Seeing as this is the Bitcoin forum let's talk about internet at sea first.
SatPhones are expensive. Making calls via SatPhone regularly is pretty much out of the question.
But is SatInternet different? I looked into this. A gyroscopic dome costs $20,000. With that you can hook up to 2 way internet. Now, true VSAT in use on commercial shipping is very expensive. Can that tech be coupled to the cheaper SatInternet designed for rural areas?
In order to cut out the cost of that $20,000 I wondered if I could use an ordinary $400 satphone and just accept way lower speeds... but I couldn't figure out if the simcards would fit etc... anyone know? Even $10/mb prepay internet from a satphone might be useful to get emails. (p.s. need to sort that blockchain!!)
VSAT equipment isn't that expensive. Yeah gyroscopic dome mounts can go $5K to $20K but using crappy DirectWay terminal is still going to require a stable alignment. Their terminals are pure garbage and only work w/ their birds. Everyone else uses standardized components which can be programmed to work w/ a large variety of sats. A standard terminal is going to run you about $2K.
When people say sat is expensive they mean compared to land based connectivity not impossibly expensive.
A C-band VSAT link runs about $2K to $3K per month for a 1 Mbps link (remember you pay both ways). Ku band is about double that price (but does better in bad weather - less signal fade due to rain). That gives you a rough idea of what a link is going to cost you. That price may vary 30% or so depending on where you are, which sat you are connecting to, how large your dish is, how much bandwidth you are buying, preemption rights, etc. With a dedicated link you are giving a timeslice, transponder frequency, and sat assignment and that time is yours. Technically the sat is likely operating at 34Mbps so if you have a 1Mbps link then you are assigned ~3% of the timeslots. So you are operating at 34Mbps 3% of the time = 1 Mbps effective.
To save money you can use contention. Commercial sat is available in 5:1, 10:1, 20:1 or even 50:1 contention. That just means multiple end points are sharing the same link. So with 10:1 contention if everyone is on at the same time well your 1Mbps link is going to feel like a 100kbps link. A 20:1 contention link off NSS7 likely will run you $300 or so per month for 2Mbps down & 1Mbps up if you prepay a year.
Also remember your contract is w/ a single bird. If you can't see it then you got no internet. For example say you contracted for a link on NSS-7 North America spot beam (possibly useful for seasteading because it is used by caribbean nations for internet). This is your roaming rangehttp://www.satsig.net/global-teleports/NSS-7-north-america-ku-spot-beam.jpg
If you want to sail around the world either that is going to require multiple contracts w/ multiple birds or some company to sell your contention across multiple birds. You could use a sat phone but you are still going to pay $50 per month and about $10 per MB. Good for emergencies though.
If you wonder where I learned all this ... got deployed to Iraq and our FOB ("base") had no general use internet connectivity. If we wanted internet we needed to find our own.