Is a tablet computer a good tool to use for marine navigation?

January 23, 2012 9:33 AM

Is a tablet computer a good tool to use for marine navigation? (A question related to the accuracy of a tablet computer GPS sensor when there is no WiFi or carrier based signal available)

Background: I have 2 personal watercraft (a Waverunner and a Seadoo RXT). My wife just gave me the greenlight to buy a GPS to navigate on the water. I also want to get a tablet computer, so I'm trying to sneak in that purchase by using the tablet as a GPS device.

I'm having a hard time nailing down definitive answers regarding using a tablet in place of a traditional GPS or chartplotter for navigating on a boat. I know that some tablets have integrated GPS sensors however I've been told by multiple sales people that those sensors are ineffective without a WIFI or carrier based signal. Because of that, they say that a tablet is not a good solution.

In conflict with those statements is that I've seen a number of mentions on the internet indicating that a tablet works very well. In fact, there are a number of apps sold that are specifically designed to do this including Navionics and EarthNC.

Setting aside the obvious issue of waterproofing, is a tablet computer a good tool to use for marine navigation?

posted by Dave. to technology (7 answers total)

I feel like it would be too bulky to use effectively on a jetski.

You're much more likely to find a mounting solution for a purpose-built GPS for your jetskis, versus trying to find some place to stash a tablet. Additionally, there are marine-ready GPS devices out there that are warrantied against the conditions you'll put it through. Even the best waterproofing for a tablet is still likely to fail at some point, and when it does, you're on the hook for that cost.

Additionally, I think you might run into issues with battery life. Figure you'll get maybe 4 hours of use from a fully charged tablet running the GPS radio, and a bright enough backlight to see it (yet another problem with tablets).
posted by chrisfromthelc at 9:47 AM on January 23, 2012

Gah, I say "additionally" too much!
posted by chrisfromthelc at 9:47 AM on January 23, 2012

Are there special marine-only tablets? In the aviation world a lot of us are using iPhones and iPads as backup navigation (and primary charting). It works fantastically. More background in this iPad for pilots blog post I wrote.

The GPS built into the iPad+3G works pretty well if it has a clear view of the sky. In a boat or an airplane that's pretty easy to achieve. The cell and wifi location mechanisms do work better in cities because you're in an urban canyon, but GPS-only works well in the air. It works much better if you have a power source so you can just leave the navigation app running all the time. There's also add-on GPS hardware for iOS devices now: the XGPS150 and Bad Elf are both popular. They perform quite well, I'd say as good as any handheld GPS device. I use a Bab Elf.

That being said, these GPSes are in no way a replacement for a real aviation GPS; I'd never trust my life to it. But as a backup to help me keep track of where I am on a map, it's great.

Maritime use has an added challenge, water and motion. Presumably you can't just leave an iPad lying out on deck. I'd go to the software vendors you cite above and ask them about what hardware they recommend for that.
posted by Nelson at 9:47 AM on January 23, 2012

It depends on the tablet, some tablets have standalone gps chips, some of them have it integrated with other chips on the device. Tablets aren't engineered to have excellent GPS reception (whereas a dedicated GPS receiver would), they also usually can't match the battery life. The key is if the device is relying on wifi to assist with geo location then it's going to be less effective and generally less accurate. I think it's down to antenna's and battery life. You can find super durable and water tight ipad cases, but I just sort of get nervous at the thought of relying on a product that was not engineered for a marine environment when it comes to navigation.
posted by iamabot at 9:52 AM on January 23, 2012

I've been told by multiple sales people that those sensors are ineffective without a WIFI or carrier based signal

Never trust a salesmen.

iPads for example have their own dedicated gps chips. They will find your location with no wifi or 3G signal. (although software that needs the Internet to download map info won't work).

However they will use the internet to improve their accuracy and reduce the time t
Taken to locate you.
posted by schwa at 10:04 AM on January 23, 2012

On Android (and perhaps on iOS? I don't know), you can "pre-cache" map areas in Google Maps and have full functionality with no data coverage.
posted by JMOZ at 10:51 AM on January 23, 2012

I want to reiterate and build on what schwa said: cell phones/tablets/etc that have GPS chips in them will take a while to locate you in the absence of cellular or Wifi signal. Devices that have cellular connectivity use AGPS to get signal lock, which is why your average smartphone shows you where you are within seconds. A tablet with no such connectivity, on the other hand, would be expected to be much slower. It should locate you, eventually, but you seriously might wait 5-10 minutes for it to get signal. If you are out in the middle of a lake trying to figure out which way to go to get home, 5 minutes is a pretty long time to wait. Once you have signal lock, you should be good to go until you turn it off, at which point you might have to wait to get signal lock again.

A dedicated GPS receiver, on the other hand, will have much better dedicated antennas and algorithms to get lock, despite not using AGPS either.
posted by wondercow at 7:15 PM on January 23, 2012 [1 favorite]