same experience
range I was last year, the first season I rode every weekend, you
probibly have some technique learning to do. One thing about the donek
wide/incline series compared to say, a burton, is that they require a
bit more input to make slow turns on steep slopes. But if you stick
with it, you'll get there no problem. By the end of last year I was
having a blast doing fairly steep trees at bachelor on my wide.

If we can get back into the physics here for a minute, without anyone
getting their panties in a twist, I'd like that.

lift = K x board_area x (speed)^2 x snow_density

This seems right to me, except for one thing: snow becomes
increasingly resistant to displacement as it's compressed. If my
childhood snowball experience applies, this depends mostly on the
water content of the snow. So, say, a big storm that dumps feet of
fresh in someplace with very fine grain dry snow, like utah or
where-ever, I think it'll be mostly like the above.

But for say, the PNW or sierras where the 'powder' can be pretty wet,
I think there's more to it. At least around here, I've definatley had
the experience where if I'm losing to much speed on a flat in fresh
snow, if I can make it on top of someone elses track, then I get a lot
of speed. So for 'resort powder' I think the effect of compressing the
snow down to a more solid support under you is pretty important to the
feeling of 'flotation'.

So what kind of things might we guess based on that? Well, a board
with more surface area will exert less pressure per unit of snow... so
the threshold of when the snow will support you without any further
compression needed is lower (less displacement).

But the other thing I think is important is, how the front of the
board compresses snow. Does it have a big soft nose that flexes up,
providing the lift angle effect mentioned before? If so, then I think
it also has a 2nd benefit: it displaces more snow down under the board
to become support, rather than pushing it to the sides or letting the
snow wash over the top.

And here is where a small difference in width might become magnified a
bit. A wider nose, a wider bow wake, and so proportionally more snow
gets displaced down rather than at some sideways angle.

What do you think?

Jason Watkins wrote:

If we can get back into the physics here for a minute, without anyone
getting their panties in a twist, I'd like that.

:-)

Warning: Procede with caution, the following may prove indigestible
and/or boring!


lift = K x board_area x (speed)^2 x snow_density


This seems right to me, except for one thing: snow becomes
increasingly resistant to displacement as it's compressed.

Agreed!

If my
childhood snowball experience applies, this depends mostly on the
water content of the snow. So, say, a big storm that dumps feet of
fresh in someplace with very fine grain dry snow, like utah or
where-ever, I think it'll be mostly like the above.

I'd just like to add a note about K in the equation because it is far
from constant.
In the above K = CL/2 where CL = coefficient_of_lift. CL is a function
of many things. In our snowboard case it is a function of (at least):
board shape, camber, flex, angle of attack, how much of the board is
submerged in snow. We therefore need to be careful comparing the lift of
different snowboards: there's more to it that board area.
If you want to see just how complex CL can be, take a look at
http://naca.larc.nasa.gov/reports/1958/naca-tn-4168/
There is a link to a pdf in the middle of the page but it's a big file
full of heavy stuff. Actually a paper from 1958 but quite relevant - so
far I've only skimmed it. It determines the CL for a rectangular plate
acting as a hydrofoil at different depths in water. It includes the
planing condition which has similarities with the snowboard in powder -
in that there's no flow over the top of the plate/snowboard (unlike the
airflow over an aircraft wing). It does indicate how complex the CL is -
and I'm sure it's equally complex for snowboards

But for say, the PNW or sierras where the 'powder' can be pretty wet,
I think there's more to it. At least around here, I've definatley had
the experience where if I'm losing to much speed on a flat in fresh
snow, if I can make it on top of someone elses track, then I get a lot
of speed. So for 'resort powder' I think the effect of compressing the
snow down to a more solid support under you is pretty important to the
feeling of 'flotation'.

I agree. I think there are (at least) two different effects going on:
the one you mention and the aerodynamic effect. The relative
contribution of the 2 effects will depend on (at least): speed of
travel, depth of snow, type of snow (including wetness). The lower the
speed the higher the lift proportion from the 'Jason effect'

So what kind of things might we guess based on that? Well, a board
with more surface area will exert less pressure per unit of snow... so
the threshold of when the snow will support you without any further
compression needed is lower (less displacement).

Agreed

But the other thing I think is important is, how the front of the
board compresses snow. Does it have a big soft nose that flexes up,
providing the lift angle effect mentioned before? If so, then I think
it also has a 2nd benefit: it displaces more snow down under the board
to become support, rather than pushing it to the sides or letting the
snow wash over the top.

Yes, that's interesting. If you took it to the extreme where all the
snow was being pushed to the sides, and the board was travelling flat,
there'd be no compression and the board would sink lower and lower
(until it hit a firm base)

And here is where a small difference in width might become magnified a
bit. A wider nose, a wider bow wake, and so proportionally more snow
gets displaced down rather than at some sideways angle.

I think there are 2 cases to consider
1) displacement (i.e. aerodynamic only)
2) displacement + compression (as in Jason's example)

Let's focus on the displacement (or aerodynamic term). Along the centre
line of the board, we can confidently say that the snow will only be
displaced downwards (and not sideways). As you get nearer to the edges,
more snow will be pushed sideways - there will be an edge effect.
Pushing snow sideways doesn't generate lift. As the board gets wider the
ratio of snow displaced downwards, to snow displace sideways will
increase. However, the total snow displaced sideways is unlikely to
decrease (and may actually increase). I therefore think it's unlikely
there would be a magnifying effect

What do you think?

Great stuff, Jason. Thanks for helping move the thinking forward! One
more practical consideration is new powder is seldom bottomless and the
firm base that it's fallen on will also play a part - in the case of 2
inches of light pow on a hardpack, a very big part! I'm sure I'll find
myself thinking more about this

Iain

id wrote:

Jason Watkins wrote:

But for say, the PNW or sierras where the 'powder' can be pretty wet,
I think there's more to it. At least around here, I've definatley had
the experience where if I'm losing to much speed on a flat in fresh
snow, if I can make it on top of someone elses track, then I get a lot
of speed. So for 'resort powder' I think the effect of compressing the
snow down to a more solid support under you is pretty important to the
feeling of 'flotation'.

Great stuff, Jason. Thanks for helping move the thinking forward! One
more practical consideration is new powder is seldom bottomless and the
firm base that it's fallen on will also play a part - in the case of 2
inches of light pow on a hardpack, a very big part! I'm sure I'll find
myself thinking more about this

Jason, I think you've just explained why boards like the Fish work so
well in wet snow conditions. Your compression factor means that there
will be a lot more flotation at the tail (lots of compression) than at
the nose (at the surface so little compression). This fits with my own
experiences comparing a 165W with a 156 Fish in 3ft of *very* wet fresh
at Baker. On the other had, with the aerodynamic effect, the lift
distribution will more towards the nose.

Iain

Great stuff, Jason. Thanks for helping move the thinking forward! One
more practical consideration is new powder is seldom bottomless and the
firm base that it's fallen on will also play a part - in the case of 2
inches of light pow on a hardpack, a very big part! I'm sure I'll find
myself thinking more about this

Iain

Physics aside. (Too) deep dry powder sucks! You can't turn, you're
flying through sketchy terrain and it's physically very demanding.
This phenomenon is rare and short lived because in time and in
daylight the snow WILL settle
to a better consistancy. This is the reason why I prefer West Coast
powder
to Utah Powder for boarding. Deep Sierra snow typically has some
texture to it and provides better flotation. Conversely, the super
light deep powder is good for skiers becuase of their angle of attck.

IMO: Deep bottomless powder is overrated. It's better than ice but I
prefer snow that's had some time to settle.