[Bryan Herbst]

You do not need to. FIRST imposes no restrictions on how you build your robot, FIRST only restricts the materials you use to build it.

However, you will find that an engineering notebook may come in handy in a number of situations.

At competition you will find it useful for talking to judges. Having a notebook with a log of your progress through the season will greatly assist you in sharing your team's experience.

In future years, you can reflect on the journal and find ways to improve your team. You can look back on how meetings were run, which designs did and didn't work, etc.

All in all, an engineering journal is easy to keep up to date (spend 5 minutes or so at the end of every meeting logging your progress), and can reap great rewards.