Sorry, no pics. I built a cheapie anemomenter for our previous boat. it consisted of 3 black plastic 1tbl measuring spoons ($3.00 at the dollar store), one black spray paint can lid (free), a bearing out of a dead VCR (Free), a little magnet that I had and a digital bike speedometer ($10).
Assembly consisted of cutting 3 slots into the paint can lid and gluing in the measuring spoons with hot melt glue. Next glue the magnet to the inside of the paint can lid, near the bottom and the bearing carefully glued into the center of the cap with lots of hot melt glue.
Next I mounted the whole thing on a shortened stantion which had a BBQ rail mount fitting at the bottom. (Both rescued from the trash at the club).
Tie wrap the bicycle spedometer sensor in place so that it picks up the magnet when it goes by.
To calibrate, I borrowed a friend's anemometer and my wife's hair dryer. Get the hair dryer wind speed reading from the anemometer and play with the wheel diameter on the bike speedo until you get the right wind speed.
Moutin a convenient spot on your boat. This worked great any my speedo had memory settings for max speed , average speed etc.