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Weymouth Speed Week - GT-31 Usage

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GT-31 Data Logger

The only GPS Data Logger eligible for use at Weymouth Speed Week is the Locosys Navi/Genie GT-31 and it's bluetooth variant the BGT-31. All references below to GT-31 include the BGT-31. All runs are timed using this equipment and results are dependent upon the use of the GT-31 and its recorded data.

GT-31 Usage

A memory card must be used with the GT-31 during the event. A 2GB SD Card is recommended - please ensure your card has sufficient empty space to record your week's activities. The use of an Aquapac, or other waterproof pouch, is required in order to make the GT-31 waterproof and suitable for use during sailing. Cards of more than 2GB won't work.

After you have switched your GT-31 on, please wait for the confirmation beeps of the unit as it locks on to the satellites and observe the screen to confirm the unit displays the "CARD FOUND" and "NEW FILE" messages. If you don't see a "CARD FOUND" message soon after the unit is switched on, then switch the unit off and check the memory card is properly inserted.

GT-31s at the Event

You may either 1) bring your own own unit or 2) hire one from the organisers (NB. a limited supply is available):

  1. If you are using your own unit then the following applies:
    1. Before the event, you MUST:
      1. check the firmware version and determine if an update is necessary - see the information below to validate your firmware.
      2. check the settings in accordance with those required for the event below.
      3. check the card capactity; An SD card of 2Gb is recommended::
        • the unit may not work with an SD card > 2Gb. If you have a 4Gb card, for example change it.
        • the unit may not work with a micro-SD card and adaptor. Using a normal SD card is recommended.
      4. Format the card so that it has NO files on it. To format the card, go into the "Memory Card" menu,
        1. turn "Log Switch" to "Off".
        2. select the format card option and wait until the card is formatted.
        3. turn the  "Log Switch" to "On-Fix".
    2. Ensure the unit is fully charged and that you are sure it is able to write data to a good, formatted SD card with sufficient empty space.
    3. Turn on the unit and leave outside for 10 minutes before going on the water in order to acquire a satellite signal of sufficient strength and quality.
      1. when turning on, view the screen and ensure the unit displays a "CARD FOUND" message.
      2. wait a few seconds to see if an error message is displayed: If you see "BAD FORMAT", then the card is not properly formatted or is of an invalid size.
      3. When gaining a satellite signal , you may see the "Acquiring Signal" message. This is Ok and is expected. You need to gain a good signal before sailing.
    4. Go sailing - DO NOT TURN THE UNIT OFF DURING THE DAY.
    5. Bring the unit back to the "data collection point" NO LATER THAN 30 MINUTES AFTER THE COURSE CLOSES.
    6. WSW will turn the unit off and COPY your data.
    7. The unit and SD card will be returned to you and it is your responsibility to charge the unit and ensure sufficient memory capacity remains for the next day - i.e. back to 3. above and repeat each day.
  2. If you are hiring a unit then please read the following:
    1. Bring a deposit for £150 (preferably a cheque made out to "Weymouth Speed Week") which is fully refundable. The cost to rent a unit and Aquapac will be £20 for a week or £10 for two days and will be payable upon entry.
    2. Collect the unit each morning from the "data collection point". Go sailing - DO NOT TURN THE UNIT OFF DURING THE DAY OR REMOVE IT FROM THE AQUAPAC.
      • The GT-31 will have been prepared, turned on and placed in an Aquapac ready for use.
    3. Bring the unit back to the "data collection point"  NO LATER THAN 30 MINUTES AFTER THE COURSE CLOSES. IT SHOULD STILL BE IN THE AQUAPAC AND TURNED ON.
    4. WSW will dry the bag, remove the unit, turn it off and read your data.
    5. WSW will charge the unit overnight and prepare it for use the following day.
    6. Finally, please don't forget to return the unit and Aquapac, and collect your deposit before leaving Weymouth.

GT-31 Firmware Version

Please ensure your GT-31 or BGT-31 is using a firmware of version 1.3 or higher; see the last section on this page for information relating to firmware upgrade.

WSW requires a minimum firmware version of V1.3(B1123T) to be installed but recommends that firmware version of v1.4(B0803T) is used. Note also that the latest version v1.4(D0428T) has been released and may also be used. Note that an earlier firmware version v1.4(B0315T) has been found to have a bug and is not able to be used at WSW; if your unit has the v1.4(B0315T) firmware then it must be upgraded.

Please note that the number of data points that can be recorded on the internal (data logger) memory varies with the version number. Data logger points are useful as a backup in case of a memory card failure, but note that the number of data points available with the newest firmware versions (16256 data points) may only be sufficient for about 4.5 hours of sailing if the data logger settings are set with 1 second interval and very low speed values. Please see the recommended values below.

GT-31 Quick Guide to Changing the Settings

 If you are new to the GT-31 unit, this very simple guide to using the navigation may help change the settings: 

  1. Turn on the unit and wait until it has found the SD card and displays the "CARD FOUND" message;
  2. Briefly touch of the power on/off to bring up the menu headings;
  3. Left and right movements on the thumb ‘joystick’ will scroll sideways through the menu headings;
  4. Click the joystick to selec the menu and make the items within that menu heading appear;
  5. Then scroll up/down and click to select a specific sub menu item;
  6. And scroll to select the preferred value;
  7. A brief touch of the power on/off will back you out of menu items and menus.

Please note that if you update the unit's username, then please ensure you switch the unit OFF and ON again in order to write a new file with the correct name.

 

GT-31 Settings for Weymouth Speed Week

GT-31 Usernames

There are normally more than 100 competitors at Weymouth Speed Week, each using a GT-31. In order to accurately and reliably process the results, we require that each competitor not only has a unique id, but also that it does not form a partial match with any other. Prior to 2014 we had to manually check your unit's username and settings at registration to ensure it was suitable.

From 2014 we used a "self service" system that enables the competitor to plug their GT-31 into a laptop that then sets the unit correctly and assigns it a unique username prior to registering that information with the data already provided when the competitor entered on-line. The old settings and username are recorded and can be read back to the unit after the event if required.

See the video explaining how this works.

Sailing with a 2nd GT-31 Unit

If you sail with 2 GT-31 units, both units will need to be registered to your name. Please bring them both to the race office for registration. That way, you will be able to hand either unit in at the end of the day for results processing.

GT-31 Settings

The following table shows the required and recommended settings. Those highlighted in green are mandatory for this event in order to provide a common basis for results processing. Units not conforming to these mandatory settings will be updated upon registration/check-in at the event. Settings highlighted in yellow are recommended for either preserving the unit's battery life or most usefully displaying the information. Settings in the ALERT and MISC menus, including Speed Genie settings, are down to personal preference and do not have any required values. Please note that where it is deemed necessary to upload a file with the mandatory settings, then other settings may also be reset.

'SETTINGS' MENU

LANGUAGE
TIME ZONE
UNIT
TIME FORMAT
DATE FORMAT
ARRIVED
MAP DATUM
POSITION
USER GRID
POWER MODE
DGPS SOURCE
INTERFACE
BACKLIGHT
BACKLIGHT TIME
CONTRAST
EXT.POWER MODE
USERNAME
USAGE
DEFAULT&RESET
SPEED AVG TIME
SPEEDGENIE
HOLD KEY
SERIAL NO.
VERSION
BLUETOOTH (BGT-31 only)
BT SNIFF (BGT-31 only)

 

  'MEMORY CARD' MENU

LOG SWITCH
MIN SPEED
NMEA ITEMS
FILE SIZE
FORMAT CARD
REMOVE CARD

 

'DATA LOGGER' MENU

INTERVAL
MIN SPEED
SAVE TO CARD
CLEAR

 

ENGLISH
OTHERS ,+1:00
NM (for knots)
24H
DD/MM/YY
-
WGS84
DD°MM'SS.S"
-
NORMAL
OFF
NMEA (38400)
ON or OFF
10 SECONDS (if Backlight is ON)
-
OFF
Set ny WSW upon registration
-
-
10 SEC or 21 SEC
25 KTS
KEY LOCK
-
see firmware notes above
OFF
OFF

 


ON-FIX
5 (knots), but 1 knot for slow craft
SBN, 1 SEC
CARD SIZE
FAT16 (only do this once with a new SD-card)
-




1 SEC
(knots)
-
-

 

GT-31 Firmware Upgrades

 Firmware upgrade instructions are copied from Dr Tom Chalko (http://mtbest.net/setting-up-navi-GT31.htm) ...

  1. After you downoaded the appriopriate ZIP file above, you need to "unzip" the content. The file with extension *.s is the firmware. V1.4 firmware has two *.s files, one firmware file and a GT31boot file. After unzipping, please read README and UPDATE-INSTRUCTIONS files
  2. Install GT31Updater V0.71 or higher software, if not already installed (it is included in zip archive)
  3. Install USB-serial driver from GT31 CD, if not already installed. The driver is necessary to communicate with GT31.
  4. Clear GT31 Data Logger (DATA LOGGER>CLEAR>YES) 
  5. Turn your GT31 OFF
  6. Remove the SD card and find a tiny sliding switch "inside the card slot" on the pcb, on "display side" of the card slot. The switch has a black lever and metallic body. The default position of the switch lever is labelled in white on pcb.
  7. Slide the switch lever using a match or a similar object away from the white mark
  8. As a precaution, exit all Windows applications and disconect from Internet. Run GT31Updater V0.71(or later). Select the correct COM port from the pop-up menu and choose "INTERNAL" mode. Then use "browse" function to select and load 2 files that you unzipped in step 1, one at a time:
       a) V31BOOT_V4D.s (you only need to update this when upgrading to V1.4 from lower V versions)
       b) V1.4 firmware
              It may be necessary to quit and re-start GT31 Upgrader V0.71 after the first file update.
  9. when Updater finishes, disconnect GT31 from USB cable, move the switch lever to its normal position, labelled white on pcb. Your GT31 should be ready to use. Power in ON, go to Settings and select Version. You should see the Version Number corresponding to the name of the file in step 1 and 8b.

gt31 Switch

gt31 Switch PositionMark

If you experience any difficulty please contact Nick Povey.

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