NorthStar Navigation 491 - Manual (Page 9)

SECTION TWO — Installing the transducer
491 INSTALLATION MANUAL Revision A PAGE 5
Installation
considerations
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
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
noise-producing electronics, such as alternators, AC generators, radars,
etc. To avoid problems with noise, route the transducer cable by itself
(not in a bundle) and away from other wires or cables and the engine.
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
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.