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Teacher
Edition Contents
Skill,
Tools, & Craftsmanship
Cutting
& Drying Fish
Sharpening
Nails,
Pegs, & Lashings
Falling
Trees &
Small-Scale
Logging
Guns
Chainsaw
Clutch & Chain
Ice
Pick
Shelters
Wood
Stoves
Wall
Tents
Steambaths
Insulation
& Vapor Barriers
Gas
Lamps & Gas Stoves
Travel
Piloting
A Boat
Boat
Design
Magnetos
& Spark Plugs
Carburetors
Compression
Outboard
Motor Lower Unit
Outboard
Motor Cooling System
Dogsleds
Snowmachine
Tracks
Snowmachine
Clutch
Snowshoes
Winter
Trails
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Activities
- If there are any dog teams in your area, study the sleds. What
is the length? Is there rocker in the runners? What are the sleds
used for: racing, cross country, hauling loads, or what?
- Study the snowmachine sleds and hitches in your area. What
are the features people look for? What materials are best?
- What did people there use for runners before plastic became
available? Before that what did they use? Ask about different
weather conditions. Does their experience compare with the above
text?
- Ask the oldtimers how they determined where to put the bridle
of the sled and why they did it that way.
- What is the load most often hauled now by sleds in your village?
What used to be the main load?
- Ask people in your area why they switched from dogs to snowmachines.
What are the advantages and disadvantages of each?
- Watch dogs as they train. What rhythms do you see? Do all the
dogs in the team go from a walk to a trot to a full run at the
same speed? Watch the team on uneven ground. Why is the musher
pushing?
- Try pushing the different sleds in your village. Which runners
are best and why?
- Rough-lock the runners of a sled. Try to push or pull it.
- Try roughlocking a sled’s runners and going down a small
hill. Roughlock only one side. Try again.
- Ask the oldtimers in your area how they traveled in the mountains
with dogs.
- Push an empty sled. Load it and push it again. Is there a difference
in getting it going? Is there a difference once it is going?
- Put most of the load in the sled on the front. Try to pull it
around corners. Now put the same load in the back of the sled.
Pull it around the same course. What is the difference?
- Put a temporary bridle on a sled. Move it from center. Pull
the sled. Is the difference obvious?
- If possible, try a long, short, and medium sled (eight, ten,
and twelve foot) on a rough trail. What differences do you observe?
The longer sled should glide over the bumps better.
- Get a big load in a sled and hook up a few dogs. Let them try
to get the load going. Stop. Pull slack in the towline, and command
the dogs to pull. When they hit the end of the slack, there is
a jerk. ( as in the section “Moving a Big Load” Is there
an easier way you know of to get the sled going with a big load?
- Put a fisherman’s scale on the end of a line from a small
sled. How many pounds do you have to pull to break the sled free
from static friction? How many pounds is the sled pulling once
it is moving? Of course, some of the resistance while the sled
is stopped is from inertia, but much is static friction.
- Look at the sled brakes in the village or ask the oldtimers
what they used for a brake. Were the conditions mostly powder
snow, or clear ice?
Student Response
- What five things are dogs pulling against when they pull a sled?
Friction
Lifting the sled up banks and hills
Inertia
Keeping the sled on the trail
Very small effect of wind resistance
- What kind of runners did the oldtimers have for warm and cold
weather?
For warm weather they used steel.
For cold weather they used ironwood
- What were some of the local alternatives to ironwood runners
imported from the lower 48?
Split green spruce or the hardwood from the downhill side
of a spruce tree.
- Why have we changed to plastic?
It has less friction, and is good in all weather conditions.
- Draw a picture of roughlocking.
- Describe inertia as it relates to driving a dog sled.
It takes energy to overcome inertia and regain speed as a
sled either gets going or hits bumps and is slowed down.
- Why is rhythm important?
When a musher allows the dogs to keep a rhythm they aren’t
spending too much energy overcoming inertia as the sled speeds
up and slows down.
- What happens if a long sled doesn’t have any rocker in
the runners?
It will be very hard to steer
- What happens if the sled has too much rocker?
It will shift from side to side and will require constant steering.
- What happens if the bridle on the sled isn’t centered?
Explain, or draw the result.
It will pull to one side. If one side is longer, the shorter
side will pull harder and the sled will pull to the opposite side.
- Draw a picture that illustrates the advantages of a long sled
on a rough trail.
- Thinking of the five things that a dog is working against, tell
as much as you can about making the dog’s job easier and
increasing the miles traveled in a day.
Plastic and other low friction runners will greatly reduce
the resistance to forward motion.
The musher can push the sled over bumps and hills
The musher can push, kick or drag to keep the sled going at a
constant pace and therefore maintain the dog’s rhythm.
As the musher steers to keep the sled on the trail, he/she avoids
the energy drain of getting stuck or slowed down by deep snow.
A musher can try to minimize wind resistance.
- Draw the top view of a sled that would be pulled by a man and
two dogs. Include the method by which he would steer.
- Why is traveling in March or April difficult?
The trail becomes high and the sled tends to slide off to the
side.
- What two forces have to be overcome to get a sled moving?
Inertia and static friction
- Draw a picture showing the disadvantage of a sled with a bend
in the runner that is too abrupt.
- What is the purpose of a sled brake?
To stop or slow the sled.
Math
- A sled has a runner that is in contact with the snow for 8.5
feet. Each runner is 2” wide. (remember, there are two runners.)
The sled, including driver and load, weigh 275 lbs. What is the
psi of the runners? What would it be if the runners were 1.75”
wide? 3” wide?
2” wide = .674 psi
1.75” wide = .77 psi
3” wide = .44 psi
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