An update. I had a great day today for dives 1 and 2.
On the first dive, we used the circular search pattern to locate a weight belt stashed in the reeds. Viz was about 15 feet max. A DM anchored the rope and we used signals to indicate the start, ok, let out more rope, etc. We let out rope in 10-foot increments. I found the weight belt about 3/4 of the way through the third pass. If the viz had been poorer I would have needed one more pass to find it. I marked the belt with a float and then raised it directly to the surface using a lift bag. I had to release air from the lift bag as we ascended and then add a bit of air to it at the surface.
On the second dive, we used the U-search pattern to locate a discarded cement block that the instructor had seen on the preious dive. It weighed about 25 pounds. I practiced the compass work on land first during our surface interval. This time I had to improvise a lift bag by placing a garbage bag inside a mesh bag. The rope that I was given was too long so I cut it to a manageable length before rigging the block with the knots that I had practiced many times beforehand (even with my golves on and eyes closed). This time, I swam the block back to shore underwater. Not having the convenience of a lift bag dump valve made the task a bit more challenging.
On the dive, we also came across a grocery store cart that someone had dumped, so the DM and I went back to it, raised it with the lift bag and brought it back to shore, again underwater. Of course the DM made me do all of the work.
All in all it was a great day of searching and recovering.