In my last post on the topic I covered the need to delve into vehicle rules and pointed out the disappointing lack of rules for land vehicles in Dungeons and Dragons: 5th Edition. I am here back with Part 2 of my quest to make some sane land vehicle rules and options for the games I run. Click here to check out part 1.
So far the goal remains the same but the RV equivalent of mundane fantasy land vehicles is pretty much confirmed to not exist. That doesn’t mean we are dead in the water, we need to find something that we can use on a different end of the spectrum. My initial thought was to take a look at some other sourcebooks that have vehicle rules, namely Acquisitions Inc. and Ghosts of Saltmarsh. I have taken a good look at the ships in the saltmarsh content before but revisiting it now made a few things click.
I needed another analog, something above the mark I am trying to hit. This is where the sailing ship comes in. I won’t fully quote rules as written here since there is a lot but let’s call out of key points we did from the carriage, with some “assumptions”:
Sailing Ship
Type: Vehicle (Water)
Cost: 10,000 gp
Weight: No clue…..
It is worth noting the price of the ship comes from the equipment list and the rest from Ghosts of Saltmarsh. The question becomes, why were these not merged in dndbeyond? Wizards of the coast tend to have good book keeping as far as uniquely named items being identical, or at least making it obvious if something is different with some change to its name. I have to assume these two things are one and the same and it is more a matter of having a reason to buy Saltmarsh? Not ideal, but logically sound considering the link from the Mounts and Vehicles page links to Saltmarsh.
Tangent complete, back to the ship…
Aside from the items above there is clear rules on how the vehicle functions, can be equipped and its passenger/crew capacity. These are all important things to take into consideration. Right now our range, price wise, is 100 – 10,000 gold. Quite a broad range but this might be good for us. Having something that is overkill and underkill gives us a distinct top and bottom end to restrict us to. We also have the keelboat as a reference point once we get some data. Yesterday when I was wrapping my head around what is the RAW Carriage I called it a wrap once I realize how low it ranked. But we are going back down that road to get some common parameters, more specifically overlay what we have for the carriage over the specs of the sailing ship one section at a time.
Lets look at the end result, followed by my path to get there (spoiler alert not conclusive… yet)
So.. we have some numbers here. I included the Draft Horse as de-facto source of “horsepower”. Puns aside before we could figure out movement speed we needs some maths. I got a lot of data from Charleston Cares when I found it yesterday including this handy page. Yaaaay Physics. This is a great resource for calculations we need to do. However there is an important flaw in our application, coefficient of friction is not part of their calculations since they are relying on near zero values. Lets give a visit to my friend the Engineering Toolbox to get some data. If we look at the Wood and Clean metal statistics we see a coefficient of 0.2 – 0.6.
Damn, a range.
Well we can make assumptions around craftsmanship to get a more refined value here. Ideally axles would be constructed as efficient as possible, which makes be think its fair to say a value of 0.3 could logically apply here. Near perfect but not quite. I considered a value of 0.2 but this felt too good for “primitive” technology. There is also the argument that the construction would involve the best possible materials and raw surface friction would not be the mechanical operation of choice. All that rambling considered we should lock in at 0.2 and call it the best of the worst. There is another coefficient we need for the wheels on terrain. So we consult the data and wood wheels on stone is 0.2 – 0.4.
Damn, another range.
Well this one I have already had some preconceptions. But is my madness reaching a point of being a lost cause? We have a lot of data thanks to Charleston Cares and not a lot of solid answers just guesses. That page already confirmed another data point we needed to solve, the travel speed of 3 mph. I am going to have to table my math on this for another day, I have read to many papers on rolling friction than I care for this evening. Back to CC there is a statistic that rings home, “1.8lbs to a 200lb person”. This would take a 600 lbs carriage to be 5.4 lbs of strain on the horse? Sounds too good to be true but lets run with that 9:1000 ratio. Assuming we have three 200 lb riders we double it to 10.8 lbs. Then assume a physical cargo capacity on this vehicle as another 600 lbs of cargo (if the cart doesn’t reach a break point under shearing forces) we are at 16.2lbs as a sustained load, more so for starting load.
That feels low… We may have to solve for proper friction coefficients…
We need some kind of conclusion on this and I think we focus on travel speed since we are still at “back of napkin equations”. I mentioned the travel speed of 3 mph referenced, but consider the DND math around the Draft horse: 40 ft. per round equates to 4.54545455 miles per hour. Essentially the horse would not be impeded by this load, we are not even close to 540 lbs, so there is no need to make any changes to travel speed. Even if we consider the coefficient applied in the equation at a higher speed, there is no way a carriage loaded to its physical capacity is hindering our faithful steed. The horse dragging the carriage without wheels is right at its capacity. Considering a Draft Horse can be “burdened” with a load of 540 lbs I see no need to limit its speed when not burdened and the stats for the draft animal is fine… for now.
So what did we gain from this, pretty much nothing related to the carriage besides the concept that the carriage would potentially break under load of cargo before be burden the horse. I am starting to think we need more information to get where we need to be to understand how many horses will be needed to haul a vehicle. Like I said before, lets put a pin in this until I can make some more concrete calculations. CC was giving us some useful math, but I feel the numbers don’t add up. The sailing ship was a bit pointless in this exercise since we are not trying to sort out cost as of yet. Next Part will not be finished before the next session so no need to find out how we want to size this fantasy RV. Depending on the results of the session we may shift gears a little bit and enjoy this confusing math nugget.
See you then!
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