When you first start surf lessons you need a really big board - long, wide and thick - this makes building your basic skills easy and makes it easier to paddle, catch waves and stable enough to stand. It is also very forgiving so if you make a small error or mistime a wave you can generally get away with it.
As you improve you want to reduce your board size to be able to turn faster, sharper and push your surfing but if you make a jump too fast it can work against you. The overall volume of your surfboard is a very important factor too, more important than just looking at the length. If you need help choosing a surfboard as a surf coach and pay for a coaching session as they can see how you surf and how your current surfboard works. They can then make the best judgement on board improvements. Some guys in surf shops are great to chat to as well but there are some that just want to sell you a board as they want to get rid of it - whether it is suitable or not!
