Monday, February 25, 2019

The Flux Capacitor


At last, a real post.

The image above is the flux capacitor, it's what makes this work.  The two-tiered hex map above enables me to put together the rules of D&D with those of the war game Wooden Ships & Iron Men (WSIM)It is the invention of the "ship hex."

The smaller hexes in the image above are standard combat hexes, 5 feet in diameter, just as I've been using for all my combat posts going back well before the start of this blog.  My online characters and those who have read my campaigns are familiar with these.

The larger white hexes are "ship hexes," 20 feet in diameter and juxtaposed with the combat hex.  Most important is this: a ship that is moving 1 knot per hour will cross a ship hex in the space of one combat round, in my game 12 seconds.  This makes the movement of the ship fully compatible with the movement of individual combatants during the naval battle.

1970s Artwork
Compare the image on the right from the original wargame.  The ships depicted here are from the late 18th to early 19th century, much bigger than the ships of my world would be, 150 years earlier.  And I don't have ships with cannon, so picture vessels smaller still.  The ships as shown are moving through game hexes ~ ship hexes for me ~ and on a time frame that WSIM doesn't explain.  But, with the two-tier hex system I'm proposing, the ships can move through the ship hexes just as shown, while at the same time the individual people can move through the standard combat hexes, firing at other ships with bows and ship's weapons, throwing lines to grapple over actual space and fighting boarding battles, while the ships themselves move independently of the characters aboard them.

When the ship turns, it will follow the ships hex, NOT the combat hex ... this will enable the game to be managed without having to figure out the fiddly hell of figuring out the ship's movement using scores of tiny little hexes.  It will make writing out the orders practical.  Orders?

I'm adopting a five-round game-term for the ships's movement called the "sequence of play," which will be staggered and simulataneous, encouraging collisions.  At the beginning of round 1, just as in WSIM, the captains will write out their orders, which will then take place over the next five rounds.  Then the combat rounds will be played out one at a time; there should be room for the players to pick off crew, load and fire weapons, reducing the success of a ship's maneuvering ... while each round the ships will move part of their pre-written movement orders.  Depending on speed, turning, the effectiveness of the crew to follow the orders (which I'm putting in even though it isn't there in WSIM), a ship may move quickly out of range or it may suddenly turn and collide.

PLUS, as I have rules for galley combat that can be fit into the system, I can mesh the systems WSIM and Trireme, since the Turks were still using galleys ~ and in a world without cannon, perhaps a galley is still a terrifically effective sea weapon.

If the reader is familiar with war games, it should be seen how seamlessly this can be made to fit together ... though of course it will need playtesting.  I'm looking forward to getting there.

There's just one little thing about ship movement that is plaguing me.  All the ships in WSIM and Trireme are only two hexes long.  And I have ships that could be potentially nine hexes long.  Here's the question ~ and I expect Sterling can answer it:
If a ship nine hexes long makes a right hand turn at 4 knots, swinging it's bow 20 feet to the right, does the back end of the ship remain "in its lane" or does the back end swing out opposite the bow?  And if it does swing out, by how much?

Any sailors, please weigh in.  I'll listen.  I promise.

13 comments:

  1. I'm speaking of maneuvering only by rudder in my previous comment. A galley, or any oar-powered vessel, would have greater maneuverability and could choose to rotate about its center if it backed one bank of oars.

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  2. Didn't get your previous comment, I think.

    Trireme has great rules for galley movement.

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  3. I am not a sailor, but found the following using google-fu, hope it helps.

    "When you turn a boat, it pivots around the centre of lateral resistance (usually this will be somewhere near the centre of the keel), but there is also a tendency for the boat to slew towards the outside of the bend (Though this can be neglected for small angles at reasonably high speeds). The rudder works simply by deflecting the flow of water to one side, from flow parallel to the boat, to flow parallel to the rudder. This force can be resolved laterally and then the position of the rudder with respect to the centre of lateral resistance can be used to calculate a turning moment due to the rudder's angle. With a value for the moment of inertia of the boat, you can calculate the rate of turn of the boat from rudder position. It would be a question of exactly how much water is deflected by the rudder that determines the difficulty of this problem."

    Reference https://www.physicsforums.com/threads/sailboat-rudder-physics-and-water-flow-estimate.858026/

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  4. Okay, so it swings out. Because its a game and not a sailing model plan for winning the America's Cup, we can muff it inexactly; the original WSIM rules indicate the boat swings out an entire 60 degrees before moving forward the one hex. We could say that it swings out 1 combat hex per total length -2, so that a 2-hex length boat doesn't swing out at all and a 9-hex length boat would swing out 7 hexes (over a period of two normal combat rounds) before being dragged along in the direction of the turn.

    I know that's most likely inaccurate, but I don't care about that. It creates great opportunities for a collision if you sail too close to a massive 400 ton frigate. Can the readers live with that?

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  5. Sorry, that's confusing. Let me write that again. The boat swings out 1 combt hex per total number of ship hexes in length, -2, so that 2 ship hex length boat (8 combat hexes) doesn't swing out at all and a 9 ship hex length boat (36 combat hexes) would swing out over 7 combat hexes ...

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  6. You've recently mapped Iceland and the Juvenis party has access to a small craft...

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  7. Ugh! My original comment was lost! You've managed quite beautifully without my input anyway.

    The gist of my lost comment is that the stern does swing out a little, but not a whole 20' hex. I've been in racing situations where my maneuvering has been constrained by the fact that my stern would bump another boat on the outside of my course change. I had suggested that if another vessel is in the hex adjacent to the stern of the vessel in question on the outside of its intended turn, it could only turn 60 degrees without connecting with the other vessel unless that vessel was turning in tandem or was sailing astern and turning the opposite way.

    I had even gotten a little technical and referred to my copy of Larsson's and Eliassson's excellent Principles of Yacht Design to talk about the rudder's center of effort and the rest of the submerged hull's center of lateral resistance creating a pivot point. Too much to be playable there, and I think where you've ended up works.

    The only objection I raise here is with the stopped vessel. With its head to the wind and making no way forward, the only thing the vessel can do is drift backward and, using sails, bring its head off the wind. The effective pivot point would be the stern of the boat, however, not the midpoint. In this case it's the sails (potentially important to note, the forward sails), that are doing the turning because the rudder is useless without water flowing (the right way) past it. The head sails are need to bring the bow off the wind because you need the sails' center of effort to be forward of the hull's center of lateral resistance. If not, the stern swings off the wind, not the bow, and the ship can't do anything but drift downwind.

    [And now I see why my original comment was lost. I tried to underline a book title, but the U tag is not allowed, so I'm here using the B tag instead.]

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  8. Sterling,

    "The effective pivot point would be the stern of the boat, however, not the midpoint."

    I definitly grok that, and that is precisely how it works in WSIM. The problem is that I am not using boats that are max. 2 hexes long ... and yet to keep the system manageable, I need to adhere that bow to the ship hex or else there are endless debates. In a ship that is three (ship) hexes long, that bow turn from the stern now becomes two hexes; in a ship that is eight hexes long, like my 158 ft. frigate (443 tons), that bow swing from the stern becomes ludicrous. So I am forced to (unrealistically) use the center of the boat as the pivot, even though I have read descriptions that would agree with your point.

    As regards the "stopped vessel," I believe this is merely the suspension of it's forward momentum in game terms ~ like taking turns between combatants in melee. Naturally, the boat would swing through the wind the next move, or back again, so it is a temporary suspension of the boat's natural movement broken up for game/round purposes.

    In both cases, I think it best to maintain these two fictions for the greater good.

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  9. And now I'm looking at it, and thinking that maybe it can swing from the stern after all? Except that the stern will end up backing up a little, because of the way the hexes still govern movement.

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  10. Yes! I was thinking the same if I read you right. Coming off a full stop, the vessel drifts back 1 hex and the bow turns off the wind, captain's choice of direction. If they were my rules the first turn with the sails set on a sailable course, i.e., not into the wind, the vessel would her as far as arresting her drift only to gain way on the new heading the following round.

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  11. *solemnly* ... I have made the change in figure 4.

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  12. Wooden Ships & Iron Men was the very first adult game I played. It was my gateway to wargaming, RPGs, and the rest. Fond memories.

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