Edgetech 2000-TVD, User Hardware Manual, Page: 64 / 111

3-16 3.0: SETUP AND ACTIVATION
2000-TVD COMBINED SONAR 0017424_REV_B
3.9 Towfish Deployment
Consider the following Cautions and Notes before deploying the Towfish:
CAUTION!
When lowering the towfish in an area where the bottom
topography is not known, be careful not to strike the bottom or a
submerged object, otherwise damage to the towfish may occur. In
addition, at all times during the survey, be sure to carefully monitor
towfish altitude, as failure to do so may result in the towfish hitting the
bottom or becoming snagged.
CAUTION! Do not tow the towfish too close to the survey vessel. Towing
in this manner can cause the towfish to be pulled in against the hull of
the ship due to the low pressure of the propeller wash and the effect of
the water flowing by the hull. In addition, sonar reflections from the hull
may be evident in the records.
CAUTION! Do not tow the towfish with the nose angled up or down.
Doing so can degrade the sonar imagery. Verify that the towfish is as level
as possible when towing it.
NOTE: For detailed information about the EdgeTech DISCOVER software,
including how to record data, refer to the “DISCOVER 2000-C Dual
Frequency Side Scan Software User’s Manual” or to the “DISCOVER Sub-
Bottom Software User’s Manual.”
To deploy the towfish:
1. With the survey vessel under way at up to two knots, slowly and carefully lower the towfish into
the water, well away from the propeller. Do not let the towfish strike the hull of the survey vessel.
2. Lower the towfish to a depth of about three meters, or just below the propeller wash.
3. In the DISCOVER 2000-C Dual Frequency Side Scan Main window, click the Transmit tab in the
Lower Control panel, and then select the range for each frequency. This tab is shown in
F
IGURE
3-5 .