Since you asked, I do think it is odd that your grandchildren sleep with you if you have other accommodation available for them. Also, a nine-year-old should be able to bathe or shower alone. I would worry more about lack of independence at that age than anything improper, but at age 9 I would expect a boy to be more modest than you are describing.
Free printable topographic map of Morro Bay (aka Moro Bay and Bernard's Bay) in San Luis Obispo County, CA including photos, elevation & GPS coordinates.
From Thursday afternoon into Friday, damaging surf of 15 to 20 feet with local sets up to 25 feet is likely for the Central Coast. For Los Angeles and Ventura counties surf is expected to increase to between 8 and 12 feet Thursday night into Friday, with local sets as high as 15 feet near Ventura Pier. During this time, there will be the potential for breaking waves into the Morro Bay and Ventura Harbor entrances, as well as an increased threat of minor beach erosion and coastal flooding into beach parking lots near times of high tide.