I used to rally, extensively, in South Florida many moons ago. There are several types of rallies, the most popular and more serious of the bunch being the TSD, or as mentioned above, the Time/Speed/Distance rally, You definitely need a navigator, most clubs will turn you into a helper if you show up without one. The driver watches for the turns and drives, cusses the navigator and traffic, etc. The navigator will read the instructions, decipher them (there's always some instructions that aren't quite so obvious and a good knowledge of the sanctioning body's rules is paramount), plus keep the mathematical portion under control. Let's say that an instruction states:
#37 - MM248 CAS165 1.2 miles
Deciphered it means that beginning at Mile Marker 248 the car should change its average speed to 165 mph for exactly 1.2 miles. Obviously you can't drive 165 (well, most can't
) and the navigator needs to do the math to account for the difference between actual and called for speeds. Later in the instructions you'll be put on a highway and told to drive at 16 mph - making up the difference. This is just a small piece of what can be thrown at you. It's imperative that the driver and navigator get along well as it can be a very trying day with serious competitors. The winner in a TSD rally is determined by the team closest to the actual time determined by the rallymaster. A point is levied against a team for every second above or below the correct time at the end of each stage. Most of our rally winners scored below 15 points, with typical rallies totaling approximately 150 miles and having in excess of 200 instructions.
Another less trying rally would be a 'sign hunt' where most instructions are 'turn here', etc. and the winner being the closest to correct time without coming in under time (speeding is normally discouraged for liability reasons.)
Either type of rally can be a ball. The stress of a TSD rally is what you make of it, the more competitive you are the more stressful. Don't be surprised to find cars loaded with electronics at a TSD event (I used to be one of those guys.) I would hazard to guess however that a tulip rally is more along the lines of a tour rather than a rally, but I've been wrong before...