While I can't give you latitude and longitude for Hastings, what I can tell you is that generally, it's still a pretty good boat ride from Sandhills. It's near Clear Creek. As you're heading east, past the Sandhills, watch the wind turbines on shore and look for a radio tower. When you see the last wind turbine and that radio tower, you're pretty much where "Hastings" is. As for depth to start looking, depends on what your electronics say. They could be in as shallow as 25 FOW or less.......or they could be out in the deeper water (50 FOW or more)
From Burwell, depending on the lake conditions, your boat and what you have for a motor on it, you could be looking at at least half hour to 40 minutes to get there.