As you spend more time on the water progressing, you’ll want to jump down in board and foil size to increase performance.
The question for most people is ‘which should I size down first? The board or the foil?’ I always recommend taking this process one step at a time. Changing up both the foil and the board can be a challenge if you aren’t a very comfortable foiler. Which to downsize first really depends on what you started with initially. If you are using a board in the 110L size or larger, I would downsize the board first, provided your foil is in the 1800sq cm range or smaller. If your board is under 110L I would downsize the foil first, provided the foil is in the 1500sqcm size or larger.
Downsizing the board will reduce the swingweight, making transitions, pumping and carving easier.
The downside to a smaller board is the board becomes less stable when trying to get up on foil. How do you know if you’re ready to step down in board size? There are two things to look for: the first is general balance. The better your balance is, the easier it will be to kneel on the board, stand on the board, and pump your way up onto foil. If you are able to easily stand on your board in choppy or wavy conditions while trying to get going with the wing in light winds, you’ve mastered this part. The other portion is efficiency. The more efficient you are with pumping the wing and the board as well as utilizing board angle for maximum board speed, the quicker you’ll be able to take off and the smaller board you are able to utilize. If you can get up on foil while underpowered with just a few wing pumps, you have this bit down. Once you have both of these down, you’ll be ready for a smaller board.
Downsizing the foil increases performance in your ability to carve, transition, and in some cases pump.
The downside of a smaller foil is it requires more speed to plane out the foil and release the surface tension. The key to preparing to downsize your foil is to spend time becoming efficient with your take off. The quicker you are able to get up on foil, the easier it will be to get enough speed to get up on a smaller foil and to stay on foil in the lulls and transitions. If you are able to pump up on foil in any rideable conditions with just a few wing pumps, you have this part down. Transitions are the other factor in knowing if you are ready to reduce your foil size. You want to be hitting the majority of your transitions on your existing foil set up before downsizing to something smaller. If you’re feeling confident with both of these, you’re ready for a smaller foil.
In summary, balance, efficiency, and transitions are key factors when deciding if you are ready to size down your gear. For board size I would say 10-15L smaller for most people is about about right. 20-30L smaller is the most I would jump if you are starting on a large board. Any jump larger than that is too much unless you are starting on something in the 150L+ size. For foil size I would say about 200-300sqcm smaller is about right for most people. 400-500sqcm smaller would be the most I would jump if you are starting with a very large foil or progressing very fast.