XBT User's Guide
A Collection of Practical and Helpful Hints for the Use and Operation
of Sippican's Expendable Bathythermograph (XBT) Systems
Probe Packaging and Storage
XBT probes are packaged in cardboard (degradable) cartons which must be protected from direct exposure to rain, snow, salt spray etc. Handle the cartons carefully and protect them from heavy shock loads and dropping. They must be stored upright as damage may occur to the fine wire in the probes if they are stored on their sides or upside down for any length of time. Probes should also be protected from extremes in temperature and whenever possible should be stored in air conditioned spaces. Acceptable storage temperatures range between -60°C to +70°C, however, probes should be protected from extremes.
Launchers
The three versions of launchers, LM-2A Deck Launcher, LM-3A Hand Launcher and LM-4A Thru-Hull Launcher, interface with the MK12 system through the Connector Box. The LM-3A is the most commonly used launcher aboard VOS ships and is usually equipped with 100 ft. of cable. Proper connector box installation/wiring is critical for reliable operation (see below). Care should be taken to prevent damage to the cable when passing through hatches and doorways. Whenever possible the LM-3A should be stored inside and protected from extremes in temperature. It is not necessary or recommended that a spent XBT canister be stored in the LM-3A between probe drops.
Connector Box and System Grounding
The launcher is connected to the MK21 card through the Connector Box. This is also where the system ground is connected to seawater ground. This connection is made from the lug on the outside of the connector box to some metal part on the ship's hull (rudder post, plumbing pipe, lug to the metal hull). The seawater ground should be as electrically clean and pure as possible. This connection should make excellent metal-to-metal contact with a 12 awg minimum wire or braided cable, and be protected from corrosion and vibration. It should measure less than 100 ohms (from connector box lug to seawater). There should be only one ground in the system to avoid ground loops. For hand-held launchers, the internal connector box wiring should look like the drawing below.
Launching Hints
Probes should be launched from the leeward side of the vessel and as far aft as possible. Launching from these locations helps obtain high reliability and will minimize the chances that the fine copper probe wire will come in contact with the ships hull which may cause spikes in the data or a catastrophic wire break. It is permissible to gently handle the wire as it dereels in order to lead it away from the ships hull or superstructure. In extreme cases where the weather conditions or ships heading continuously blow the wire into the hull, it is possible to launch the probe into your hand and then gently toss it over the side away from the ship. Avoid using radio transmitters (VHF,HF, SSB) during the XBT deployment as the fine copper wire will act as an antenna. The RF transmission may interrupt the XBT data which will cause large spikes and noise on the profile. Deploying XBT's during thunderstorms should also be avoided as there is always the potential danger of a lightning strike to the operator and / or damage to the XBT system.
System Verification
Verification of the system using a Sippican 1A8 test canister, lab equipment (as described in the MK21 manual and online help) or the "bucket test" using a live probe (as described in the MK21 manual and online help for XBT's only) is the most valuable procedure for maintaining your system and isolating problems, without expending probes. If you cannot obtain data from a simulated drop, swap out or bypass elements of the system to isolate the problem. You can find most problems by checking for electrical continuity with an ohm meter. The other common source if problems is computer related: get back to as minimal and stand-alone a system as possible.
System Troubleshooting
The Sippican XBT System is extremely reliable, but problems may occur. The majority will be related to the wire; either spiking of the data as a result of the wire touching the ship or actual wire breaks which will result in data loss (see Launching Hints above). The usual fix is to move the launcher location to one that offers more protection for the wire. Refer to the table below to identify problems and their potential causes.
With proper setup, storage and launch procedures, high reliability and accurate probe data should be achieved. If problems persist, Click here to complete a System Reliability Report.
of Sippican's Expendable Bathythermograph (XBT) Systems
Probe Packaging and Storage
XBT probes are packaged in cardboard (degradable) cartons which must be protected from direct exposure to rain, snow, salt spray etc. Handle the cartons carefully and protect them from heavy shock loads and dropping. They must be stored upright as damage may occur to the fine wire in the probes if they are stored on their sides or upside down for any length of time. Probes should also be protected from extremes in temperature and whenever possible should be stored in air conditioned spaces. Acceptable storage temperatures range between -60°C to +70°C, however, probes should be protected from extremes.
Launchers
The three versions of launchers, LM-2A Deck Launcher, LM-3A Hand Launcher and LM-4A Thru-Hull Launcher, interface with the MK12 system through the Connector Box. The LM-3A is the most commonly used launcher aboard VOS ships and is usually equipped with 100 ft. of cable. Proper connector box installation/wiring is critical for reliable operation (see below). Care should be taken to prevent damage to the cable when passing through hatches and doorways. Whenever possible the LM-3A should be stored inside and protected from extremes in temperature. It is not necessary or recommended that a spent XBT canister be stored in the LM-3A between probe drops.
Connector Box and System Grounding
The launcher is connected to the MK21 card through the Connector Box. This is also where the system ground is connected to seawater ground. This connection is made from the lug on the outside of the connector box to some metal part on the ship's hull (rudder post, plumbing pipe, lug to the metal hull). The seawater ground should be as electrically clean and pure as possible. This connection should make excellent metal-to-metal contact with a 12 awg minimum wire or braided cable, and be protected from corrosion and vibration. It should measure less than 100 ohms (from connector box lug to seawater). There should be only one ground in the system to avoid ground loops. For hand-held launchers, the internal connector box wiring should look like the drawing below.
Launching Hints
Probes should be launched from the leeward side of the vessel and as far aft as possible. Launching from these locations helps obtain high reliability and will minimize the chances that the fine copper probe wire will come in contact with the ships hull which may cause spikes in the data or a catastrophic wire break. It is permissible to gently handle the wire as it dereels in order to lead it away from the ships hull or superstructure. In extreme cases where the weather conditions or ships heading continuously blow the wire into the hull, it is possible to launch the probe into your hand and then gently toss it over the side away from the ship. Avoid using radio transmitters (VHF,HF, SSB) during the XBT deployment as the fine copper wire will act as an antenna. The RF transmission may interrupt the XBT data which will cause large spikes and noise on the profile. Deploying XBT's during thunderstorms should also be avoided as there is always the potential danger of a lightning strike to the operator and / or damage to the XBT system.
System Verification
Verification of the system using a Sippican 1A8 test canister, lab equipment (as described in the MK21 manual and online help) or the "bucket test" using a live probe (as described in the MK21 manual and online help for XBT's only) is the most valuable procedure for maintaining your system and isolating problems, without expending probes. If you cannot obtain data from a simulated drop, swap out or bypass elements of the system to isolate the problem. You can find most problems by checking for electrical continuity with an ohm meter. The other common source if problems is computer related: get back to as minimal and stand-alone a system as possible.
System Troubleshooting
The Sippican XBT System is extremely reliable, but problems may occur. The majority will be related to the wire; either spiking of the data as a result of the wire touching the ship or actual wire breaks which will result in data loss (see Launching Hints above). The usual fix is to move the launcher location to one that offers more protection for the wire. Refer to the table below to identify problems and their potential causes.
|
No data at launch, noisy data |
Poor (high resistance) or loose ground. (See Connector Box and System Grounding) |
|
Intermittent data (drop out) during profile |
Intermittent ground, launcher or launcher cable connection (where cable passes through hatch or doorway) |
|
Profile break-ups, large spikes or hash |
RF interference. Avoid use of VHF, HF, SSB radio transmitters during XBT deployment. |
|
MK12 not available message |
IRQ conflict with another device in computer (typically a sound card). Change IRQ of one of the devices. |
|
Strange computer error messages |
Usually a computer problem, program / operating system mismatch, or computer network interface. |
|
Hung data acquisition |
Incompatibility of MK21 and computer, computer network interfering with data acquisition. |
With proper setup, storage and launch procedures, high reliability and accurate probe data should be achieved. If problems persist, Click here to complete a System Reliability Report.