There are many informal marine radio “nets” which allow cruisers to keep in contact
with one another to exchange information and to seek assistance. Being a radio system
(as opposed to satellite), reception quality depends on time of day, distance apart
of the two stations and atmospheric conditions, particularly sun-spot activity. We
have a computer programme which gives the optimum frequencies to use depending on
Email by SSB
By using a radio modem between our laptop computer and the SSB set we can send/receive
emails, in theory, at any time and anywhere. This is a very powerful tool, as it
allows communications with shore when offshore or ocean sailing and beyond the reach
of cell-phone signals. We use a provider called Sailmail (www.sailmail.com) and pay
a fixed annual charge of $250 regardless of usage. This is email only and not Internet.
Transmission speeds are relatively slow and attachments are not allowed, but nevertheless
it is an extremely useful service even when we are at anchor, as it avoids the need
to plodge ashore in the rain to an Internet Café!
To avoid collecting unsolicited material (spam), which would swamp us, we are particularly
careful about revealing our Sailmail address only to friends and family. If you would
like to communicate with us by Sailmail, please send an email using the link at the
bottom of the page.
This is a satellite-based, data only (not voice) system primarily intended for commercial
shipping. It has almost worldwide coverage and provides free weather forecasts, navigational
warnings, email and delivery of fax messages ashore. However, its most important
function is sending of an automated distress signal by satellite to a Maritime Rescue
Co-ordination Centre, in our case, Falmouth Coast Guard. This distress signal contains
the boat’s name and current position. It allows messages and email to be sent between
vessels similarly equipped. Email, however, is expensive and not very user-friendly
so we normally use Sailmail.
Our IMN number for Inmarsat C contact is: 423590216. We only have this system switched
on during ocean passages due mainly to its power consumption.
Obviously, cell phones are only usable when a signal can be received and this is
normally only within 10 miles of shore, although in remote areas there is often no
coverage at all, even on land.
Our UK cell phone numbers is: + 44 77 66 66 33 94
In the USA we normally buy a pre-paid SIMM card but these tend to lapse if not used
for more than 90 days, so our US numbers change annually!
Thanks to the fabulous generosity of my two sons we have just been given a satellite
telephone which we shall be using aboard in 2010 and also in the Land Rover in remote
places. A SatPhone allows calls to be made from practically anywhere to anywhere
and also presents another option for email.
Internet, email and Skype
In the USA, the standard “Internet Café” has all but disappeared and has been replaced
by WiFi services (normally free) in coffee-shops, public libraries and marinas. Normally,
this means taking the laptop ashore, although it is sometimes possible to receive
a signal at a mooring and enjoy free, fast, Internet on the boat. We use WiFi extensively
and have now installed a WiFi antenna which greatly enhances reception and means
we can often pick up a usable signal out at an anchorage. A secondary feature of
this is the use of the VOIP service, Skype, which gives us voice calls free of charge
between computers and at nominal rates to land lines. We use Skype extensively to
call family and friends in the UK and South Africa.
AIS (Automatic Identification System)
We have recently fitted a Class B AIS transmitter/receiver aboard Al Shaheen. Strictly
this is a communication system, in that we receive certain data on vessels in our
vicinity and transmit our data to be received by other vessels. AIS is a transponder
system rather like that which has been used by aircraft for many years.
AIS signals are transmitted and received digitally on a dedicated VHF frequency and,
as a minimum, give a vessel’s name, MMSI number, vessel type, position, course and
speed over the ground, closest position of approach (CPA) and time of CPA. As the
signals are carried on the VHF frequency this restricts range to line-of-sight and
normally less than 20 miles. By International regulation, vessels over 300 g.r.t
are now required to fit Class A AIS transponders whilst other vessels may voluntarily
fit Class A or Class B equipment. Class B sets are primarily intended for small
craft and leisure craft, are built to lesser standards than Class A and transmit
more restricted data than Class A.
Data received may be displayed on a dedicated screen or overlaid on a chart plotter
or radar screen. In our case we display it on our Raymarine C80 chart plotter, where
AIS targets appear as a magenta arrow in their true position on the chart. Clicking
the cursor on a target brings up a data screen showing all the data on that target.
AIS is a very valuable information system and an aid to collision avoidance. It is
not infallible and should be used in conjunction with radar and visual observations.
One great benefit is that it identifies a target by name so that one can now call
up the target by voice VHF and address it by name with a much better chance of response
than by calling an anonymous target.
Voice distress messages would be transmitted over VHF and/or SSB and satellite data
messages sent by Inmarsat C or EPIRB (see below).
The EPIRB (Emergency Position-Indicating Radio Beacon) is a device which, when activated,
transmits a signal by satellite on a dedicated frequency, continuously for a period
of about 30 hours or until its battery is exhausted. This signal contains a unique
code, which is registered to the vessel, and the position of the beacon is determined
by the satellite. The beacon may be activated manually or by immersion in sea water.
Aboard “Al Shaheen” we have the following means of communication:
This is our primary means of voice communication for short distances (up to 30 miles)
and is used for talking to other vessels within range, marinas, harbourmasters, Coastguard
etc. VHF is line-of-sight, and range depends on the height of the transmitting and
receiving aerials (antennas) above sea level. Many coastguard stations have very
high antennas, often giving a 50 mile range. Yacht-to-yacht communication distances
are rarely better than 10-15 miles. VHF is a “broadcast” system, which means that
any station tuned to the same channel can hear our transmissions. Thus, it is not
secure for private conversations, but this feature makes it ideal for distress working.
An advanced feature of VHF communication is Digital Selective Calling (DSC), which
allows a set equipped with DSC to alert either all vessels within range (for distress),
or a single station using their individual MMSI number. Many yachts are not yet equipped
with DSC, especially in the USA, although Al Shaheen is.
Our radio call sign is: ZQYF3 and our MMSI number is 235000882.
This is the “work horse” of long-distance cruisers. It is a system of radio transmission
using medium and high frequencies (short wavelengths) and allows long-distance communications,
subject to the vagaries of propogation. It allows radio contact over distances of
several thousand miles. We use it mainly to talk to other yachts beyond VHF range
and to obtain weather forecasts, although it may be used for distress and for placing
telephone calls whilst at sea to lines ashore.