What uses more power?

[Fascadale]

……….over 24 hours? A biggish iPad running charting software, with built in GPS and receiving wireless AIS or a 9 inch (maybe Axiom) MFD on an existing NMEA setup used as a chart plotter and AIS display?

(I have tried looking at the “specs” for each system but am so far none the wiser. A reflection on me, not the specs)

One advantage of the MFD is that I can add a radar at a later date

 

[NormanS]

……….over 24 hours? A biggish iPad running charting software, with built in GPS and receiving wireless AIS or a 9 inch (maybe Axiom) MFD on an existing NMEA setup used as a chart plotter and AIS display?

(I have tried looking at the “specs” for each system but am so far none the wiser. A reflection on me, not the specs)

One advantage of the MFD is that I can add a radar at a later date

I don't know about the power, but I do know that you'll be able to see the MFD in sunshine.

 

[V1701]

Don't know but my guess would be that the iPad would be the more hungry...

 

[jdc]

The Axiom 9 consumes around 9W, but that's while using various sensors. Raymarine don't publish figures for just chart-plotter mode but it won't be a great deal less.

An iPad Air with an equally big screen has a 28WHr battery which lasts about 9 hours, so 3W average consumption. Offset against that you have to charge it from the boat's 12V supply, which is probably only 85% efficient, so instead of 3W you have to reckon 3.5W average.

So the iPad wins hands down on power consumption. Hardly surprising given the amount of engineering put into it compared to the Raymarine devices, justified by the iPad sales volume probably being more than 1000 x greater than any chart plotter.

However, is 9W a real issue? 9W at 12V = 0.75A. Which, when x 24 hours is 18AHr. Only you can relate this to your overall consumption: for us it just doesn't figure compared to the fridge, the VHF set, lights and, when under-way, the autopilot.

 

[Buck Turgidson]

The Axiom 9 consumes around 9W, but that's while using various sensors. Raymarine don't publish figures for just chart-plotter mode but it won't be a great deal less.

An iPad Air with an equally big screen has a 28WHr battery which lasts about 9 hours, so 3W average consumption. Offset against that you have to charge it from the boat's 12V supply, which is probably only 85% efficient, so instead of 3W you have to reckon 3.5W average.

So the iPad wins hands down on power consumption. Hardly surprising given the amount of engineering put into it compared to the Raymarine devices, justified by the iPad sales volume probably being more than 1000 x greater than any chart plotter.

However, is 9W a real issue? 9W at 12V = 0.75A. Which, when x 24 hours is 18AHr. Only you can relate this to your overall consumption: for us it just doesn't figure compared to the fridge, the VHF set, lights and, when under-way, the autopilot.

Yep. Ipad consumes a lot less.
You don't have to charge it from the boat if you don't want to. I have a combined 10W solar panel and battery system from Voltaic which allows me to run my iPad and/or Garmin inReach independently.
they don't make this model anymore.

 

[Sea-Fever]

I would be careful to rely on published data on the ipad - most modern devices use far more power when the gps chip is continuously used and I doubt the standard usage figures are based on that use case.

 

[bergie]

I would be careful to rely on published data on the ipad - most modern devices use far more power when the gps chip is continuously used and I doubt the standard usage figures are based on that use case.

On our boat Navionics gets boat GPS from same WiFi NMEA0183 stream as AIS data (and depth). I don’t have measurements, but the tablet batteries seem to last a lot longer when using boat GPS vs. when that isn’t available (and I assume Navionics enables the tablet GPS).

Note that only the cellular iPads have a GPS, so there is benefit for using the boat GPS apart from power consumption.

We’re using a waterproof 8“ Galaxy Tab Active as our “chartplotter”, and it is running completely happily from a 1A (@5V) USB outlet.

 

[Fascadale]

Thanks for the useful comments.

However, is 9W a real issue? 9W at 12V = 0.75A. Which, when x 24 hours is 18AHr. Only you can relate this to your overall consumption: for us it just doesn't figure compared to the fridge, the VHF set, lights and, when under-way, the autopilot.

I’m a bit anal with the amps. The boat has 200(nominal) watts of solar and 240 Ahrs of domestic battery with a fridge, lights and instruments to power. The wind vane also saves a pile of power. But all the same…..

I’ve been swithering on this question for a while now. A new MFD/plotter or just use an iPad? Other than the possibility of adding a radar in future to the MFD, a biggish iPad was looking more attractive. Had the iPad used masses of power that might have tipped the balance towards the MFD.

My present iPad and plotter are both below the hood so direct sunlight is seldom a problem.

One great advantage of the tablet is its ability so carry a variety of charting software. At times I prefer iSailor to Navionics and Antares works so well with UKHO charts on Memory Map.

 

[Neeves]

When its 2am, you need to make some delicate navigational decision and its raining - you will be glad of the completely waterproof MFD at the helm and even better when you have radar. You can use the iPad as a repeater (and control the MFD from the iPad) but that reliable access at the helm can be a god send (complicated river passages, weaving between small islands and rocks........

However as mentioned its not the power usage of either - neither use much (though a few devices using 'not much' add up to a lot) its the basic cost of the units - and there is no answer to that other than the size of your wallet.

Our old MFD was at the chart table and we soon realised - wrong place. We replaced, later when we had to replace the radar, with a small MFD at helm, 7", and we use a WiFi enabled iPad Pro for roaming about 'indoors'. (making the toast) We have radar and you need a compatible MFD if you want radar..

Its money not power.

The equation will change if anyone introduces a daylight viewable, waterproof and touchscreen reliable tablet but..........the market is not big enough, I guess

Jonathan

 

[KompetentKrew]

I'm sure the MFDs use the same ARM chips as the iPad so, whilst one may consume a bit more than the other (particularly the one with the daylight visible screen), their consumption should be in the same order of magnitude.

 

[noelex]

The iPad is less. I took the following measurements a couple of years ago. All results are for a 24v system ( so 12v current consumption will be about double). They are for a large (12.9 inch?) iPad ( the first large screen model) vs a B&G 10 inch Zeus 3.

iPad
Full brightness 0.37 A
Half brightness 0.15 A
Low brightness 0.10 A

Zeus 3
Full brightness no radar 1.00A
Full brightness radar 1.23A

Keep in mind the Zeus brightness is higher than the IPad. I don't have any actual measurements for the Zeus 3 at lower brightness but from memory it reduced significantly when the brightness was reduced to around 70% (around 0.65A without radar) but did not drop much more as the brightness was reduced further.

The newer iPad pro has a better screen and faster processor (and there is a newer Zeus with a faster processor) so is likely to be little more than the above measurments, but these protable devices are optimised for battery life.

 

[LittleSister]

Note also it's not obligatory to have whatever you get on all the time!

How much of your sailing do you actually need to have the chart in front of you, and know your position to within a few metres, etc?

 

[Fascadale]

How much of your sailing do you actually need to have the chart in front of you, and know your position to within a few metres, etc?

Very good point but even well off shore I like to have the AIS on plus having data available for the hourly log entry

 

[Neeves]

Note also it's not obligatory to have whatever you get on all the time!

How much of your sailing do you actually need to have the chart in front of you, and know your position to within a few metres, etc?

Valid point

When we sail up and down the east coast of Australia on a fine summers day - we don't need any instrumentation. Going north just keep off the beaches (and count the lighthouses) coming south just keep the coast on the horizon (as roughly that's where you will benefit from the 3-4 knots of the East Australian Current, EAC) - hopefully you can also count the lighthouses. We generally have little commercial traffic, visibility is generally good and if you miss seeing a container ship - you should not be sailing - so for us (or anyone crossing an ocean AIS is 'nice' not essential (until it is essential ).

But I'm also not sure the simple question - which uses more power - a tablet or MFD is the correct question - surely it might be which uses more power when displaying all the instrumentation, wind,, depth ,WiFi (for instrumentation) etc. For us speed through the water and speed by GPS are important - as they tell us whether we are being affected by the EAC. We can get some of this from water temperature The EAC is warm - but that necessitates knowing the temperature outside the current (easy if you check in advance (close inshore).

The answer might be more complex than first envisaged. Why do you need a monster screen? will use more power.....

I still think the power differences pale when you also consider cost and put a value on having the display at your finger tips 24/7 rain or shine.

Jonathan

 

[NormanS]

We have a fridge on all the time, 24 hours. We have a few other gizmos, but I'm sure the fridge will be our hungriest user of electrical power. Compared with it, plotter(s), phones and tablets, use very little, so we don't worry about it. We have an MFD at the outside wheel, but sometimes, when using for instance, Antares Charts, we have a tablet outside as well, with provision for its own plug in power supply. The outside MFD has hybrid controls, but in practice we seldom use the touchscreen facility, as it's hopeless in the wet.
Having a deck saloon, where steering, engine controls, and navigation equipment is duplicated, we have a touch screen plotter. All sailing is handled from outside, but I have to admit that motoring in nasty cold wet weather, is much more pleasant from the inside.
When underway sailing, the outside plotter is invariably switched on, although the vast majority of the time, it's not required.

 

[dune16]

Regarding being able to not see a tablet screen in sunshine, I added an antiglare screen protector film to my Samsung tablet and it made a great improvement to this issue. It's basically a matt/satin film rather than the usual gloss. All still touch sensitive so no drawbacks and makes the tablet perfectly usable in the med sunshine

 

[Koeketiene]

We have a fridge on all the time, 24 hours. We have a few other gizmos, but I'm sure the fridge will be our hungriest user of electrical power.

I have found my fridge is somewhat power-hungry the first 18-24 hours of operation.
Once it's 'on temp' it uses far less power.

 

[Buck Turgidson]

Very good point but even well off shore I like to have the AIS on plus having data available for the hourly log entry

I do all that from my triton2 instrument.

 

[Fascadale]

I do all that from my triton2 instrument.

That’s a very good point. All the data would be there but I’m not sure if my Triton2 has AIS alarms, but that would not be a serious problem in good vis.

 

[jdc]

... most modern devices use far more power when the gps chip is continuously used and I doubt the standard usage figures are based on that use case.

A modern GPS chip, probably manufactured in a 40nm process, consumes about 10mA at 1.2V when running continuously. so 12mW. Not really significant.