2005 Kawasaki STx-12F Jet Ski Factory Service Manual., Page 379Get this manual
15-2 STORAGE Preparation for Storage
During the winter, or whenever the watercraft will not be in use for ong period time, proper storage is essentialIt consists of checking and replacing missing or worn parts; lubricating parts to ensure that they do not become rusted; and, in general, preparing the watercraft so that when the time comes to use it again, it will be in top condition
Personal watercraft is not meant to be left in the water
for extended periodsContinuous exposure to water over long period of time will cause the hull paint to bubble and peelIt also causes electrolytic erosion of the metal parts of the pump, decreasing its service lifeLarger boats which are left in the water must be hauled out periodically, so the bottom of the hull can be scraped and repainted with anti-fouling paintThey also usually have sacrificial anode to reduce electrolytic erosion of metal parts in contact with the water