There has been at least three attempts that I know of over the last 15 years or so, None succeeded.
I agree with you that it makes a lot of sense if one leaves out the financials (which of course will not happen). The drive (bus or car) all the way up to Bangkok, round the corner, then all the way down to Pattaya is a pain in the ass and the last stretch can easily be bumper to bumper quite often.
A ferry service would be almost straight across the gulf. A car ferry would be the best bet I would guess, but that's a very expensive proposition.
This apparent new start up ferry service is news to me however ... obviously I'm not paying attention. I'll post a message on this thread if I can find out more details.
The Bangkok link in the OP sounds adventurous.
Thank you Francois for trying to foist visitors uninvited on me. Obviously you have not heard of my anti-social leanings.The firm’s ferry would cruise at 27 knots on the 113-km journey across the Gulf of Thailand with a maximum passenger capacity of 150 for each trip. A bigger ferry carrying up to 260 people would be added to the service later, Mr Sorasak said.