AIS Positon

Sunday, December 21, 2008

Nav Comparison

When sailing last weekend in Fort Myers Beach I was able to test the full spectrum of Nav programs available for the iPhone. The only program I don't have is Active Captain as they haven't ported it to the iPhone yet. I was able to compare iNavX with NOAA Raster Charts, iNavX version 2 with Navionics Vector Charts, Navimatics Marine Maps (Now Charts and Tides), and Fly to Maps Water Map Navigator. By far the best chart data available was the Navionics Vector Data.

As this product hasn't been released and Navionics is handleing the PR side of things I can't show you a full screen shot, but here is the chart portion of the screen shot. The raster chart above was usable, but due to the low scale of the Raster, the free chart was not great for navigating the narrow channel (not that it really mattered as we still bumped a sand bar heading out due to the unusually low tide even though we were dead smack in the middle of the channel). My understanding of the plans for iNavX are that when version 2 comes out (free upgrade) Navionics will have a method to purchase and download their Vector charts (in addition to the free NOAA Raster charts). No word yet on regional packaging or pricing, but if I lived up this inlet, I would spend the money for the Navionics Vector chart as it fills in nicely for the less than stellar Raster of the region.

I unfortunately forgot to load the correct region of the Navimatics charts, an inherent flaw in a system with separate programs for different regions. That said, you can load more than one region at a time and the icon shows the active chart region. Below is what the Navimatics chart of the region looks like.

Certainly workable, but not really as good as the NOAA raster let alone the Navionics Vector. It doesn't show all the Nav Aids that line the channel, just the larger Piles at the entrance. It does show the location of the channel with a different water color, but without the smaller posts shown, it would be harder to follow.

Fly To Map's product uses the free NOAA Vector charts (S57 format). Unfortunately, there are still ~30% of the raster charts that have not been converted yet. Also, they aren't the prettiest things in the world by any means. Clearly this is a region where the detailed charts haven't been converted to Vector format yet making the software completely un-usable in this situation. Sure it only costs $10, but if you lived or sailed in Fort Myers it wouldn't be worth 10 cents.

Overall, I am very excited about the partnership of Navionics and iNavX. The iNavX software is by far the most powerful, with the new features of waypoint and track import/export just adding to the functionality. They also keep developing with promises of eventual Grib weather overlays and several other features on top of the added support for Navionics Vector charts. The Vectors are sure to be somewhat costly, but hopefully they will be priced fairly and reasonably or at least in a way that you can pick and choose the charts you want to buy to fill in areas where the rasters aren't that great, or for international use.


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Anonymous said...

"By far the best chart data available was the Navionics Vector Data"

Well now, where do you think that Navionics gets their data from? Do you think they are out in ships collecting bathemetric data for the Ft. Myers area?

Navionics traces the existing NOAA raster charts. It might very well be true that with vector charts, you can then zoom that data up to the point where the channel looks huge. But the reality is that the data on the raster chart is as good as it gets based on the scale of the data collection and the imagery of showing the channel at a much greater size is just fake and giving an invalid sense of reality. That exact type of navigation ("honey, zoom up so I can keep the boat in the middle") will run a bunch of boats aground as they learn first-hand about the limits of scale and vector charts.

Beware what you advise others to use...

Ibsailn said...

I don't know for sure about the inlet at Fort Myers Beach, but Navionics does go out in boats surveying areas with less than ideal coverage. See this panbo article for a look at the work they do on Lakes and the Bahamas (

They also do take in reports from users and if verified by multiple users will make corrections to the charts that NOAA may not get to for years.

I understand the potential errors from overzooming, but for this narrow channel with a lot of bouys and a small scale NOAA chart, even if the data isn't better, it is far more readable in Vector format. Personally this is the first time I have ever liked the vector chart of an area better than the Raster.

Ibsailn said...

Also....from Navionics Website:

">Where do you get the information you use in Navionics Charts?
A: It may vary by Navionics product as well as by continent, country and/or area, but most commonly Navionics sources its data from official government hydrographic offices such as NOAA and NIMA to name just a few. Navionics also conducts its own on-the-water surveys when existing information is not available, is out-of-date, or is not of good quality. "

Again, I don't know if they did their own survey of the region I was looking at, but it did seem noticeably better than the NOAA Raster.

Anonymous said...

Navionics doesn't map coastal waters of the US themselves. The only thing they do that way is their lake maps - and it appears they scan some parts of the Bahamas too.

Personally, I'd rather have my charts showing me what I need for accurate navigation rather than drawing pretty pictures that distort the view. You might be experienced enough to know the difference. Others won't be...

It isn't about how good the picture looks. You're doing a dis-service to suggest otherwise. You know I'm right - just come clean and admit it!

Ibsailn said...

Anonymous says "Navionics doesn't map coastal waters of the US themselves" yet Navionics says "Navionics also conducts its own on-the-water surveys when existing information is not available, is out-of-date, or is not of good quality". I don't know which is correct and I will agree with Anonymous that there is the potential for error when overzooming a vector chart as you don't know that you are overzooming the base data and anyone using this software should keep that in mind when purchasing Raster charts.

That said, when actually navigating this channel, I was flipping back and forth between the two charts and found the Vector chart far easier to navigate with. Maybe it was a false sense of security, but I wasn't using the chart in that manner, I was using it to give me a good sense of the spacial relationships of what I was looking at in real life, and for this I stand by my comment that the Vector was preferred.

The bigger point of the article was that the other vector based charts by Navimatics and the S57 ENC's were far inferior to either option from iNavX for this particular inlet, something I don't see as often in the well charted waters of New England.

GPSNavX said...

I think the best option is to offer the user more than one chart source so he/she can have the most information. While the NOAA US water RNCs (Raster) coverage is currently the best data, vector charts do offer significant advantages - text stays same size and orientation, no anti-aliasing, generally quicker display, smaller download size, user selectable depth units, and easier to maintain by producer. Vector versus Raster has been debated for years and there is no perfect solution.

john said...

wow anonymous, you are a pompous dick. get out and enjoy some sailing and get back on the anti depressants.

Anonymous said...

The spirit of debate thrives in this place!

Nice comment john. It added a lot to the conversation.