Wind sensor

To build an autonomous sailing vessel, a wind direction sensor is necessarily for the boat to function. Unfortunately there are no off the shell wind direction sensors which are cheap. On the internet there are amazing prices starting from $150 till thousands of dollars.

The target for me was to build a wind direction sensor for less than $15 dollars (10% of the lowest internet price).

Finding the good electronics took some time, potmeters aren't able to rotate continously so the best solution was to use a rotary encoder. There are 2 types of absolute rotary encoders; optical and mechanical.

In this case to optical rotary encoder is used works with gray code and works in the following way:
the optical encoder's disc is made of glass or plastic with transparent and opaque areas. A light source and photo detector array reads the optical pattern that results from the disc's position at any one time.
This code can be read by a controlling device, such as a microprocessor or microcontroller to determine the angle of the shaft. (source: wikipedia.org)

the other materials I choose to work with are perspex because in this way it is easy to see how the wind direction sensor is build, but essentially can be made out of every material at hand. 

The most important part is to protect the rotary encoder from the force of the wind and only let the rotational force work on the rotary encoder. Therefore I build a shaft around the rotary encoder which will prevent the wind banner to bent the electronic parts.

The total costs of all the materials are:
COM-09117 rotary encoder from sparkfun                               €2.24
2 perspex tubes diameter 21*16 and 15*11                                 €2,00

Vivak sheet 300*300 mm*1                                                              €1.69

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total                                                                                                               €5.93