ok ,NASA wind unit is going in the bin - again , i give up with trying to keep it working by replacing mast head unit annually, so which is the best deal in price and reliability ?
I was thinking of the Raymarine ST40 & did a bit of research. The sensor a "Rotavector" type. i.e. the 3 cups of a normal speed sensor are off-ballanced by a small tab on one cup. It then works out the direction somehow from that. The result is something that's OK in a blow but inaccurate otherwise.
A couple of people on the forum reported that it was of little use for direction on a yacht. On one supplier site it was being sold as suitable for power boats only.
I went for an ST60 in the end. Not as cheap as I'd have liked but integrates easily with the rest of the kit on board.
You must have a landing light on your masthead unit cos my Nassa unit on my previous boat was 4 years old and never had any problems with it, and current boat has Nassa kit and they are 5 years old in Feb, again no problems. For the money I think they are very good, always work and simple to re-align when something has perched on it. The only hassle with the Nassa kit is with the speed and log, not having a cover on the hull opening means a lot and I mean a lot of water comes in when you need to displace the shrimps, barnacles et all. I took my Navtex to their workshop and they updated whilst I waited, even gave me tea. Serviceable and good value and with a human at the end of the phone what more can you ask for