From 2016 to 2020, we used a Iridium GO! satellite phone to relay our position to our land crew (Devine's dad), and to communicate with our friends and family via SMS & emails, from anywhere in the world—even the middle of the ocean.
Satellite phones lists positions in decimal degrees. To convert positions to degrees minutes seconds(Navionics coordinate format), use this formula:
d = M.m / 60 Decimal Degrees = Degrees + .d Example: To convert 124° 44.740, a DMS coordinate, to DD. 44.740(m.m) / 60 = 0.74566667 124(degrees) + 0.74566667(.d) = 124.0.74566667 And so 124° 44.740 is 124.0.74566667 in Decimal Degrees.
Satellite phones are an expensive option (costs around about 100US$/month), and should you choose to go this route we recommend getting an unlimited plan, because data minutes run out quickly. The Iridium connects to overhead satellites and demands a stable connection to download weather data, like grib files.
During our north pacific ocean crossing, we bought blocks of data that we thought would be sufficient for a 2-month long sail, but we ran out at the start of the second month. Our connection was often poor, and the Iridium continues to gobble up minutes even when failing to send or receive data (a poor system, really). Getting additional data was complicated, and expensive. We let our unlimited plan expire in 2019, because we knew we wouldn't be sailing offshore for a while and would not need it then, but SIM cards expire when you don't use them, and when renewing a plan you need to buy a new card, and have it shipped to you—which may be difficult, depending on where you are in the world. It is why people like to leave with multiple cards, so they are never stuck. A new card means paying for a high activation fee.
A satellite phone is handy at times, but not perfect. The Iridium GO companions apps for phone are absolute garbage, and was a serious point of friction for us.
Can you send photos and documents with it? Yes, but it takes a long time, and requires a stable connection. Plus, the documents and photos need to be as compressed as possible, while being readable. We had to send authorities in Ogasawara passport scans, and entry documents after first sending it to the wrong office, had we not done this they would have fined us on arrival. It worked in the end, but it took a while (had many failed uploads). Don't even think of sending data like this without an unlimited plan.