The most inexpensive set up would be the asymmetric spinnaker because it does not need the gear that the regular spinnaker requires. It also takes fewer crew to deploy, trim and haul it down. It is not a great dead downwind sail, but you can carry it further to weather than a symmetrical kite. The regular spinnaker that is symmetrical comes in various designs and weights as well, but for starters you need to have the following gear installed: Halyard, 2 sheets (the one attached to the pole end is called the after guy), spinnaker pole, track on the mast with car for the pole, spinnaker pole topping lift, pole downhaul and possibly tweakers or twing lines for choking down the sheet and after guy. If you have a large boat, which I see you do, then you probably will want to dip gybe the pole instead of end for ending it, which means you have to have a car on the mast track that can be raised and lowered with a control line. Then lazy sheets are useful (two sets of sheets to the two corners of the sail). It is more crew hungry as well. You need to have a bow man to do the pole work on a gybe, a mast man to adjust the car on the mast, and at least one trimmer and one person to raise and lower the halyard.
With an asymmetrical spinnaker, you have a halyard, a tack line and two sheets. The halyard is forward of the forestay like a regular spinnaker and you gybe the sail around the front of the forestay like you do a genoa (which is inside the foretriangle). You adjust the luff of the sail with the use of the halyard and/or the tack line (which is a line that goes through a block attached near the stem head fitting) and runs aft to the cockpit where it can be adjusted and cleated off. When sailing closer to the wind, you need to make the luff straighter and as you fall off the wind, you open up the luff to give the sail more belly when sailing more down wind. You trim accordingly just on the edge of luffing feeling good pressure in the sail. Performance boats have a retractable sprit which pushes the tack of the asymmetrical kite outboard so that the mainsail does not blanket it so much. There are after market retractable sprits available through Selden spars that you can install to do the same thing.
One person added that if the main is blocking the spinnaker too much, then drop the main. Not a good idea unless the wind is light. The main can be useful because it can block the wind. If you have ever raised a spinnaker in heavier air with out a main, you are in for a surprise. It will catch the wind and tear the lines out of your hands. The mainsail is very helpful to keep things under control. Two or three people can raise, trim and lower an asymmetrical spinnaker (also called a Gennaker by North Sails, or a cruising spinnaker as a general term).
