Basic Strategy for Swirl Large
I play lots of BSP, since it came out. I am sometimes to be seen on the ranked island capture leader board. I am a fleet admiral since a long time ago, without boosting. The numbers playing multiplayer has dropped from a peak of maybe above 10,000 to probably no more than 1,000 today. There appears to be a slight resurgence in sales and we are seeing a substantial number of new players. This map is highly popular so when I am hosting and trying to get to the top of the ranked large map island capture leader board I offer this to all comers. So that new players can avoid being slaughtered on this map in a very crushing way I do not offer a full strategy course but just a simple starting strategy that will allow you to keep some dignity and respect.
First, new players almost always copy the offline artificial intelligence opponent strategy, which is to spawn a fleet at either HQ2 (for the US) or HQ17 (for the Japs) and send it to the center or to HQ6 (US) or HQ12 (Jap). This is a disaster online against top players and the game will be over before your fleet gets into any action. The next thing new players progress to is the bomber rush (yawn) intending to fly right across the map and blow up enemy starting bases. Against top players the bombers are shot down and meantime all the key bases are occupied.
The basic strategy for a beginner is as follows. First wave is 6 fighter squadrons to the center (guards against bomber rushes and other aerial invasions and crucially denies enemy capture of center base by paratroop drop); 2 paratroop squadrons to HQ6 (US) or HQ12 (Jap) to capture; 1 paratroop plane to nearest cluster of 3 supply bases, especially autoreloader and targeting computer. Whilst you must never let your guard down in the air you then switch to a second wave of battleships from HQ6 (US) or HQ12 (Jap) to fight for the middle base HQ9. This is ONLY a basic beginners strategy to avoid total humiliation. There is nothing guaranteed about it, there are variations and nuances, and also very often it depends upon whether it is 1 versus 1, or 2-4 versus 2-4. Another key factor is player skill with their selected units, some players can take out a base or shipyard with a single squadron of bombers and this can have a strategic impact.
Note that you should always buy the Mustang DLC as this is in common use and the units are very important game changers.
Swirl Large appears to many as a battleship map where BBs slog it out in the middle. Its really an air-sea battle, the distance of the airfields is not so bad as it seems when you consider that planes are 3 times faster than ships at crossing the map, and that the purpose of planes is to break the BB deadlock in the center, primarily by taking down shipyards and protecting the advance of your own BBs from subsequent mass air attacks.
Because it is an air-sea battle there is a big difference between 1 versus 1 and 2-4 versus 2-4. In 1 versus 1 you must choose either an offensive BB unlock (usually Montana or Super Yamato) or an offensive air unlock (usually P51 for US and Okha for Jap). With 2-4 versus 2-4 you can unlock both an offensive BB and an offensive strike plane. You should use your BBs up the middle and your offensive air around the flanks (but NOT all the way to the map edges!).
Remember my warning and disclaimer, this is basic for beginners to allow them to put up a fight.
One more thing. Etiquette. Never QUIT. Either surrender (which can only be done by unanimous team vote) or fight to the end. You keep your xp for ranking up which eventually unlocks jets. The top players, who are already usually ranked up, keep their win for leader boards. If this etiquette is not followed your name becomes known and eventually you are being kicked from games. If you are a sociable player you may eventually get tutored by someone like me, and this will vastly increase your skills and wins. This is NOT like most dumbed down first person shooter multiplayers, and your social skills are important.