If a towed sensor such as a side scan sonar is used on a survey, then HIPS and SIPS can compute the sensor’s position relative to the ship's position by calculating the horizontal layback and a direction to the sensor.
1. Click Towed in the Sensors list box to highlight the selection and display the Towed data fields.
2. Type data as needed in the following fields:
• Date: The year and Julian day of the current towed sensor time stamp.
• Time: The hour and minute of the current towed sensor time stamp.
• Time Correction: The time correction value.
• Layback Error: The error in the computed or recorded horizontal layback. This can be used, for example, to compensate the recorded layback data or tow cable length for the distance between the origin of the measurements and the defined tow point location in the tow cable length. This value is subtracted from the computed horizontal layback.
• X: Offset of the tow point from the vessel’s reference position.
• Y: Offset of the tow point from the vessel’s reference position.
• Z: Height of the tow point (negative upwards) in relation to the datum that is referenced to the sensor depth (in most cases, this is the waterline height).
• Manufacturer: The maker of the towed sensor.
• Model: The make of the towed sensor.
• Serial Number: The serial number of the towed sensor.