ARDOP[0] is the planned replacement data protocol for Winlink, and is slowly shaping out to be a faster, OS-agnostic open source system.
Unfortunately, there's still a FCC limit[1] on HAM radio "symbol rate", which hamstrings these systems by forcing low bandwidth operation, though there has been some official traction in updating the rules.
There's also SailMail.[1] This is a minimal e-mail system for ocean sailing yachts. It uses HF radio, and there are 20 shore stations licensed in the Maritime Radio Service for connections. It's intended for boats with limited electrical power and electronics. Stan Honey, who invented ETAK, the first car navigation system, is behind it. He's into sailing, and holds the transatlantic sailing speed record.
I was really disappointed to see that Winlink was dependent on Microsoft Windows but I was absolutely astonished that the only open source client (e.g. pac linux) were hosted on SourceForge and _still_ kept in CVS repository. That was a complete show stopper for me to even try to use the software or even feel compelled to contribute.
However, it's very disappointing to see all the closed sourced / propriety software and protocols in the Amateur Radio community since I feel the whole hobby is founded on DIY and hackers, in the true definition of the word.
Luckily, some very smart people are re-writing the Winlink 2000 libraries and apps using Golang, it's called Pat[1] which makes this tech much more viable in 2017. It's projects like this that give me a little more hope that this hobby is still active and has a chance at surviving.
The amateur radio population is getting older. Most hams I know are running Windows anyways (on at least one machine) -- for controlling their radios, weather stations, and such -- so most of the software they write is also for Windows. I imagine the target audience here (amateur radio operators who run Linux on the desktop and have a desire to use this protocol) is very small.
(On a side note, you should write your own open source Winlink client for Linux. Then, you can use the latest VCS-of-the-week and host it wherever you like. Apparently the author preferred to use Windows, CVS, and Sourceforge. It was extremely rude and disrespectful of him to not check with you first, so before you get started make sure that you ask me which language I want you to write it in.)
I've sailed with a guy who had a Pactor modem + SSB radio + frequency thingy + one of the rigging cables made into 11 meter antenna.
Yes, it was cool AF from nerdy standpoint - calculate propagation and you can dial anywhere in the world. But also it's a huge investment. IIRC Inmarsat gives you all-you-can-eat (apparently the spectrum gets quite saturated in some areas quite saturated) matchbox sized modem that connects to your iPhone for $100 per month.
You'd have to sail for many years to break even and probably have worse experience all the time.
Until very recently, satellite broadband was unobtanium for most leisure sailors. It's much cheaper now, but $800 for an Iridium Go hotspot and $124/mo for service is still steep for leisure sailors who might occasionally need to send an email at sea. Any bluewater boat should have a decent HF rig for safety, so adding a Winlink system is basically free.
Unfortunately, there's still a FCC limit[1] on HAM radio "symbol rate", which hamstrings these systems by forcing low bandwidth operation, though there has been some official traction in updating the rules.
[0]: https://www.winlink.org/content/ardop_overview
[1]: http://www.arrl.org/news/arrl-files-symbol-rate-petition-wit...