[HR] Naval Rules

Most likely it will be gradual penalties for too much time in the water, to simulate both how ancient galleys became waterlogged over time and the fouling of ships in general. Ships can be dried out, careened, plated, or coated. Likely the first two will be actions that can be taken, while plating will be a ship option and coating (white stuff, black stuff, brown stuff) will be something that can be bought and applied to extend the time before the ship starts suffering penalties.

I was looking over the ship speeds in the corebook again, and there’s something that doesn’t jibe with what I’ve been reading.

The implication is that the more oarsmen that are powering a ship, the faster it is (under oars). So a pentekonter might be more nimble than a trireme, but it’s also slower. However, under sail the smaller vessel is faster.

At the risk of this phrase becoming cliche, ship speed is…complicated. It relies on many things. Among them are the amount of power (whether from oars, sails, a mechanical engine, etc), the ship’s length (which generally increases speed), and the ship’s block coefficient (essentially, how streamlined it is under water; the sleeker the ship, the faster it is).

Comparing the pentekonter to the trireme, a trireme was slightly longer (around 37 meters to 33 meters), about equally sleek, quite a bit heavier, and with a lot more power (170 rowers to 50 rowers). Both types of ships used a single sail, although I don’t know how different the sails were. So, the trireme should have a higher top speed under oars (although possibly slower to accelerate) under optimal conditions, but be the same speed or slower under sail and less nimble due to the heavier weight and need to coordinate multiple tiers of oars.

Note that the “less nimble” is still relative, though. A Greek trireme is still lightly built and quite nimble compared to a Hellenistic polyreme, when fours to sixes were the main battle fleet and larger ships were used as floating siege batteries.

I received some information today from a very helpful research historian regarding masts and sails and how much certain things weigh in relation to other things, which means I will be revising and expanding on the Ship Construction section of the document.

I thought the trieres/trireme had two masts and thus two sails (at least the later ones did). There's countless images of two-mast triremes, and the Olympias had two.

Talking of construction, one other thing that occurred to me: reconstruction. You might take a ship of one type, and rebuild it as something else (either by design or when repairing storm/battle damage). That might be as simple as turning an aphract vessel into a cataphract by adding decking, but also more complex such as adding a bank of oars to a single or two-decked vessel to increase the number of rowers.

As you noted in an earlier reply, a pentekonter, for example, wasn’t much smaller than a trireme, adding another bank of oars (which would make it higher, but also sit lower in the water due to the extra weight) would double it’s power under oars. Rebuilding it with a broader beam might also allow you to accommodate a second rower on each oar of the top bank.

While it might be complicated and involve compromises, it’s still probably cheaper than building a new ship, and may require a lower level of shipwright skill.

Sorry, I’m just getting back to this - my understanding (although I’ll need to re-read the Olympias trials again) is that the boat mast (the forward mast) did very little to speed the ship up if the mainmast was functioning. It ended up having two functions: it was an emergency mast that would allow sailing if the mainmast wasn’t aboard (i.e. in a combat situation) or if the mainmast broke. Also, when both sails were used, it helped the ship when turning because it could be set for the new angle and catch the wind while the mainsail was being reset.

I do already have rules for a bowsprit that reflect the second use, but I’ll need to modify the rule to allow use of a bowsprit as an emergency sail.

Just to test the construction system, I decided to try out a giant merchantman. It’s loosely based on the Roman grain ship Isis.

Our starting point is that the ship was 180 feet long, over a quarter that in width, and had a cargo hold that was 44 feet deep from the main deck to the keel.

So, to start, we’ll use a 180 foot length and a 3:1 beam, which gives us a rather tubby 180x60 ship, with a 15 foot draught. That’s probably not enough to be 44 feet from the main deck, so we’ll add a second deck to drop the draught to 22.5 feet. The ship has a seaworthiness of 5, and as a giant merchant ship, no rowers will be added. Isis is a 2068 ton ship, with a base capacity of 413,600 stone. Her base shp are equal to her tonnage, which is 2068. Because the Romans used mortise and tenon joining, she’ll be considered a clinker ship. This give +10% shp and +1 seaworthiness, but means rowers or artillery cannot be carried on any deck except the top deck. This means Isis has 2275 shp and a seaworthiness of 6.

At 180 feet, she could have up to six masts, for a total of 13 sails, but that’s far more than what the Romans actually did. Instead, we’ll go for a modest 3 masts and 5 sails. With square sails and the beaminess of the ship, that will require 66 crew to handle the sails. This also gives her a speed of 2 hexes per round when sailing with a fresh breeze (0 modifier) from an aft quarter (also 0 modifier). Given that the base turn rate for Isis is 11 (one 60 degree turn every 11 rounds), we’ll also add a bowsprit (which requires 2 more crew), to improve the turn rate to 10. It’s not much, but it makes her a little less of a wallowing pig. The total weight of masts, sails, and rigging is 5400 stone. Carrying a full spare set of sails and rigging adds another 1800 stone, so the total rig is 7200 stone.

With 68 crew needed to run the ship, an additional 7 crew (captain, navigator, bosun, and 4 spare sailors) are added to make an even 75 crew. At an average of 15 stone weight for a human, the crew weighs 1,125 stone. For the sake of this example, each crew member has 200 stone of personal gear and rations for the voyage, for another 15,000 stone in crew weight. The total crew weight is 16,125 stone.

Adding crew weight plus rig weight, the ship could sail with equipment taking up 23,325 stone, which would allow Isis to theoretically carry up to 390,275 stone in cargo, or about 1950 tons. However, a ship like this would also have marines aboard, and the real Isis also carried artillery on her top deck. These would reduce cargo space accordingly, but it shows the massive amounts she could theoretically carry.

For cost, the hull of Isis alone costs 227,500 gold pieces. The masts cost 36,000 gold pieces. Rigging costs haven’t been figured yet, but I anticipate they’d be somewhere around the cost of the masts, maybe a bit more. A normal crew would be 563 gold per month. So, it would cost approximately 300,000 gold to have the ship built, and a minimum of 563 gold a month to have a competent crew handle her. She can haul large amounts of cargo, but only at a speed of 4 knots in a moderate breeze, and she’ll pretty much only be used between Class I markets because of the amount of cargo she needs to haul to be profitable.

Excellent stuff.

How would a vessel at that level of seaworthiness handle storms and other bad weather at sea?

Seaworthiness 6 can withstand up to Beaufort Wind Force 9 before it starts taking damage. That’s more than I intended pseudo-Isis to be able to withstand, but it gives me a starting point to work from in balancing the rules. I haven’t done all the ship options yet, and this convinces me there need to be some that add a benefit but reduce seaworthiness to reflect ships designed for areas with calmer weather.

Out of curiosity, what happens under your rules if you add 13 masts to this design? I ask because the Romans presumably didn’t do so because the marginal return past the number of masts it actually had was poor, or even negative…

There are two constraints on masts. The first is a hard rule that a ship can only have 1 mast per 30 full feet of length, so the 13-mast ship would need to be 390 feet or longer. The second is an effect rule that if a ship has more masts than its Base Seaworthiness, it gets -1 to Seaworthiness for each additional mast. This represents the fact that as masts are added on, there are more stresses on their anchoring points and amount of weight higher in the hull increases, reducing stability. There are also diminishing returns built into the speed chart once you get to about 8 knots or so. Below that, each pair of sails adds about 2 knots to speed. Above it, each pair adds about half a knot.

Cool! I have zero knowledge that would allow me to assess the accuracy, but it certainly sounds real-world.

Just a small “ah-ha!” update. I took most of September off from writing because it’s my company’s end-of-fiscal-year, and my job gets crazy for about six weeks. When I came back to my files and started reading, I realized I had been trying to write the combat rules, non-combat rules, and construction system all at the same time, which made things incredibly convoluted. I am going to go back and reorganize what I have, and then focus on one area at a time. Hopefully that will let me be more efficient in how I write…stuff.

Good to hear. Making me feel a little guilty on how little I’ve done on MLT lately…

I’m doing a major revision right now - the original draft of the rules used a movement chart where speed bonuses or penalties moved you up or down the chart, but it had a lot of fractional movements. It worked OK for single-ship actions, but would be totally unwieldy for even a small squadron. I’m switching instead to a point-based movement system, which (so far) is going much smoother. There’s still math involved, but it’s much simpler math.

Damn, this is cool!

I might have missed these points, but here’s my two cents:

What happens if the captain decides to cancel a burst half way through? Or if the burts has to stop before the 2d3 rounds are up? Is the downtime in which the ship is slowed affected?

Perhaps you could look into defenses like protecting a harbour with a large chain - that would certainly ruin someone’s day.

And a few things I’m sure my players would come up with:

  • what happens if I chain 40 zombies to the oars? Obviously they won’t get tired, but I’m guessing bursts are out of the question as well.
  • more importantly: fire. Do you have riles for people trying to set other ships ablaze? Or was that historically not as common as I would imagine?

Good to hear you’re still working on this, I’m really looking forward to the results.

“What happens if the captain decides to cancel a burst half way through? Or if the burts has to stop before the 2d3 rounds are up? Is the downtime in which the ship is slowed affected?”

Good question - I hadn’t considered that yet. There should still be some downtime, but it probably shouldn’t be the full time, since the rowers haven’t been worked to exhaustion.

“Perhaps you could look into defenses like protecting a harbour with a large chain - that would certainly ruin someone’s day.”

evil grin I should point out that one of my major sources recently is William Murray’s ‘Age of Titans,’ which is heavily about naval siege warfare, including harbor defenses and using ships to ram city walls(!).

"And a few things I’m sure my players would come up with:

  • what happens if I chain 40 zombies to the oars? Obviously they won’t get tired, but I’m guessing bursts are out of the question as well."

Yes, undead won’t be able to do bursts. However, there is discussion of “non-living” power sources in the strategic movement section. That could be a steam engine, a magical engine, or Residual Human Resources. They may not be as fast for tactical movement, but their endurance is higher than living rowers.

“- more importantly: fire. Do you have riles for people trying to set other ships ablaze? Or was that historically not as common as I would imagine?”

…OK, that needs to be added to the To-Do list. If nothing else, there were the Rhodians (I think - may have been Cretans) using firepots, fire arrows, and (of course) Greek Fire. Plus, PCs have a tendency towards pyromania, so even if it wasn’t totally historical, it would still need to be included. Besides, at some point, somebody with a ship WILL anger a dragon (in addition to pyromania, PCs have a tendency to rather poor life decisions).

I’m somewhat wondering now how many water elementals it would take to move a ship of a given size, if they flatten themselves up underneath it and essentially “carry” it.

As an aside, it would be fun to have some sort of conversion system from whatever horrible sea monster to the statistics that would be compatible with your ships in combat, for polyreme vs. dragon turtle (next on SyFy!)