I was just getting some stuff on paper for a friend with a few questions on travellers and downwind in Bytes. Thought you might find it interesting...
First of all, the primary function of the traveller is to depower the boat by opening the angle of the leech to the wind. When going upwind, it allows you to dump the leech without the mast straightening and the sail becoming more full. (The vang also helps keep the mast bent, but primarily in the bottom section). The traveller has many other advantages as well:
1) When you need height (off the line at the start, around a bottom mark, on the starboard layline... basically any time you need to make a mark or hold a lane) you can have the traveller up higher than normal (even above centerline in light flat stuff) to get that extra bit of height you need for a short time.
2) When going downwind in light stuff you can let it off to open the sail some more.
3) When sailing in puffy conditions, it is the easiest and most effective gear change you can do puff-to-puff. So if you're over powered in the puffs but not in the lulls, drop the traveller down just before you get into the puff so that the boat accelerates forward when it hits the extra wind instead of keeling over and slipping sideways before you can get it flat again. In extremely heavy wind (upwind) you can have the traveller off all the way to de-power (and even have the centerboard up a couple inches).
4) Any time you need to foot (to get to the next oscillating shift, to get into a better lane, to get to a mark, to get speed through the chop, etc) you can crack off on the traveller without affecting the sail shape. The only thing the traveller does is change the angle of the 'wing' (your sail) to the wind. Like an airplane changes the angle of the trailing edge of its wing to the wind to change direction, a Byte can change the trailing edge of its sail to go higher or lower.
When sailing upwind, remember that you can only hike at 60-75% for most of the race. You need the extra energy to hike the boat flat in the puffs, do a few tacks, and of course, think. So set up your gears to keep the boat flat with you hiking 65%.... do whatever it takes to the gears to keep the boat flat. The only way you get lift off the centerboard is if the boat is completely flat. The only time you would want a little heel (in hiking conditions) is if there is a steep set of chop (maybe 4-5 waves)... sometimes the boat slices through them better with a 5-10 degree heel. But to steer the boat through normal waves, the boat needs to be flat... which brings me to downwind.
Downwind, the boat is also steered more easily when it is flat, so remember this when you are going up and then down for the waves... it's really hard to make a boat bear off with heel (this is also the case for rounding the windward mark). Now, for stability, there are two things you can do: 1) Sit near the back, where the bottom of the hull is flatter (in the water), and 2) Sheet!!! Doug tells me someone told you to have your mainsheet out past 90 degrees to be fast. In my experience, that's too far in most cases.
If there is enough wind to surf, there will be huge speed differences in sailors downwind (way more than upwind). It's a 'feel' that has a lot to do with anticipation. Downwind, you get what you plan for... so look ahead when you're surfing for the exit out of that wave, and the entrance to the next. In sets of waves there is always a path of least resistance. You don't always want to be on the steepest part... that means the biggest trough too, and if you dig your bow... well, you know what happens! It's not just about getting on a wave... you need to get on a wave, go fast, get off it and get onto the next one! So let’s go downwind for a moment...
You're going up on a broad reach angle, looking for a good one... of course, the boat is flat, with maybe a five degree heel to leeward, and you are TAKING YOUR MAINSHEET WITH YOU. This means connecting your arm to your body at the shoulder, and taking the mainsheet in as you lean back and pop onto the wave. When you get a nice roller, you do a million things at once:
1)pump the sheet to get on it,
2) once surfing, flatten the boat, scoot forward, and turn it downwind
3) Hold the mainsheet when you turn onto a by-the-lee angle (when you turn the boat and hold the sheet, it's like another pump of the sheet!)
4) now when you're surfing on the new angle, let out the sheet (90 degrees or just past) until you feel the leech catch the wind - STOP letting it out abruptly, and this will act like another pump of the sheet (you will feel the leech pop),
5) at the same time, go across the boat in the direction of the sail to flatten it out again (because the leech pump at that angle will start the boat on a death roll),
6) as the boat skips down the back of the wave, you will be in the center of the cockpit, stretched out over the leeward rail... the leach will flick a couple times without you even moving the mainsheet (more legal pumps in your favor!).
Now go back up for a couple more waves until you pick a good one again! Always look behind you at this broad reach angle... it's your only chance and you just might see a nice puff coming that you will want to work towards. Catching that puff will be like catching 10 waves in a row!!
The windier it is, the further in you need to sheet, and the less of a by-the-lee angle you can maintain. The trick is to stay just on the edge of being out of control, while totally managing the boat's every move so that you're not out of control! One capsize in a race will ruin all your hard work downwind, and that's where training comes in. You need to find that line in training so you can push it in a race without actually going over.
Ok, now you know my secrets!!! Keep in mind that this technique made me one of the fastest girls in the world downwind in Europes, and in my entire sailing career (age 14 to 24) I have never once been yellow flagged. This is how you go fast without cheating!!
Hope you all find it useful!