question on pre green box days(before depth finders)

[mmillelacs]

My daughter recently met a gentleman (her friends father), who claims he invented the technology for the civilian version of the sonar that is used today in the depth finders we all have. He is an older fellow and is quite wealthy and swears his wealth is from the money he made from selling this patent back in the early 60's. I am a little suspicious about his claims, as i had always thought lowrance was the first civilian depth finder (the green box), but i don't know enough about the subject to let the air out of this gentlemens sails. Anybody out there know a little more about the early days of the depth finder? Thanks

[tjsker]

I'm not sure from my brief search on the internet, but Reginald Fessenden invented a depth finder, and he died in 1932.

[BD]

I would let him tell his story; true or false, and not torpedo him. Who knows; you might be in his will. If you are serious about finding out who invented the modern day depth finders do a patent search. You can find the gov. patent office URL with any search engine.

[tjsker]

Try lowrance.com and go to their history. It looks like they're the one.