How do the vehicle acceleration rules in Ultimate Combat work?

Question

I'm looking through the Vehicles section in Ultimate Combat and I'm rather confused about vehicle acceleration.

I thought I understood it but then I read this section on acceleration and it confused me;

Accelerate (standard action): With a successful driving check, the vehicle’s current speed increases up to its acceleration (in 5-foot increments; minimum 5 feet), but no higher than its maximum speed. The vehicle can move forward or forward diagonally. In other words, each time a vehicle enters a new 5-foot square, it can choose any of its forward-facing squares—the ones directly in front or either of the squares directly forward and diagonal. This allows the vehicle to swerve. A driver who fails her driving check can only move into squares directly in front of the vehicle’s forward facing.

Emphasis mine. That's the part that really throws me off. If someone could explain this to me, maybe using an example, that'd be really appreciated.

Here is an example of why I'm confused;

If the PCs are controlling say, a galley, using the air currents. The acceleration of the galley would be 30 ft. If at the beginning of the turn, the vehicle is still and has a current speed of 0 ft. does the driver's check to accelerate increase the galley's speed to 30ft (since that's its acceleration) or does it increase to 5ft. and eventually, after enough checks increase to 30 ft. acceleration?

Answer 1

The highlighted section means that with a successful driving check the driver can cause the vehicle to accelerate an amount at least 5 ft and at most its acceleration rate in 5ft increments.

For your galley, this means that you get the choice of 5ft, 10ft, 15ft, 20ft 25ft or 30ft. So long as the total speed does not exceed 180ft (the maximum speed).

If just trying to get to max velocity using the maximum acceleration (30 ft), it will take 6 rounds to get up to the maximum speed of 180 ft / round.

If you have to navigate through a fjord or something and you want to take it slow and steady, you have the option to accelerate 15 ft on the first round and then hold that speed or accelerate 5 ft or decelerate 5ft each round.