@neauoire @cathos You don't really need any fancy antenna to receive wefax on HF. On a boat you're supposed not to have too much noise. You just put up a small wire dipole on the mast and you're good. As others said, just use fldigi and an old HF receiver. I just received this map on 11MHz with my kiwiSDR.
Here you find the schedules:
@neauoire @cathos regarding which radio to get, I'd suggest something like an ICOM IC-7100. It's not marine grade (they cost 3X!), but it's HF, VHF, UHF, the display is separated from the main unit, it has an integrated USB sound card so you connect the linux pc with fldigi just with a single cable. So, if you can install it in a protected spot on the boat, I'd say it's a perfect little radio for your kind of use.
@zabow @neauoire @cathos I get pretty good results with just a simple HF receiver (Sony ICF-SW7600GR) and the "HF Weather Fax" app on my Android phone.
I received this image an hour ago by just putting my phone next to the speaker of the receiver, so I didn't even use a cable to connect. Also, the receiver was placed indoors in our living room in a city - no additional outdoor antenna.