Here is my Furuno FCV 262 2kW dual frequency fish finding echo sounder. This has the usual excellent fish finding and  bottom monitoring performance for which Furuno is famous.
This system has not been used to find fish but detect the presence of naturally occurring plumes of gas which can help find oil and gas reserves beneath deep water. Some of the photos show screen shots of gas plumes in depths of more than 1000m. The system gains are set higher than usual to detect these faint signals. This unit has also been used to target deep sea coring into methane hydrates and submarine dives to sample oil and gas eating mussels and tubeworms.
The 28 kHz signal has some bottom penetrating action (sub-bottom profiling). I have not tried this but it may be used to search for partially hidden wrecks or other features below soft sediments. This action can be seen in some of the photos.
This unit has the additional connectors fitted to allow the echo sounder return echos to be fed to a Furuno EX-7 switch box and MT12 signal conditioner. A cassette recorder can then be used to record the sonar signals with voice annotation and play them back later with, if I remember correctly, different settings of gain if required.
These additional connections are fed to the correct parts of the main unit circuit boards but are not now connected. Their connecting plug has been replaces by the original jumper plugs to make the FCV 262 operate normally. If the EX-7/MT12 is required (see below) the plugs can be changed back in about 5 minutes.
The inside of the case and electronics are neat and clean with no sign of corrosion.
The 262 can be set up with a number of special settings - e.g. the ranges can be selected up to 2000m. Changes in these settings from the default is held in memory with a small rechargeable when switched off. It is possible that this battery will not hold charge for long after many years without power. If this is a problem it would be easy to detach the battery from the board and fit a replacement (any small 3.6V NiCd/NiMH) nearby.
The display unit has a fixed tilted plinth plate beneath for fixing and the 24V power lead.
The 50kHz 50B-12 and 28kHz  28F-18 transducers each have 6m cables and 4 pin sockets. These cables can be extended using heavy gauge twin screened cables joined with soldered twist joints with self-amalgamating tape insulation. My work was all done with cables of up to 50m. Several short surveys were carried out with the transducers mounted on braced poles on the side of the ship.
This sale is for the FCV-262 with the two transducers, power lead and instruction manuals.
I should be able to pack this into a moderate size box for carriage by a courier who accepts heavy cases.
I am offering the EX-7 and MT12 separately as most people will not need them.
If the FCV 262 sells here I will be offering a totally unused pair of 28 and 50 kHz transducer that were held as spares for my surveys. The 28 kHz transducer has been just been fitted with a 4 pin socket to allow testing on the main unit. The 50 kHz has its sealed end as supplied and I have a used socket for this.
Please let me know if you are interested in these extra parts.
You are welcome to visit me to see this kit working out of water. I am at Curdridge, about 8 miles NE of Southampton in Hampshire.
It would suit me best if the buyer can collect from me (I do not have much selection of suitable boxes).
However, there is not much deep sea around here and I will find the most practicable way of sending when I know where it must go.
My price here is for collection. I will find the cost of packing and courier when I have a destination.
Please contact me for any other information.
Thank you.