A few years back, my in-laws purchased a house in a neighborhood where all of the houses back up to a man-made, 7-fingered lake. A 24' long pontoon boat, named "Sweet Chariot", came with the house.... for free. (I've since learned to be very, very leery of free boats and the required amount of work, time and expense to get said free boat sea-worthy again.)
Sweet Chariot was a mess. The wood decking was rotted and the fasteners were either rusty or non-existent. Most of these existing ones had to be removed with a torch, salz-all, crow bars, cutting wheels, a 3' long bolt cutter and other implements of destruction. (The head of a rusty bolt, when snapped in half with a bolt cutter, makes an interesting noise as it whizzes by your head close to speed of sound.) Every time the trolling motor batteries went out, the previous owner would acquire a new set and leave the old ones on the boat. There were 8 HEAVY DUTY batteries which ultimately resulted in creating the same number of hernias after trying to get them loaded in the truck for environmentally-friendly disposal.
I worked on Sweet Chariot for months stripping everything off, throwing most of it away and rebuilding it from the frame up with new marine grade plywood, paint, carpet, etc. While she was never going to win any beauty contests and she was a tad underpowered with a 70lb thrust trolling motor, it was sea-worthy (lake-worthy).
After a few trips with the family around the lake, a couple of friends and I got the bright idea for a midnight fishing excursion which would end with breakfast (all before an early morning meeting at church). THIS was a good plan. We were younger and "stupider" then and could sleep later.
After waking up half the neighborhood getting our gear loaded on the boat just past midnight, we were off. Since we had NO IDEA about this lake regarding structure, depth, etc., my buddy Genaro hooked up his depth finder. A wire was shorted out and I was quite impressed that he, without missing a beat, immediately found a replacement fuse and had the unit working!
We flew into action. "Should we anchor on an edge and fish in a channel?"... "Should we anchor in the deep and fish up in the shallows?" The boat was abuzz with excitement, chatter and people fighting to get their gear ready.
After a few minutes, Dave, quite innocently, mentioned.... "Hey guys, I think we've seen that fish before". A few seconds later, someone else noticed we were in DEMO mode.
The lake was pool table flat and has a depth of 5' with the occasional "hole" of 5.5'.