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Easy Installation
Boat Monitor with Bilge Sentry

Before mounting the water level module and the mounting bracket, please locate an appropriate position in the boat. The Boat Monitor is usually placed in the middle or back of the boat. For the best GPS and 4G radio communication, the unit should be placed as high as possible, and on a surface with the fewest possible metal components or materials obstructing radio signals. For steel and aluminium boats, the main unit must be mounted on an outer surface.

The water level module should be placed on a vertical surface near the bilge pump. The bulkhead will often be a good mounting surface. For motor boats, the bulkhead in front of the motor and batteries should be a suitable placement. For sailboats, a good placement would be in the middle of the boat, close to the Boat Monitor device and boat batteries. Mount the unit as high as possible.If the distance between the main unit and the water level module is more than 1,5m, or if the distance to the batteries is more than 2m, we recommend an extension cable. These are available at sensarmarine.com or your local dealer.

When you have found a suitable position in the boat, you can start the installation.

Mounting with screws: When using screws to connect the water level module, be careful not to penetrate the hull. Using screws in fiberglass requires pre-drilled holes. The included screws are Phillips Pan Head No.6 (stainless steel) 3,5mm x 13mm. Recommended size for the pre-drilled hole is 2.946mm

Mounting with tape: The included tape has great adhesion. It will be hard to remove when attached to a surface. Clean the surface with the included cleaning wipes, or use another alcohol based cleaner. The tape can withstand down to 40°F when mounting. It will obtain full adhesion after 24 hours.When using tape, press and hold for 30 seconds.

Mounting with screws is the strongest way to fasten the components. If you want to avoid using screws, but want a stronger adhesive than tape, Tec7 or equivalent is a good option.

Make sure the boat is moored securely, the engine turned off and the boat is not connected to electricity while you are installing the Boat Monitor. Working near a lead battery can be dangerous, as lead batteries can generate explosive gasses. Avoid sparks or flames near a battery, and make sure you have sufficient ventilation surrounding the battery.

Use eye protective gear, and avoid eye contact while working near batteries. Wash hands when finished. If skin or clothes come into contact with battery acid, wash immediately with soap and water. If you get acid in your eyes, wash with cold water for at least 15 minutes, and contact medical assistance immediately. Be careful when using metal tools around batteries.

Dropping metal tools on a battery can create a short circuit, and possibly explosion or fire. Remove any personal elements like rings, bracelets, necklaces, watches or similar accessories when working with batteries. Batteries can generate a short circuit current strong enough to melt rings etc, thereby causing severe burns. Please mount cables to avoid wear and tear, to prevent short circuits or sparks on broken cables. Make sure the battery terminals are clean and the contacts are tightly fastened.

The Boat Monitor should only be opened by authorized personnel. The opening of the unit by unauthorized personnel will void the warranty. In the unlikely event of a fire in the Boat Monitor unit, toxic gasses can be emitted. Should this occur, ventilate the area properly. A fire inside the unit will not spread further.

Boat Monitor


Battery/Bilge-pump Cable

(6 ft.)

Bilge Sentry

(cable 5 ft.)

Mounting bracket


Information card

(ID and connection code)

Quick connection


T-splice cable


Double sided tape

(4 pcs.)

Cleaning wipes

(2 pcs.)

Cable Ties

(4 pcs.)

Mounting screws


1. Mounting the Bilge Sentry


  • Find a surface as straight and even as possible to mount the module.
  • The Bilge Sentry mounts vertically with the cable on top.
  • Place the Bilge Sentry near the bilge pump, as close to the bottom as possible.
See installation video


  • The Bilge Sentry can be mounted with screws, tape or glue. Do not attach anything around the module itself.
  • Because of the Bilge Sentry’s sensor technology, it should not be mounted nearby metal compnents, fluid-carrying hoses, or wet surfaces. This can contribute to false readings of higher water levels than actually present.
See installation video


2. Connect the batteries

Installation for 1 battery

  • Connect the red wire, labeled “Consumption/house battery” to the positive (+) pin on the battery.
  • Connect the black wire labeled “Ground” to the negative (-) pin on the battery.
  • The purple wire labeled “Starter battery” is not used. To make sure the wire is not loose, it can be attached to the positive pin, together with the red wire labeled “Consumption/house battery”. Remove the fuse from the purple wire. Alternately, the battery cable lug on the purple wire can be isolated, and the wire attached to a suitable place with a strip.
  • Make sure the negative pin on the battery is connected to common ground
See installation video


Installation for 2 batteries

  • Connect the red wire labeled “Consumption/house battery” to the positive pin (+) on the consumption battery.
  • Connect the purple wire labeled “Starter battery” to the positive pin (+) on the starter battery.
  • Connect the black wire labeled “Ground” to the negative pin (-) on the consumption battery.
  • Make sure the negative pin (-) on both batteries is connected to common ground.
See installation video


3. Connect the bilge pump

For bilge pumps with automatic or internal level switch and bilge pumps with external level switch.

  • To be able to connect the Boat Monitor to the bilge pump we first need to mount the T-splice wire on the correct bilge pump wires. This is done with a Tap Connector.
  • Bilge pump with automatic or internal level switch. This type of pump usually has three wires, labelled: Black (-), brown/white (+) and brown (+)‍.
  • Bilge pump where an external level switch is necessary. This type of pump usually has two wires, labelled: Black (-), brown (+) or red (+).
See installation video


How to mount the T-splice wire:

See the sections below, to decide where the T-splice wire shall be installed.

  • Open “hinged side wall” on the Tap Connector.
  • Place the Tap Connector on the wire from the bilge pump, so that the wire is positioned in the “run channel”. Close “hinged side wall”.
  • Insert T-Splice wire end into the tap port. The wire shall be inserted until it stops in the Tap Connector end wall.
  • Use a set of pliers, hold the pliers perpendicular to the wire, and make the connection by crimping the u-contact down flush with the top of the Tap Connector.
  • Close Tap Connector top-lid, and make sure the locking mechanism clicks into place.
See installation video


Bilge pump with automatic or internal level switch:

The T-splice cable mounts to the manual cable. This is usually brown/white or just brown, and typically the same cable that connects to the instrument dashboard for manual operation of the Bilge pump and indicator light.

The brown/white cable from the I/O cable labelled “Bilge Pump” is then attached to the T-splice cable. The illustration suggests proper placement.

See installation video


Bilge pump with external level switch.

The T-splice cable mounts to the brown (+) or red (+) wire between the bilge pump and level switch. Then the brown/white wire from the IO cable labelled “Bilge pump” is connected to the T-splice cable. The illustration suggests proper placement.

If the cable labelled “Bilge Pump” is too short, use an extension cable.

See installation video



4. Mounting the Boat Monitor

Mounting the bracket

  • Do not attach the Boat Monitor to the bracket before mounting. Make sure that you have at least 8cm space below the bracket, so there's space to connect the cables underneath the main unit.
  • Mount the bracket on a solid surface in the rear or middle of the boat, as high as possible.
  • For best GPS and 4G radio communication, the unit should be placed on a surface with the fewest possible metal components and materials obstructing radio signals. For steel and aluminium boats, the main unit must be mounted on an outer surface.
  • Screw, tape or glue the bracket into place.
See installation video


Connecting cables to the main unit

  • Connect the Bilge Sentry to the 5 pinned contact.
  • Connect the Battery/Bilge Pump cable to the 4 pinned contact. When the cables are connected to the main unit, the LED lights on the SmartBoat One will light for a few seconds. If they don't, please check the battery connection.
See installation video

Mounting Boat Monitor to the mounting bracket:

  • Mount the Boat Monitor with the bottom down (blue part down) and insert into the rails.
  • The Boat Monitor is mounted correctly when you hear a click in the mounting bracket.
See installation video

5. Download the Sensar Marine app

Download and install the Sensar Marine app from the Google Play store or Apple App Store, search for Sensar Marine. Follow the instructions in the app for user registration. Enter your email address to register a user account.

Connect to the unit with a unique pairing code. The pairing code is found on the card in the box, or the unit itself.



Boat Monitor can monitor up to 2 batteries (starter battery and consumption battery) Measurement levels: 0V - 30V.
Boat Monitor monitors the bilge pump activity
The Bilge Sentry can measure the water level in the boat and send alert when water levels are too high.
The Bilge Sentry contains two temperature sensors. One temperature sensor is placed at the bottom of the water level module. The other temperature sensor is placed on the top of the water level module to measure the engine room temperature. Measurement levels for both sensors: -4°F to 140°F.
Provides position of boat utilizing all available satellites.
Geofence is a service that alerts you if your boat leaves a specific area. This is a fully automatic function- Geofence will activate when the boat has been still for 15 minutes. By creating a virtual boundary around your boat (a 150 yard circle around your boat), the virtual geofence will trigger a response when the boat exits that area.
Visualize your current trip and see history of previous voyages.
The unit has an integrated accelerometer that displays G-force. Measurement area: 0g to 8g.


When all LED lights are green, the unit has established network connection and sent data to the server. The app is then updated based on the latest data.
Data transfers are configured in intervals of 1min to once every 24hrs. Usually, the Boat Monitor will transfer the data once an hour, and more frequently when the boat is in use. Sensar Marine can monitor sensors as often as 25 times a second. If an emergency arises, data is sent immediately.

The battery is charged when necessary. The Boat Monitor can run an estimated 40 days without charging, potentially up to 6 months, depending on factors such as sensor configurations, data speed and whether it is receiving 4G signals. Sensar Marine will charge the internal battery when the boat is in use, or when the consumption battery is charging. If the internal battery runs empty, the Boat Monitor will automatically start an emergency mode, charging the internal battery from the consumption battery to maintain continuous monitoring and alerts. A full charging cycle of the internal battery will use approximately 15Wh from the consumption battery. A standard 80Ah (1016Wh) boat battery has 67 times that capacity.

Sensar Marine´s app is available for free download from the Google Play store or the Apple App store.

The subscription includes:

Continuous monitoring
Operations and maintenance of the system
Data traffic from the boat to the owner's app
SMS alert when an alarm is triggered
Tracking and location of boat