Spellcasting and archery from vehicles.

[Vivificient]

I have a player who is considering buying a vehicle and wondering about the effect it would have on spellcasting. The rules for vehicles in Ultimate Combat describe using vehicles to attack, but don't seem to talk about the effects of riding a vehicle on other kinds of actions.

For example, take the scenario of an archer or a spellcaster driving a chariot. If the driver drives the chariot forward as a move action, she could presumably also cast a spell or make a ranged attack as a standard action. Should the character suffer an attack penalty on the ranged attack, or need to make a concentration check to cast a spell, as she would if she were to attempt the same thing while riding a horse?

On the one hand, I imagine it would be hard to concentrate while riding a cart at full speed down a bumpy road; on the other hand, the rules don't appear to specify any penalties, and a vehicle might offer a more stable platform than a horse.

[Bob Bob Bob]

...you should read concentration, it actually addresses this.

Concentration wrote:

Vigorous Motion

If you are riding on a moving mount, taking a bouncy ride in a wagon, on a small boat in rough water, below-decks in a storm-tossed ship, or simply being jostled in a similar fashion, you must make a concentration check (DC 10 + the level of the spell you're casting) or lose the spell.
Violent Motion

If you are on a galloping horse, taking a very rough ride in a wagon, on a small boat in rapids or in a storm, on deck in a storm-tossed ship, or being pitched roughly about in a similar fashion, you must make a concentration check (DC 15 + the level of the spell you're casting) or lose the spell. If the motion is extremely violent, such as that caused by an earthquake, the DC is equal to 20 + the level of the spell you're casting.

So on perfectly smooth modern roads they're probably fine, on anything else they're riding on rocks or dirt in something without shock absorbers (presumably). It'll be bouncy, minimum.

As for ranged attacks:

Mounted Combat wrote:

You can use ranged weapons while your mount is taking a double move, but at a –4 penalty on the attack roll. You can use ranged weapons while your mount is running (quadruple speed) at a –8 penalty. In either case, you make the attack roll when your mount has completed half its movement. You can make a full attack with a ranged weapon while your mount is moving. Likewise, you can take move actions normally.

You don't take penalties on ranged attacks unless your mount double moves so it looks like no penalty on ranged attacks unless your vehicle is a "very rough ride" (similar to a galloping horse, which is presumably similar to a double moving mount).

In the case of the chariot, wouldn't the driver need both hands on the reins? I don't see any listed requirement for using up hands but presumably they are required to operate the "Driving Device" you use to drive the vehicles.

[Vivificient]

Oh, thank you very much! I totally missed that in the concentration rules.

[CraziFuzzy]

There are also modifiers in the acrobatics skill for various levels of motion, but I've seen nothing that actually triggers needing to make a check to do any specific action, or even remain standing.