NASA Wind, Pressure, and Temperature
Choice of equipment: The NASA “Meteoman” instrument is a digital barograph which can be purchased with a NASA “NMEA” masthead sensor unit which measures wind speed, direction, and outside air temperature. Note that this is a different masthead unit from the NASA Clipper Wind version which does not measure temperature. However this “NMEA” masthead unit can be interfaced with the NASA Clipper Wind Repeater display units without the need to purchase the Clipper Wind master unit.
Installation: Swallow Boats mounted the masthead unit above and forward of the mast top. The Meteoman is on the bulkhead in the cabin, and wind repeaters are in the cockpit to either side of the cabin bulkhead.
In Use: I am very pleased with this system. When not sailing the Meteoman gives an in cabin display of outside conditions (or inside temperature and supply voltage). It can be used as a digital barograph to show how the air pressure is changing, and also to display what the relative wind speed has been over the last day or two. When sailing I use it in clock mode to display the time – it can be seen from the cockpit and the time is useful information in tidal waters! The wind speed and direction are shown on the wind repeaters. I thought I was being excessive fitting a wind repeater to either side of the cockpit but I am really pleased with their position being close to one’s line of sight on either tack.
The combination of the Meteoman with the Clipper Wind Repeaters works well once you know how to calibrate direction. When you first set everything up, to align the wind direction the mast must be lowered and the wind vane fixed fore and aft. The output from the masthead unit is then zeroed by switching on with the NMEA signal wire connected to earth. This calibrates the wind repeaters, however for the instructions on doing this – look in the Meteoman manual! Comprehensive instructions for the Meteoman itself are displayed on the Meteoman screen rather than the manual. It is calibrated separately using the “setup” function. Note that the wind repeaters do not work if the Meteoman is in the low power “standby” mode – I don’t know why!
The only slight disappointment is that the NMEA wind direction information from the NASA system is different from the specific format needed by the Raymarine Tiller pilot, I blame the latter. A big advantage for the NASA system is that spare parts are available. When I broke the wind vane by running it along the underside of Northam Bridge, replacing it cost less than £20 (including postage). Other manufacturers make you buy a new unit.
N.B. : The opinions expressed are my own after a relatively short period of use; there may be ways around any problems identified. Other users will have different priorities!