14th September 2019

We’re anchored in the bay at Lundy Island. Being 11 miles offshore, mobile reception on the island is weak and variable. Here in the bay today we have 1-2 bars 4G which drops out completely from time to time. It’s hard to get the weather forecast.

Anchored in Landing Bay, Lundy Island off the Devon coast

In the old days I used to hoist a ‘dongle’ (or my phone) up the mast on a halyard, in a little sack, to create a wifi hot-spot when the signal was weak. It might have looked a bit daft, but it enabled me to squeeze a bit more Internet out of the ether – except in the rain, or when we were sailing, when I didn’t risk it. Today there’s another option: install a dedicated waterproof aerial. Some manufacturers make big claims. Do they work? We’ve been trying, with some surprising results. Carry on reading if you want the full story, or skip to conclusion.

The internet challenge

Sailors increasingly depend on internet connectivity for weather forecasts. And even if you discount social media, there are plenty of other reasonable excuses for wanting a good internet connection at sea and in port: updates on navigation, local information, travel planning, and – in my case – staying in touch with work emails and the occasional Skype call.

For world cruisers, slow and costly satellite systems are the only option – from companies like Iridium or Inmarsat. Plans are afoot to make these faster and more affordable (with Samsung, Amazon, SpaceX, Oneweb and even Facebook planning huge constellations of new low-orbit satellites). However for coastal sailors, land-based mobile telephone networks remain the best bet.

While equipping Nova for this voyage, we searched and found a range of dedicated aerials from a company called Poynting. We bought a good basic non-marine aerial (XPOL-1), spoke with their helpful and knowledgeable UK distributor Solwise, and ended up agreeing they’d provide us with the more substantial fully marinised (waterproof IP68) Poynting Omni-402 for the voyage. Both these aerials can be used to enhance marina wifi too, but we weren’t equipped for that – we wanted to use our own mobile SIM card when possible, for speed and security. 

Signal boosters are also advertised on the internet, but are not legal. The best legal option is a high-gain aerial or two aerials with some separation between them, connected to a mobile hub (router) which creates its own wifi network. Both aerials we tested had two antennae in a single enclosure, and two cables to the router. The XPOL-1 usefully comes with two 5m cables, whereas the Omni-402 has short cables that we needed to extend (adding another unwelcome variable). We connected the aerial (each in turn) to a domestic Huawei B593s-22, which we hid in a dry place (in a cupboard) wired into the boat’s 12V supply.

How we tested it

There are a lot of variables affecting mobile data, including frequency of transmission (which is different between mobile companies), weather conditions, aerial, wiring, router, and wifi from the router to the user’s device. We aren’t equipped to carry out formal tests, which would require simultaneous readings from multiple set-ups, but we wanted to get a real-world impression of how the aerial performs compared with a phone, and if possible to test the cheaper, much smaller, non-marinised aerial too.

Where to fit the aerial?

The first question was where to fit the aerial? The Beaulieu river, where Nova is based, seemed like the perfect place to test this – there’s almost no signal. Lord Montagu, we were told, doesn’t allow transmitters on the estate. So it was here that we first wired up the XPOL-1 aerial and tried it down in the cabin, in the aft locker, on the stern rail, and even hoisted it part-way up the mast. To my surprise, up the mast gained us little or nothing, and whatever we gained might easily be offset by longer wiring. So we concluded that the pushpit rail (aft) was the best practical location. That coincided with the advice from Solwise themselves. Mobile signals are strange things – radio waves are influenced by atmospheric conditions and other factors that can’t be compensated for by fitting an aerial up the mast.

Mobile SIM cards

We chose EE for various reasons. Their coverage is said to be good: they have the contract for emergency services which comes with an obligation to cover a high % of the country, not just in populated areas. Then we took out a contract for 15GB per month, which we thought would be plenty (I typically use less than 4GB on my phone, which I use a lot).

Strength of connection and speed

We’ve used the aerial intermittently in marinas, anchorages and at sea several miles offshore. On a few occasions we have specifically made a comparison, which is written up below. We didn’t make detailed speed-tests in every location because they consume a lot of data.

Beaulieu RiverArisaig, W. ScotlandIsle of Jura, W. ScotlandHolyhead, N.WalesLundy IslandPlymouth (centre)
Bars (max 5)0-11-3 (E)No signal324
Download (Mbps)  023106
Upload (Mbps)  010520
Small aerial XPOL-1     
Bars (max 5)12 (4G) 3  
Download (Mbps)2.840 18  
Upload (Mbps)0.64.3 10  
Large aerial OMNI-402      
Bars (max 5)12 (4G)2425
Download (Mbps)5.52681667
Upload (Mbps)1.46.0429318


When there’s a good signal with 4G (technically ‘LTE’), mobile phones alone provide sufficient data speed for most normal purposes. It is when you can’t get a decent signal on your phone that an aerial would be most useful. Any kind of objective test is difficult because weak signals tend to come and go. If there’s no signal, we’ve found that our aerial usually fails to conjure one from the ether. When there IS a signal but it’s weak, having an aerial does obtain better reception. It’s an improvement but not a dramatic one.

From our handful of tests with the small XPOL-1 aerial, it performs as well as the large one – some of our readings were even better. The one area of dramatic improvement from the larger Omni-402 is upload speeds. Its performance was spectacular in this respect on one occasion (Holyhead – see table). That may be relevant if you’re making a call over internet, doing a Skype video call, backing up files, or uploading large amounts of video to social media.

Data monsters

With our shiny new aerial in place and a SIM contract with EE, I expected to be almost continuously connected with almost unlimited broadband, like at home. After all, if 4GB is plenty on my phone, 15GB should be luxury. Unfortunately not. We discovered we have data-hungry monsters on the boat, and the effectiveness of our aerial has become a problem. When any of our devices gets a sniff of wifi, it starts gobbling data. We battled with the monsters for weeks:

  • Switched off ‘background app refresh’ for apps, and ensured auto-updates are off (actually both these were already off).
  • Prevented Dropbox loading on start-up, and switched off any other file-syncing or cloud backup software (I use Egnyte for work). They can be turned on when needed.
  • Photo uploads: Switched these off, on phones and tablets.
  • Switching social media apps to low bandwidth (Twitter has a useful setting which stops photos and videos from loading automatically. Facebook does not, sadly – they dropped Facebook Lite or restricted it to certain countries).
  • Youtube: Reduced the default quality for video playback.
  • Virus checking: Checked settings and made a judgment about web updates.
  • We have also been trying a browser called Opera at the moment (but so far not finding it as user friendly as others).

Unfortunately despite all these efforts, we lost the battle with the data monsters. They lurk everywhere, even in the simplest of activities like web-page browsing (embedded video adverts perhaps?). Some of the weather forecasting apps seem data hungry too. So for most of our voyage, our beautiful new aerial has been switched off and held back for emergency use only. In Ipswich, part-way through our voyage, I upgraded my existing phone contract to ‘unlimited data’ with Three, and since then we’ve been using a hotspot on my phone more than the aerial. At the time, EE didn’t offer anything like it (I gather they’re now offering unlimited data too, at a price). We could have bought an unlimited Three contract for the boat, but we were tied into a contract with EE and didn’t want to duplicate our costs. We could also have moved my phone SIM into the router (to make use of the aerial) but having done that once and almost lost the tiny SIM, we knew that moving the SIM back and forth wouldn’t be a viable option.

Aside from an unlimited contract, the only solution that we can think of is to ‘throttle’ the speed of our router, to deliberately slow down our internet connection. We haven’t found a way to do that yet. It is not huge speed we need, it is making the most of weak signals to do basic things, like checking the weather, doing email and posting to social media.

Even in cities, an aerial can be helpful. (This is Bristol).


To maximise access to mobile internet, having an aerial above deck clearly helps. A phone located below decks is not as good as an aerial above. From our test in one location, there seems to be no need to have it up the mast – the stern rail works well.

Which aerial you choose seems to matter less. It makes sense to have one that will withstand salt water conditions. The aerial we’ve been using (the Poynting Omni-402) is beautifully made, robustly mounted, and it’s reassuring to have a waterproof device. It is larger than we would like on a small boat. We prefer the small size of the Poynting XPOL-1, with its convenient long (5m) cables, but that’s not fully waterproof.

It was disappointing that neither of these aerials work miracles – they won’t sniff out a signal in a remote location where no signal is detected on our phones. However when there’s a signal, either of the aerials we’ve tested will help strengthen the signal and boost the speed, especially upload speed.

However our main conclusion has not been about aerials at all but about SIM cards and contracts. We have been shocked by the amount of data consumed by all our devices when they lock onto a wifi network. We purchased an unlimited data contract to avoid endless frustration. Another time that’s what we would subscribe to from the start.

What’s your experience? Feel free to share it in the comments.


Poynting, who provided the fully-marinised Omni-402 aerial and stainless steel mounting bracket, commented: ‘We thank Jonathan for taking the time and effort to use our antennas during this limited testing exercise. We really appreciate the feedback on how well the XPOL-1 antenna performed at sea, even though this antenna was not designed for maritime use’