Cruise Ship Project and Test

So I wanted to put this up here for a matter of record and reference for others who may want to use the GTM for the same purposes I plan to use them for.

Early next month, my family is taking a cruise out of Puerto Rico. We have a group of friends joining us.

I have 4 GTMs. Another family will have two GTMs and one more family will have two more GTMs. So far that’s a pretty good amount for a 1000 foot long ship with 14 decks. Being the nerd that I am, I plan to do some tests on the ship to see how many decks we can go and what distance can be covered. I’ll use this thread to report my results.

I purchased a temporary clamp on mast that is 36" long which I plan to attach to a Pelican micro case. Inside the case I will have a small battery and a single GTM.

Clamp on Mast:

Pelican Box:

The plan is for me to clamp this on to my balcony railing or something on my balcony. If by chance my balcony is facing our ports of call, it should help greatly with range acting as a relay node. I’ll probably use it as a relay node in this fashion while we are at sea as well. Can’t hurt. Just won’t leave it clamped to the balcony. Somewhere a little safer where it can’t accidentally fall overboard. :slight_smile:

While we are on the islands I’ll want to test a little also but not take away from my vacation.

I’ll try to post updates while on the ship. If anyone has any ideas for tests they want me to do, please let me know here.



See relevant thread here:


Yeah I saw that one. :slight_smile:

A couple ideas for tests…

  • How much does height matter? Would one highly mounted GTM suffice compared to several GTM’s posted on lower decks?
  • Can you find any good hiding places on the ship for a relay node? I suppose you don’t want to risk it, but it sounds like you have plenty of devices to leave around from time to time.

Question for staff… what frequencies does the goTenna use while in motion? If I start it as a relay node, what frequencies will it listen on?


Height is the single best thing you can do to help reception. But on ships, by design, it is difficult to take full advantage of line of sight advantages of height. Getting the ideal spot up high to locate one is probably preempted by lots of radio gear the ship uses. Still, for those outside on deck, the best you can do here is very advantageous. In port, because of the ship’s height, such a location can carry ashore quite a way.

However, it’s difficult to carry a signal very far below deck simply with this height advantage.

Not really, unless they had strategic locations on balconies scattered about or possibly located in windows. The UHF radio waves from the goTenna Mesh travel mostly in a straight line. And ships are made mostly of metal, which tends to block radio waves. A relay that works within spaces inside the ship often has no way to reach a stationary relay directly above them. The openings in the ship’s hull that would allow radio waves to enter are located so that radio would have to go perpendicular to the hull somehow. That’s where a balcony or perhaps a large window can come in handy.

A balcony extends out to allow placing a gtm ti catch the suhiifhelp catch the signal, but a GTM located there can then relay the signal through a door or window into the hull space that is otherwise shielded by the metal of the ship’s structure. A relay located high up on the ship could then link multiple such balconies and the people they serve inside. The extra hops now available help simplify the task.

Before you get too far here with this idea in planning for your next cruise, a cautionary story from my youth is probably in order to suggest the potential pitfalls of secret goTennas all over a ship. While it didn’t ride the seas, the riverboat Admiral sailed from the St. Louis riverfront for many decades taking torurists to see the sights along the Mississippi while enjoying the food and amusements aboard. I had an aunt and uncle plus cousins in St. Louis and around or about 1968 mom and I went to visit them. Mom helped her sister with household tasks while one of my cousins went in for kidney surgery. One of our distractions was a trip on the Admiral.

I vaguely remember being in a game room, maybe pin ball machines, etc. I was bored, so thought I’d try a couple of doors to see what was behind them. The first one was unlocked, so it came right open when I tugged at it to reveal… GIANT PADDLEWHEEL SPINNING!

WHOA! Wasn’t expecting that, it looked like a broom closet from where I was!

As I gazed transfixed by the unexpected and rather awesome sight, a young member of the crew not all that much older than me, began yelling to shut the door before he had me thrown off the ship. OK, I could see it clearly was a place I had no place being in. I quickly shut the door and the crew-kid upheld his end of the bargain by not making me walk the plank.

Moral of the Story: It’s not 1968 anymore. Be cautious about poking around on a ship in this day and age. Some places are clearly off limits and marked so. Some places require a certain dress code or behavior. But there are some places and behaviors that may cause you trouble and it might not end with simply getting yelled at by some low ranked swabbie. Instead, the Department of Homeland Security might warn you about scattering suspicious stuff. Make sure to make arrangement with the crew so they understand what you’re up to. Your gear should be clearly marked to indicate it’s yours as a legit passenger. The last thing you want to start on your vacation is a panic over mysterious goings on that some folks mistakenly think should invoke the T word.


Let me state that I agree with you. In NO WAY SHAPE OR FORM am I going to go around a ship and hide GTM units or anything for that matter. That’s a receipt for disaster. I know if I saw someone doing that I would not be too keen with it.

With that said, this is all good discussion.

Right now everyone sailing in my group has gotten GTMs. 5 cabins with at least 2 in each.
That should mean 11 GTMs roaming around the ship and 1 I will have fixed as a relay on my balcony.

I’m going to put a list of test scenarios together and share them here later. I want to have a list of tests to make sure I am doing everything possible to prove these things out.

There are some obvious ones like making sure I can go end to end from front of the ship and to the back. How many decks I can go through. Inside tests from my stateroom to the front and from my stateroom to the back. (I am in the middle of the ship)

Just a few ideas there. If anyone has suggestions let me know.

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It’s a good discussion of an important venue that goTenna Mesh can enhance. I don’t think kevin_s intended to touch on anything other than being discrete about placement so a relay unit wouldn’t be found and discarded, for instance. That’s when my Admiral cruise experience popped into my head, so I thought I’d tie the whole thing up in a package that reminded that it’s important that discrete shouldn’t edge into surreptitious, given the age we live in.

One idea I didn’t quite get to but implied is to try to get a relay up high at both ends of the ship where they are able to connect to each other. That gives you double (or better) chance of hitting at least one of the relays. It would then bounce the message to the other relay, which would have a different set of line of sight angles to try. You’ll likely find that, if it’s possible, it will greatly improve over the use of only one relay. Kind of depends in where the cabins are located, but an easy to implement strategy.

Our cabins are all next to each other really on the same side of the ship. I don’t see any way of putting one in the front and one in the back without “hiding” one.

Never having the pleasure, but having looked at lots of brochures, perhaps there’s a bar or restaurant where you could do some testing albeit temporarily. Have some in the group go for drinks and/or dinner in a good location that does have the sort of favorable exposure. They take the relay and place it where it has a good view of the rest of the ship, then others can move about and test the reception as long as the party continues at the relay location.

Maybe you can enlist the assistance of the crew in some way, which also tends to take care of them understanding what you’re up to. I know it’s often possible to meet the officers and other crew, perhaps tour the bridge? If you get a moment, you could produce the goTenna, ask if they know what it is or have passengers used them aboard, then remark how great it would be if a few relays were scattered around for passengers to use since it’s been the topic of some discussion on the internet. :wink:

Officers in particular are attentive to things that enhance passenger experience aboard, so it might lead to how easy it would be to take a charged goTenna and set it up in a nice spot for a few hours or a day in a place where only crew has access. They might be very interested in the results.

Sometimes, all it takes is a good conversation to start things in a productive direction.


This will depend on where the ship is and if the device goTenna Mesh is paired has updated it’s location.

In the US, CA, AU, and NZ, goTenna Mesh will operate on frequencies between 902 - 928 with 1W of power. In UE Regions and Singapore, it will operate between 865 - 870 with .5V of power.

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For my specific application it will be the islands of Puerto Rico, St. Maarten, St. Kitts, St. Lucia, Antigua, and Barbados.

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That should give you a chance to compare the difference between 1 W and 1/2 W. Puerto Rico is US territory, so a full watt.

St. Maarten is Dutch/French, St. Kitts and St. Lucia are independent but associated with the UK, as is Barbados. Antigua was in a similar status, but “dissociated” itself from the UK in 1981. The CE standard likely governs mostly, but these islands are also known for being rather independent in some respects, but would imagine they follow whatever national governing policies they generally follow for amateur and commercial radio with goTenna. I would think that the half watt that the CE standard follows would reduce range, but it may be that you’ll never get far enough from the ship to notice if you have a dockside location to relay from?


Well thank you for all of that extra detail. I am a bit discouraged though that the power will be lowered for much of our trip. This does concern me.

What should I expect while at sea? I’ll be in airplane mode most of the time with just Bluetooth on and WiFi enabled on occasion. Less power is certainly not going to help my cause on the ship.



In international waters, I’m not sure what goTenna does. Perhaps someone in the know at goTenna on the way it sorts location can help with this?

At sea, I suspect the default would be to 1 W, but not sure the goTenna would parse things at sea. I’m also not sure of the granularity of how it detects being in a CE vs US/AUS/NZ location and whether it gets down to the island level detail in the Caribbean. Then there’s the fact that because a country observes CE standards, does that mean it actually part of the CE in how goTenna applies that to prompting the power level switching?

Sounds like you have a full plate of testing, but fortunately it’s the sort of thing that can be done at your leisure for the most part, which fits in with the whole point of going on a cruise. Looking forward to what you experience with your goTennas. Bon voyage! :passenger_ship:


one thing to remember is that if you set any as a relay in one frequency range and your maned units change range you will need to pair the relay again so that changes also as it will not relay your messages anymore.


Also try and keep them on US range as the 1w of power will give you better range.

i’m doing a cruise in November and was thinking of using my mesh units on-board on the days i don’t sign up for wifi or if the ship loses satellite signal so the wifi would be down.

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They default to US when in the water. This was the result when using a location spoofer on my one Android device to get around stacked location warnings.


Sounds like an incredible trip! In those areas, goTenna mesh would default to the 902 - 928 & 1w settings.


Thanks for the clarification. I’m happy to read that. Can you also share the logic as to why we get to use the full watt while in these islands regardless of the managing territory?

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Probably split by ITU Region maps? Just a wild guess on my part.

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