Thursday, June 3, 2010

A Wind Direction Finder for Small Boats

My dad has been an avid small boat sailor his whole life and has shared his passion with me by taking me sailing many times.  Being a tinkerer, he continually improves his boat, changing cables, removing winches, adding lines, etc. to make sailing easier (and faster).  He recently sold his Coronado 15 and purchased a Holder 20, and as you might expect, many new alterations needed to be made from the get go.

A Holder 20 (not my dad's)
One such improvement was to address an issue all small boat sailors face: how to see the tiny wind vane atop the mast. Knowing the wind direction is crucial because it allows the sails to be set to best take advantage of the wind. The vane needs to be at the top of the mast, clear from interference from lines and sails, but this location is difficult to see being far away, in an awkward location, and more often than not - directly in the sun. (The wind vane in the above photo can be seen as a black speck above the mast)

There are existing systems that will transmit wind speed and direction data to a screen mounted in the cockpit of the boat. However, you've got to be prepared to fork out the cash. This entry level system from Tacktick (http://www.tacktick.com/products/145) costs £459.99... that's over $900 American! ...and cost prohibitive for many small boat sailors.

Enter the Arduino micro-controller solution. I proposed that a practical solution was feasible using an Arduino to detect wind direction and display it in the cockpit for a fraction of the cost of existing products. With my interested father as a corporate backer, I've set out to design and build said instrument.

The R&D for this project will be broken up into a couple stages. First, an appropriate sensor needs to be found that will output angular position over 360 degrees. The sensor shaft also needs to be able to continuously rotate so as not to provide faulty data after reaching an end stop (as would be the case with most potentiometers). After some online research, I found this device (http://www.usdigital.com/products/ma3/) from US Digital that should fit the bill. The sensor must then be mounted to the mast with an appropriate wind vane.

Second, the sensor must be connected to the Arduino (by a small cable through the mast) and a suitable program written to collect the incoming analog data and process it into a usable information. (Note: I imagine some form of averaging needs to be performed to reduce jitter and provide a more stable readout)

Lastly, a display needs to be made to make the wind direction information easily viewable. Ideally, I'll have an LCD screen showing wind direction relative to boat position, but as a simpler prototype I could create a ring of LEDs indicating wind direction.

Once a working system has been developed, further improvements could be made such as: wireless transmitting from wind vane to Arduino, powering the device via solar panel, adding a hot-wire anemometer, temperature gauge, or solid state magnetometer for additional nautical data.

I'd like be able to build the project for under $100 (nearly 1/10 the cost of the TackTick), but knowing how project costs quickly add up (see this blog entry), I think I'll double that and hope for the best. Either way, it should be a great solution! Stay tuned...

2 comments:

Hernan Curras said...

Hey! nice project, how much did you spend on the "http://www.usdigital.com/products/ma3/" device ?

I'm in the middle of the nightmare of the process building of a wind vane using a magnetic hall effect sensor from austriamicrosystems AG, and the PCB is really simple but have some problems since the sensor is a surface mounting one, and reallllyyy small (2mmx2mm) any information will be much appreciated.

Glenn Langton said...

Hi Hernan, I opted for the low friction ball bearing option so I think I paid about $50US including shipping. Expensive, but it's a great little sensor! Unfortunately, I don't have any experience with surface mount electronics. My only recommendation would be to look online for a tutorial. Best of luck!

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