Downloads
GPS VMG Waypoint Circle Generator
This Excel-based utility lets you set up a GPS receiver to calculate VMG (velocity made good) relative to a desired heading, to help you fine tune your sailing angles (choosing between pinching and footing upwind, and heating up vs. soaking downwind).
Essentially, this tool will generate a circle of waypoints centered around your sailing area, but several hundred miles away. By uploading these waypoints to your GPS receiver you enable “VMG relative to a heading” functionality, similar to what is available on the ultra-cool Velocitek SC-1. As long as your GPS receiver can calculate VMG to a waypoint, and you can upload waypoints to it from a “.gpx” file, you should be able to use this tool/hack to improve the sailing usefulness of your GPS.
Download: VMG_circle_waypoint_generator_B4.xls
(requires Microsoft Excel 2003 or later to run)
How does it work? Why is this better than simple VMG towards a mark? See the FAQ.
Screenshots:
Please note: while this tool allows you to configure your “standard” GPS to approximate the VMG functionality of a Velocitek SC-1, it is NOT meant to replace or compete with the Velocitek. If you use this tool/hack, and like the “VMG to a heading” functionality, you should consider upgrading to a Velocitek SC-1, which will give you “VMG to a heading” in a much easier to read display, plus many more useful features, and a more rapid refresh rate (2x per second, compared to most GPS receivers which only update 1x per second). Oh, and FYI… I have no relationship whatsoever to Velocitek. I just like their product!
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Latitude/Longitude Format Converter
Have you ever suffered the frustration of having to manually convert a latitude/longitude between degrees-minutes-seconds and decimal degrees, or degrees with decimal minutes?
Different GPS receivers, maps, web sites, and documents will express lat/lon in one of the three formats above, and while it ain’t rocket science, it can be tedious to manually convert from one format to another, given that you have to go to and from base-60 (minutes, seconds) to base-100 (decimals).
The little spreadsheet below was created to simplify that process. It’ll let you enter a latitude or longitude in any of three formats, and return the latitude or longitude in any of the other formats.
Download: lat_lon_format_converter.xls
Screenshot:
