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NavCal Marine Services LLC 865-765-3407


is a computerized version of a traditional paper log book with electronic input from a GPS or LORAN receiver plus manual log entries from the Captain.



Marine log with NEMA0183 data input from GPS or LORAN Version 3.05   August 1998

NCDRLOG is an electronic marine log program that takes Latitude, Longitude, Course, and Speed data from the NMEA0183 family one or family two data outputs from a GPS or LORAN receiver. It takes date and time information from your computer and typed inputs from the Captain to produce an accurate electronic marine log of your boat's path. This log is displayed on the screen, recorded on your disk, and can be printed out on your printer after the cruise.

The major feature of this program is SAFETY. Many navigators place far too much reliance on electronic aids to navigation and neglect traditional log keeping. If the electronic aid fails the navigator may only have a very crude idea of his position and little or no knowledge of how existing conditions are effecting his vessels' movement. If this program is consistently used it is less likely that you will be left in the dark as to vital navigational data even if you experience a GPS or LORAN receiver failure.

For the highest reliability you should operate your receiver on one battery and your computer on another and preferably use a Laptop computer with its own internal battery. If your receiver fails or looses its signal the computer will have recorded your DR log data. The chances of both receiver and computer failing are less than depending on just one method alone. To add further safety, this program warns you when the variation of the average of several Latitude and Longitude readings is excessive.

This program will run on any IBM compatible microcomputer with an available serial port. This full users manual can be printed out and contains installation instructions.

You should read this users manual thoroughly before you attempt installation and use of this package. Its use is not difficult but we want to insure that you thoroughly understand the features and LIMITATIONS of this program. Your package should contain a floppy disk of 3 1/2 inch diameter for your computer.

Your first task is to have a competent electronics technician fabricate a data cable per the information below using a connector for your receiver. Use shielded cable of at lease 22Ga and no longer that 50 feet total.

DB9 (9-pin) connector
P2 Receive data = receiver output
P7 Signal ground = receiver ground
Cable shield = receiver ground
No connection at computer end

DB25 (25-pin) connector
P3 Receive data = receiver output
P7 Signal ground = receiver ground
P1 Protective ground = cable shield
No connection at receiver end

Route the cable away from any electronic interference and to your computer. You can connect the cable to serial port one or two on your computer and select the proper port when you start the program.

Make sure all connections are electrically and mechanically sound. Remember the marine environment can be very harsh on electronics. Be sure your computer is placed in a convenient but well protected place. The navigator will need ready access to the keyboard for making manual entries at major course or speed changes etc. The log is laid out like a traditional nonelectronic log and is intended to be used in a similar fashion.

Once you have the proper data cable connections you should copy the program from the master floppy supplied to the disk you plan to use it from and store the master floppy in a safe place. This program will run from either a hard or floppy disk. It is suggested that you used a hard disk if your computer has one as it will be faster. Be sure to see any last minute notes etc. by typing the "README" file to the screen or copying it to your printer.

PROGRAM START To get the README notes insert the master floppy and change it to the default device (A: if it is in floppy drive A). Type "README" for screen display or "COPY READ.ME PRN:" for DOS or similar Windows actions to get a written copy on your printer. Then copy the program to your selected disk by typing "INSTALL C" for your hard drive.

Now you are ready to run the program for a trial. Change to the disk and subdirectory containing the program and type NCDRLOG. The program will fill the screen with the NavCal standard screen logo/program header. Note the version number displayed on the far left side on line one. Please refer to this version number and the program name (far right on line one; NCDRLOG) in any correspondence. Item number one gives you a chance to enter the name of the file you want the log data stored in. The prompt contains a default file name that you used the last time that you can use by pressing the Enter-Key. You will always have a line near the bottom of the screen that provides more information about the item you are entering. You can use any valid file name if you like and you can include a drive or path definition if needed. You cannot include a file name extension as the program automatically supplies a ".LOG" extension. You should put all your files in the same place on the disk and preferably in the same subdirectory as the program so they can be easily found.

OPTION SELECTION The program will automatically select a file name in the LYYMMDDN format where: L = first character YY = year MM = month DD = day N = 0 to 9 for up to 10 trips per day. Type "NEW" for the file name to use this option and allow you to easily track log activity. If you are continuing a trip the program will default to the last trip name that you used for easy entry. Look at the information at the bottom of the screen for instructions until you learn the program. It is suggested that you use the default automatic names for ease of file location. The program uses the MM/DD form of its dates as this puts the most and least significant parts of the date in their proper order. For your first try just hit the Enter-Key to accept the default file name. If you enter a file name of "END" the program will exit properly at this point. The program will attempt to open the file with the name and any path that you entered. If it finds a file you will be asked to "Select Log or Hard copy L" with the default to logging as indicated. If no data file exists you will automatically go to the log mode. In the log mode several additional questions will appear on your screen. Item number two asks which serial port you connected your receiver to. You can use either port one or port two for the data cable. The default is port one. The port you select will be set up properly for true NMEA0183 input at 4800 baud that is the standard for navigational data exchange between electronic devices. Your receiver must match. Don't worry if you make a mistake in entering options as you will have a chance to correct your answers later before going into the logging mode. Next you will be asked to select the minutes you want to wait between automatic log entries. The maximum time is 60 minutes and we recommend the default of 15 minutes unless this is going to be a long trip. You can log as often as every minute for short runs or only once an hour when offshore. You can enter a manual log entry any time you like and these times are for the automatic log entries only. Select a time that will give you the information you need in the log. You can get 50 lines on a printed log page and at 15-minute intervals and this is about 12 hours without any manual entries. Next you will be asked for the error limit for latitude plus longitude variation. This program takes the average of several readings from your receiver for each update of the immediate display line on the bottom of the screen. It also calculates the statistical variation (n-1 method) of latitude and longitude. These L and Lo variations are added and displayed as a way to indicate the relative reliability of the position data. This combined L plus Lo variation is displayed on the immediate display line. Any time this variation exceeds the limit value you enter you will get an alarm to warn you that the data is possibly unreliable. We suggest that you start with the default value of 10. Faster boats may need to increase this value as your boat location is changing more rapidly between receiver reads.

PROGRAM RUN You will also see instructions on the screen about using the up/down arrow keys and page up/down keys to change the display window location. You can have 18 lines of data on the screen at any one time and these keys give you a way to look back through your log if needed. You are also instructed to enter a manual line in the log any time you change course or speed. This is standard practice in manual logging and you should do it here also. This program averages your course and speed during the time between log entries either automatic or manual. If you change course and do not enter a manual line the course recorded will be the average course during the time between log lines. This may not be desirable and could be confusing later when you look back at your log. You are also asked not to leave the program in keyboard input mode for long periods of time while you are logging. You must give your computer time to read the receiver and the time needed varies with your computer and your receiver. Type your manual entries promptly and press the Enter-Key. After reading and entering the alarm limit you will be asked "Item number to edit". This will give you a chance to change any answers if necessary. If you change item one (the file name) you will restart the program. If you have no changes to make just press the Enter-Key to begin logging.

The computer will open the proper serial port, clear and reset the screen and display an example log line if this is a new file. The screen display contains: North/South and East/West L and Lo indicators in the header line Date in MM/DD format Time in HH:MM format Latitude in DD MM.MM format (last) Longitude in DDD MM.MM format (last) Course in DDD format (averaged true) Speed in KK.K format (knots over ground averaged) Remarks contains any remarks entered. After you are in this logging mode the computer will receive data from your GPS or LORAN if it is turned on and properly connected to the serial port you selected. It will average a small number of reads and then update the information near the bottom of the screen.

This update line begins with "VAR" followed by a number which is the absolute value of the sum of the statistical variations of the latitude and longitude values in minutes. If this variation gets larger that the limit you entered you will get a warning message "WARNING LATITUDE PLUS LONGITUDE VARIATION IS EXCESSIVE!!!!!!" plus a varying tone. This is a warning that the data is varying and indicates you may be out of range of the transmitters you are using or have some receiving problem. You may need to switch to another set of stations or check your equipment. This variation analysis only looks at the Latitude and Longitude variation. The update line also contains the time to the nearest second from your computer plus the other normal display information. If this is the first pass since the program started it will write this data to the log. You can then enter remarks like "Leaving the pier" etc. if you like. After this first line is logged the other automatic lines will be at the interval you selected.

If you selected a 15-minute logging interval the program will now make automatic log entries at every HH:00, HH:15, HH:30 and HH:45. The program uses your computer's date and time values so make sure they are correct. You can check/change the date by typing DATE at the DOS system prompt (not in this program). The time can be checked/changed by typing TIME. You can enter manual log entries any time you like. You must end the keyboard entry with an Enter-Key to write the data to your file and restart reading the receiver. Do not leave the program in keyboard input mode for long periods of time as it will not be able to read your receiver during these times. The program will not allow you to type beyond the end of a line. Any excess characters will be ignored. As mentioned earlier, you should make an entry every time you make a significant course or speed change as is normal in any log. The program averages the course and speed data between log lines. You can press the Enter-Key to enter a blank remark/manual line if you don't want to take the time to enter a remark at a course change. This will at least insure that consistent data is averaged for the log entries. If you enter a remark before the program has read the receiver you will see a line with some data missing which is normal. This program rounds Latitude and Longitude to the nearest 0.01 minute, speed to the nearest 0.1 knot, and course to the nearest whole degree.

Your GPS or LORAN may provide more digits but they may or may not be significant depending on conditions. The format of the output is dictated by the NMEA standard and is not indicative of the accuracy of the data from a particular device. When you are ready to stop the program press the Escape-Key BEFORE TURNING THE RECEIVER OFF! If you turn the receiver off first or if it stops you may have to reboot (CTRL-ALT-DEL) your computer. You will still have the last valid position even if your receiver fails. You can show all of your log file names in a subdirectory by typing DIR *.LOG Any files that are no longer needed can be removed using the normal erase command.

IN CASE OF DIFFICULTY If you experience difficulty with this program please recheck these instructions carefully. Check your receiver's instructions also. Do you have it setup to output the proper data. This program must have NMEA0183 family one or family two data at 4800 baud to function correctly. If your receiver provides some other ASCII format and you can send us details and we will consider adding it if it can be added without causing problems to the standard formats. This program will not handle the NMEA0180 (BCD) format at this time and we do not anticipate adding this capability. If you inadvertently send the program NMEA0180 data it will stop since it cannot decode this data type. The program will properly handle receivers that output both family one and family two data. It will use the family two "recommended minimum sentence" if available.

This program does NOT use the check sum or signal validity data since it is either not available or requires decoding additional lines of data in one or the other formats. The extra line decoding would slow the program down. Your receiver should warn you of this type of problem. Make sure you do not have any TSR or "POT-UP" programs running that might cause problems. Check your manual carefully. This is an interrupt driven program and timing is critical to its proper operation. It must read the receiver and also watch for keyboard input. If you are still experiencing problems after rechecking everything carefully please give us all the details you can about your equipment and the exact nature of the problem. Please include: Computer type; 386, 468, Pentium, etc. Manufacturer; IBM, etc. Ram memory; 32M etc. Hard disk drive size; 500M etc. Floppy disk type; 3.5" 1.44M etc. Serial port using; 1 etc. Operating system; MS DOS 6.22 etc. Any other computer information GPS or LORAN Manufacturer Model NMEA format provided. Other information Detailed problem description We will respond to your written requests promptly with a detailed written response.

INTENDED USAGE As with all software we cannot grantee the results of this program and CAN NOT BE HELD RESPONSIBLE FOR ITS FAILURE. IT IS INTENDED ONLY AS AN AID IN LOGGING AND NOT FOR ANY OTHER PURPOSE EXPRESSED OR IMPLIED. We will provide reasonable assistance in resolving problems. If your receiver is not sending data to the program and you have the proper cable connections and serial port selected you should consult a reputable repair shop and have your receiver tested for proper output. Also have your computer's serial port tested. Modern electronic instruments can take much of the effort out of ROUTINE navigational chores ONLY IF PROPERLY INSTALLED AND TESTED BY COMPETENT TECHNICIANS! WE STRONGLY ENCOURAGE YOU TO MAINTAIN, AT AN ABSOLUTE MINIMUM, TWO COMPLETELY INDEPENDENT MEANS OF ACCURATELY FIXING YOUR POSITION AND ONE SHOULD BE NONELECTRONIC!

This program IF CONSISTENTLY USED will assist you and reduce the possibility of loosing your DR position. Neither this program nor any other electronic aid can in any way reduce the navigator's responsibility for the ultimate safety of his vessel and crew. This program will assist you and thus leave you more time for the proper practice of marine navigational duties.


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Mail to NavCal Marine Services, 8016 Ellisville Lane, Knoxville, TN 37909.
We may be reached by phone at (865) 765-3407.  (c) NavCal Marine Services LLC

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