Updated 2/7/2022
Preface
The purpose of this post is not to tell you what we think YOU need to do! Everyone’s “use case” is different.
We simply want to explain our use case and what we ended up with after researching everything, and explaining some adjustments made along the way.
Here are a few ‘authoritative’ Internet resources which were very helpful in our decision making:
antennagear.net (M39T source)
An excellent (technical) youtube webinar on engineering LTE antenna systems on ships and cruisers:https://youtu.be/v24MqUQMxXI
I am an IT professional (still working), and an Extra class ham radio operator / instructor. I design networks to work reliably.
Most people want a simple connectivity solution that just works. In my career, “simple for the end-user” sometimes means some added complexity “under the hood!”
I lean on sound fundamental RF theory which I’ll touch on some here. I keep the cost down wherever I can. There are some things where best-costs-more; there are other places where best-costs-less as you will read below!
A new Q&A section has been added to the end, due to popular demand. Feel free to ask me anything more, your Q might get added on!
January 2023: The past year’s success of Elon Musk’s Starlink network has been impressive. If we were to start over TODAY I am pretty sure we’d go down that path rather than what we have done as described herein.
Our boat’s network.
So, here is our answer to a boat mobile network that “just works” most everywhere we go on America’s Great Loop.
Our main router is the Pepwave Max Transit Duo. It has two modems so it generally stays connected to two different carriers all the time. I can configure priority between them. When one fails, switching between them is instantaneous and automatic, even right in the middle of a call. No interruption!
We primarily rely on the 4G-5G-LTE-Cellular carriers (currently VZW & T-Mobile) … marina WiFi not so much.
When using marina WiFi, however, we found having a separate very basic ($95) WiFi router (e.g. WiFi Ranger model: “Poplar”) was much more reliable than expecting the Pepwave to handle BOTH the boat’s WiFi devices AND the marina WiFi connections. A short CAT 5 cable connects the Ranger into the Pepwave WAN port. (When we use this, our devices simply stay connected to the same SSID Shellerina on the Pepwave.)
A simple directional yagi antenna ($30 on Amazon) pointed at the marina’s WiFi also enhances reliability, even from slips quite some distance away. Sometimes we point it at a local business with WiFi!
Antennas are the key to success.
Two vertical MiMo M39T with good quality coax give us omni directional Internet connectivity to the carriers. The M39T was chosen because it provides good gain on all cellular bands used in North America including Band 71, the 600 mHz band that T-Mobile is building out on. 
This lower frequency band has better propagation at longer distances for mobile applications like boats and RVs.
Through the rivers from Chicago to Mobile AL we had reliable Internet in all but a few spots. Shelly’s music streaming and my Zoom meetings and office IP telephone worked well almost everywhere!
Total cost for everything described was just under $2000. Reliable Internet for our boat’s network is a “business expense!” Ray still works full time, so we can justify a well-designed system that can adapt well to a variety of marine settings.
While that may sound like a lot of money to some, “How much does a new chart plotter with radar cost? How about Auto Pilot?!” There are several systems on a live-aboard boat like this one. Internet is simply one of those systems.
Again, as an IT professional, I design networks to “just work” reliably.
Latest news on 5G:
Chris Dunphy and Cherie Ve Ard are great mobile Internet resources. As you do your research online, it won’t take long before you start to see their content. Thank you Chris and Cherie!
2022 This post from them is “hot news!”
youtube.com/watch?v=HtWeClwgExw
Q&A! As requested by our followers.
Q: Do I really need an external antenna?
A: If you are near good WiFi at your marina, or always near your carrier’s cell tower(s), No. You don’t need an external antenna.
If you are mobile and you want good performance most anywhere you go, external antennas will help. Sometimes they will be essential to you getting a usable signal vs. no signal at all.
“Paddle” antennas on a router will generally outperform the antenna built into your phone or tablet.
But even more performance is possible with directional antennas or some omnidirectional antennas so long as the feed line losses don’t undo the external antenna’s advantages. More details on feed-line loss follows below.
Also, just as two ears can hear better than one, two omnidirectional antennas can receive (and transmit) better than one.
Your router probably comes with multiple antenna ports. There is a reason for that! So use them.
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Q: Why are certain coax cables so expensive? “I do not want to spend that much money on wire!”
A: The chart below shows how much signal is LOST to waste in longer 1/4″ coax lines.
Good quality 1/2″ coax helps overcome feed-line loss a LOT!
This chart illustrates feed-line losses at different radio frequencies (RF) used on a boat.
Feed-line loss is operative at lower VHF Marine frequencies, but feed-line losses get even worse the higher you go in frequency. The chart quantifies these losses at lower VHF frequencies and then up into the higher Cellular 5G-LTE freqs.
Good quality coax ensures more signal gets out and gets heard (transmit and recieve).
Quality feed-line makes everything work better with your network. It is a critical part of your network’s antenna system.
(Above) 1/4″ RG 58 with PL-259 connector, common with VHF Marine radios.
Personally, I am a big fan of good high gain exterior antennas with short high-quality feed-lines. This is just fundamental RF theory applied to my boat’s network.
The theoretical router down in the engine room with a really long length of 1/4″ cheap feed-line will not work very well compared to the same router located up high near the same antenna with shorter good quality feed-line. (In both cases being protected from moisture etc.)
(Pictured above) Good Quality 1/2″ LRM 400 with “N” Connector and “SMA” Connector (typical router end).
It is important to realize that feed-line loss affects BOTH transmit AND receive. Getting a “good signal” on your devices requires both.
At higher frequencies, there is also loss with every connector in the antenna system. So avoid “extension” cables to antennas that come with cables too short for your boat’s installation.
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Q: I see that the 5-in-one or seven-in-one “dome” antennas work for everything! (Cell, WiFi, GPS all in one unit). Are they good for a boat so long as I have a ground plane?
A: They work. But those are really made for the roof of an RV. If a tree branch hits them while going down the road, they can survive the impact. A vertically oriented MiMo antenna would not likely fair very well atop an RV!
Those tree branches are not a hazard on my boat; I am a fan of vertically oriented omni-directional antennas when omni-directional is needed.
Fundamental RF theory: The most antenna surface area perpendicular to the cell tower will out perform a short profile dome antenna.
Also, a key word in antenna design is “compromise”. There is no such thing as a free lunch. A single antenna that tries to do multiple things on multiple different frequencies will not do any of those things as well as separate antennas specifically designed for the different frequency bands. If all-in-one is important to you, that compromise will be part of your system’s design. No problem.
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Q: If marina WiFi is generally less reliable compared to a Cellular 5G-LTE strategy, why bother with it at all?
A: Some marinas have good WiFi, and some have good WiFi that work during the weekdays, but it may not work as well on the weekends when the number of WiFi users doubles or triples on the docks.
In those [few] marinas when it works well, why not take the “free ride” and NOT consume data on your monthly data plan. Save the Cellular 5G-LTE data plan for where and when it is really needed! That’s what I do.
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Q: Some marinas’ WiFi work great at or near the office, but not out on the far edges of the marina. What can I do to “pull it in?”
A: This is an easy one! A directional Yagi or Log Periodic antenna increases signal strength on both transmit AND receive. Mine only cost me $35 at Amazon shipped with a 6 foot coax cable.
I also hear dock mates succeed with RedPort and other brand “WiFi Extenders”, but they cost more than my yagi! Plus, some marinas don’t allow powered WiFi Extenders including this marina in FL where we are wintering for 3 months. Some say the powered WiFi Extenders are not “friendly” to other boats nearby who are trying to connect to the same network. (I haven’t experience that yet.)
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Q: Do I need a “dual modem” router?
A: This is a great question. You may not.
((IMO, This is an example of simpler operation for the end-user can be enhanced by a little more complexity “under the hood!”))
My first Pepwave router was a single modem CAT 18 unit. Once I could see how the Priority “queue” worked, e.g. enabling my home’s Internet automatically take over if my Cellular LTE carrier dropped out below “x” number of bars… (a customized parameter), it “clicked” for me. I understood. A dual-modem router can instantaneously switch LTE Cellular carriers if the primary one goes below “x” number of bars… without a delay.
With a single modem router, it took me 1-2 minutes to change from one carrier to another, and it was something I manually had to do each time. Not for me.
I wanted simpler , automatic router operation for my boat’s network!
MY use-case requires smooth switching between carriers while I am on a call or a Zoom meeting. I didn’t want to have Shelly take the helm while went down to make a router configuration change, just to switch carriers while underway!
Your use case may not require that. It’s a choice you get to make!
While traversing the western rivers, my wife Shelly was the “DJ” streaming music underway, and occasionally I was on a business phone call. If you are mobile the ability to seamlessly have your connectivity stay resilient, working all the time, a dual modem is for you! I could actually watch this switching happen while underway on my smart phone.
I had saved all my boxes and returned my CAT 18 router for a dual-modem CAT 12 router within the time allowed by my vendor.
The dual-modem feature proved more important for us than a single modem CAT 18 which “theoretically” might be faster in certain unique conditions and locations.
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Q: Ray, How much do you spend on your router’s data plans?
T-Mobile is $50/mo for 100 GB (then it throttles down). (50 cents per GB.)
VZW: I recently bumped this up to $80 for 150 GB, as we are underway again. (53 cents per GB).
We may have way more than need here, but it’s easier to manage that way. I don’t even have to think about it anymore. (It is a business expense!)
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Our iPad Pro 12″ has its own 15 GB plan and it is usually enough. It is what we use for TV. During the NFL playoff weekends it chewed up its own data plan, so we connected it to the Shellerina network for crisp viewing of the games through the boat’s data plans.
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Q: Which carrier is better once you use up your premium data plan(s)?
A: Both T-Mobile and VZW are “Unlimited” but both may/will slow things down once you use it up. VZW’s performance after using it up is definitely better than T-Mobile’s plan after it is used up.
So, we default to T-Mobile, fail over to VZW as needed.
Both carriers have a mobile app that lets me monitor my consumption, and tells me how many days are left in the current billing cycle, as shown below:
I read on one of the forums today that, ATT Business is the only carrier with a ‘truly unlimited’ data plan (never throttled down), but I then learned that it is restricted: NO streaming audio + video, i.e. no “entertainment.” It is oriented for all ‘business’ uses… and it is truly unlimited.
I may look into that!!!
March 2, 2022 Update:
Well, I did try out ATT. Started Feb 7, 2022. Just cancelled it. Horrible customer service, and poor performance on their network compared to what I am accustomed to. The plan I signed up for was “Business Essentials”. $70mo truly unlimited, (but no entertainment streaming), but there were billing problems too. So the actual bill was $108 and change! It took many many hours to get it fixed and then hours to ultimately cancel the service.
There are a LOT of ATT fans out there on the forums, so I do not know why my first-hand experience was so different.
But, I had to try!
The good news is this: There is no long-term commit with any of these companies. I think experimenting is fun.
Side Note: Years ago, cruising east of Camden-Rockland Maine my wife’s ATT phone had zero connectivity at all. Fortunately I had VZW. We’ll be back up there this summer. We’ll see if things have changed. Bottom line is this: having a dual modem router that can “switch hit” carriers on the fly is important to this boat’s crew!
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Q: Do you need a DC/AC Inverter for any of this “stuff” to work?
A: Nope. It all runs on 12vdc!
Latest news on Starlink
Https://youtube.com/watch?v=dwoz49N7Qsk
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https://www.cnbc.com/2022/06/30/fcc-approves-spacex-starlink-service-to-vehicles-boats-planes.html
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https://seabits.com/using-starlink-with-peplink ((This fellow had done a commendable job configuring a Pepwave router like mine with Starlink, for very resilient connectivity.))
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We have not “gone there” yet… to Starlink. But we follow it closely, and listen for feedback from cruising boaters who have, like the Bowlins:
https://momwithamap.com/2022/06/starlink-portability/
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Shawn from Freedom takes his marine installation of Starlink to a new level: https://www.youtube.com/watch?v=RQ7HS7txPw0
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And, Part 2:
https://www.youtube.com/watch?=GHHCK6aARn0
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