Vehicle speed w / alchemical propulsion

[gergLeft]

I see there are two sample vehicles (Steam Giant and Alchemical Dragon) however, neither in the rules, or divining from the stats of these - I cannot tell how to derive the speed of the vehicle (or how many squares of alchemical engines are necessary relative to the size of the vehicle).

The alchemical dragon has 60 squares of space, but only 6 engines, but moves 100ft while the steam giant has only 16 squares with 10 engines, but only moves at a speed of 60ft.

The rules never seem to cover if adding more engines will increase speed, or increase the size of the ship, or what the required number of squares of engines are per size of ship, or base speed of alchemical propulsion.

I know of one player in my party that is wanting to build custom creations (I know a dwarven gyrocopter is in the works and the player wants it to be powered by alchemy)

[HaraldKlak]

Given that alchemical (just as magical) propulsion can be a whole range of different things, I don't think it makes sense to define how much power the got in generel rules.

I'd take a look at the actual vehicle, comparing it to existing vehicles, and work from there.

[gergLeft]

I can understand magical - you construct it with overland flight (like magic carpets & flying cauldrons, it gets speed based on overland flight...but then again, those aren't vehicles). size of a ship seems to be relevant (alchemical says something to the effect of being able to powering ships many times its size) - or did Paizo just leave that for DMs to wave their hand at. Sad if they say you can use alchemical propulsion and then give NO guidelines for it, except for 2 samples.