Use the Correct DATUM for the Lake Pontchartrain Reefs
Captain Paul's response to: ~ GARY KROUSE ~
You are absolutely correct in performing the changes as you stated to enter the unfamiliar DATUM that was used in the published GPS positions.
You will find that your GPS unit has over 200 different DATUM settings. Some of these settings should be used when you are in that part of the world or when you are plotting positions that were determined using these different Datum.
Using the wrong datum can result of a position shift in some cases of a distance of 5 miles or more miles between WGS 84 and some of the more odd, to us, DATAUM settings.
Improper DATUM between the new radar determined WGS 84 and older datum used in the United States such as North American Datum of 1927 (NAD 27), NAD 79 and NAD 83 can result in a position error of over 200 feet.
In the days of using the sextant as the prime navigation this error was not of great consequence as most sextants could only deliver accuracy by highly-skilled and experienced navigator can determine position to an accuracy of about 0.25-nautical-mile about 1500 feet. So a position shift of 400 or 500 feet was not of great concern. Why, even the U.S. Coast Guard designed LORAN is only accurate to about 1200 feet.
But today a consumer GPS with the WAAS Differential option can discern a position to within 3 meters, about 9.8 feet. This technology has enabled fisherman to mark their honey holes, oyster reefs, tree stands, deer scrapes and of course underwater artificial reefs with the accuracy consistent with modern GPS units.
Being off position by 200-500 feet can cause the user to completely miss his deer stand or an underwater reef.
If you EVER find GPS coordinates published or obtained from a friend, etc., in any DATUM other than the one you normally use, change the DATUM setting in your GPS unit to the other datum, enter the positions, then change the DATUM setting back to the DATUM that you normally use.
The GPS unit will do the converting for you.
Of course that is another way, there always is, and that is for you to convert the datum to the one you are using by means of one of several conversion programs.
Some of the available sites on the use of DATUM can be found on the web.
The most used program is that offered by the U.S. Army Corp of Engineers on their web site called Corpscon 6.
It can be found @
http://crunch.tec.army.mil/software/corpscon/corpscon.html
You can download the program and place it in your computer with a desk top link. It is an interesting tool that you should at least have.
Other info on DATUM can be found at the following web sites:
http://www.nps.gov/gis/gps/gps4gis/how2s_byCatagories/6-GPSPostProcessing/datum_advise_NPS-AKSO.doc
http://www.colorado.edu/geography/gcraft/notes/datum/datum_f.html
By the way you should ALSO check the POSITION FORMAT settings. Sometimes positions are shown as Degrees, Minutes, Seconds and tenths of seconds (DDD,MM,SS.s) and sometimes they are shown as Degrees, minutes and thousandths of a minute. (DD,MM.mmm). Be sure to use the correct format when entering the positions as well as the datum.
About the Lake Pontchartrain Artificial reefs, I have a program that I call CAPTAIN PAUL’S FISHING EDGE OF GPS WAYPOINTS.
The Lake Pontchartrain ~ Maurepas Edge file has over 280 waypoints which of course includes all of the Lake Pontchartrain artificial reefs.
THE CAPTAIN PAUL’S FISHING EDGE FILES ARE ONLY AVAILABLE ON THIS WEB SITE. (
www.louisianasportsman.com)
Check out the OUTDOOR STORE button near the left top of HOME page in the dark banner. Click on that button, then when the Outdoor Store page appears, click on the “ FISHING EDGE” button.
When ordering the areas you want you MUST indicate what type of GPS system you have as different brands write their data files in different protocols. Simply select which EDGE program(s) you want and click on that box. Follow the directions and the EDGE will be delivered to you via email as an attachment.
I call the Programs, CAPTAIN PAUL’S FISHING EDGE,” because I believe that they will give the fisher an advantage in getting to, finding fishing spots, moving around, and getting back from some of the more favorite fishing areas in the state.
The “CAPTAIN PAUL’S FISHING EDGE” is a very unique ELECTRONIC MEDIA Program that can be downloaded directly into various GPS units from their manufacturer’s Mapping program or via several of Maptech’s mapping software programs.
This technology saves countless hours of having to manually enter each separate waypoint value into the GPS receiver. The entire procedure of loading over 200 odd waypoints from a CAPTAIN PAUL’S FISHING EDGE file takes less than three minutes from the time you view the email file to the time that they are loaded in the GPS receiver.
Presently I have NINETEEN Captain Paul’s Fishing Edge Files. They include Barataria Bay, Lake Borgne, HOPEDALE MRGO to the Miss Sound, Hopedale to Bayou Terre Boeufs, DELACROIX to Point a la Hache, Bayou Bienvenue, Port Sulphur, Lake Calcasieu, Lake Pontchartrain, Myrtle Grove-Lake Hermitage, Empire to Buras, Leeville-West, Leeville-East, Lafitte, the Pearl River WMA, Vermillion Bay, The Rigolets, Big Branch NWR, and Bayou Sauvage NWR.
To download The CAPTAIN PAUL’S FISHING EDGE program(s) in your GPS, you MUST have FIVE items.
FIRST, a GPS Receiver; SECOND, that manufacturers Mapping Program or its Waypoint Manager software; THIRD, a computer with a connecting cable to the GPS unit or data card; FOURTH, a valid E-Mail Address that accepts attachments, and FIFTH, a CAPTAIN PAUL’S FISHING EDGE FILE.
Separate Program Files are designed for GARMIN, DeLORME, HUMMINBIRD, MAGELLAN, RAY MARINE, LOWRANCE and other GPS receivers and their mapping programs that use a GPX data protocol as well as for MYTOPO TERRAIN NAVIGATOR.
These Edge files are NOT interchangeable.
ALL of the CAPTAIN PAUL’S FISHING EDGE of GPS WAYPOINTS are ONLY available at the LOUISIANA SPORTSMAN'S 'OUTDOOR STORE.'
The OUTDOOR STORE link button may be found in dark banner at the top of the SPORTSMAN’s HOME PAGE. From the OUTDOOR site, simply follow the instructions for ordering from the Louisiana Sportsman’s Shopping Cart.
The Lake Pontchartrain Reefs (in WGS 84 Datum) that are included in the EDGE file are as follows:
LAKE PONTCHARTRAIN ARTIFICIAL REEFS
Orleans Parish Reefs
The first and oldest artificial reef in Lake Pontchartrain is located along the south shore of Lake Pontchartrain, about two miles east of the New Orleans Lakefront Airport. The reef according to my readings, is a random placement of rocks, believed to be limestone, that total a distance of about 341 feet from the buoy at a bearing of 342º (Mag).
The “reef” is NOT a continuous reef, but looked like several piles of rocks placed from a point just south of the official marker buoy extending to the North-northwest. I have been told that Katrina “moved” the buoy, but that the reefs are still in the stated positions.
Marker Buoy 30º 03.521’ N. lat ~ 89º 59.608’ W. long.
Center of the reef 30º 03.518’ N. ~ 89º 59.618’ W. long.
Another reef is located in Orleans Parish East of the Lake Pontchartrain Causeway, about 7 miles north (15° Mag) of the Municipal Yacht Harbor at West End.
The reef is made of two different size dome shaped reef balls, or rather one half of a hollow ball. The hollow concrete structures have random sized holes through out the surface of the half sphere. They look like half of a “Wiffle” baseball and are placed in 13 to 15 feet of water.
It is designated as “Orleans site Reef Ball Lake Pontchartrain” and is at or about 30° 07.441’~ N. Latitude ~ 90° 04.695’ ~ W. Longitude
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
Jefferson Parish Reefs
These reefs are located about 7.5 miles west of the Lake Pontchartrain Causeway Bridge and about 5 miles north east (58° Mag) of the Kenner boat launch at the lake front. The reefs form a triangle around existing shell oil-field pads and are made of over 600 reef balls. It too has two different sized reef balls. Each reef is separate and is marked with a yellow buoy.
These “Reef Balls” are at or about:
Reef # H-1. 30° 05.028’ N. Latitude ~ 90° 12.096’ W. Longitude
Reef # H-3 30° 05.034’ N. Latitude ~ 90° 12.582’ W. Longitude
Reef # H-4 30° 05.274’ N. Latitude ~ 90° 12.336’ W. Longitude
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
St. Tammany Parish Reef
St. Tammany at this time has three different reef locations.
One of them, the oldest is located near the north shore between the Lake Pontchartrain Causeway and Goose point. A friend of mine investigated the reef in mid January of 2007. He indicated that there is a small yellow marker buoy over the site and that there are several cane flags marking the general area. The location is about 2.8 miles due east (90°Mag) from the causeway, 3.8 miles SSW (199° Mag) of Green Point and about 4.4 miles west northwest (275°) of Goose Point and about 6.5 miles SSE( 164° Mag) from the entrance to Mandeville harbor at the Causeway by the north shore. It is designated as N1 Reef Ball LP.
He advised that the reef is a rather small area and that it is located at or about:
30° 16.298’ N. Latitude ~ 90° 03.753’ W. Longitude.
The newer St. Tammany reefs are in an eastern and western direction from the N1 Mandeville Reef.
St. Tammany EAST, Reef Ball LP is at or about 30° 13.455’ ~ N. Latitude ~ 89° 56.854’~ W. Longitude .
It is about 2.5 miles south (170° Mag) from the mouth of Bayou Lacombe.
The St. Tammany WEST, Reef Ball LP, is located at or about 30° 18.348’~ N. Latitude ~ 90° 09.000’ ~ W. Longitude. It is about 5 miles south, southeast ( 71° Mag) from the mouth of the Tchefuncta River at Lake Pontchartrain and about 2.7 miles west of the Lake Pontchartrain Causeway.
All of these reefs are made of the concrete balls.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
St. Charles Parish Reef
The St. Charles Parish Reef ~ Reef Balls are located about 6.6 miles at a bearing of 72° (mag) from the PEUINE Road Boat Launch at Feinier Beach and about 6 miles at a bearing of 29° (mag) from the Bonnet Carre Spillway launch at Lake Pontchartrain. This is also constructed out of the hollow concrete balls.
It is at or about : 30° 08.085’~ N. Latitude ~ 90° 19.038’~ W. Longitude.
Unless otherwise specified, all positions are stated as H,DDD,MM.mmm and were determined using WGS 84 DATUM. All Headings / bearings / courses are stated in Magnetic Degrees and statute miles.
~ Captain Paul ~
I got mine on Amazon.com
I'm not sure on which website to order it from. I'm just....
Yea I'm young I'll probably order it online in the next....
no worries dude. when u get it, if you have trouble email....
I think ima go with the oregon but I'm a little worried....