Navigation & Route Selection

The Essence of Being a Responsible Boater

What do you choose as a course or route to meet your goals of safety, adventure and opportunities given the group's abilities and the varying environmental factors?  What about dangers, safety spots, escape routes that lie ahead? Where are the un/wanted wave shapes, how do you use the tides, and avoid the traffic? What might the afternoon’s wind do to the sea state? Where are the play areas? How do you get home in the fog or the dark?

Primary factors to consider:

  • Wind & Waves
  • Tides & Currents 
  • Races & Overfalls
  • Chart & Compass
  • Weather Systems
  • Dangers, exposures, safety zones
  • Equipment limitations
  • Island ethics
Tom studying the chart.

Chart & Compass Fundamentals

"The secret to not getting lost is to always know where you are."

DEAD RECKONING or PILOTING
  • Dead Reckoning. The intended or assumed path through water. Plotted as a line on chart. Based on a course and speed. Mathematical.
  • Piloting. Navigation as art. Use of all available information. Develop a navigator's eye.   ie chart, wind, waves, weather landmarks, bouyage.
CHART & COMPASS
  • Types of compasses – Floating, fixed dial, cruiser & orienteering.
  • Orienteering compass can determine bearings and courses more easily.
  • Variation is the difference between magnetic and true direction.
  • Deviation is the difference between compass and magnetic direction due to magnetic disturbances. 
  • Nav-Aids and their use.
TRUE NORTH AND THE  MAGNETIC POLE
  • Variation (Declination).
  • Agonic line goes through true and magnetic poles.
CHARTS
  • NOAA Chart No 1.
  • Notice the shoreline, cliffs, bars, deep channels, ship routes, buoys, exposure, amount of water flowing. 
  • Latitude, Longitude. 
  • True, Magnetic and Grid North. Compass rose. 
  • Scale on chart.
  • Depths in fathoms, feet or meters.
  • Composition of shore material.
  • Locations of reefs, wash rocks, major tide rips & some hazards.
  • Scale
      • 1:62,500 =  15 minute. 1” = 1 mile.
      • 1:24,000 = 7.5 minute. 2.5” = 1 mile.
COURSE, HEADING, BEARING
  • Heading: direction boat pointed.
  • Course: direction want to go.
  • Bearing: direction to a landmark. 1 of 360 degrees.
ACCURACY
  • One degree of error is 92 ft in a mile.
  • Ten degrees of error is therefore 920 feet in a mile.
AIMING OFF
  • "Put Something in the bank.”
TRIANGULATION
  • The use of multiple bearings to give you probable location.
RANGES
  • Navigational Ranges: A Line of Position that we imagine and use – between two fixed objects. Objects lining up such as a tall tree behind a boat at anchor, or a house with a steeple behind it, any two stationery things.

These are the most important and most used tool in small boating, a kayaker’s primary navigational aid in current or winds as well as assisting in your location.

Is an approaching boat passing off our bow? Our stern? Or are we on a collision course?

CHART PREPARATION

You can't do much on the water where its more seat of the pants. What are you going to need on this trip, the next leg of your route.

Course and other info best plotted before departing. Plot course lines, compute current info. Determine and label compass headings for each leg of the course. Scale off miles. Draw out your ranges. Mark potential ranges that may be useful - to monitor progress,  check position, set danger headings. Info on tides and currents need be ploted. Anticipate drift. Notice water depth over reefs and mudflats and probable wave structure in channels.

V = D/T    Your speed = a measured distance divided by the time to paddle that distance.

D = VxT/60    The distance traveled = your speed times the amount of time you've been paddling.

Plotting a Course Using a Compass

  1. Draw a line on the chart from the starting point to finish point (rum line)
  2. Ignore the needle.  Use the compass as a protractor
  3. Place the base plate of the compass along the rum line so direction of travel arrow points toward your finish point on the chart
  4. Turn the dial so orienting lines are parallel to N-S grid lines on the chart and the North sign on the dial faces North on the chart
  5. Read the number off the index line
  6. Adjust for magnetic variation (in Maine add 20 degree West). That is your magnetic heading. 
Magnetic Variation

Magnetic Variation