I'll speak for our Nobeltec trident Timeszero's routing pack (same as, MaxSea) features that I have used. There may be some differences. I've not really delved into it's intricacies completely, so I apologize if I miss something.

You need to have
- Your boat's polar diagrams (target speeds depending on wind, sail set, and direction). If you use a standard chart for some listed boats with a polar in its library, it's going to assume you reef as certain points, change to a smaller jib, put-up a spinnaker, asymmetrical, etc. ANYWAY, If you only use one sail, then so be it. In fact you can do one for just motoring. The program can respond to a simple or dumbed-down polar chart.

- Then you take the GRIB files which are available over the web or phone. That would input the wind strengths, directions, veering, and anticipated wave heights over a period of time. (It's only as accurate as any weather report, or not. The GRIB projections show what is projected to happen when projected things happen at certain times. The times and intensities can vary a lot. It's just a projection. It can be from spot-on, to generally correct, to full of shit. It's the weather over a relatively broad area.

- Then you add your "route" route between two points. In the case of our Nobeltec, it doesn't distinguish between running through an obstruction (including an island). You need to segment key multiple routes.

- The program will include "current" effects along your route that from it's "tide and current" library. The efficacy of those are different. MINE doesn't seem to be able to take the Gulf Stream charts (maybe I just know how)...

- Finally, you can get it to adjust for limits of wave and wind conditions -- "I don't PREFER to sail in greater than ___ kt winds; or, __ height (predominant, PREDICTED) wave heights. (Of course, the issue is usually not the height of the wave, but it's period and "breaking nature. I could care less about a 20' non-breaking wave with a period of 20 seconds -- that's more like a swell.

- You put-in your start time and click - GO (or whatever)

BLACK MAGIC HAPPENS

Depending on your processor speed, and the length of the route, and complexity of the GRIB, suddenly a chart appears with one or more "optimum" actual sailing approach to getting between two points over the course of the projected time. It shows the strength of the speed of the PROJECTED wind, it's general direction compared to the boat at the times it reaches those points along the route, etc.

It gives you a snapshot of the strategy that the computer deduces you should sail.

You can try alternatives and see what the machine deduces the impact might be. You can play around with changing some variable about when a wind direction of speed might occur along the route (e.g., whether a shift occurs sooner or later, whether with wind is really stronger or weaker than predicted, etc.) That way you can adjust what you set as your strategy and how you 'readjust' during a passage. (You can use an GRIB file from yesterday, and adjust the time/wind constraints, and re-analyze during a passage. If you have a method of downloading update GRIB files under way, you can re-load, re-plot, re-everything along the way.

In fact you never have to appear in the cockpit, you can play NAVIGATOR and weapons control officer for the full trip -- as long as the rest of your crew is doing their job or (as the Volvo Race showed) you don't run into anything.

IT'S A POWERFUL WHAT-IF TOOL that is so digital, I think it becomes analog. But its a tool! I think its useful to help think through what is LIKELY to happen an how you might approach a passage. You do the same things now if you're a thinking sailor. You don't simply point your boat at the point on the route and sail as closely to that rhumb line. This tool allows you visualize and conceptualize what might be happening. I do think it useful and "fun". It can help approach a passage. But there are so many variable and fluctuating "scales" of time; and so many inaccuracies of projections vs. local conditions, that it ultimately becomes a conceptual tool.

In the right hands, I think it can be very valuable. In any event, I find it fun to mess around with and believe it helps set your path and approach to a passage.

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