Understanding Nautical Charts :   You landlubbers may call them maps, but to the mariner the actual name is "nautical charts".  These charts can be quite large depending on the area encompassed.   You can purchase paper charts from many marine supply stores.  And if you need one for an area that they do not stock, most will be happy to order the ones you need.  You need to aware that the depth readings shown on these charts may be in either fathoms, (6 feet), meters (about 3 feet) or feet if for shallower bays.  On each chart there will be a title bar somewhere depicting this unit of measurement.   All charts (at least the northern hemisphere) are laid out so North points UP.

For the mariner, you will usually have to roll them tightly & store them with a rubber band around them, as there is not much room to store 3 foot square chart in the small boat.  Some small boat owners build wooden racks attached to the cabin ceiling with round holes drilled to accommodate many of their rolled up charts.

Charts are laid out with horizontal & vertical lines overlaid on the chart.  The vertical numbers are latitude (north/south) & the horizontal are longitude (east/west).  These numbers will always be shown on the edges of the chart.  The latitude number lines will not be equal as they go north/south because of the earth's being a sphere.  The reference numbers start at the equator.   The latitude reference is taken at the earth's surface at the equator.  And reference is then made to Latitude being north or south of the equator.

All readings for location of a reference point will be written as Latitude/ Longitude as this example Lat 48-26-506 N, &  Lon 124-36-125 W.   This is referring degrees, minutes & seconds.  These numbers are all in increments of 60.  However since the advent of modern technology GPS has made a change in the old seconds from 60 to now in 100ths.  So if your GPS readings were taken off a chart or are years old GPS numbers with only 2 digits, your exact location may be a few feet off using current GPS units.

You can take a reading off a chart, say for a sunken ship by using a 36" ruler, laying it horizontally thru your position & then reading the corresponding number on the vertical edge of the chart for your Latitude.  Then do the same for the Longitude by laying the ruler vertically thru your position & reading the numbers off the bottom or top of the chart.

As an example by using the information below, you can calculate your approximate position in relationship to another position

Longitude     ---   using Westport North Jetty     West 124-11-078 N as a reference

1 degree = 60.7 nautical miles at the equator               124    7525.8 NM west of datum line of Grenich Village (England)
1 minute = 1 nautical mile (6071')                                  124-11   11 NM west of 124-00
1 second = 60.7'                                                              124-11-0    0 feet west of 124-11
.010 of a second = 6.07'                                                 124-11-07   42.49 feet west of 124-11-0
.001 of a second = 7.28"                                                124-11-078    58.24 inches west of  124-11-07
.0001 of a second =.728"                                               124-11-0782   1.456 inches west of 124-11-078

Latitude   ---  using Westport North Jetty  -                46-55-540  N as a reference, uses the same basic principle as Longitude,
                                                                                         but the first digit 00 is the Equator

Longitude  ---  Westport North jetty                            124-11-078 W
Westport Buoy #5    (west of North Jetty)                   124-12-700  (1 mile plus 4127.6'   =  approx.  1  5/8 miles west of north jetty

For instance if we use Westport Washington's buoy #3  as your position (46-55-005, 124-14-820), we see the Latitude as the first set of numbers, with the Longitude as the second set.   For Latitude, the numbers get larger as they go farther north, & the Longitude get larger the farther west you go.   So from this you can quickly calculate if your friend calls you on the radio & says he is at 47-10-501, 124-24-802, if you compare his numbers to yours, this means he fairly close by & is slightly north & somewhat west of you.

From the above you can see how precise a good GPS reading can get you.  Engineering/surveying goes one more digit (.0001) on the seconds numbers as you can see above is rather precise.

Electronic Charts :  I envy the owners of larger boats that have computer satellite capabilities who can at the click of a mouse call up charts of about anywhere.

With today's modern technology you can tap into free internet NOAA charting at http://www.ngdc.noaa.gov/mgg/bathymetry/maps/area5.html    However these are really only good for fishing if you are looking for rock or gravel structure.  I have not been able to find a way to use the mouse to provide a GPS Lat/Lon location on the screen chart however.  But you could get close by doing a split screen with Google Earth which does give you GPS numbers & do a comparison to the NOAA chart.

Chart Usage For Navigation :   Most of us will not be normally traveling up or down the coast or real far offshore, but will be using charts/GPS to navigate under limited sight conditions.  I suggest you set down with charts for your intended area & locate by hand some locations that you foresee that could be beneficial to you at a later date & enter them in your GPS unit.  This can be buoys, piling markers, river entrance channels, boat basin entrances, jetty ends or anything that may be of assistance to get you out & then back in safely if the weather visibility turns bad.

If you run offshore 20 miles or so, always have a go-to buoy or landmark to get back to your entrance location.

Chart Usage For Fishing:   Now the use of GPS for fishing pretty well go hand in hand with the navigation requirements, with the addition of those know spots that hold concentrations of fish.  This could be underwater rock structure if you are after bottom-fish or known current/eddy locations where bait is usually found on a particular tide.  Many times you may be able to share some of this info with other fishermen.   Or gather yourself when you repeatedly catch a nice fish in the same locations.  For the newcomer go not be bashful, ask & many times you will receive more than you ever dreamed was available.

Most of us fishermen over the years have put together a loose-leaf notebook that we photo-copy sections of the actual nautical chart that pertains more to the area we may be fishing.  It is best to purchase clear plastic pouches with the ring binder holes punched so you can keep your using charts somewhat protected.

Years ago in the early 1950s when I fished with my uncle at Westport, our boats were rentals either 16' or 18' open boats that we used 7.5hp or 10hp outboard motors on.  We had no charts, did not know what a depth-finder was (other than stripping off line 2' at a time while dropping a baited mooching rig & sinker over the side).  We never used a compass as we were always within sight of land & did not have to run that far to catch a limit of salmon.  And if it was foggy, we never went beyond the end of the south jetty, & could simply follow the shoreline back to the boat basin.

Times have changed.  Now we would not think of leaving the boat basin without the sonar & GPS functioning.   Although while off topic here, be sure to turn on your VHF radio also.

Take Time to Learn Your GPS Unit:  Most of us do not use our electronics enough to become fully informed as to what is available.  I have found many things that I wanted on my units, or what was there that added to cluttered screen that I wanted taken off.   Part of it was that I do not understand their terminology.   I have made it a point to write down my questions & the go to a sportsmans show where I ask the factory representatives.  Usually once we can communicate as to what my situation is, (they inevitably call it different than I do) it is easier then to at least know where to go in the menu & then stumble around until I get it thru my feeble mind to get added what I want.  I have not had much luck talking to local salespersons at even supposedly good marine stores.   They seem to have a basic knowledge, but need to be at a unit, punch the menu & try to figure out what I am trying to inquire about.

I have a tutorial GPS/Sonar program downloaded on my computer for my Lowrance unit.  It helps, however I do spend a lot of time on my new boat with the GPS /Sonar unit learning & changing settings.  The hardest is when I make a change & did not really understand what it meant or the consequences until after I turned off something I really did not in tend to do.   Out comes the manual & head scratching time to figure out how to restore what I just deleted.   Keep your manual handy.  But keep in mind that these technical writers are usually writing over our heads most of the times.   They need to pull a person off the street that has no understanding or interest in what they are writing about & have them be able to understand what the techies have just put on paper & how to make the unit function by reading the instructions.  Also keep in mind that men & women's minds think differently (not sure if this is a condition here or not, BUT) .

But the more you understand your unit the better equipped you are & the more you can gain in the long run.  If you do not use it to near the maximum, why did you just spend big bucks when you only needed a unit that just shows you water depth & a plotter.  If you were trying to impress your fishing friends, they will soon figure you out if they ever fish on your boat & you only know how to turn your unit on & off.

Personal Experience:  One day a few of years ago, I went Columbia River sturgeon fishing with a friend in his boat.  Since we had fished this area many times, he did not turn on his sonar/GPS unit.  He seems to have an aversion to running his battery down, so he turns the sonar on only to find his fishing hole or to locate fish.   He really does not understand the GPS, only to the point of seeing the boat on the plotter screen & being able to following his trail back.  Anyway this particular morning we got outside the boat basin & it was slightly foggy, no problem he had done this route many times.  Well the fog got thicker & when he started churning up mud off the lower end of Puget Island with his prop did he listen to me & turn on the sonar/GPS plotter. 

Things got worse as he did not know where he was when he turned the GPS unit on, he had no reference point as to where he had been.  We now knew the water depth, & we were near the island but that was about it.  And to add to his excitement, a freighter we could not see in the fog blew it's horn.  Mind you these freighter's horns sound formidable in the fog especially when you have no idea how close she is or where she is at.   With us being unsure where we were in the fog we surely did not know whether the freighter was in bound or outbound.  

I suggested we head west knowing we would have to encounter the river side of Telleashee island.  When we picked up some piling on the edge of the island we knew then where we were & we were then out of the shipping channel enough to let the freighter pass by.  The problem that he could not tell where he was is that his GPS unit was set for the chart to always be forward of the boat's bow.  So every time he steered the boat in a different direction the chart changed it's appearance & nothing looked familiar.   It took a bit of looking in his manual for me change his unit to now read chart NORTH or top of the screen.  Even though he knew the river, with the GPS chart constantly changing he was being confused & not really watching his compass as he should.   He was out of his elements & did not really know exactly where he was.   This is just one example of what can happen & with the potential of being disastrous.

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