Craft does not mean you can invent things. Craft is designed to allow you to create existing technology.
There are no real rules for that. You could try a professional skill, but any campaign changing technology really falls under GM fiat.
| 1 person marked this as a favorite. |
I think you should stick with a single DC for the whole thing... that's what crafting rules assume, and part by part just seems tedious.
Air ships exist in the game rules: http://www.d20pfsrd.com/equipment---final/vehicles/air-vehicles/airship
That's 50,000 gp of cost. It's part magic, though, which complicates things.
If we compare to a boat by dimension, the closest thing is a keelboat, at 13,000 gp. But you've got to add that balloon, which is probably quite expensive. What is it anyways, helium, nitrogen, or hot air? I would probably consider that magic is required to build such a balloon that is able to lift a boat. Plus the engine is magical too.
So 13,000 gp of crafting (ships) and 37,000 gp of crafting magical items (wondrous item) to get it to fly.
Rules for craft: http://www.d20pfsrd.com/skills/craft
rules for craft wondrous item: http://www.d20pfsrd.com/feats/item-creation-feats/craft-wondrous-item-item- creation---final
Additional crafting rules here: http://www.d20pfsrd.com/skills/alternate-crafting-rules
So a keelboat is a DC20 craft check. Note, it puts a DC30 on airships, which I would personally only use for the magical part of the ship.
How long would it take? For the magical part, simple, 37 days. Maybe I'd allow it to be split into two, maybe, one for the engine and one for the balloon, but probably not.
For the mundane part... variable. You can have up to 10 untrained laborers help you, which will have a 50% chance of giving you a +2 aid another bonus each. So let's say that's +10 average. and you roll 10 on average, so a roll of 20 so far. Add in skill focus (craft) for an extra +3, and 14 int for an extra +2, for a total of 25 on the check every week. That's 50gp progress per week. Keep at it for 1820 days, and you'll have yourself a keelboat.
Now, there are rules for using *trained* labour, so let's say you use really qualified people instead. They always succeed their aid another check, and give you an additional +10 on your check. you'd do 70gp per week instead. And it's take you 1300 days instead. But don't forget to pay your guys, that's 1820gp of untrained labor or 19500gp of trained labor. Yup, trained labor will save you days, but their wages alone will cost you more than the price of the ship, and that's not even considering material costs of 6500gp.
If that tech doesn't actually exist in your setting, though, that's an extra layer of difficulty added on that. I'd probably require it needing a lot of time, many knowledge (engineering) and (arcana), and a lot of gold to spend on prototypes.
Also, they'll need a workshop to even begin the work.
Use the magic item creation rules from pathfinder unchained. I would also then use the rules for researching new spells, or something similair
I'm assuming the OP is the GM based on how the question is worded. What I'd do is adapt the library research subsystem into researching a design for the airship. It'd require some pretty difficult Knowledge (Engineering) and Knowledge (Arcana) checks, as without engines to speak of you'll need magic to make the thing fly. From there, you'll need to hire a mess of workers to help build the thing, unless the PCs are talking about a really small airship or taking a very long time to craft it. Also, they'll need to research and build a dock/port for it so it can land.
Once the blueprints are made, relevant crafting skills/feats seem to be Craft Wondrous Item (for the engine), Craft (Ships), and Craft (Carpentry). Set DCs as appropriate for how challenging you want this to be. I'd set the market price at 100k gp for this endeavor to acknowledge that making this thing for the first time is going to be expensive. As a ballpark, perhaps break that down into a 40k gp magic engine, 10k of wood/balloon, and 50k for making the dock to build the ship in as well as non-functional prototypes that fail in various ways until the design solidifies to something that works. You can, of course, pick your own numbers instead.
Once built, use the standard airship stat block to adjudicate how it flies/works. You can find it here. Note while the price listed in the PRD is 50k gp, I have the figure of twice that above to account for it being a brand new never-before-built thing rather than a ubiquitous travel vehicle.
Using the cost of the ship as cost of research seems fair to me. So is adding a sizable cost for the workshop, which is likely to have special restraints (maybe access to water, maybe distance from residences, proximity to labor, needs for camps, etc.).
You could consider allowing more than 10 untrained laborers if the PCs also hire trained laborers to overlook their work. I would have every team roll separately their checks, and every team that beats the DC would then add its bonus to the main check.
A pier is 16BP, so 64 000 gp, per the ultimate campaign rules. So 64 000gp for infrastructure, 50 000gp for research, and then cost as per the crafting rules according to how "quickly" they want to make it.
Needless to say, this is no small endeavor.