One of the sails that came with my boat is made of spinnaker cloth and the label on it says 'coaster' its narrower than the spinnaker at the head. Is it the same thing as a cruising chute or something else.
Is it symetrical in shape and cut? If it is symetrical it is intend3ed probably for use on a spin poole and intended to be jibed by swapping corner for corner so that tack bocomes clue like most racing spin. If it is not symetrical then it is intended that one corner is a tack probably attached near the bow whi9le the other corner is the clew with one or two sheets attach3d to be tacked or jibed more like a jib. The narrower head indicates it may be assymetrical or if symetrical then more for use is stronger winds and more for reaching as a spinnacker. Is it made of light cloth or heavier spinnacker cloth. Light cloth and very large would indicate it is a ghoster as suggested however heavy cloth and smaller size indicates it is for stronger winds. Perhaps don't take too much notice of the name. good luck will
I have one that came with my boat - made by Butler Verner - and I also have a sort of handbook that came with it. I finally looked at this after I had trouble setting it properly (I was trying to set it like a cruising chute) . I can fax/email the relevant bits if you like.