Monday, January 19, 2015

Trouble with the Tides, the Sun, and the Moon.

If you're going to be involving pirates, mighty armadas of warships, or even simple river crossings on the mighty Amazon or Mississippi you're going to have to deal with tides. Now it is entirely possible to hand wave this side of things and simply say that the tide rises at X time and goes out at Y time every day which is fine but doesn't reflect the changes in the sun and moon rising. Oh you could hand wave that as well by saying that each always rise at the same time every day (with each on their own cycle) but that tends to create a world that feels far from real and much closer to a boring world that doesn't reflect a change in seasons, the earth solar positioning, or any other factor that might make the world feel real. 

Now at this point you might be saying to yourself that you really don't want to go for the simulationist aspect and you just want to go for good enough. So you go online to find a few charts for simulating the tides and the rise and set of the Sun and Moon. Then you start rolling and recording the results for every day of the year in the hopes that you actually get to use them in your game. Or maybe you're down for that simulationist slog so you go out there and do a couple of years worth of research (or hours of cribbing notes off Wikipedia). Finally, your research done it's time to start building spreadsheets to work out the complex equations and build your campaign world a complex, yet entirely plausible, series of times for the rising of tides, the patterns of celestial bodies as viewed from the earth, and a never ending sense of pride in your hard work.

Only here's the thing about all that hard work you've put in: it means exactly dick in the greater scheme of things. Your players aren't going to suddenly look at you in the middle of the a game and say, "You know, Ted, I don't normally appreciate the detailed efforts of a Dungeon Master for creating a sense of verisimilitude in relation to the tides - but damned if you haven't made me gain a whole new sense of appreciation for it all." That's never going to happen.

These sorts of questions tend to fall into a gaming sphere that I like to call "Nice to Know." They have some importance on the overall world but researching them and devoting myself to studying them in any level of detail beyond the simple facts I need to know is a wasted effort. For a lot of people online this is a question that they devote to building random charts and filling spreadsheets with so that they can easily create a world that feels real. 

I don't waste my time on such things and instead buy old Farmer's Almanacs. Farmer's Almanacs are filled with everything you need to make your world feel real from the times the sun and moon rise and set; to when crops are being planted and harvested; to when the tides come in and out. Plus the things are filled with lots of holidays that you can crib over for your favorite fantasy game without having to invent things wholesale. 

If you've never bought a Farmer's Almanac - and while it seems a foreign concept to me I'm told that it happens - then I suggest the Old Farmer's Almanac that's published by Yankee Magazine. You can find old volumes of this magazine running back decades (and they're usually very cheap  with differing forecasts in each one and filled with great articles on just about every subject under the sun. Now other versions of the Almanac can be found for cheaper, but the Old Farmer's Almanac is my personal favorite as it tends to be filled with a lot of useful information that I can use not only in my games but in my actual life. 


  1. An excellent suggestion. I've wasted much time writing random weather generators. If you're cheap like me, you can look up the daily weather since 1945 on the Farmer's Almanac site.

  2. Great idea!
    that's a bit like using this
    for general store stock and prices which I do and it works great!

  3. We've used the Old Farmer's Almanac to plan planting our garden and our fishing trips but I've never thought of using them to give my game verisimilitude. My wife & I go to a fair number of estate sales when the weather is decent and I've run across a lot of old almanacs for cheap. Estate sales can be a goldmine of game-able material. I think my biggest missed opportunity at an estate sale was when we arrived late at one sale for a guy who had worked for a logging company. He had a collection of survey maps of the company's land pre-land clearing. Unfortunately, someone else had already snagged them. All those detailed maps of forests with creeks and elevations waiting to be filled with bandits, orcs and dragons ... gone.

    1. Oh, that would have been such a great resource to use for your maps!

    2. Though not as cool as physical maps, especially on aged paper, you can download pretty much the same thing for free from the USGS Store.

      The scales most useful for gaming are "7.5 minute" and "3.25 minute". they display 1/16th or 1/64th, respectively of a quadrangle with 1 degree of lat x long sides

  4. Yes, the Farmer's Almanac is an excellent source for tide tables, weather, and nearly everything related to agricultural societies -- as long as your world is very earthlike. And even then there can be huge variations. Compare the roughly 4-8 ft tides much of the U.S. coastline experiences to the extremes like 75+ feet in the Bay of Fundy.

    And what if your world differs from Earth in significant ways?

    For example Oerth, with its 2 moons and 30 degree axial tilt. I actually just got sucked down that rabbit hole. It started simply enough with writing an app to tell me the rise & set times for the sun & moons for any date and latitude. easy. then i decided to throw in the the 5 visible planets, and the moon phases. and hey, at that point, how much harder could tide tables be? ... Answer: A LOT. look up tidal physics some time. not something you want to mess with as a DM looking for a casual half-ass system that provides realism w/o much effort.

    stick to the Almanac unless you're insane like me. your players probably won't appreciate that you put the effort into being realistic, let alone notice that there's an entire moon missing from the tidal fluctuations.

    1. tom I'm kind of convinced that you and I would have a lot of fun playing D&D together!


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