Satellite Communications [Updated Apr-2019]

  ➛ ➛ From our list of Stuff we have and use [and do...] in the right sidebar ➛ ➛   

This is part of a series describing some of our common boat systems and their operation.

We refer to these often not only for our own use, but also when asked specific questions about systems on Denali Rose, and when participating in discussions on various forums.

We aren't implying our choices are the best or only way to go; they just happen to be the decisions we made [...or sometimes what came with our boat...]

And since we are talking about electronics, in the future our choices in this post may become dated and/or obsolete, so we will endeavor to keep this information current regarding what we have and use, and what we are researching/considering for the future.

––––– Updated 20-Apr-2019 [by Bill] –––––
[Iridium raising our airtime plan price 20% on 1-May; Iridium Next phone compatibility update.]

Satellite Communications:

We have HAM and Marine SSB radio capability [with DSC and packet modem] onboard, and used long distance radio exclusively [with SailMaillast time around [on a different vessel...]

This discussion is about augmenting that long distance radio capability on our current boat with Satellite Communications; why we did, and with which device(s) and service(s). 
Keep in mind we are speaking from the perspective of typical small sailboat cruisers on a budget- us. Therefore, systems requiring a dome are beyond the scope of this discussion. [Not to mention our needs and budget... See the Additional Resources section, below, for articles which also include some dome systems...]
When shopping satellite communications choices, don't start with the hardware: begin with the service area(s) covered. Many intriguing bits of kit are limited to specific geographic regions of the world. [e.g., the Thuraya smart phone sleeve that converts a smart phone to a sat phone doesn't currently work on the N. American continent except in cell phone mode- which the smart phone already does all by itself...]

From our research, [current as of the the last update in the title] if you want to use your satellite communications device anywhere in the world, Iridium is your only choice.

But which Iridium satellite device? Delorme Garmin InReach? A sat phone? Iridium GO!? 

It depends upon your communication needs. 
Our requirements include email, data [e.g., weather], text messaging, voice, and SOS [in that order of preference...]
We have only had experience with Sat phones, and they have proved essential for remote medical support [voice, email, and text messing.] 
Unfortunately we have put this to the test [successfully] during past serious [but not necessarily life threatening] medical events occurring in remote areas where we were on our own... Therefore we will always have a sat phone [or similar device] for voice comms. We are also both trained EMTs [Emergency Medical Technician] because remote support is not as effective nor efficient without some first responder knowledge... I couldn't imagine having to choose between using my hands to render critical first aid while talking on a speaker [sat] phone, or clean them up and [mis]type text messages to a remote support entity instead... [Although the latter is certainly better than nothing...]
What about an SMS [i.e., texting only] device like a DeLorme Garmin Inreach? Isn't that cheaper? 

Not necessarily... We have evaluated some SMS satellite comm devices, and even provided weather support [feeds] to several cruising friends who use them because the device is not capable of supporting anything more than spot weather forecasts. [e.g., No WeFax, GRIBs, Sat images, text forecasts, etc.]

Upon considered evaluation, we found them to cost about the same as a sat phone and plan for what we do [and they could only perform 2 of our 4 requirements; SMS and SOS] so we prefer the more capable Sat Phone for now... [There are more details in our blog post discussing this comparison.]

What about an Iridium GO! with an unlimited data plan?  

Very enticing, and discussed in more detail, below.

We ended up buying an Iridium Extreme [9575] and this passive external antenna [which requires LMR-400 coax cable...] in May-2014 [before the Iridium GO! was released] so this is what we have experience with so far...
Side note: As of the most recent update to this page [see title] the 9575 is still the current model from Iridium- with a cousin that includes PTT (Push-to-Talk radio like) capability- for extra airtime plan fees...
We use the sat phone almost exclusively with UUplus for extraordinary email, SMS, and file [think weather] transmission performance. [UUplus Personal version still pays for itself- ofttimes more than 2x or 3x- in sat phone time saved each month. A technical overview describing why is included below...]

We chose Iridium because of their proven and dependable coverage at higher latitudes.
Shop your desired sat phone airtime plans carefully; reseller pricing and contracts vary greatly.
We chose the Iridium Extreme [9575] over the prior Iridium model sat phone [9555] for multiple reasons [e.g., the slightly higher cost (~12% at the time) was worth it to us...]:
  • Ruggedized
  • Water and dust resistant [IP65]
  • GPS built-in [Handset must have clear view of sky; our passive external satellite antenna has no GPS capability...]
    • Update July-2017: We now have a BEAM LiteDock Extreem dock for the 9575- which has a connector for an external GPS puck. We installed this external GPS receiver in the headliner under the fiberglass deck and it works well- reporting accurate positions via the phone. [Note re: GPS puck: The base is magnetic for mounting on an automobile roof; therefore it needs a small diameter (e.g., 6") rust resistant metal plate for a ground plane... Use a small non-stick baking pan or the like...]
  • SOS [via GEOS- like devices from Spot, DeLorme, Garmin, etc.]
  • Direct USB connection to laptop computer [i.e., no intermediary black box required]
Side Note: There are many businesses that rent satellite phones by the day, week, and month. [e.g., Here is the source we have used in times past in Alaska, and where we ended up buying our complete 9575 kit. They ship (US) nationwide and rent complete kits including a spare battery for US$225/month + airtime.] 
This is what we did for finite duration land and sea based excursions before we could justify owning our own satellite phone.
What is our typically daily usage while boating? 

Email, SMS [text] messages, daily [or sometimes twice daily] weather files including text forecasts and discussions, GRIBs, Weather Fax charts, satellite imagery, etc. All of this is as needed... [e.g., Many times we don't download the WeFax, Sat images, or GRIB files because the text forecasts and Forecaster's Discussion may suffice for our needs at that moment.]
See our Weather and Computers, Devices, and Applications pages for links to the weather resources we use...
All of this is accomplished using UUplus. [Our sat phone alerts us- for free- when a new email or SMS message is received so we only check UUplus then, or when we have something to send, or wait until the next Wx file session- all of which we choose to initiate manually so we don't have any surprise sat phone bills...] 

What about an Iridium GO!? [Many good follow-up articles in Resources section, below...]

I suspect a sat hot-spot device [e.g., an IP device (i.e., internet only)] like the Iridium GO!] is in our future. 

However, we aren't there yet because based upon our current usage and Alaska-Canada only sat phone plan [US$1.05/minute; NO rollover minutes. Here is a plan WITH roll over minutes for US$1.23/min] the GO! unlimited data plan [US$125 $139/month; increase noticed Apr-2018] would cost us 3 to 4+ times what we now pay- including our UUplus subscription. [But the data would be unlimited... more below...]

Once we either start needing an additional 1,000+ minutes per year on a regular basis [this in addition to the 400 minute minimum we purchase now; 200 mins every 6 months...] on our current plan [or when have to switch to International minutes at US$700/6 months for 750 minutes] the Sat Phone approaches the cost of an annual unlimited data plan [12 months X $139/mo = US$1,668] for an Iridium GO!- but without unlimited data. [This will likely be one of our primary tipping points for that decision.] 

For example, our current sat phone plan [Northern Lights Plan- Alaska and Canada only; WITH rollover minutes... Somewhat cheaper @ US$210/6 month WITHOUT rollover... shop carefully!] requires a minimum of 200 mins every 6 months [US$245 $295 increase effective 1-May-2019 ] for data to roll-over, and can only be bumped in 200 min increments... [Here is a blog post with a bit more detail about our sat phone plan if you are interested..]

If/when we obtain an Iridium GO!, it will connect to the same external antenna we use now, and the 9575 will be kept on hand for land and emergency use, and as a back-up to the GO! for email, etc. 

Wait; you plan to pay for two active Iridium devices? 

Probably not...

An alternative to keeping two Satellite SIMs active is to use the GO! SIM in the Sat phone in emergency situations as needed. 
The SIM card for an Iridium GO! is verified compatible with our Iridium Extreme (9575) sat phone (and the prior 9555 model as well...) Therefore our future strategy may be to use the GO! with its unlimited data day-to-day and in the event of an emergency, transfer the SIM to the sat phone. [Note: The unlimited data does NOT transfer to the Sat phone; you would be using voice minutes for voice and data. All the more reason to keep UUplus active...]
Another factor that would make an Iridium GO! even more enticing [with an unlimited data plan] is once Iridium activates their new satellite constellation, Iridium Next  with improved data speeds. 
Iridium Next Notes 
  • All Next satellites are now in orbit.. [Jan-2019]
  • It remains unconfirmed whether the current generation of GO! devices will be able to take advantage of the Iridium Next increased bandwidth. 
  • Purportedly the 9575 can use the faster speeds, but this is also currently unsubstantiated by the vendor 
    • Update: 20-Apr-2019; According to our Iridium airtime reseller, the Iridium Extreme [9575] model phone we have will NOT take advantage of the faster data speeds that will be offered [eventually] from Iridium Next. They indicated Iridium will instead be offering a new model phone that is compatible with Iridium Next features. As of the last update to this page, above, we have not found any corroborating information available from Iridium. 
  • There is also no information about pricing for the faster speeds and new service levels Iridium Next will provide.

eMail, Weather, news, and document retrieval:

The service we use with our Iridium sat phone is UUplus Satellite email. [Personal Edition. It requires a computer and runs on Windows*, Mac OS X, and Linux] 
Update Apr-2018: The May 2016 warning [below] about Windows 10 Iridium USB driver compatibility issues may be resolved with this recent USB driver update from Iridium. [Unconfirmed and untested by us- we don't run Windows...] 
* May-2016 [and reconfirmed Jun-2017]; per UUplus regarding Windows 10: 
There is a bug in the Iridium USB driver for the 9555/9575 that messes up the RUDICS connect on Win10. No problems with Win8 and Win7 [and Mac OS X] (we no longer support XP). Iridium knows about the bug but hasn't updated the driver since 2012. 
Reconfirm this for yourself as this may change in the future without our knowledge; we don't run Windows...
UUplus works over any internet connection- i.e., it is not limited to sat phone only use; unlike the email software that comes with the GO! This means you can set it up and use UUplus on WiFi or cell data as well as your sat phone. 

For us it saves a lot of air time because of efficiencies gained via compression and connection streamlining using Iridium RUDICS data optimization service. [
RUDICS is not available via the Iridium GO! since that is an IP device, but the unlimited data plan partially mitigates the advantage of quicker dial-in connection time and optimized data transfer... ] 

UUplus has a pretty complete database of web data and SailDocs requests built-in [and you can create your own requests] so you can download GRIBs, WeFax, NAVTEX, text Wx forecasts, news, PredictWind, etc.

More about UUplus [and GO!: With technical details provided by UUplus from their recent testing using an Iridium GO! on their office rooftop- i.e., without an external antenna...]

How does UUplus more than pay for itself for us on our Iridium Extreme [9575] model sat phone? 

UUplus can communicate directly with the modem in Iridium [and perhaps other?] sat phones. And UUPlus also uses Iridium RUDICS data optimization service [with no additional cost...]

This allows it to bypass the usual internet protocols [e.g., Unreliable PPP for connections, and overhead intensive TCP] in favor of a hybrid protocol [a variant of UUCP] optimizing throughput over slow and relatively high latency sat phone connections. 
For example, a typical UUplus session takes about 15-20 seconds to log in and begin data transfer [compared to almost a minute without UUplus.]

Within the first minute, UUplus has connected and downloaded an uncompressed 40k of data.
Without UUplus, the first minute is consumed connecting to the service... [Yes, this is unimpressive by today's broadband standards, but this is 1980s era satellite technology we are talking about (until Iridium Next goes live anyway...) therefore our text only email and the Wx files we choose are correspondingly small in size.]
Note: [per UUplus Nov-2015]: the throughput optimization gained with a sat phone using UUplus will be diminished somewhat with an Iridium GO! because a GO! is [currently] dependent upon Internet Protocols [PPP and TCP] since it allows smart phones to use [specific] apps online. 
This also means the GO! cannot use the Iridium RUDICS data optimization service, so those gains are also lost. 

However one could argue these losses [i.e., more dropped connections and slower performance] are partially mitigated by an unlimited data plan... Time will tell...

Installation considerations on a boat:

The 9575 [and GO! per trusted 3rd parties] work adequately [but not optimally] below fiberglass decked boats. However, from our own experience, an external antenna greatly improves reception and consequently saves considerable sat phone minutes [and improves connection reliability] when used for data transfer. [This is measurable using UUplus...]

Antenna options:

As of this writing there are 3 basic choices. [See Beam Communication's offerings for excellent examples of each.]

  • Passive
    • What we use very successfully
    • Passive is great if your coax cable run is less than ~60 ft [18 m]
  • Active
    • Best for longer coax cable runs where cost of active antenna is offset by ability to use cheaper coax cable
  • Dual mode: Sat phone and GPS
    • This would be the best option with a 9575 phone- which has built-in GPS that doesn't work well below decks... 
    • Eliminates use of the puck GPS antenna we went with [see above]
    • This antenna would make your SOS button live anytime the phone is connected to the cradle; otherwise you have to take the phone outside so the GPS gets a clear view of the sky.
      • We have seen the 9575 built-in GPS off by as much as 10 miles off when below deck or even under the cloth bimini...

Coax cable considerations [for external antennas]:

Passive antennas [the cheapest] require the best coax cable [low loss = most expensive]Marine grade LMR-400. [0.4 inches (10 mm) in diameter— and not very flexible...]

Active antennas [~4x the cost of a passive antenna] can use lower grade [e.g., cheaper] coax cable and are therefore more suitable for large vessels with a very long coax cable run.

Mounting Considerations:

When we are in locations where no WiFi or cell signals are available, we have our sat phone on full time. While the sat phones are robustly built, the cabling connections are somewhat fragile [and repairs are expensive...]  

We started out mounting our phone at the nave station using a velcro based mount for a VHF radio. But by the time you connect external power, the external antenna, and the USB cable running to the computer with UUplus, it becomes a mess and puts a lot of strain on the fragile cable connections on the 9575 cable adapter [Other phone models are different.] 

Therefore we decided to spring for a purpose made cradle [as mentioned above.] This makes it quick to remove the sat phone in an emergency since all cables are connected to the cradle; not the phone. 

This was also the only way we could connect an external GPS receiver to the phone to improve accuracy [over the built-in GPS receiver] facilitating our automated position reports as well as SOS function [when the phone is not in clear view of the sky- like when it is below deck in its cradle...]

Closing position statement: It is worth reiterating that regardless of whether we ever acquire a sat hot-spot device like the Iridium GO!, we will also keep a sat phone onboard because it is currently the least complicated communications device in an emergency.

The Iridium GO! is dependent upon smart phones [with one exception- keep reading...] so that means 2+ devices that need to be grabbed {and have fully charged batteries} adding more complication in an emergency situation with one recently discovered [yet undocumented] exception:

  • Per Navigation Mac, the GO! can function as a speaker phone, but only when the SOS button is activated. This reduces the dependence on smart phones for voice comms during an emergency after an SOS request is activated. [The speaker phone on SOS functionality is undocumented by the vendor, Iridium. We prefer to not count on undocumented features...]

I also suspect a speaker phone capability would not be very useful if there was a lot of ambient noise from stormy weather, etc. and I have as yet no first hand nor vendor verification of this capability.

Since, as mentioned above, the GO! SIM card will work in the Iridium Extreme [and the prior Iridium model 9555] it is easy to justify keeping the sat phone should we ever convert over to an IP satellite device like the GO!

Additional Resources:


  1. Keep your E9575 it is a lot better then the Iridium GO.
    Iridium will soon come with more speed and I thin the 9575 is set for new times, the Go is not set for higher speed.

    1. Thank you, Geir.

      We are very pleased with our Iridium Extreme [9575]. It is really all we need at present.

      We have also been following this as well, and also wonder if there will be higher fees once faster data rates are available.

      The outcomes of Iridium's new satellites [2 in orbit being tested now...] in the next year or two will be very interesting for us all.

  2. Thank you Bill for a very well researched article on satellite comms. So many choices and even more variables. As I mentioned in Facebook, for us the Go/Predictwind Sim was a better choice as primary comms for us with full time cruising, lots of passagemaking and three kids homeschooling but I certainly understand the argument for keeping with a handheld if you have an external antenna etc. For us the handheld becomes the ditch bag phone and the trusty SSB/Pactor another layer of redundancy.

    I actually started reading and taking notes from your blog awhile ago as we are intending to go to Alaska next season and then liveaboard in BC for a few years. Lots of learning to do after six years in the tropics.

    Thanks again,

    SV Fluenta

    1. Max, thank you for your vote of confidence, and kind comments.

      If we weren't cruising in areas where we receive the occasional [usable] cell signal to supplement our sat usage, I wouldn't hesitate to install a GO.

      Your 'Cautionary Tale' post is sobering. I have added a link to it in the reference section at the bottom of this page.

      It looks like you guys are having too much fun in the S Pac. [It has been a couple of decades since my coconut milk run...]

      If you are so inclined, it would be fun to meet up when you pass through Alaska. In the meantime, if we can answer any questions/provide any info, let us know. [You can contact us through the 'Hail Us' link at the bottom of the right hand column on this page, and we will email you back...]

      Cheers! Bill


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