Six important points to consider before ditching your chartplotter

An iPad offers access to
email, internet, photos and videos, books, radio, TV and music on board – but can
it also serve as a primary means of yacht navigation?

To find out, we loaded Navionics
cartography and iNavX plotter apps onto an iPad and sailed aboard a Hallberg Rassy 352 from Hamble to

1. Can you mount an iPad
at the helm?

We took the
iPad up to the binnacle compass and found that it spun the compass around with a 8°W to 5°E deviation when the bottom of the iPad was 15cm (6in) above the
compass glass, then 20°W to 18°E deviation when the iPad was 9cm away. The bottom of the
iPad eventually needed to be at least 23cm (9in) from the binnacle compass to rule out local

2. Does the iPad
need protection?

If you don’t have
somewhere secure to put your device, you will need some sort of bracket.
are now quite a few good iPad cases on the market, starting at around £30.
The new Lifedge iPad case, for instance, gives IP68 (waterproof) protection for just £99.

3. How long does the
battery last?

Running iNavx, we
found that a full charge lasts 5½ hours. We then kept the charger plugged in for the rest of the time, which ran the iPad while keeping the battery 100% charged.

4. How accurate was iPad navigation?

We switched off
the iPad’s roaming and 3G. If it was getting any GPS data now, it had to be
from GPS and could not be triangulated. We placed it alongside a handheld
Garmin 175C in the cockpit and it matched it 1/1000th of a minute to 1/1000th
of a minute from Universal Marina in the Hamble to Cherbourg and back. The
Garmin 192 by the nav station has its own antenna on the pushpit and it too
gave the same information. The 175 and the 192 are WAAS-enabled and the iPad
matched them. Remember that the iPad will give your heading as the direction in
which it is facing. So for an accurate heading you must line the iPad up fore
and aft. COG (course over ground) remains the same whichever way the iPad is
facing, of course.

5. How quickly does iPad navigation
fix your position?

If you are using
the GPS chip on its own without ‘assisted’ GPS triangulation, it can take the
iPad several minutes to get a fix – especially if the current location has not
recently been determined (for example if you had the iPad switched off and
drove to the boat). Once it has found its position, it takes a few seconds to
acquire subsequent fixes. Turn it off, turn it on again and it will have locked

6. So, how useful is tablet/iPad navigation when sailing a yacht?
Navigating with it
was a bit of fun and it is very useful to run in the cockpit as a spare
chartplotter. We found the touch-screen much quicker to use than any
push-button plotter.
iPad navigation is cheaper, but it is not as reliable
as a chartplotter designed specifically for the conditions. An iPad also shuts down
when it gets too hot, it is only just bright enough during the day and far too
bright at night.