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PostPosted: August 20th, 2004, 2:16 pm 
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Location: San Antonio, Texas
I'm trying to think outside the box here...

Maybe with my lack of experience...this line of thought will reach a deadend, but with plenty of time to consider it, here goes:

This past Spring, after a lengthly rain spell, I had the unfortunate circumstance of getting my van stuck in the mud on a piece of property where I store some equipment. At the time I was towing a little tow-behind trailer to this tract of land, where I keep it when not in use.

In any event, after unhitching the trailer and then trying to leave the property, I then got myself in a pickel....with the tires spinning in mud, etc.

Before matters got worse, we called a tow truck driver.

When he arrived...I was amazed to find that as he began to do his "setup" for retrieving my van, he had no intention of bringing his vehicle even remotely close to where I was stuck.

Instead, he began pulling out a series of blocks and tackles, or whatever you want to call them....along with related steel cable.

Actually, just prior to pulling out his tools....he took a long hard look at the available trees in the immediate area.

Then working off the trees with the pulleys...he set about getting the van freed, from a dry vantage point at least 200 yards away...using the electric winch on the back of his truck.

It was such an effortless approach, that the notion has stuck with me.

Of course there would be no use of electrical winch...but the idea of somehow snowshoeing ahead...and then bringing the sled up to you....in sort of a "hop-a-long" fashion, intrigues me.

I brought this notion up briefly once before...and someone said it wouldn't work well with snowshoes. But again, I think it's worthy of at least a little debate.

The following is a random mental list I've compiled regarding the possible use of this technique:

a) Technique would obviously not be able to be employed over large treeless expanses such as a frozen lake.

b) My aim for the technique would be to utilize it not soley for steep inclines or descents....but also for relatively flat terrain. Thus, as a main means of transport. Basically anywhere where trees could be employed for rigging up a pulley system.

c) I'm thinking that rope to be used....would probably have to be something like a lightweight yellow poly rope.

d) Maybe the hiker's technique could be to have a backpack that employs some type of unfurling of the rope....sort of like a throwbag on your back that unfurls as you progress ahead.

e) Gloves would have to be something worthy of continual abuse....(something like neoprene would get torn up with the continual repeated use)

f) I guess that instead of getting ahead of the sled and then just simply pulling it up to yourself via a 1 to 1 ratio, (straight grunt pulling)....I was envisioning some type of quick snatch block you could hook to a tree trunk...and do a 2 or 3 to 1 ratio. This would mean that what was being unfurled would have to already be working "within" the confines of the block and pulley setup, if you know what I mean.

g) Because sled would be moving over a larger stretch of distance...than what would be found with the shorter distance typically associated with just pulling via harness.....it would seem to me that bow of sled would be susceptible to getting hung up or stuck. Maybe having the bow ride high by having more weight at the back...or having good curvature at the front would help.

Anyways....just thought I'd throw this notion out as a "think outside the box" deal and see what anyone thought.

Here's a couple related hyperlinks on the subject...(note the tradeoff between force and distance):

http://www.jimloy.com/cindy/block.htm

http://www.howstuffworks.com/pulley.htm

Thanks,
-Mike


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PostPosted: August 20th, 2004, 3:06 pm 
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Location: Copper Cliff, Ontario, Canada
Pulling over flat ground isn't that difficult (unless you're breaking trail in deep snow).

For climbing hills, there's not doubt that it's much better to climb the hill without any weight and then pull up the sled using a long rope. It may even be worth using the technique of a pulley at the top of the hill and pulling the rope back downhill to get the sled up.

Mind you, this simple pull through a single pulley doesn't give you any mechanical advantage. You're still pulling the same weight. But you're pulling it going downhill, or standing in a stable position at the top of the hill.

To get mechanical advantage, you need multiple pulleys (like a block and tackle). That means you'll need a corresponding longer length of rope and go to the time and bother of a setup. ie: to get a 2x mechanical advantage, you'll need a lot more rope - pulling in 10 ft. of rope will only advance the sled 5 ft.

I think you'l find that just getting up top, digging in your feet and hauling the sled up will do the trick nicely. Believe me, it's way, way easier than trying to scramble up a steep hill with a heavy sled 8 ft. behind you.


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PostPosted: August 20th, 2004, 3:20 pm 
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Joined: April 21st, 2004, 10:52 am
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Location: Near Ottawa ON
Richard wrote:
To get mechanical advantage, you need multiple pulleys
You get a X2 advantage with one pully by attaching it to the sled.


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PostPosted: August 20th, 2004, 3:24 pm 
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Joined: July 15th, 2002, 7:00 pm
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Location: Big Flats, New York USA
What are you planning on pulling? The hardest part of winter trekking is breaking trail in deep snow, pulling the sled is relatively easy (once you figure out how to keep the darn thing from flipping on its side). You keep the bow from digging in by wearing snowshoes that nest so you pack the trail the width of the sled, and as you suggested make the rear of the sled heavier.

The hardest part of sled pulling is dealing with control of the sled on hills, going up and down. This is not a major issue in Canadian shield, but it does become a problem in alpine settings. There are times when your idea may help, but generally just getting good purchase with your feet will deal with most slopes. I've never had to deal with long, steep sections of unbroken snow. On steep packed trails I switch to mountaineering shoes with good crampons. Two people controlling one sled works really well.

Tony


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PostPosted: August 20th, 2004, 3:57 pm 
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Location: San Antonio, Texas
Tony,

Could you clarify what you mean by this....the "nesting" bit:

Quote:
You keep the bow from digging in by wearing snowshoes that nest so you pack the trail the width of the sled


Krusty....(really like your avatar, btw)....I like your acknowledgment of a single pulley on the sled giving you a x2 factor.

Let me take that one step further with some illustrations...

a) First, you'd probaby want that pulley to be of the swivel variety...something like this:

Image

With this simple swiveling single pulley fastened to the bow of the sled...you could then work on the design of a belt for the hiker.

This next diagram really helps me visualize things:

http://www.jimloy.com/cindy/block.htm

It's the image on the right...that I'm referring to.

Imagine that the gray box is the sled...and the circular disk attached to it...is that single swiveling pulley.

Now the hiker comes into play....

He/she wears some type of outer belt...maybe something a little wider like weightlifters wear...although it's not really necessary.

My point is this....fabricated into one side of the belt...let's say the right hand side....is a metal loop...that a carabiner from one end of the poly rope can snatch to.

The poly rope then is strung thru the swivel pulley on the sled.

The long loose slack of rope is then stuffed into a "throw bag" that is snatched to a metal loop on the left side of the hiker's belt.

When he/she gets to a tree that will work, the carabiner on the right side of his/her belt is attached to a tree as the "deadend" of the system.

The other end of the rope is strung thru another pulley that he or she works around the trunk of a tree.

Anyways....that's kind of what I'm thinking....to minimize entanglement...and having a quick means of cutting the force required to pull.....in half!.... :)

But then again, I'm not expert.

Just trying to think of some rigging to reduce the expenditure of energy so that greater distances can be traveled.

-Mike


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PostPosted: August 20th, 2004, 4:45 pm 
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Location: Big Flats, New York USA
Different types of snowshoes leave different track patterns, The traditional style, big round nose with a tapered, long tail at the back leaves a nested track pattern. That is, the trail you pack will essentially be entirely packed along its length, with a consistent width a bit wider than a shoe and a half. You would want your sled to be narrower than this width.

Tracks from standard mountaineering shoes tend to look like foot prints, lots of unpacked snow between steps on given side, and an unpacked section in the middle of the trail.

I like the idea of a single pulley on the nose of the sled, However, this will probably see minimal use on only the steepest slopes. As I mentioned earlier, breaking trail is the bulk of the exertion. Imagine climbing a set of stairs with ankle weights, that is what breaking trail on powder is like. Frequent stops to set up and pull the sled will not save much energy, but cost you a lot of time. Distance travelled in the winter is usually limited not only by the exertion required, but also by the short days.

If you find you need mechanical advantage to pull the sled on the flats or moderate slopes, you need to either get more excercise or lose a bunch of weight (from the sled). :wink:

Tony


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PostPosted: August 20th, 2004, 6:09 pm 
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Hi Tony,

Thanks for the further explanation...with this to be my first year of tripping in the snow....it paints a better picture.

Here's the look of the snowshoes I got from an ebayer:

Image

Their widest part measures approximately 13.5 inches....would that mean that I don't want to exceed a sled width of approximately 24 inches?.....(rounding the 26" down a few)

I haven't started on the sled yet....I guess I'm going to make something like Dave Hadfield's approach....(I would think that would be the most frictionless).

I'm, (by no means), in any type of triathalon shape. Although I've decided to move my bench press upstairs sometime soon. Just your average type 200 lber that drinks too much coffee and comes up with his share of hair-brain ideas.

No idea on the sled weight yet. The canvas tent with poles is 20 lbs...(not requiring anything from the bush).

Getting back to the rigging I was talking about above.....I may just go with my pig-headedness and figure it in with my plan. Sometimes I just get a kick out of seeing how something from the drawing board works (or doesn't) in the field. Besides, I used to do a lot of sailing....ropes, pulleys, etc.

Also, I just like how it'd make you that much "free and clear" of the drudgery of the sled. In any event, I'd at least be able to do some time trials with and without it's usage, etc.

Anyone else want to chime in on this? I'm sure it's got it's drawbacks, but....

-Mike


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PostPosted: August 20th, 2004, 6:16 pm 
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Location: San Antonio, Texas
Likewise Richard....

Your descriptions help to give a better idea of what one is up against.

Thanks,
-Mike


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PostPosted: August 20th, 2004, 7:17 pm 
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If you use your method of rope & pullies, you'll be moving ahead & then stopping to set the pulley & pull the sled. Arms aren't anywhere near as strong as legs, so pulling the sled by arm power would be inefficient & slow even with mechanical advantage. I can see the pulley system's advantage for steep hills, but I'd want to walk the rope, not pull it by hand.

A good sled pulls quite easily on a broken level trail. The best way to break the trail is to have a bunch of snowshoers who take turns in the lead. Followers wouldn't appreciate someone with a method that prevents continuous forward movement.


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PostPosted: August 20th, 2004, 7:43 pm 
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points well taken...mk.

I like the hip belt though...right side being the deadend...then poly line strung thru the pulley of the sled's bow...and then feeds out from the left side "throw bag". At the top of the hill you'd then have 1/2 the weight of the sled. (Maybe it's overkill....but it's cheap enough to try)

But yes, maybe just a steep incline technique, though.

Aside from group travel as with DF '05...I'm trying to get set for some soloing prior to that.

Thanks again for your angle,
-Mike


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PostPosted: August 20th, 2004, 10:52 pm 
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Location: London, Ontario CANADA
Tonycc wrote:
If you find you need mechanical advantage to pull the sled on the flats or moderate slopes, you need to either get more excercise or lose a bunch of weight (from the sled). :wink:

Tony



OR!

get yourself a SH.I.T !

(Sherpa in Training)

Last season, I estimate that my total gear/sled/food/drink weight was about 220 Lbs going in. Sleigh Beast hit 46 Lbs alone.
With help from Scouter Joe, we corrected the ski's to bow up and really improve the digging in effect.

_________________

[color=green]For love of the wilderness, A journey begins...[/color] [color=brown][b][Nature's Calling...] So get OFF(!) THAT(!!) THUNDERBOX !!![/b][/color]




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PostPosted: August 20th, 2004, 11:05 pm 
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Location: Big Flats, New York USA
MVGMVG wrote:
I'm, (by no means), in any type of triathalon shape. Although I've decided to move my bench press upstairs sometime soon. Just your average type 200 lber that drinks too much coffee and comes up with his share of hair-brain ideas.
That's OK, whenever I start thinking I'm in good shape my wife always agrees since "round is a shape". :wink:

What you are proposing is a good idea if you do need a mechanical advantage on a steep slope. It doesn't add much to your gear or equipment. Get out there and give it a try, then let us know how it works.

Tony


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PostPosted: August 22nd, 2004, 7:06 am 
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Location: Barrie, Ontario Canada
I have tried a variation on this when a few bodies are available: put a pulley at the top of the hill, and take a line from the sled at the bottom up through it and onto a person. That person then goes down the hill while the other helps pull and guide the sled up.

Takes a bit of a set-up, but it works (if there's a tree).

The pulley on the sled might work, but often you have to guide the sled around minor obstacles to keep it on the packed trail, in which case you have to be right with it. And as was said, legs are stronger than arms.

Good idea to take a block (pulley) anyway. The climber's snatch-blocks are easy to use and lightweight.

My sled design lends itself to using 2 sleds hitched together. This is very convenient on steep hills -- you can divide the load.


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