The Oceanis Systems’ 3281 NMEA2000® Fresh Water Level Sender measures the tank level or tank volume of the
vessels fresh water tanks.
It is very important that it is installed and set up correctly according to this manual. Please read and follow the
installation and setup instructions carefully to achieve the best results.
The 3281 NMEA2000® Fresh Water Sender has the following features:
• Water level sensing from 250mm to 2 metres
• User settable for tank Level or tank Volume output
• User settable tank instance from 0 to 15
• Heartbeat blue LED to indicate normal activity
• Red Warning LED to indicate damaged rods.
• 1.25” BSP single threaded mount
• NMEA2000® Interface
FIRMWARE REVISION
The information in this manual corresponds to firmware revision 4.0
Take great care when unpacking the sender that the coated rod is not damaged in any way. If the coating is
scraped or punctured the sender will not work.
We test every sender before it is packed so the coated rod is protected against transit damage. Do not remove the
protective packaging until you are ready to install the sender.
You should find the following items in the 3281 shipping tube:
1 x 3281 NMEA2000® Fresh Water Level Sender
1 x Water Sender Probe End Cap (May already be attached)
1 x 3281 User Manual (This document)
1x 30g tube of silicone, if unit is not already cut to length
1.1 MOUNTING LOCATION AND REQUIREMENTS
The sender is designed to be mounted on a flat area on the top of the water tank over the tank’s deepest part.
Examine the tank internal structure and choose a location that ensures the sender probes will not chafe on any of
the tank’s internal structure or baffles.
The sender requires a 1.25 inch standard BSP threaded mounting hole with a small 45° machine chamfer at the
top to seal against the sender mounting O ring.
If the tank has an existing SAE 5 bolt hole then the optional
3261 Mounting ring can be attached to the SAE 5 bolt holes to
provide a 1.25” BSP threaded hole mount for the Water Sender.
1.2 MEASURING SENDER LENGTH
The sender may be supplied already cut to length with the probe end cap already installed and be ready to install
into the tank if you have supplied the required cut length at the point of ordering. In this case there is no extra
work to do in this part.
If the sender was supplied in a standard length to be cut down then the finished length should be determined by
measuring as shown in the diagram.
INSTALLATION
1
Magnet Area
Make certain sender and water
pickup are at the same level.
Water tank/container
Tank Type
Tank No.
Red LED Indicator
Blue LED Indicator
Optional 3261 Mounting Ring.
Finished Length
25mm / 1” between the
end of the sender and
the bottom of the tank
25mm / 1”
Measure from
the underside of the
Water Sender
FRESH WATER LEVEL SENDER
Part Numbers: 3281
INSTALLATION AND OPERATING INSTRUCTIONS
