New DST reminder, and some tide notes
Today is not exactly like 12/31/1999, but there definitely are some questions about what’s going to automatically understand the Daylight Saving Change tomorrow, and what isn’t. For instance, will your Windows PC? Apparently that depends on update status, and ditto for Macs. Now, I already discussed the update planned for Nobeltec’s Tides & Currents, but it turns out that the 9.1.2213 service pack for VNS and Admiral 9 just finally released today, which seems a bit tardy! (I also understand that Nobeltec is not yet supporting Vista, but I’m not sure any other ECS is.)
I got wondering about other tide prediction programs. It turns out that at least Coastal Explorer get its time from the computer it’s on. Why didn’t T&C take this easy approach? Well, if a program doesn’t know about DST, it can’t use it when predicting tides in the future. That’s why there’s no sign of the DST change tomorrow in CE’s tide table above, and bigger here, as calculated today. (I also notice that CE is figuring Rockland tides off of Bar Harbor, whereas T&C uses NOAA’s harmonics for Rockland, not wicked important but more accurate). As for all the chart plotters that can predict tides, I think they all base their time on GPS input plus or minus a local, user entered, offset. For instance, if you’re in Eastern Standard Time, five hours later than Universal Time (aka GMT), tomorrow you “spring ahead” to EDT by changing a Raymarine’s offset to -4.0.