Last Friday we were all prepared to go sailing with four guests. It was a beautiful day. Just breezy enough, sunny with low humidity. George had gone to the boat to get everything set up. After we all boarded, one of the last things to do was turn on the navigation system. I turned it on at the control panel. The system powered up but had no data readings. No GPS, no depth, no wind readings. We turned it off and on several times with the same results. George and I pulled out manuals, opened up electrical panels and tried to figure it out. I thought it was probably a blown fuse but they all looked okay. After about 1/2 hour I came back up into the cockpit and joined the others. One of our guests went into the cabin to try to help. I eventually got the food out for lunch, so instead of sailing and anchoring for lunch, we ate at the dock. George and I were disappointed but our guests were really good sports about it. After a few hours everyone but George gave up and came home. George tal...