We've got a Garmin anemometer/vain tied into our plotter. (I will look up the model when my wife wakes up and I can get to our manuals.)
The only thing we really use is the ability for the system to estimate true wind speed and direction. Kind of handy when we are motoring along at hull speed and wondering if there is enough wind to sail.
Today, we were motoring almost directly into the wind at about 6.5 kts over ground. The while the wind vain was pointed directly into the apparent wind, and the plotter showed the correct apparent wind direction, it was reporting 12-14 kts true wind speed. The actual speed was definitely lower - probably in the 8 kt range.
At 6.5 kts over ground with a 12 kt head wind, the anemometer would have had to experience about 18.5 kts. It was spinning more like a good breeze. We stopped to see what winds were actually doing and, like I said, they were at about 8 kts.
So, the mystery to me is what would cause it to overestimate a head wind? I can understand underestimating - like if the anemometer was gummed up and turning slow. Or, if we were going downwind and the anemometer was running slow, that could cause an overestimating.
Very confused. And, this is new. It worked correctly (or at least not nearly so far off that I would notice) just a few months ago.
Any ideas?
The only thing we really use is the ability for the system to estimate true wind speed and direction. Kind of handy when we are motoring along at hull speed and wondering if there is enough wind to sail.
Today, we were motoring almost directly into the wind at about 6.5 kts over ground. The while the wind vain was pointed directly into the apparent wind, and the plotter showed the correct apparent wind direction, it was reporting 12-14 kts true wind speed. The actual speed was definitely lower - probably in the 8 kt range.
At 6.5 kts over ground with a 12 kt head wind, the anemometer would have had to experience about 18.5 kts. It was spinning more like a good breeze. We stopped to see what winds were actually doing and, like I said, they were at about 8 kts.
So, the mystery to me is what would cause it to overestimate a head wind? I can understand underestimating - like if the anemometer was gummed up and turning slow. Or, if we were going downwind and the anemometer was running slow, that could cause an overestimating.
Very confused. And, this is new. It worked correctly (or at least not nearly so far off that I would notice) just a few months ago.
Any ideas?