Introduction - NorthStar NS3100 Multi Instrument Reference Manual

1 Introduction

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The NS3100 Multi measures and displays speed,
water depth and water temperature. It can calculate
and display average speed, maximum speed, trim
speed, trip log (distance) and total log.
An installed NS3100 Multi usually has two parts:
The display unit.
Depth and speed / temperature transducers
which are attached to the hull and wired to the
display unit.
The unit is powered from the boat's power supply.
The NS3100 Multi is part of the Northstar family of
instruments for boats, which includes instruments
for speed, depth, wind and repeaters. These
instruments can be connected together to form an
integrated data system for a boat (see section 8).
For maximum benefit, please read this manual
carefully before installation and use.
How the transducer measures depth
The depth transducer generates an ultrasonic
(sound) pulse, which travels down through the water.
When the pulse meets the bottom, some of the
pulse is reflected back up towards the boat and is
received by the transducer.
The NS3100 Multi display unit
The display unit analyses the reflections from each
pulse. It removes unwanted reflections (from bubbles
and other objects) and calculates the depth by
measuring the time between sending the pulse and
receiving its echo.
How the transducer measures speed
The speed transducer has a small paddlewheel
which spins as the boat moves through the water.
The transducer measures how fast the paddlewheel
is spinning and calculates the boat speed by
averaging several measurements.
Cleaning and maintenance
Clean the display unit and any plastic transducers
with a damp cloth or mild detergent. Avoid abrasive
cleaners, petrol or other solvents.
When repainting the hull, cover or remove any
visible transducers. Depth transducers may be
coated with a thin layer of antifouling paint; gently
sand off any previous paint first.
Northstar NS3100 MULTI