Using the Nautical Charts provided by the NOAA

Introduction

In October, 2008, the NOAA redesigned their Nautical Charts website.

First, the NOAA has made it a bit easier to download and use the typical Raster Navigational Charts - RNCs. These charts are simply bitmaps (like digital photographs) - scanned versions of paper charts that we see for sale in stores. For the most part, this webpage shows you how to download these charts and appropriate software (like from MapTech) to plan a voyage (i.e. determine your waypoints.)

Second, the NOAA in September, 2008 began offering downloads of Electronic Navigational Charts - ENCs. These charts are vector charts. Essentially, vector charts consist of many pairs of points. A program that displays an ENC, simply draws straight lines (vectors) on your computer screen connecting the many pairs of points. Think of the jagged lines that make up a coast line.

ENC's are the charts that are loaded into your chartplotters, marine GPS and automotive GPS units. You can download ENC's. BUT as far as I know there is no public domain software that you can download and use to view ENCs. There is an online site where you can view ENCs. See link. To learn more about ENC's, you can follow this link: http://www.nauticalcharts.noaa.gov/mcd/enc/index.htm

The big questions is: At sometime in future will we be able to freely download ENCs (Electronic (vector) Nautical Charts) into our marine GPS units???

Part 1. The Difference Between Raster Navigation Charts
and
Electronic (vector) Navigation Charts

You can skip reading this section. It has no bearing on Part 2

The important difference between raster and vector charts is that vector charts require a lot less memory. Consequently, vector charts are used in most navigation systems.

To understand what raster graphics is, read this Wikipedia entry - link.
Your digital camera uses raster graphics. It generates jpg files.
Program like Adobe Photoshop, Corel PhotoPaint or any "paint" program are used to manipulate the pixels of a raster graphics document.

To understand what vector graphics is, read this Wikepedia entry - link.
Programs like Adobe Illustrator, CorelDraw, CAD programs like AutoCad, and many game generators create and manipulate vector graphics files.

PDF (Portable Document Format) files are interesting in that they are a mixture of raster and vector graphics. Read out this Wikipedia entry - link. PDF files began their life as Postscript files, which are a type of vector graphics. Postscript is actually a language used to describe something graphical. When the language is interpreted, a graphics image is displayed. Read this Wikipedia entry about Postscript - link.

The earliest Cathod Ray Tubes displayed vector graphics objects - like architectual drawings, etc. They were called vector monitors. Here is a Wikipedia link.

Essentially, here is how early vector monitors displayed a vector graphics design. Suppose the design contained the lines of a house and a garage. The vector graphics software would first display all the lines of the house by moving the electron beam on the phorosphous coated screen according to the position of the line - lighting the pixels. Then it would do the same for the garage. This it would have to do 30 or 60 times a second. Here is a Problem. What happens if you have a very complicated design? CRT could not work fast enough

Consequently, now all CRTs work by directly the electron beam along horizonatal lines. A vector graphics object must now be rasterized to be display on a screen. A rasterisation link.

Your television and computer monitor are raster display devices. Again Wikipedia has a nice entry on cathod ray tubes - link.

Part 2 How to download RNCs and Software to use them

If you want to explore the NOAA Nautical Charts website on your own, you can start here:
http://www.nauticalcharts.noaa.gov/

Or if you want to begin further down the tree with Nautical Charts and Publications, then start here:
http://www.nauticalcharts.noaa.gov/staff/chartspubs.html

To Quickly View and Use Raster Navigation Charts

Here are some links to the NOAA site that will get you viewing charts immediately.

Then, after viewing some charts, we briefly explain how to download a free version of Maptech's navigation program so that you can do some actual trip planning.

Just viewing charts:

To view chart 12354 "All of long Island Sound," click http://www.charts.noaa.gov/OnLineViewer/12354.shtml
At the bottom of the screen you can read how to move around the chart.

To start at the beginning with Chart Viewer, click http://www.nauticalcharts.noaa.gov/mcd/OnLineViewer.html
Once here you first have to select an area of the US and then a specific chart. If you choose the Atlantic coast, then you be presented with a long list of charts - in sequence by chart number. For us in Connecticut, the first one of interest might be chart number 12354.

Downloading and Using a free program for trip planning

There are two steps to using nautical charts.

Step 1) You have to get a program that will allow to manipulate the charts. And then,
Step 2) you have to get the individual charts.

You can do this proceeding on your own at the following site:
http://www.nauticalcharts.noaa.gov/mcd/Raster/index.htm

OR you can follow the steps below which concentrate on using the FREE Maptech program.

Note: Before you start downloading stuff, I suggest you create a new folder where you will store the program and raster chart files.

Step 1: Downloading the free Maptech program onto your computer

Note: Since you may be taking a USPS course, you may already have a copy of this program on a CD.

If not, you can download it by clicking here:
http://www.maptech.com/support/doc.cfm?docid=123&CFID=13886007&CFTOKEN=67195671

Step 2: Downloading charts (raster charts) to use with the Maptech program.

Go to the following page, and then scroll to the bottom where you will click to continue. http://www.nauticalcharts.noaa.gov/mcd/Raster/download_agreement.htm