The Iridium GO satellite wifi device is an appealing alternative to a satellite phone is a compact device that functions in much the same way as a MiFi hub for terrestrial mobile data, but with the addition of a facility for voice calls, SMS text messaging and an SOS facility.

An additional benefit, which will appeal to anyone other than light users, is the option of buying unlimited data for just US$125 per month. It’s the only Iridium device with this offer, which is priced at around two hours worth of data connection at typical pay as you go rates. It therefore represents a huge cost saving, although with the speed capped at the industry standard of 2.4kbps (4 per cent of the speed of old-fashioned dial-up internet) it’s still a long way from fully unlimited web access.

The unit is easy to set up and activated simply by rotating the antenna 90 degrees into the upright position. Communication with tablets or smartphones is via wifi – we found the unit produced a consistently strong signal. The interface is then via two free apps that need to be downloaded in advance – Iridium GO! for voice and SMS text messaging, and Iridium Mail for email and web browsing.

An additional cost saving is that the third party data compression service that is normally needed for satphone data connections is not required, which saves a further monthly fee.

We tried the Iridium GO! first using an iPad 2, which functioned flawlessly. As default the system is set such that only emails of less than 50kb are downloaded, along with the headers of larger ones, allowing users to select which (if any) of the bigger ones they want to download.

Given the data speed, the system is only intended for looking at basic mobile websites. Even then, the recommendation is to do so via the Opera Mini browser, which offers a compression option that can reduce data requirements by up to 90 percent. Again this worked well, with pages downloading surprisingly quickly given the slow data rate.

Next we tried it with a Nexus 5 mobile phone running Android 4.4.2, which was similarly straightforward to set up. However, it appeared to suffer from one bug, in which the header obscured the top four lines of emails. As with tablet, when making calls it’s the Iridium GO’s sim and phone number that are used, not that of the mobile phone.

There is also an SOS button on the unit that will send your position, plus an emergency message, to a user-defined group of contacts. In addition there’s a tracking function that automatically sends regular position updates to anyone you chose. Finally, there’s a growing list of third party apps designed to integrate with the system, such as Predict Wind Offshore.

An external antenna is the single most useful accessory for use afloat – this will enable the unit to be kept dry below deck, with the antenna located where it can get a good view of the sky. However, the unit is water resistant to IP65, so for occasional use in good weather it could be placed on deck and the addition of a dry bag would give it protection in more severe conditions.

RRP: £799 / $695

Iridium Go deals

Buy Iridium Go from Global Telesat Communications via Amazon.co.uk

Buy Iridium Go with 400 mins and 180 days sim card from Global Telesat Communications via Amazon.co.uk

Buy it now on Amazon (US)

Buy it now on eBay

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