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Support: smarttune

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Safety Considerations

Please read all instructions before using Cyclops smart sensors to measure loads. Always perform a safety evaluation before use to ensure that use of the sensor is not dangerous to nearby people or property.




If a smart sensor has been under load for a significant length of time, the sensor may take 1-2 minutes to return to zero when the load is removed. This is to be expected.

Operation of Sensor

Please note that smarttune is designed to work in tension only, with the load applied by studs threaded into the turnscrew.

Any loads applied to the plastic body (e.g. squeezing due to sails furled tightly around the sensor), may result in unexpected or incorrect reported loads, including negative loads. This is to be expected, and provided the sails do not cause physical damage to the plastic body, the sensor will continue to report the loads correctly when the squeezing is removed (i.e. when the sail is unfurled).

What size smarttune sensor is right for my boat?

The easiest way to figure this out is to measure the male threaded stud that is screwed into your current turnscrew. The different sizes correspond to the thread sizes:

Imperial Thread Metric Thread
5/16″ 7.9mm
7/16” 11.1mm
1/2″ 12.5mm
5/8″ 15.9mm
3/4″ 19.1mm

Measuring the thread diameter is best achieved using verniers, as shown below.

Can I install the smarttune sensor myself?

Absolutely. The whole process takes approximately an hour and requires a few tools, which you may already have onboard. Please download the guide above for instructions.

What batteries are suitable, how long do they last and how to change them?

(All sizes excluding 5/16) 2x AAA batteries, with a battery life of 4 months. The use of lithium AAA batteries will likely double the battery life (not supplied).

Removing battery & cover (5/16”only)

Use a coin that fills the battery cover slot and twist until the cover pops out and comes completely free. If necessary, free the battery with a gentle tap to the opposite face of the sensor.

Replace the CR2032 battery with equivalent. Do not use non-standard batteries or other sizes, as this can cause damage.

Cyclops recommends Renata CR2032 batteries for maximum battery life and performance.

Replacing battery & cover

To reinstall the battery & cover, install battery +ve side up, insert cover, line up the arrow on the cover with the diagonal dash on the housing. Press firmly so the cover is flush with the housing. Use a coin to twist the cover until the arrows in the cover are aligned, and the battery cover is flush with the housing.

7/16” and above

Carefully remove each of the battery covers on the side of the sensor by unscrewing 2x Phillips head screws with a small Phillips screwdriver.

Lift off the plastic battery cover and place down without disturbing the seal on the body.

Check the ‘O’ ring seal (shown in blue) is seated properly and re-lubricate if dry.

Remove the old batteries and replace with 2x new AAA.

Replace the plastic battery cover and carefully locate the 2 screws, tightening until the battery cover and screws are flush. DO NOT OVER TIGHTEN THE SCREWS.


How do I turn the sensor on/off?


There is a smartpower button on one side.

Press button: Light flashes Powered on for:
1 time Once 30 seconds
2 times Twice 20 minutes
3 times 3 times 2 hours
4 times 4 times 8 hours
5 times 5 times Continuously

If the sensor is on, press the button once to power it down after 30 seconds.

7/16″ and above

The sensor is powered on as soon as there are batteries installed. Due to the 4 month battery life, there is no need for a power button.

Does smarttune work with headsail furlers?

At this stage our smarttune sensors are unable to be used with structural furlers, because there is no turnscrew that can be easily replaced with our sensor. If you are unsure, speak to your rigger or please send us a photo of your forestay set up and we will be able to give you a more definitive answer.

Is the sensor waterproof?

The sensors are IP67 rated, which means they are completely dust proof, and will not have any water ingress while submerged at 0.5m depth for 30 minutes.

If you have any other questions, please contact us.