Windsurfing encompases 5 main different facets or diciplines: beginner/progression windsurfing, wave sailing, freestyle, freeride and freerace/slalom/race. Each dicipline demands different elements of handling and control out of the gear. Some equipment does a very good job of crossing over between diciplines.
Here a bit of a rundown on how gear differs:
Learner and Progression Gear
The key to making the whole learning process nice and easy is board stability. A good wide board with plenty of volume is what you're after. 160 litres and upwards is ideal. A centreboard is good to have while you are learning but as you progress and start planing it becomes a bit redundant and tends adds a lot of weight and drag to your gear. As soon as you start planing you'll be looking to learn how to use footstraps and the harness.
A good progression board will have inboard and outboard footstrap positions so that you can master sailing skills without having to buy new gear. The inboard positions make getting into the footstraps nice and easy. The outboard positions are where you and aiming to get to. They allow you to get greater performance out of your board. Changing the fin will also let you get a greater range of performance out of your board. A short wide fin is excellent for learning. It is powerful at low speeds and is less likely to hit the bottom when you are in shallow water, however they do tend to be quite slow. A long, narrow (high aspect) fin is a lot faster and allows you to point higher into the wind but requires you to be comfortably planning to get the most out of it.
Learners sails are focused on keeping things light weight, so that uphauling the sail is made as easy as possible. To achieve this the sail generally has less battens and minimal reinforcement. Beginner specific sails make learning heaps easier for people that don't have so much body strength. Learning sails are a bit limiting when the sailor starts progressing into higher winds as they tend to be more unstable and don't handle a beating so well.
Freeride boards are designed to make blasting fun and easy. Their volume tends falls between 100 and 150ltrs. A good amount of volume will make getting planing easier and will mean that you'll still have no problems uphauling. Freeride boards have reasonably rounded rails to make turning manouvres easy.The volume that you choose will depend on your skill level, body weight and the sail sizes that you aim to be using. The fins have a good amount of rake and a swept tip to make the board ride smoothly and turn easily. A quiver of two or three fins will enable to to use your board in a much wider range of wind and water conditions.
Freeride sails are designed for blasting and a bit of bump 'n' jump. They are relatively light weight with good top end (fast and stable when overpowered), good bottom end (powerful so it gets planing early) and easy to rig. To reach these goals freeride sails generally have 6 or 7 battens, tube battens through the body of the sail, no cams and mostly mono-film construction with some x-ply re-enforcedment. These are our most popular sails. While they are a bit heavier than learners sails they are still fine to learn on plus you'll be able to progress for years without outgrowing the sail.
Free Race / Race / Slalom Gear
These boards are all about speed. White knuckles. Adrenalin fuelled. An all-or-nothing existance on the edge of control. Pure race and slalom gear is focused on the top end which is all good and well but can make the boards demanding to sail and, at times, difficult to control.,especially through transitions. Free race gear on the other hand, allows a little bit more control and useability. Speed is one element of going fast... so is survival... Freerace gear will make sure that you are super fast yet still make gybes and tacks easy enough to pull off.
Width, rails and rocker are the keys here. The wider the board the greater the fin size that they can run, providing more lift and allowing you to run bigger sails. Flatter rocker lowers the board's angle of attack to the surface of the water, thereby reducing drag. Rails are harder to provide more edge and drive. All of these elements tend to sacrifice some of the boards manouverability.
Like the boards, these sails are all about speed. And at the top end speed sail stability is essential. This stability can really only be reached with the use of camber inducers. These cambers lock in the shape of the sail despite the insane pressures that the wind deals out. This locked in feel is amazing - Being able to handle stupid amounts of power and keep pushing faster is and addiction for many. But these cams and extra battens add weight to the sail and the locked in shape can make transitions difficult. Once again we see a sacrifice in manouverability plus the added increase in rigging hassles. Speed, race and slalom sails have four or more cams while free race sails will opt for two or three, making the sails easier to use and rig. But don't be fooled - free race gear is still blisteringly quick.
Wave riding is all about slashing and carving. The boards tend to have more rocker (nose lift), rounder rails and more shape in the bottom. All of these elements effectively loose up the board and provide the ultimate carving control. The flipside is a reduction in top end speed and upwind ability. Wave boards get one hell of a beating so a robust construction is generally a key goal of the designer. As a result they can be a bit heavier but provided this is not too excessive it doesn't really pose too many problems.
Wave sails must be easy to throw around and super-robust to cut the mustard. The feel and handling of sails can differ quite a bit between brands. Some go for a soft flowing feeling and others tend towards a more tight and locked in feel. It all comes down to personal preference. The materials used in wave sail construction tend to be focused on being able to handle a fit bit of punishment and wipeouts can be massive. X-Ply a term that you may hear thrown around quite a bit. This is a cross weave of technora or fibreglass strands sandwiched between two thin layers of monofilm. This reinforcement makes the sail really strong. Most modern wave sail are primarily made out of X-Ply. Dacron is a another material that is sometimes used. It is a woven fabric and therefore has a bit of give and flex. Sails with Dacron tent to have a softer feeling in the hands.
So why do you want a stiff boom anyhow?
Whats the big deal? Well it is all about the stability of your rig when overpowered. Picture this: You are blasting along and this massive gust hits you. The wind is pushing hard against the sail and you're showing no fear, sheeting in hard, pulling on the boom to counter this power and keep the nose of the board down. The forces at play are huge! You've got all that power of the sail and it is pulling very hard on the boom's outhaul. And then there is you pulling against the boom. Both of these forces are working to bend the boom out in the centre and pull the ends inwards. So if your boom has a bit of flex this is exactly what will happen - the arms will flex out, the ends will pull in. In effect this effectively lets off the tension on the out haul, powering up the sail and allowing the draft to destablise and move forwards. The exact opposite of what you need to survive overpowered. Stiff booms give you much more control and top end out of your rig.