A common question we get over here at The Ski Monster and see in forums is 'How do I weight my wakeboard boat for wake surfing?' I've owned Malibus and MasterCrafts and have friends with Nautiques and Supras, and the same is true for every boat out there you need to buy aftermarket ballast, stock ballast isn't enough. If you have been surfing with just stock ballast and have trouble finding the sweet spot, or staying with the wave, keep reading, epic wake surfing is with in reach. (<- That totally sounded like an infomercial selling something for $19.95)
Use the stock ballast to sink your boat, completely fill up all the tanks. This will make your surf wake longer and give it a larger sweet spot, making it much easier for beginners to toss the rope in. Use the additional ballast to give your boat lean, and use your voice activated ballast (the passengers on your boat ;)) to help fine tune the length of your surf wake. If you feel like the wake is huge and your surfing to close to the boat, add weight to bow of the boat to make the wake longer. If the wake feels long and like your having to fight to keep up with the boat, add more lean or weight to the back of the boat to give the wake more push. The bigger your boat is, the more aftermarket ballast you will need. On most 20-22ft V-Drive wakeboard boats, adding 1500 - 2500 is ideal.
Speed is the next piece of the pie. Everybody's speedometer is a little different unless your using Zero Off, a GPS Speed Control system. Your going to be in between 10 and 12mph. The more weight you add to your boat the faster you'll be able to go. Having a faster wave will make tricks especially getting air much easier.
In our current boat a 2009 MasterCraft X-2, we add an addtional 1500-2200 pounds of ballast, including voice activated ballast. Our surf wake is about 4ft tall and 20ft long at 11.2 mph (we have Perfect Pass not Zero Off, Speed will vary slightly), plenty big for experts and a huge sweet spot for beginners.
A few additional wake surfing tips: Surf in the deeper parts of you lake, when the water gets under 10ft the wave starts to get smaller. Wake Surf competitions are done on sections of lakes and rivers that are no less than 20ft deep for optimal wake shape and size. Drive the boat straight, there is no need to drive in a circle, driving in a circle messes up the water for other boaters and makes it harder for beginners and kids after they have fallen. What I've suggested for ballast is more than the capacity on your boat, be careful, make sure you bilges are working and that you don't add way too much weight to your boat, ski boats can't take as much weight as a wakeboard boat, the gunnel isn't as big. Do not use lead weights, cement etc. this can cause your boat to sink instead of just swamp with the use of water ballast. Only surf behind inboard boats no I/O's or outboards. Lastly have fun, wake surfing is one of the most fun low impact sports you can do on the water.