No, you don't need the class. It might be worth mentioning that at my test, almost everyone failed, some for the second time. I passed quite easily. A lot of that will be your ability to study on your own and learn the material. I happen to be very good at reading a book and then being tested on it.
The "Class" isn't anything more than reading the
books and doing the exercises. If you have the books, you won't gain any education from the class.
ASA105 has a lot of chart
work, and I think was helpful. It had been a while since I had taken 105, but it mostly all came back as I was trying to
work the problems. I would suggest working though the charting exercises a few times as they were a significant part of the test.
I enrolled in Mariners Learning System
classes for a different reason. It allowed me to take the test locally. Normally USCG tests need to take place at a USCG testing facility, and there were none near me. But, the
school is allowed to proctor a test, and they happened to do that near me. So I enrolled in the class to avoid needing to travel to take the test.