eSeaChart for ipad or iphone-gctid379889

[Guest]

Does anyone else have experience with this app? I have it for ipad and have used it a little and for what it is, it seems well worth the $7.99. I was just wondering how accurate it was compared to others and anyone else's experience with it. It doesn't require internet access while using as long as your device is gps capable and the charts look exactly like NOAA charts to me.

http://www.eseachart.com/

Thanks

Matt

[Guest]

Those look like raster charts, and there are significant disadvantages. That's why it's so cheap. I'm not aware of any advantages to a raster chart, but maybe someone else can think of one.

[Guest]

Also it is ocean only, while Navionics covers both ocean and inland lakes.

[Guest]

This is one of those religious discussions similar to what's the best anchor but...

Turning the question around there are disadvantages to some vector charts in the way they display hazards at various zoom levels. This might be a contributing cause to the recent loss of the sailboat on Coronado Island.

I have all available nav programs on my iPad and iPhone and they all work reasonably well. All have different approaches to interfaces and processes so it mostly boils down to what you like or can get used to. eSeaChart and EarthNC both display raster charts. They have their place.

[Guest]

I do have a raster application that I would use for previewing a route along with the vector charts when we did ocean trips. MotionX, it's $3. Also covers land, lakes, topo, etc.

And John does make a great point. SOME vector charts have issues with certain hazards at certain zoom levels.

EDITED: Used the wrong term, VECTOR charts can have errors at certain zoom levels.

[Guest]

SwampNut wrote:


And John does make a great point. SOME raster charts have issues with certain hazards at certain zoom levels.

Maybe you two guys could clear something up for me as my last purchase of electronic navigation equipment was a Garmin GPS 48 quite a number of years ago. And thanks for the info by the way guys. Swampnut you stated that

"some raster charts have issues with certain hazards at certain zoom levels" and John States that

"Turning the question around there are disadvantages to some vector charts in the way they display hazards at various zoom levels. This might be a contributing cause to the recent loss of the sailboat on Coronado Island."

So my question is which type of chart has issues with hazards at different zoom levels?

Both of you guys seem to have contradicted each other. I think?

Matt

[Guest]

Sorry, I completely screwed that up! I will go edit it.

Some VECTOR charts have issues with hazards at some zoom levels. I used the wrong word.

Here's a very simple explanation of the difference... A raster chart is basically a photo. Just like a photo, you can zoom in/out but you lose details as you zoom out, and you only have so much you can zoom in. The resolution of the raster is a limit, just like a paper chart can only show so much. Zooming in a raster is like putting your face real close to a paper chart. Zooming out is like putting 20 paper charts on a wall and looking at them from across the room. A vector chart is a mathematical representation of the image. It says "draw a line from this XY coordinate to that XY coordinate." Zoom on these is essentially unlimited. You can preserve detail in a zoom-out by increasing their relative size (text, bouys, etc). What has happened in some vector charts is some hazards scale improperly because of the way they were marked (single XY instead of a series of XY coordinates showing their boundaries).

Hope that helps. This is why I *always* review appropriate paper charts before any trip in unknown water, then plot it on a vector plotter, and make sure no hazards are shown on either.

I believe electronics can replace paper for navigating, but not for planning.

[Guest]

Thank you that does clear it up. I am most familiar with paper charts and ancient gps so I will continue my experimentation with eSeaChart. So far it seems to pinpoint me on the apps chart very close to my actual position on the water. For me it functions as a very low cost chartplotter and trip planner. I think it may lack a lot of the bells and whistles of other apps but for the basics it seems to work for me.

Matt