Installation considerations
SECTION TWO — Installing the transducer
The following basic setup information isn’t a substitute for the installa- tion instructions provided by the transducer’s manufacturer. To ensure that you meet all critical installation parameters, be sure to read and fol- low all of the requirements in their instructions. Northstar assumes no responsibility for improper installation.
Choosing a mounting location
CAUTION!
Do not mount the transducer:
behind strakes, fittings, or hull irregularities (mount- ing in those locations may increase turbulence, aer- ation, and cavitation) or near the keel
near openings for water intake or discharge
where it might be loosened by the vessel’s vibration
less than four feet away from the Northstar 961/962 processor or other similar equipment to minimize interference
Choose the mounting location to obtain the best possible performance from the transducer and the 491.
Take into account the vessel’s maximum speed when selecting a mounting location, as turbulence can affect echo sounding capabilities.
The two most common problems with echo sounder installations stem from electrical noise and cavitation. Either of these situations can produce poor performance.
Electrical noise occurs when the transducer cable is routed too closely to
Cavitation can occur at high speeds. During cavitation, bubbles form between the transducer and the water. When this happens, the trans- ducer can’t get its energy into the water properly and won’t be able to detect any echoes. To avoid cavitation, choose a mounting location with good water flow all around it at all speeds.
Before any drilling or cutting takes place, carefully choose a mounting location for the transducer that meets the following criteria (also see Figure 1 on page 7), depending on the type of vessel:
•the transducer is more than four feet away from the Northstar navi- gator and other similar equipment, to prevent mutual electrical and magnetic interference
•the transducer and its cable are as far as possible from other electri- cal cables
•there is space above the transducer for the transducer’s stem, hous- ing, and cable
491 INSTALLATION MANUAL Revision A | PAGE 5 |