Maine Island Kayak Resources and Links

Charts and Maps - an introduction

Guiding principle:  Understanding maps and charts, their symbols and notation, and their applied uses, is a fundamental base for good seamanship and interpreting the marine environment.

 

Performance Objectives:
Students should be able to:

  1. Identify chart and map types
  2. Recognize chart symbols and know how to find ones they don’t recognize.
  3. Understand the importance of chart symbols and notation for applied seamanship
  4. Identify several methods of preparing charts for trips

Materials:

  • Topographic Maps
  • Nautical charts of different scale
  • Waterproof Charts
  • Laminated Charts
  • Chart case
  • Chart Book of Eastern seaboard
  • Computer software (CD’s and online software)
  • Chart 1

 

Content:
Maps and Charts are representations of earth from a bird’s eye view.  Maps concentrate on land features, charts concentrate on sea features.  Both have practical uses for sea kayakers depending on the nature of the journey and the environment.  The many islands, submerged ledges, extensive intertidal zones, and aids to navigation make charts a common choice for the Maine coast. 

 

map of peaks isl
chart of peaks isl
Topographic Map of Peaks Island
Nautical Chart of Peaks Island

 

Scale:
A map or chart’s scale refers to the distances that they represent.  They are presented as a ratio 1:20,000 or 1:40,000 is a common ratio for charts used by kayakers while 1:100,000 would cover a much larger area.   The charts below represent Peaks Island at two different scales.  The chart on the left would provide more uses while afloat for keeping track of exact location.  The chart on the right would be useful for planning a multi-day trip. 

 

map of peaks isl
chart of peaks isl
Small Scale Chart
Large Scale Chart

 

Latitude and Longitude

Provide a way to slice up the earth so that exact location can be determined.
Latitude and Longitude of the boathouse on Peaks Island - Latitude = 43o 39’ 25” N, Longitude = 70o 11’ 55” W (read seventy degrees, eleven minutes, fifty five seconds West).  Rarely used piloting but useful for those who Navigate with GPS.

 

Finding Distance and Speed

Distances on the sea are generally in nautical miles (nm)

1 minute of latitude (marked on the side of the chart) = 1 nautical mile ~ 6,080 ft
1 nautical mile = 1.15 land miles

Paddler can use dividers, fingers, or a length of string to determine the distance between two points. 

1 nautical mile per hour = 1 knot (kn)

A group of fairly competent paddlers in light sea conditions can travel at aprox. 3 knots but this varies significantly depending on group and conditions.

 

Symbols and notation –

  1. Some symbols for common hazards and/or obstructions:

obstructions

  1. Aids to Navigation, natural features, anomalies and hazards– all have unique notation. The level of detail can be high and symbols can be esoteric - even for veterans.

chart details

  1. Paddlers can refer to NOAA Chart 1 for a complete index of symbols and notation.  Available at most nautical supply stores. 

Chart Datum, Depths, and Drying Heights

Depths on the chart are generally taken at Mean Lowest Low Water (MLLW), or at the average of low water on spring tides.  This is known as chart datum.  Specific underwater obstructions sometimes have a number associated with them and which can mean different things depending on the notation

 

The Compass Rose

Compass roses are located at several locations on charts.  These are valuable for:

  1. Plotting a course
  2. Finding a bearing to a landmark
  3. Finding the variation between true North and magnetic North

compass rose

 

Preparation for sea kayaking

Charts are the wrong shape to put on the deck of the kayak so the paddler has several options:

  1. Color photocopy the desired sections of the chart and laminate the photocopy.  Be sure to include a scale for distance and a compass rose on the photocopy.
  2. Use charts made from waterproof paper and fold to the correct size
  3. Fold charts and carry in a “waterproof” chart case

Where to purchase

Printed topographical maps are available from many reputable outdoor stores.  Printed charts may be purchased from marine supply stores.   Online maps and charts are available from http://mapserver.maptech.com/bp/mapserver/index.cfm.  Chart software that combines tide and current information is also available from Maptech and Delorme.  This software can now be used in conjunction with modern GPS.

 

Tasks/Activities:

  1. Have paddlers determine distance from one point to another.
  2. Have paddlers compare and contrast features on a nautical chart with a topographical map
  3. Find the lat/long of a point.
  4. Divide up symbols on a map/chart and have paddlers find what those symbols mean and share with the rest of the class. 

Assessment Tools:

  1. Paddlers should show knowledge of advantages and disadvantages of maps and charts
  2. Paddlers should demonstrate knowledge of chart symbols and notation
  3. Paddlers should prepare charts and place on their deck in the appropriate way
  4.  

Resources:
http://mapserver.maptech.com/bp/mapserver/index.cfm
Free online Topographic Maps and Nautical Charts

Burch Fundamentals of Kayak Navigation
Ferrero, Sea Kayak Navigation
Eyges, The Practical Pilot