Tuesday, 13 July 2021

Bluewater Cruising Long Range Communications

This is a technical post!  It describes the methods blue-water cruisers use for long-range communication between themselves and to keep in touch with the outside world.  I wrote it recently for the Bluewater section of the Cruising Association.  You can view it on their website here (login required).

WinLink Coast Station Network

HF/SSB (High Frequency/Single Side Band) and satellites are the two ways of achieving long range (beyond line of sight) communication.  The former uses the ionosphere.  The latter uses communication satellites as intermediaries.

Our blog includes a number of technical posts including HF/SSB, satellite communication and many other topics.  You can search for content using the "Search this Blog" box at the top left of this page or the "Word Cloud" on the right (eg HF or SatCom).  Alternately use these links:


Marine HF/SSB radios are used to keep in touch directly with other cruisers, to access email and to obtain weather information.  A GMDSS DSC-equipped marine HF/SSB provides long distance distress and safety communication with coast stations, ships and potentially other yachts in an emergency.


HF/SSB radios require proper installation with an antenna tuner to a back stay or whip antenna and an effective ground.  Installation can significantly add to the cost.  Careful attention must be paid to initial testing and ongoing maintenance.  HF/SSB optimisation often takes time and experimentation and this can’t be done effectively in a marina.


HF/SSB radios are designed to run on 12V DC power.  Transmit power consumption is high (around 30A), requiring careful installation with minimal connections.  However transmission is usually for short periods and so consumes few AmpHours.  In contrast receive power consumption is 1A to 2A and so consumes significant AmpHours if run continuously.  This impacts on marine HF/SSB DSC routine calling since few cruisers have their radios running continuously.


Marine HF/SSB radios can receive over the full LF/MF/HF range (100kHz to 30MHz) but limit transmission to marine bands.  This limit can be overridden on most radios.  Transmitting on amateur bands requires an amateur licence. Transmitting on other bands (eg aviation, military etc) is forbidden except in emergency.

Zen Again's previous Icom M802 Marine HF/SSB

Marine HF/SSB radios are designed and built to high standards imposed for marine communication.  Amateur HF/SSB radios are less expensive, just as capable and can be more fun to use.  But they do NOT meet the marine standards.  Therefore marine HF/SSB radios are allowed to transmit on amateur bands, but amateur radios must NOT transmit on marine bands.  The extent to which this is enforced appears limited, particularly mid-ocean and in remote areas.  Many blue-water boats fit amateur HF/SSB radios.


Selection of frequency and time of day are vital to successful use of HF/SSB.  This is due to the dynamic nature of the ionosphere which delivers (or removes) long range HF propagation.  Low cost software is available to predict the best frequencies and times of day for communication between nominated locations.

Keeping in Touch

Many cruisers keep in touch with other cruisers via SSB ‘nets’ or ‘skeds’.  These are simply an agreement to meet on a given frequency at a given time.  They range from informal nets between pairs or groups of boats to more formal nets, some of which are run by coast stations.  For example the ARC organisers run nets for participants to report position and weather, and to allow participants to chat afterwards.


Groups of cruising boats embarking on ocean passages often arrange a daily net to keep in touch.  They allow the exchange of safety information and social chat which can be a highlight of the day.  Nets are sometimes followed by a kid’s net, where younger cruisers can catch up with their pals.


Net control is often handled by the boat with the best radio installation.  The controller first requests any safety traffic then asks each participant for their report in turn, logging key information.  Each report includes the boat position, their status, plus perhaps weather and a daily highlight.  Positions should be stated slowly and clearly, and NOT contain decimals of minutes.


Email can be sent and received via HF/SSB.  For non-amateur license holders this requires a Pactor hardware modem, Airmail PC software and (most commonly) a subscription to the SailMail global network of coast stations.  Amateur licence holders can use a Pactor modem or a software modem embedded in PC software to access the Winlink global network of coast stations.


The email data rate is similar to that achieved using a satellite phone, being hundreds of bytes/second.  Data rate varies dynamically with HF propagation conditions.  Sensible frequency and time of day selection is important.  Attachments such as GRIB files are supported, allowing the reception of weather GRIB data from services such as SailDocs.


RadioFax, RTTY and Shortwave

Radio facsimiles of weather, ice and other information are transmitted from a shrinking set of coast stations around the world.  A RadioTeletype (RTTY) weather service is also provided in some areas.  Shortwave broadcast stations all around the world allow blue-water cruisers to monitor news mid-ocean.  These services require only a SSB receiver.  Radiofax and RTTY are decoded using low cost software available for PC and tablets.


Amateur (Ham) Radio

Amateur radio operators are licenced following completion of a training course.  Courses are run by amateur radio clubs.  Licenced amateurs can communicate with other amateurs across the world.  They can use voice, CW (morse) and data in designated amateur frequency bands which span MF, HF and beyond.  This opens up a global network of contacts useful for both routine and emergency traffic.  Licenced amateurs can join the free Winlink email service and take part in amateur nets.

Zen Again's current Icom IC-7300 Amateur HF/SSB


Several nets are run by groups of amateur coast stations.  An example is the Maritime Mobile Net on 14300Hz.  Some of the coast stations have rotatable directional antennas, very high transmit power and very sensitive receivers.  These nets provide safety coverage over very wide areas.


Amateur bands below 10MHz use LSB (Lower Side Band) for voice – unlike marine bands which use USB (Upper Side Band) regardless of frequency.  There are no predefined voice channels in amateur bands, one simply picks a free frequency within an amateur band.  CW is usually found at the lower frequencies in each band, then data, then voice at the higher frequencies.  Amateur nets run on published frequencies.


Most blue-water cruisers carry one or more satellite devices.  These range from simple messaging devices to email-capable satellite phones to internet-capable broadband satellite terminals.  Portable satellite devices run on their internal batteries and so can be used in a liferaft, unlike a HF/SSB.


Satellite devices generally allow voice communication between two parties.  This is fundamentally different to HF/SSB where anyone within range can take part in a conversation (eg a net).  Hence HF/SSB is more social.  Satellite devices and services are rapidly evolving and are easier to use.

Satellite Messaging Devices

These devices are inexpensive and simple to use.  They provide a means of sending and receiving short messages.  They include a GNSS receiver, allowing position to be transmitted with each message.  These positions can be used to create a web page showing your track.  Many include a (non GMDSS) emergency function.  They use a built-in antenna.

Satellite Phones

These devices provide voice, text and many are also data capable.  Data rate is hundreds of bytes/second which is sufficient for email but not for internet browsing.  The most common use of satellite phones is for email, including accessing weather GRIB files.


These devices can use either their built-in or an external antenna.  For data use the external antenna is recommended.  The external antenna is omnidirectional and usually no larger than a coffee mug.

Iridium Go! 

A popular satellite phone is the Iridium Go!.  This unit provides a WiFi hotspot to which smart phones and tablets can connect to use voice, text and email.  PC software such as Airmail, Winlink, XGate and PredictWind’s Offshore app can control the Go! to access email and/or download weather information.  The Go! incorporates a GNSS receiver for tracking purposes.  The GNSS antenna is built into the base unit - it isn't in the external antenna!

Broadband Satellite Terminals

These devices provide broadband data rates and provide voice, text, email and full internet browsing.  Until recently they have required large mechanically-stabilised antennas.  Newer units use electronic ‘beam steering’ antenna technology which do not require stabilisation and are smaller.  These systems remain expensive to buy and expensive to run.


New satellite constellations such as StarLink may soon offer broadband at similar cost to satellite phones.  This may revolutionise safety at sea by allowing real-time traffic, weather and ocean surface current viewing.  It is not yet available.

Monday, 12 July 2021

UK to Tunisia - A Schengen Cruise

Hi everyone,

Here is a brief summary of our cruise from the UK to Tunisia during the months from April to July.  We can have up to 90 in 180 days in the Schengen Zone.  We escaped Schengen on day 76 and cleared-in to Tunisia on day 78.  From Gosport to Monastir took 92 days.

We tried to make our Schengen time a cruise and not a delivery.  We spent extended periods in Baiona and La Linea (Gibraltar) while waiting on adverse weather to pass.  We stayed longer in particularly nice places with a lot we wanted to see including the Spanish Rias, Cartagena and the Balearics.  In the Balearics we only stepped ashore in one place (Mahon in Menorca) to keep costs down, so it was all about the scenery there.

Here is the our overall track...

Overall Track

And here are the vital stats for the cruise…

    • Distances/Speeds
        • Duration = 92 days (76 in Schengen)
        • At Sea = 529 hours
        • GPS Distance = 2499nm
        • Average speed over ground = 4.7 kt
        • Minimum boat speed = 3 kt
        • Maximum boat speed = 10 kt
    • Weather
        • Minimum wind speed = 0 kt
        • Average wind speed = approx 10 kt
        • Maximum wind speed = 25 kt gusting 30 kt
        • Apparent wind angle range = 40 to 150
        • Seas up to 2.0m
        • Swell up to 2.0m
        • Water temperature from 12C in Falmouth to 28C in Monastir
        • Thunderstorms approaching Gibraltar Strait, near Almerimar and leaving Sardinia
    • Engine
        • Total = 215 hours (used 335 litres for a burn rate of 1.6 litres/hour)
        • Engine Usage 41% overall, 26% in Atlantic and 57% in the Med

From an officialdom perspective we had no problems from either entry/exit or Covid perspectives.

With regard to entry/exit we we able to get Schengen Entry stamps in A Coruna at the Police Station.  We were NOT able to do so in Carloforte.  Perhaps we should have gone to Cagliari.  Entry into Tunisia was straightforward and similar to other non-EU countries except they showed no interest in paperwork from the last port.

With regard to Covid it was not mentioned in the Atlantic part of our cruise, other than the need to wear masks.  No questions about vaccination or tests there.  The first questions came up when booking a marina berth in the Balearics.  There the marina accepted self-administered UK NHS test kit results on arrival.  In Sardinia the marina arranged a doctor to test us on arrival for 40 Euros per person.

On arrival in Monastir our test certificates from Sardinia were sufficient for the Police to waive quarantine (which would have been aboard Zen Again).

We had a great cruise.  Here are the highlights and lowlights...

        • Zen Again!
        • Great sailing on the Atlantic coast
        • Spanish Rias
        • Leixoes/Porto
        • Cascais/Lisbon
        • Gibraltar
        • Cartagena

        • Motoring for so long in the Med's light airs
        • Selden RodKicker's gas strut failed (fair enough, it's 11 years old)
        • Mainsail clew slug failed (same type fitted on the headboard which failed 5 years ago)

We'll be back out sailing in 3 months, westward out of the Med.  In the meantime stay tuned for Tunisian adventures!

What a Boat!

Mediterranean Sunset

Sardinia to Tunisia

Hi everyone,

Our final passage of our first Schengen cruise from the UK to Tunisia was the usual Mediterranean mixture of sailing and motoring.  We tried a new strategy for our route, staying clear of high CAPE (thunderstorm prone areas) in the hope of seeing the predicted gradient wind.  That seemed to work quite well.  Sadly however the gradient wind varied between light and calm after few hours of thunderstorm-related moderate wind.

Approaching Tunisia

We departed Carloforte at 1030.  Our track shows as getting our southing initially so as to stay out of high CAPE SE of Sardinia.  The worked nicely.  The sail south was in a nice breeze which veered from WNW towards NNW.  We gybed east and the NNW wind held in until after midnight, giving us a very pleasant sail.

The motor stayed on until 1000 on day 2.  A new bank of high cloud came over early in the morning, presumably from the high CAPE area now to our north.    By 1000 the cloud was starting to clear and with that came a little wind - 7 to 9 knots, gusting to 12 knots.  Zen Again loves reaching in light airs and we made pretty good time.

The engine came back on at 2100 on day 2 and stayed on until 1700 on day 3.  We were alternating between motoring and motor-sailing as the wind varied between flat calm and 5-6 knots.  Around sunset we zigged south to 'cut the corner' and cross the main shipping lane between Suez and the western Med.

Shortly after passing Cap Bon the Tunisia Coastguard called us on VHF 16.  They wanted our destination, last port, flag and crew nationalities, very like when approaching Australia except they didn't ask if we had animals aboard.  It was nice to sail the last 2 hours prior to arrival in Monastir.  Our Fremantle Sailing Club friends on sv Revision II answered our call to the marina on VHF and were there to take our lines on arrival.  Twas surreal to meet them so far from home!

Here are the plots...


Arrival Detail (note the CM93 offset and lack of detail)


And here are the vital stats for the passage…

    • Distances/Speeds
        • Route Distance = 290nm
        • Logged Distance = 354nm (log still under-reading)
        • GPS Distance = 299nm
        • Duration = 57 hours
        • Average speed over ground = 5.2 kt
        • Minimum boat speed = 3 kt
        • Maximum boat speed = 7 kt
    • Weather
        • Minimum wind speed = 3 kt
        • Average wind speed = 8 kt
        • Maximum wind speed = gusts to 26 kt
        • Apparent wind angle range = 90 to 150
        • Seas up to 1.0m
        • Swell up to 0.75m
        • High overcast slowly clearing to cloud-free but hazy sky
    • Engine
        • Total = 32 hours

Sardinia in our wake

Nice sailing for part of the passage

Hazy Sunset

Approaching Monastir

Approaching Marina Cap Monastir

Entering the marina

View to north from marina entrance

Monastir Ribat

On arrival we secured Zen Again at the fuel jetty.  There's a sunken motor vessel alongside part of the jetty.  From there we walked with the Revision IIs to the police and customs office to clear in.  The police inspected our (single) Covid vaccination cards and our PCR tests done a few days ago in Sardinia.  These were sufficient for us to avoid quarantine aboard - fantastic!  Customs gave us our entry stamp in our passports, with no comment about Schengen exit stamps.

We then had to move Zen Again into her assigned berth, just on last light.  The Capitainerie staff helped us moor and then the customs officials came aboard to inspect the vessel.  We'd prepared lists of our electronics, wine/spirits and medicines prior to arrival which proved useful.  Within 2 hours we were officially in Tunisia and able to stay for 3 months.  The Q flag was struck.

Yesterday morning we paid for our 3 month stay.  A total (inc power & water) of about 2400 TND, equivalent to 1160 AUD.  The Tunisian Dollar is interesting in that each comprises 1000 millis.  So amounts look 10 times higher than they really are!  So 2400,000 is 2400 TND, not the 24000!  

Later the Revision IIs took us for an interesting walk around the town.  Lots of similarities to parts of Indonesia, unsurprisingly since both are developing Islamic countries.  There are many cafes and restaurants in the marina complex, and a small supermarket.  It's a 10 minute walk into the Medina (the old walled town with many shop-lined lanes).

Today we got our local SIM cards - 58 TND  (28 AUD) for one month including 55GB.

Looking forward to exploring Monastir and further afield in Tunisia over the next 3 months.  Watch this space!