I'm wondering if someone may be able to please assist. I'm looking for a suitable sensor that could measure the force of water against a moving surface, such as canoe paddle blade. Any thoughts or suggestions would be much appreciated thanks.
There are probably several options, but it is not clear what you actually want to measure. Can you elaborate?
Thanks for you reply jremington. I want to be able to measure the relative performance of say canoe paddlers. So if the surface of the paddle blade could measure the force against the water, the harder the person paddles, the greater the measurement would be recorded by the sensor. This measurement could therefore also be used to calculate the paddle rate being the time duration of the pressure applied to the blade surface in the water. Placement of the sensor(s) could also measure the depth of the paddle blade in the water to further measure performance. My thought was to have a sensor behind the blade surface, thereby sealing it from moisture, but with the surface around the sensor able to flex enough for the sensor to measure the relative force against that surface area.
First I thought to a pressure sensor but I believe that is difficult to distinguish between pressure due to water depth and pressure due to the force against water.
Maybe a sensor inside the handle (I don't know if handle is the right word, I mean the cylinder part between the hands and the blade) or around it's furface, is better. I think it would measure the deformation of the handle because of the force used.
I hope you can understand my bad english and what I mean.
I am aware of sensors in the stem (cylinder part) of some paddles but I have a suspicion there are some calibration issues due to the very small degree of tension that it needs to pick up from very slight movement in what can be quite a rigid stem and blade. With this method, could this be an issue between several paddles and therefore constantly needing calibration?
If the sensors were on the blade would the readings from the depth (say 200mm in the water to the middle of the blade) be significant compared to the forces you would expect to be applied to the blade surface when paddling. Perhaps there could be some adjustment factor for the depth measurement. Also a sensor on top of the blade could indicate the blade is fully immersed and therefore provide some reliable means to adjust for the water level pressure of the main sensor. What do you think?
I think of sensors on stem ( :)) surface like these
But I have no experience of them so calibration can be an issue.
Maybe another way is to modify the stem and split it in two parts connected by some type of force sensor. But maybe this will change the paddle too much so you feel the difference between paddle with and without sensor and if you have to compare paddles maybe you can’t modify them.
I used pressure sensor in seawater but they were too big for your pourpouse so I don’t know wich sensor is better.
Take in account that you will have fast change in pressure so you need a sensor that change fast.
Another question can be how do you will test paddles. I believe the best way is to use a robotized arm, but is not simple and cheap.
Thanks for your thoughts & suggestions zoomx . I'll have a more of a look into the link you provided. Do you think that type of Force-Sensing Resistor sensor could work on the surface of the blade to detect pressure against the blade surface?
I don't know but they are strip shaped so I think that are not designed for surface pressure on a large area.
They sell surface pressure film also, that are films that visually indicate pressure, they are not sensors.