To setup Expedition (or any yacht racing software) you will need the following information:
Polars are models of how a yacht will perform at certain angles to the wind, at certain wind strengths. They are essentially graphs of ideal boat performance. The software uses these, in combination with the True Wind Angle (TWA) and True Wind Speed (TWS), to calculate how fast the boat should be going. During a race this can be compared to the actual boat speed to determine if the boat is slow. Expedition ships with Polars for a number of popular makes of boat. Additional Polars can be downloaded and imported into the software. There is a good collection available from BLUR. Weather GRIBs "GRIBs" are simply a standard digital format used to convey weather forecast information in a machine readable form. They come in various resolutions and can cover large or small areas. Low resolution GRIB files can be downloaded free from GRIB.US. Low resolution files tend to cover larger areas (e.g. 30 square Nautical Miles) and have greater intervals between forecasts (e.g. 3 hours). Much higher resolution models are available from companies such as Predict Wind, but these are a subscription service. The higher the resolution of the weather (and tidal) information you can provide to the software, the more accurate it's suggested "Optimised" routes will be. Current and Tidal Flow The flow of water under the boat is also important information. The slower the boat and the greater the rate of water movement the more crucial this becomes. For inshore sailing the rush of water caused by the tide flowing in and out need to be incorporated. For offshore sailing the "set" needs to be uploaded to the software. Tidal information can be downloaded from Tide Tech in GRIB format, but this is a subscription service. TO BE CONTINUED... |