Kudos to David M for clear information. I spent a decade working on side-scan sonar and was the project
manager for development of one of the first multi-beam side-scan systems.
Some fine points:
1. the higher the area rate of coverage the greater the cost.
2. the higher the resolution the greater the cost.
3. 1 & 2 are in conflict so if you want both you will spend a lot.
4. Boat and tow winch
operation can be a very significant challenge if the depths vary quickly, particularly at higher boat speeds. Side-scan towbodies make interesting and expensive anchors.
As David M pointed out, imagery interpretation is nontrivial. Klein Associates in New Hampshire, now part of L3 used to give first-rate classes
in side-scan interpretation. I suspect they still do. There is a copy of their training manual on EBay for $100.
There is also an EG&G towfish for sale
for $5000. No tow cable, no topside processor. Decent bit of equipment
but you can miss a lot with a 100kHz system. For a fish
, rotating coupling, and processor I'd expect to pay around 50k used and 200k or more new for entry-level stuff. Lease
costs are commensurate with the capital investment.
It is very cool technology and there isn't a better way to find stuff in open water
. Bob Ballard used side scan to find the Titanic, laser optics to map out the debris field, and ROVs for the detailed imagery.