Monday, December 17, 2012

Loading that Ship

I noticed a funny thing when comparing how different games have handled ship statistics.  For example, let's take a look at a well-known historical ship, the "galleon".  The galleon in LOTFP needs a crew of 150 and can carry 150 tons of cargo.  The d20 Skull & Bones book has the galleon at 400 *tons* of cargo (crew 200).  Flashing Blades: High Seas puts the galleon at only 24 tons of cargo, and offers more nuance differentiating minimal sailing crew from gunnery crews from max crew.  With all these variances, I don't think it's pedantic to question why 3 games defining the same ship would vary by a factor of 16(!) for a vital statistic that ought to be historically verifiable.

Only, it turns out it's not that simple to verify, at all.

For starters, a common ship like the galleon was made in a wide range of sizes over a 200 year period, from 100 ton hulls up to 600 tons and even larger.  In normal usage, the tonnage of a ship is a volumetric calculation related to hull displacement, and not the actual amount of weight loaded on the ship, dead weight tonnage, which makes it sit lower in the water.  There's a calculation for the volume of a ship (length x beam x depth)/100, which calculates the volumetric tons - also represented as tuns - estimating the number of tun-sized barrels that could fit in an area for determining admiralty and harbor fees.  Measuring the loaded weight and water line is something different,  and can only be done empirically (ie, actually measuring the water line as a ship is loaded).

Game designers haven't been particularly clear what they mean by "cargo" - the 150 and 400 ton "cargo" statistics could just be representing hull volume and not how much dead weight the ship could actually carry, whereas the 24 tons for the High Seas galleon probably represents the dead weight amount the rules are suggesting.  I'm just guessing at this point.  When you read historical accounts of pirates and buccaneers, 20 tons of precious treasure was a vast sum; Drake's famous capture of the Spanish galleon Cacafuego netted 24 tons of treasure, and it was carried on a 120 ton galleon.  Other examples to put into perspective:  Black Bart captured 240,000 pieces-of-eight from a heavily laden galleon, which represents just under 8 tons of silver; Ganj-i-sawai, the famous capture by Henry Every in the Red Sea, had closer to 10 tons of coins.

A funny way of considering the problem:  the ton of feathers weighs the same as a ton of coins… but who wants to worry about calculating the volume differences?

In addition to the conflation of terms, there's a paucity of written records - lack of detail on how certain ships were actually rigged and armed, for instance.  Further muddying the waters, many ship types use the same name for a radically different vessel - a pinnace sometimes refers to a towable, single-masted ship's boat used as a tender, but also referred to a 3-mast merchant ship in its own right.  Some of the games have missed that nuance as well.

Back to weight versus cargo, it'd be very easy to go completely down the rabbit hole, and start considering how many cannons are being carried, how large the crew and provisions, and worry about how much those things add to the overall burden.   Cannons are fairly heavy - 1,000 lbs or more per gun - and the games don't indicate whether they've taken armaments into account when presenting their ship values.  A compliment of cannon, shot, and powder could weigh 20 tons or more on even a small sized ship.

There's a strong argument to be made for using a totally abstract system for something like cargo, much the same way encumbrance rules are easier to manage as equipment slots instead of micro-managing pounds and ounces (or kilos, for anyone not mired in imperial).  The Pirates of the Spanish Main RPG went completely abstract with ship sizes and cargo.  Otherwise, you're always going to run into "that guy", who makes pedantic arguments about accuracy and what the game statistics represent.  Oh, wait a second… I'm the one being that guy.  :blush:

As gamers, I wonder how many of you prefer flavor and usability over deep historical accuracy?  I don't see my own players quibbling tons over the tons.  The closest gaming analogy is probably Traveller (again) because of its emphasis on trade and cargoes.  One of my old gamers accused my Traveller game of requiring accounting skills to prepare a ship's manifest; this was back in the 90's, and I missed the forest for the trees with more frequency back then.  I certainly don't want to recreate that experience of endless manifest management while running a nautical D&D game.

This is where I'm at, comparing maritime rules across games.  In a world where some of this information exists, in books, there's no reason not to strive for accuracy, but the system also needs to be simple, usable at the table, and not lose sight the game is about fantastic exploration over bookkeeping, even if there's the chance to engage in some high seas piracy and buccaneering along the way.  Resource management is fun, but only to a point.

BTW, the D&D Expert rules has a large sailing ship, representing the Medieval cog; Cook lists the ship as carrying 300,000 coins of treasure, which reduces to 30,000 lbs, or 15 tons of dead weight - and that's at Basic D&D's inflated 10 coins to the pound size.  The largest cogs seemed to be in the 100-120 ton volume range.

I've had a running conversation with Richard from Richard's Dystopian Pokeverse; he's been able to bring some sanity to the discussion around calculating ship volumes, suggested crew sizes, potential armaments, and so forth - rules of thumb.  Here's perhaps the most cogent advice; when all else fails, use G+ to "Contact Other Plane" and summon a PHD!

*The image is from a National Geographic, (c) Roger Morris.


  1. If I could recommend checking out the "Starships" section (pp 49-55) of the free Stars Without Numberb pdf. I realize that starships aren't pirate ships, but it's a decent (and simple) system for allocating available space and resources into a ship (and I assume not too hard to re-skin for naval use). It leaves a lot of the heavy duty details to the imagination.

  2. I almost made a post a while back that I was going to call "What's a Rowboat?" which was about similar questions. It came about when I was doing the beasts of burden encumbrance sheets and thought it would be cool to have one for a row boat-- so players would know exactly how much junk they can row across the dungeon lake. But same problem: different cultures had different kinds of small water craft and even within the same culture they could be of different sizes.

    I think in the end you just have to pick some value that a) is not so unrealistic as to cause notice and b) allows players to start interacting with the things in the imagined world. But that process of reading up on it and sussing things out is what gives me the confidence to then make rulings later.

  3. If you have ACKS (which I only just got, so I am just now finding out about the neat stuff in there), there's a whole lot on merchant ships, cargo, and mercantile ventures. They have a small sailing ship carrying 10,000 stone of cargo (about 100,000-150,000 lbs, or 50-75 tons deadweight), and a large sailing ship carrying three times that. So, there's another point of view on the subject.

    1. ACKS is using the Medieval cog, a much earlier ship type, so I included that note about the Expert cog after I noticed the huge variance between ACKS (150 tons capacity) and Cook Expert (15 ton capacity) for the same ship. These aren't small margins of variance; it's like a player trying to carry around 800 lbs in his backpack - more than most humans can deadlift or squat - instead of 80 lbs.

      I give ACKS very high marks for accuracy and getting the little details right, but in this case, I think it goes back to reconciling tonnage as volume vs dead weight tons. Could an ancient 150 ton vessel get loaded with 150 tons of metal and still sail?

      There are proven formulas to calculate volume (for registered tonnage) but not so much for how much physical weight could be loaded on a ship before it hit the waterline (plimsol line). Only modern tankers and cargo specialist ships seem to be 1-to-1.

    2. Yeah, I'll buy that. I wonder what follow-on effects there might be from reducing cargo in ACKS ships to a tenth of the listed values? Maybe I'll write the authors.

  4. Don't forget that ships, even today, aren't exactly massed produced so you'll have variation among ships of the nominally same class. Plus the bulk and where you stow the cargo matters, stow it too high and your center of gravity shifts making the ship roll, too far from the turn point and your down by the head (or the stern) with adverse consequences for ship handling. None of which you want to take into account.

    Rodgers in Naval Warfare Under Oars gives an "usceiri" of 110 feet with a beam of 41 feet (Venetian) having a displacement of 2000-2100 tons and a burden of 1260 tons. That gives you a range of 60-63% for your cargo capacity. The figures are from ships built in 1268.

    I'm curious, what system will you be using for tactical ship movement, Wooden Ships & Iron Men?

    1. The more systems I scan, the more I come back to Flashing Blades: High Seas as a system that's fast, flavorful, and also abstract. I see my players zooming from one haunted or ruined island to another, and only doing some opportunistic sea roving from time to time; Heart of Oak or WS&IM is probably too detailed.

  5. Don't crew use tonnage? Tonnage for the people and all the supplies they need.

    A ton of displacement is roughly a cubic yard.

  6. Couldn't you just apply the LotFP system of equipment slots to ships? Just have the slots represent a certain amount of cargo (perhaps each month worth of supplies uses a slot, maybe a slot can hold up to 10 000 coins, I'm not being precise here).

    Ship armaments and fixtures could be handled like armor. In the end, you'd wind up with a "maneuverability" for the ship affected by its load, meaning the players would have to prioritize hauling treasure and outrunning those pesky competing privateers.

  7. What I did myself, for a GURPS pirate game, is to use the tonnage of the ship as a base value for size. Every 10 tons of displacement a ship has, it has one more cargo slot. So a 600 tons warship will have 60 cargo slots. Those cargo slot are really an abstraction of the volume needed to stow cargo and the weight that can be stowed safely.
    60 slots may seem a lot, but I also required that guns take up a certain amount of slot (1 slot per 5 pounds of shot weight if I remember right), and so did crew supplies ( 1 slot per 10 crew member for an average length journey). That way, a warship, who has many more cannons and crew, call store much less cargo then a hauler with minimal crew and defenses.
    Of course, your load will affect your speed and maneuverability will suffer from loading your ship. It is so very entertaining to watch the players decide what to throw overboard to escape the privateers. They chose the crew instead of the treasure.

  8. I think that the way to go is to dispense with the ship type names first, make a nice line progression from small to large, and then go back and assign classes. Names would vary by culture, time, and language anyway.