1

Chapter 2Chapter 2River SavvyRiver Savvy

(River Reading and Tactics)(River Reading and Tactics)

2

Enabling Learning Enabling Learning ObjectivesObjectives

1. Given a diagram of the cross section of a low head 1. Given a diagram of the cross section of a low head dam, the student will match the corresponding dam, the student will match the corresponding parts according to the class materials.parts according to the class materials.

2. Given river hazards and characteristics, the 2. Given river hazards and characteristics, the student will match them with the corresponding student will match them with the corresponding description.description.

3. Given a diagram of a river section, the student 3. Given a diagram of a river section, the student will match the current differentials according to will match the current differentials according to the class materials.the class materials.

4.4. Given a diagram of a hypothetical creek and a Given a diagram of a hypothetical creek and a multiple choice question, the student will identify multiple choice question, the student will identify the velocity of the hypothetical creek according to the velocity of the hypothetical creek according to the class materials.the class materials.

5.5. Given diagrams of a river, the student will draw Given diagrams of a river, the student will draw boat movement of river tactics for each situation boat movement of river tactics for each situation according to the class materials.according to the class materials.

3

Hypothetical

Creek

200 feet

4 feet

Cubic Feet per Second

CFS

Velocity of river is 2 feet per second

CFS is equal to 1600 feet per second

4

Cubic Feet per Second formula

Velocity = CFS

Width x Depth

Or

Depth x Width x Velocity = CFS

5

Current Speed TimingCurrent Speed Timing Measure 100 feet of riverMeasure 100 feet of river Time how long it takes a floating object to travel the 100 Time how long it takes a floating object to travel the 100

feet. feet.

TIME FOR FLOAT TOTIME FOR FLOAT TO TRAVEL 100 FT. TRAVEL 100 FT. CURRENT SPEED CURRENT SPEED Seconds Seconds Ft. per Second Ft. per Second

MPHMPH 55 20.020.0 13.6013.601010 10.010.0 6.806.801212 8.38.3 5.645.641515 6.76.7 4.564.561616 6.36.3 4.284.281717 5.95.9 4.004.001818 5.65.6 3.813.812020 5.05.0 3.403.402121 4.84.8 3.263.262323 4.44.4 2.992.992525 4.04.0 2.722.722929 3.53.5 2.432.433737 2.72.7 1.841.845050 2.02.0 1.361.368080 1.31.3 .884.884140140 0.70.7 .676 .676

6

Forces of WaterForces of Water Explain speed vs. force on body in moving water.Explain speed vs. force on body in moving water.

If a current of three feet per second exerts a force of 17 pounds on If a current of three feet per second exerts a force of 17 pounds on your legs, then you might expect that a current speed of six feet your legs, then you might expect that a current speed of six feet per second would exert a force of 34 pounds. per second would exert a force of 34 pounds. SUCHSUCH IS NOT THE IS NOT THE CASECASE because actually the force of water obeys a square law and because actually the force of water obeys a square law and this means that if the water speed doubles, the force goes up by this means that if the water speed doubles, the force goes up by four times.four times.

CURRENT VELOCITYCURRENT VELOCITY AVERAGE TOTAL FORCE OF THE WATERAVERAGE TOTAL FORCE OF THE WATER

Miles per hour Miles per hour on legs on legs body body swamped swamped boatboat

3 3 16.8 lbs. 16.8 lbs. 33.6 33.6 168168

6 6 67.2 67.2 134.0 134.0 672672

9 9 151.0 151.0 302x0 302x0 15121512

12 12 269.0 269.0 538.0 538.0 26882688

7

Current DifferentialsCurrent Differentials

Current differentials result when there are currents of different speeds and /or direction existing side by side in a river.

Many things cause these differentials including boulders, two rivers coming together, and river-bends.

These differentials can be seen on the surface by a experienced water enthusiasts.

Velocity differences in straight, bent channels, and laminar flow, helical flow.

8

River ScaleRiver Scale International river scale systemInternational river scale system

Class 1Class 1- Moving water, few riffles, and small - Moving water, few riffles, and small waveswaves

Class 2Class 2-Rapids with waves up to 3 ft. wide, -Rapids with waves up to 3 ft. wide, clear channels, and easy maneuvering.clear channels, and easy maneuvering.

Class 3Class 3-Rapids with high, irregular waves, -Rapids with high, irregular waves, narrow passages, complex maneuvering, may narrow passages, complex maneuvering, may require scouting from shore before navigatingrequire scouting from shore before navigating

Class 4Class 4-Long, difficult rapids, precise -Long, difficult rapids, precise maneuvering, scouting required, rescue maneuvering, scouting required, rescue conditions difficult.conditions difficult.

Class 5Class 5-Extremely difficult. Violent rapids, -Extremely difficult. Violent rapids, scouting required to navigate congested routes. scouting required to navigate congested routes. Contains significant hazards to life if problems Contains significant hazards to life if problems occur.occur.

Class 6Class 6-Nearly impossible to navigate, life -Nearly impossible to navigate, life hazards are more numerous, scouting is hazards are more numerous, scouting is required.required.

9

PillowPillow

Pillow—created when Pillow—created when the river or water the river or water hits an object just hits an object just below the water’s below the water’s surface and creates surface and creates a lifting effect on a lifting effect on the water above the the water above the object.object.

The closer the object The closer the object to the surface the to the surface the bigger the pillow.bigger the pillow.

10

HoleHole

Hole-created Hole-created when water when water drops drops vertically over vertically over an object that an object that is in the water.is in the water.

Usually creates Usually creates downstream downstream wave.wave.

11

HydraulicHydraulic

A hydraulic is a hole that backfills and creates a hydraulic that recirculates the water back upstream and continues to refill the hole.

Mostly seen as part of a low head dam

12

Eddy’sEddy’sRiver flows downstream around rock

River flows downstream except when an object sticking out of the water creates an area for water to flow and fill in behind object, then current moves upstream toward object.

Water differential back toward object

Eddy Line

13

Examples of Eddy’sExamples of Eddy’s

List of possible objects that create an eddy

1. Trees

2. Rocks

3. Bridge pier

4. Debris in the river

5. Islands

6. Cars

14

Upstream and Upstream and Downstream V’sDownstream V’s

River Flow Downstream

15

Standing WavesStanding WavesStanding Wave– caused by water increasing in speed as it drops over or through gentle sloping area and then piles into slower water below.

Usually found in chutes and after downstream V’s

Named because, the waves ‘stand’ in one place (the water moves through the wave; not the wave moving through the water) as in an ocean wave

16

Types of BoatsTypes of BoatsJon Boat Inflatable

17

Boats and Swift WaterBoats and Swift Water Current- most overlooked hazard on any river.Current- most overlooked hazard on any river. River Right—the right bank when looking River Right—the right bank when looking

downriverdownriver River Left– the left bank when looking River Left– the left bank when looking

downriverdownriver Up current/Down current- the direction of Up current/Down current- the direction of

current flow in relation to the hull of the boatcurrent flow in relation to the hull of the boat

18

Rotational Turning ForceRotational Turning Force

Force experienced when boat is midway Force experienced when boat is midway across a current differential.across a current differential.

Ex: Eddy line (two different current Ex: Eddy line (two different current differentials)differentials)

Very helpful in river reading and river Very helpful in river reading and river running if the force is anticipated and running if the force is anticipated and used correctly.used correctly.

Rotational capsizing force– hull is Rotational capsizing force– hull is perpendicular to the current.perpendicular to the current.

19

River Running TacticsRiver Running Tactics

Ferrying– a way to Ferrying– a way to cross a river cross a river without moving without moving upstream of upstream of downstream.downstream.

Dynamic ferrying Dynamic ferrying using a static line- using a static line- used during time used during time of horse and of horse and buggy.buggy.

20

Forward FerryForward Ferry

The current pushes the boat across. The motor simply neutralizes the current from pushing the boat downstream.

Set angle across the river up to 45°

The Greater the angle to 45°, the faster the crossing, the more power needed to maintain position.

The smaller the angle, the slower the crossing, less power needed to hold the position.

21

Going Upstream from an Going Upstream from an EddyEddy

While underway leave eddy with While underway leave eddy with power crossing current differential power crossing current differential heading upstream with power.heading upstream with power.

Power forward toward and across Power forward toward and across river using ferrying style crossing. river using ferrying style crossing.

Slow power as the other eddy Slow power as the other eddy current pulls you in across it’s current pulls you in across it’s differential line.differential line.

22

Peel OutPeel Out

Peel out– getting out of an eddy into a Peel out– getting out of an eddy into a current and going downstream.current and going downstream.

Start with the boat facing upstream in the Start with the boat facing upstream in the eddyeddy

Power forward and cross the “eddy line” Power forward and cross the “eddy line” at approximately a 45at approximately a 45° angle° angle

Lean down-current while turning (taking Lean down-current while turning (taking advantage of the rotational turning advantage of the rotational turning

force).force).

23

Additional River Running Additional River Running TacticsTactics

Crossing standing wavesCrossing standing waves Crossing from eddy to eddyCrossing from eddy to eddy Entering an eddy from up-streamEntering an eddy from up-stream Ascending a currentAscending a current Descending a currentDescending a current Review international scale of river Review international scale of river

difficulty.difficulty.

24

River Hazards:River Hazards:CurrentCurrent

Velocity and the effect on your body Velocity and the effect on your body in river current handout.in river current handout.

Current on top of the surface is Current on top of the surface is much stronger the current on much stronger the current on bottom of river.bottom of river.

Review-bends in river, helical, Review-bends in river, helical, laminar flow of current in river.laminar flow of current in river.

25

River Savvy (River River Savvy (River Hazards)Hazards)A little lesson in river current----The most overlooked

hazard on the river.

Pictures taken on the Tombigee River in 1979

Notice what effect the current has on the vessel once the captain realizes that he is in trouble

26

Getting a little to close to the bridge

27

Notice the current forcing Notice the current forcing rotational capsizing forces on the rotational capsizing forces on the

up-stream side of the boatup-stream side of the boat

28

Capsized and underneath the Capsized and underneath the bridge she goesbridge she goes

29

Pops up on the other sidePops up on the other side

30

Emptying a little waterEmptying a little water

31

She still works!!!She still works!!!

32

DamsDamsHigh Dams

Built for flood control, water supplies.

Lakes created by the dams used for recreational purposes.

Usually do not present a threat to the boater.

33

Low-head DamsLow-head DamsPerfectly engineered– “Drowning Machine”

Usually less than ten feet in height

Uniform flow of water over the top creates a keeper hydraulic, thus allowing no breaks to form where objects can get flushed out and there-fore recirculating everything within the hydraulic.

34

Low-head dam Low-head dam TerminologyTerminology

1. Hydraulic—formed when water flowing over the top hits the water below and creates a depression which is filled in by the downstream water.

2. Boil---aerated water boils up downstream of the drop creating a hill. Water on the upstream side of the hill rushes back toward face of dam to fill in the depression and water downstream continues downstream.

3. Escape route---below the aerated boil line, the escape route is from the base of the dam along the river bottom, and downstream.

35

Types of HydraulicsTypes of Hydraulics

Downstream Downstream curvedcurved

Straight acrossStraight across ConvexConvex ConcaveConcave

36

Solid ObstructionsSolid Obstructions1. Bridge piers

2. Rocks

3. Homes

4. Undercut rocks

These all can cause accidents by

a. Catching boater off guard

b. Boat strikes object , becomes swamped or capsizes

c. Unmovable object can cause people, objects to become pinned against from rushing water current.

37

StrainersStrainers

An obstruction that An obstruction that allows water to pass allows water to pass through but which through but which strains out boats, strains out boats, boaters, debris, and boaters, debris, and other objectsother objects

Examples: Trees, Examples: Trees, fences,cars,damsfences,cars,dams..

38

UndercutsUndercutsRocks can also form strainers from being undermined.

The picture to the right shows an undercut rock during low flow, be aware that this could potentially trap someone and keep them underwater during a flooding or high water event.

Remember to check these locations carefully and with training to determine location of missing persons.

Avoid these undercuts as they can trap your boat and create problems with rotational capsizing force.

39

ICEICE Ice can be a Ice can be a

layer on top of layer on top of moving watermoving water

Boaters Boaters colliding with colliding with ice may ice may capsize, capsize, current then current then pushes boater pushes boater under ice under ice surface.surface.

40

FloodsFloods

River can take on a River can take on a whole new whole new characteristic and characteristic and hazards at flood hazards at flood stage. stage.

These men here These men here give us job give us job security!security!

Are they going to Are they going to get all the cars???get all the cars???

41

Dangers of FloodsDangers of Floods

1. Dams, other features, can be washed out so only standing waves are present.

2. Water rising to bridge levels can cause strainers or hydraulics downstream.

3. Water flowing over island and trees creates strainers.

4. Water being forced through a small opening creates a vortex and sucks debris into the opening.