SailNet Community - View Single Post - Uses for Chart plotters and chart plotting software
View Single Post
  #21  
Old 02-02-2011
btrayfors btrayfors is offline
Senior Member
 
Join Date: Aug 2006
Location: Arlington, VA
Posts: 1,809
Thanks: 0
Thanked 4 Times in 4 Posts
Rep Power: 10
btrayfors will become famous soon enough btrayfors will become famous soon enough
One strategy which has proven itself to me over the past 8 years -- from Maine to the Virgin Islands -- is to use a computer-based charting program and NOAA raster charts, wherever available.

The raster charts are EXACT copies...pictures, if you will....of paper charts. And, as Labatt said, you can download the latest ones easily JIT (just in time, i.e., when you need them). They are dated and include updates thru the latest NTM before publication.

The chart plotting software allows you to do both short-term and long-term planning. It is VERY easy to plot waypoints and routes for future voyages. Much, much easier than doing it on paper charts. And, don't forget, if you're using NOAA raster charts, you ARE to all intents and purposes doing it on paper charts.

Moreover, you can retain these routes for future passages. On the first use, as Dog said, you need to be very careful to verify the accuracy of the waypoints. I'm careful to choose the routes to stay in deep water, away from obstructions, and at safe distances away from buoys. I choose the waypoints and routes keeping in mind the possibility of having to run them in absolute zero visibility conditions, which I've done several times in extremely heavy fog. This means that I don't always take the most direct route; rather, I take the safest route, even in low visibility conditions.

Once I have created a new route with appropriate waypoints, I upload it to all three of my Furuno GPS units (one at the helm, one at the nav station connected to the laptop, and one spare). That way, I can easily view my boat's position on the laptop as well as obtain detailed information such as distance and bearing to next waypoint, time to waypoint, XTrack error, SOG, etc., etc.

On portions of a route where I expect to see heavy commercial traffic, including large ships, I plot the waypoints outside the main channel, often in water too shallow for big ships. That way, I KNOW I don't have to worry about them hitting me. The Delaware Bay and Delaware River is a good example of this. There's a never-ending parade of large ships going up and down this Bay. If you stay just outside the buoys, there's still plenty of water for a yacht, but not a ship.

We are blessed at the accuracy of the NOAA raster charts for popular boating areas in the U.S. They are unbelievably good. I didn't come to that belief easily, knowing something about how charts are made and being an old navigation instructor. Nevertheless, as Dog and others have said, it behooves all of us to not follow chartplotters/GPS data slavishly, but to consider these as one of many navigational tools. A damn good one, but nevertheless only one of several we should be using when underway.

Bill

Last edited by btrayfors; 02-02-2011 at 06:55 PM.
Reply With Quote Share with Facebook