A spinnaker is really a multicolored celebration of fabric that is used by racers to publicly announce their arrival at the windward mark
during a race.
The boat will thence, usually, proceed downwind
to the next mark of the course. All the while attempting to keep the kite
flying in the most prominent manner for all to see.
The kite is not firmly attached to any part of the boat. Only precariously held by (usually) undersized strings called by various arcane names such as halyard, guy, sheet, tackline, downhaul, 'that blue one' as well as various seaman-like profanities.
This is because the art of flying the kite is arcane. The skipper and spinnaker trimmer will hold a mutual cursing competition as they (respectively) tell each other how to trim the kite and steer the bost to get where they think they're supposed to go the quickest.
Note that straight down-wind is not always the quickest - even if that's where the mext mark is located! Thus the boat has to be turned the other direction and we may get to observe another cursing contest as the crew has to jibe (or gybe) the boat (and the sails and spinnaker pole as well). This can result in a multicolored celebration of tangled fabric which has to be dropped to the deck like a lead balloon lest the other participants witness that particular boat's disgrace!
Of course, in order to advertise his glory as much as possible, a skipper will often attampt to fly the spinnaker even though there may be too much wind for the boat to handle it. This often results in a broach, or the opportunity for the rest of us to see how well he has kept up the bottom paint on his hull.
Much fun for all!