Shortboards are sexy, sleek looking things that are the definition of surfboard performance.
They easily fit under your arm, they slide into any-size car, and they're what all the guys on the world tour are riding. This makes short boards seem very desirable.
Because of this, a large percentage of surfers either prematurely move down in board size (before they have the ability) or are currently riding boards that are too small for them. You often see surfers strutting down to the waters edge with a small, shiny new board under there arm. They paddle out, still looking great... and then don't catch a single wave in 2 hours.
If you are using a board that is too small, you'll be spending entire sessions watching people around you catch loads of waves while you are missing every wave you paddle for. Frustrating! This could partly be down to your wave reading skills, but there is a good chance poor board selection is creating the low wave count.
Small (low volume) boards are amazing to use if you are at peak surf fitness, can generate your own speed on a wave, and are comfortable with super late takeoffs. If you can't do those things and are riding a small board, you are probably using unsuitable equipment and could be massively slowing down your rate of progression. Some time spent on a larger board could really pay off. Note: a larger board is a board with more volume (float), not necessarily longer.
So what does extra volume do for you?
1) Gives you a higher paddle speed. 2) Helps you glide over fat sections. 3) Gets you into waves earlier. 4) Increases your wave count. 5) Makes the board more forgiving to use (foot placement etc. is not so critical). 6) Makes paddling easier if you are not "paddle fit". 7) Enables the board to carry more speed down the line.
Overall more volume in a board makes surfing easier.
"You can't ride what you can't catch"
-Lulu Wiegers
Things to consider...
Wave Count
If you are catching less than 60% of the waves that you paddle for it may be worth considering using a bigger (higher volume) board. Once you make the switch you should soon be catching more waves. The more time spent on a bigger board > the more waves you'll catch > the better you get. As you get better (catching 60% + of waves paddled for) you can then get back onto a smaller board.
You May Have To Step Back to Step Forwards
If you are sinking on some waves or just getting sometimes getting left behind, try going back onto a bigger board just for a session or two and see how it feels. During the first surf on a larger board you will probably be catching more waves than you have done in ages, able to make more sections/waves and have the speed to do some turns.
Remember, If you can turn a big old longboard you can turn anything!! Spending time on a bigger board will always help your surfing in the long run. When you have mastered the "big 'un" and you want to move back down in board size you will actually be able to make the most of the extra maneuverability a smaller board has (maneuverability, duck dives etc.), rather than just languishing in its disadvantages (low paddle speed etc.).
The right time to go onto a different/smaller board is when the board you're riding is holding you back.
Wave Type
If you are surfing small, fat, slow, mushy waves you need to be riding a board with large volume to allow you to catch waves and cruise over fat sections (not steep). If it is big and hollow you may also need a high volume board to get enough paddle speed to get you over the ledge (catching a late steep wave).

Feel The Glide
Longboards or Mini-Mals are a great option for those that don't get the chance to surf often or who are not surf fit because they allow you to maximize the number of waves you can catch per session. The other bonus is they go well in smaller surf which is what most of us deal with day to day at our local spot (OK, I am a bit lucky on this one). Mini-Mal's or Longboards are a perfect board choice to help you get the feel of gliding across a wave and maybe starting to experiment with turning.
Get Your Calculators Out
It's now possible to calculate how much volume you need in a board for your personal weight and ability. Have a go on the volume calculators provided by Channel Island Surfboards (Al Merrick) and Firewire , see if you are currently surfing something close to their recommended volumes. Note: Use these calculators as a guideline and maybe take an average for best results (they vary).
Enjoy it!
At the end of the day, surfing is about having fun. If you can make it easier for yourself and catch more waves, why not? Get out there on a bigger board! They may not look as sleek and they wont fit in the car, but your surfing will improve more quickly and you'll probably have a far bigger smile on your face at the end of the day!
"Foam Is Your Friend"