Hi Cynthia ~
Go to the website for the U.S. Public Health Service's "Marine Hospitals" at: http://www.bigskycoa.org/coamarinegallery3.htm
Click on the photo square of Resthaven (partway down the page). You'll see a large picture of the hospital, taken in 1929. I'm not sure if it still exists or not, but on the same homepage I gave you above, you'll see a link at the bottom for the "Webmaster" (Capt. Jaloo Zelonis). Emailing him should get you more information about Resthaven (and maybe even how to obtain records regarding your grandfather or whatever else would help you out).