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

Cherbourg.

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

deviation.

2. Does the iPad

need protection?

If you don’t have

somewhere secure to put your device, you will need some sort of bracket.
There

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

on.

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.