Using Charts

April-May 2003

This is an article from WaveLength Magazine, available in print in North America and globally on the web.
To download a pdf copy of the magazine click here: > DOWNLOAD

by Timothy Sprinkle

Extensive light blue areas with rocks and reefs are great places to paddle!
Green marks tidal areas. Yellow, land.

As early as the sixth century BC, sailors began using rough maps to plot courses and find their way at sea. But today's nautical charts, based on 25 centuries of sea-going experience since then, are far more accurate, showing details as large as current patterns across entire oceans, or as small as individual rocks hidden in tiny inland rivers.

A nautical chart holds a wealth of information - water depth, distance, compass directions, tidal passes, maximum currents, shoreline, prominent topographic features, aids to navigation, and other navigational information - all of which can be a great help both in planning and executing a paddling trip.

The first step is to get the right charts. Kayaks can go many places that average recreational boats cannot, so it's helpful to get the most detailed charts you can find (unless you're on a long trip and don't want to carry a load of different charts). The more detailed a chart is,the less area it covers, but the more small obstacles on it - rocks, shore details, etc. Charts are also updated every few years, so it's good to get the most recent editions. Charts of American waters are available from the National Ocean Service (www.nos.noaa.gov), while Canada's coasts are mapped by the Canadian Hydrographic Service (www.charts.gc.ca/chs).

Next, study the charts for your proposed trip. 'Piloting' - the use of landmarks for navigation - will require that you have a basic understanding of what to look for out on the water. Look for buoy numbers, land formations, shore-based landmarks, and other clues along your course. Just like keeping track of highway exit numbers on a car trip, this pre-planning will help you realize when you've strayed off course.

As important as a chart can be for identifying where you should go, they are equally useful in understanding where you should NOT go. Those numbers scattered all over the water are depth soundings, and they serve to show commercial ships where the deepest and most passable parts of the channel are. Taking note of these areas, an informed paddler can estimate where most of the larger marine traffic will be heading and keep out of their way. Deep water readings close to shore also reveal inhospitable landing sites.

Anyone who has ever paddled in a tidal basin knows how drastically water levels can change, closing off once passable waterways and flooding seemingly open areas in a matter of hours. Coastal charts mark these tidal ranges with colour: the permanent shoreline at high tide is yellow, while inter tidal areas are shown in green. The water, always blue, travels up the green area towards the yellow high tide line. This information, paired with a local tide table, can mean the difference between a successful paddling trip and an unexpected hike over suddenly- dry tidal flood plains.

Although the United States and Canada chart their waters on a regular basis, both governments do so separately, resulting in some minor variations between the two. Some symbols differ, and channel routes and depth soundings may vary, and this can cause some confusion when switching between charts on an international trip. When in doubt, it's a good idea to have a copy of the chart legend for each country you paddle in, often called Chart 1, for reference when things start to get confusing.

Most nautical charts are large and need to be folded for use on the deck of a kayak, although it is possible for paddlers to buy specially prepared small format charts for some popular paddling areas. Plastic laminated charts can also be purchased so that they stay dry and intact while strapped to the deck in front of you. Or you can buy a transparent chart case to protect unlaminated charts. If you're leading a group, you can photocopy the relevant chart section (ideally colour copy so as not to lose the colour-coded information), and give one to each paddler in a heavy duty ziploc bag so that they can keep it in front of them and be more aware of the route you're taking.

USING YOUR CHARTS IN AN EMERGENCY

OK, so a storm has rolled in over the horizon and suddenly changed your trip plans. Maybe it's pulled you farther offshore than you'd like to be, maybe it's pushed you down the coast and off your trip course, or maybe it's got your heart pounding so loud in your chest that you can barely see straight enough to paddle. Fear not, your nautical chart can set you straight again. Here's how:

Look around. Are there any landmarks or numbered buoys in sight? If so, find them on the chart and plan a course from there.
If you can't see land or can't identify the coastline you'll have to rely on a practice known as 'dead reckoning'. On the chart, find your last known position. Then, using your compass, determine the direction and speed you've been paddling. Three to four miles per hour is generally a safe estimate (unless you've been paddling with or against significant wind or current). Trace a course from your last position based on this speed and direction - for example, 30 minutes paddling north from your point would put you 1.5 miles away. This should give you a rough position that you can find on the chart, giving you a better idea of how to get back to land.
When in doubt, remind yourself that you live in the 21st century, pull out your GPS to find your position, and then locate yourself on the chart in relation to the shore. For many boaters, GPS has replaced pencil-and-paper navigation. But remember, batteries die, electronics go bad, and a solid understanding of chart navigation can get you out of tight spots when even your GPS fails you. It's also a legal requirement for you to have appropriate charts for the area you're traversing.