I still have two 1280's which I used to set up at Volume as high as it would go, Sens. at half way, you might be able to run it higher depending where you are. Disc. set at 2 and no higher. You want it to give a double beep on a bobby pin. The 10 inch coil is better for the area covered per sweep. It's heavy and built like a tank and the best way to use it is to hip mount it or wear it from the neck. Very good on batteries. However it chatters near the waterline in saltwater.
However, there are lots better detectors out there for the water at near the same price. One is the Whites Beach Hunter ID. This has two freq. instead of just one in the Fisher. Three different tones to id the target and lights to match so your not having to use to much disc. and miss a white gold ring which reads like foil, well below pull tabs.
Next is the hot Tesoro Tiger Shark at about the same price. One freq. and tone, but it finds gold chains easy. It is the only water detector that you can change coils. A real Lifetime Warranty too. Not the false one Fisher has. It's my back up and sometimes the only one I take. Has a Saltwater mode so it is great in the surf too.
The upgrades from these are the PI types, very deep, but hardly any good discrimination. Too much deep digging for my old bones. Next is the Fisher CZ20 at near a thousand bucks and not made anymore. Fisher says they are repairing them, but there are complaints from hunters. I have a CZ20 too which I never use anymore.
Top of the line in my opinion is the Excal 1000. It's a Sov. built for the water. Earlier ones had loose knobs and cable problems, but not anymore. I would dive with mine and it has found a ton of goodies. It is the only water detectors I've used that will discriminate out a railroad spike and report on a gold ring underneath it. The Excals are almost as deep as PI detectors, but with out having to dig two feet into the sand for a hair pin.