Vettewall or corvwall, whichever you prefer, is one of the most potent formations in the game. On offense, it can quickly dispatch opposing resourcing operations, and if large enough and with heavy and/or mulitvettes, it can pose a serious threat to opposing frig fleets as well. On defense, there is no better deterrant to an enemy swarm than a triple wall (lights, heavies, multivettes).
When I first was taught the vettewall by Cathar, prior to SLS even being founded, I was being owned regularly on the ladder by people using this strat. You had to have severe firepower advantage to take down a wall of vettes with just 2 or 3 support frigs healing them, and it was quite frustrating to say the least. I was VERY green at the time, I had only been playing the game online for perhaps 2 months tops.
Cathar tells me to take all of my vettes, put them in wall formation, and set 2 or 3 support frigs to heal them. Wow, what a difference this made. The vettes had enough armor that they could withstand a beating until the supports started spraying the healing beam on them, especially the heavy vettes.
Okay, enough background. Time for the how-to's, when's and why's. The type of vettewall you make is going to depend on what your opponent is building. That goes back to an earlier post of mine on the basics, you must probe probe probe. You should probe your opponent 2 or 3 times during the game at 2 or 3 minute intervals to see what he is building, so you can build a suitable counter.
For example, you don't want to be researching and building a triple wall of vettes when your opponent is clearly going with a frig offense. He will most likely have a DFF or a gravwell on the way, which will pretty much be the demise of all your pretty vettes. Instead, you would want to build light vettes only (to suppress his scouts), 16 - 20 in number. Then you would proceed to capital ships yourself.
If you probe and see your opponent building interceptors, then you would want to continue on to heavy or multivettes. I'd recommend multis for medium to large sized maps because of the heavy's slower speed. Heavies just take too long to traverse those larger maps. But heavies are preferrable on the small to medium maps. Why you ask? Because the heavies have better armor than the multis, and slowing your entire formation down a bit isn't always a bad thing. With heavies, the wall doesn't outrun the support frigs as often (which can be a real headache if you show up without support to take on a large swarm).
Then there is the burst feature on heavy vettes. Nothing is more frustrating to an opponent (or satisfying to you) than watching his entire wing of interceptors and bombers go up in one flash. Brutal is the only way to put a well-timed burst. Don't forget to put your vettes back in wall formation after a burst though, cause the heavies separate from the group after a burst order is issued.
The ultimate in vettewalls is the triplewall. If you see your opponent going with a full swarm, then by all means build a triplewall. Lights, heavies, and multis in wall formation is enough to take out almost any ship and it is definitely the bane of the swarmer. An all-out vettewall player will typically have a group of 12 - 20 lights, 10 - 15 heavies, and 6 - 10 multis. A vettewall this large, supported by 4 or 5 supports fears only the gravwell, as it will take down frigs, and even missile destroyers, in short order.
A couple rules of thumb to remember when using vettewalls is this, use about 1 support for every 8 vettes in the vettewall. So if I have 16 lights, I would use 2 supports. If I have 30 vettes, I'd use 4 supports, and so forth.
Don't continue to build vettes if you probe and see gravwells and/or DFFs. Stop vette production immediately in favor of capital ship classes. Empty your build queues of vettes entirely, and scrap what ships you are currently building to get the RU back. Also, don't send your vettes where they are likely to encounter the wells/DFFs, i.e. the center. If you can sneak the vettes around to an unprotected sector where your opponent is harvesting, go for it.
If you have a group of vettes, and your opponent has a DFF, but not a gravwell, don't be afraid to kami your vettes into the DFF to destroy it. That way your AFs will be of use to you until you can start rolling the ion frigs out.
Last is a bit of micromanaging advice. When facing swarms, avoid bandbox attacking the entire enemy swarm. Opposing fighters often move out of your vette's firing range, and when this occurs, your vettes aren't shooting at anything. Instead, attack only a few ships at a time (2 - 3) that are near your vettewall. Reissue orders frequently so that you are always shooting at ships nearest your vettewall. This will kill opposing ships MUCH faster than simply using the bandbox "fire and forget" method. Sometimes it is necessary to bandbox the whole swarm, so don't feel like you should never do this. When you have to micromanage elsewhere "fire and forget" is fine, but otherwise try to do a little micro work.
Hope this article makes your use of vettewalls more productive. Good hunting folks.
Salute, Apollo(SLS)