Yeah world magnetic model. Good to know, thanks!

Hi Will,
I have both of your books and they're great. I would vote for option #2.
Even though there isn't really a single resource on all the areas of navigation, I think that's a good thing. Covering everything would mean your book would be either huge or incomplete. This would put it firmly in the realm of reference books that you buy but don't read cover to cover, and there are enough of those in the genre. Secondly, it's good to have experts weigh in on different areas of expertise. For instance your book is excellent for Expedition, and David Burch's Modern Marine Weather is excellent for weather. I don't want one with both because the Expedition information changes quickly but the weather fundamentals don't. Lastly, navigators are a naturally curious bunch. It's okay for us to have to find the right resource for the right set of skills. 

There are a few topics in which there is a market gap, however. 
1) There's no good book summarizing strategy for a specific set of famous races. Something like, here are the climate conditions and tactics for the Transpac, Sydney-Hobart, Fastnet, Newport-Bermuta etc. 
2) There's no good book on oceanography and geology as it pertains to offshore navigation.  
3) I'd love a book of stories from someone like you, that chronicles your races, ups and downs, progressions, etc. 

Just my 2 cents and sorry for the long post.

Wondering if there's a way to import/specify a WMM file, and separately, if the WMM impacts the routing algorithm? 
I ask because as we analyse reanalysis data for previous races, and want to find the routes that would have resulted at that time, I want to make sure using a newer WMM won't have too much impact on the results. 

The WMM could have big differences, especially near the poles, but if it isn't used by the routing algorithm then it obviously doesn't matter. 

Here are some awesome apps with a ton of weather data. All are free and most are cross-platform. 
They basically are all some combination of data ingestion and visualization. Some have features like exporting KMLs or shapefiles. 
https://www.unidata.ucar.edu/software/awips2/
https://www.unidata.ucar.edu/downloads/idv/current/index.jsp
https://www.ssec.wisc.edu/mcidas/software/v/
https://www.ncdc.noaa.gov/wct/install.php
https://www.vapor.ucar.edu/

 

Ok I'll do that! Also some feedback for the DLL, which is awesome that you even have one at all by the way. But as far as I can tell each channel has to be requested one at a time. I think the API could be improved by being able to pass an array of channels in and getting an array of channel values back, and then also possibly supporting a subscription model where callbacks get called after change events happen like an event listener. Thanks.