Best iPad chart/navigation app

[s/v Jedi]

Originally Posted by ranger58sb

I'd forgotten I have another chart source on the same tablet. This is a C-Map chart from the old Plan2Nav app (which C-Map has since replaced with the Embark app).

The chart here is very much out of date, but illustrates the difference in clutter than I mentioned with the iSailor/Transas chart.

-Chris

Yes, you need to zoom in more to get that same amount of detail.

[ranger58sb]

Originally Posted by s/v Jedi

Yes, you need to zoom in more to get that same amount of detail.

Yep, iSailor works well for that. Just happens we're already using the plotter for that level, and already have decent depth/hazard/etc. info displayed there... so we usually gravitate to using the apps for longer range views. Helps that we can display NOAA raster, NOAA vector, and Garmin vector charts (with or without radar overlay) side by side and in various scales on the two MFDs.

The one difference in that approach is when were traversing a well-known skinny area usually along the AICW, especially if we have to pass thru at less than high tides, where the Aqua Map presentation of recent USACE survey data is reassuring specifically because of the additional soundings.

-Chris

[Mike OReilly]

Maybe I'm missing something, but I'm not very hung up on raster vs vector, or even which presentation is better. You have to know how to use the tool you have, but I've not found it hard to go from one to the other.

And perhaps my expectations for charts are lower than some here -- but I don't expect them to be perfect. I always use them as a guide, so am always seeking other confirming data (Eye Balls, sonar, radar). I started cruising in an area where charts were known to be inaccurate, and I'm still in such an area, so I just carry that skepticism with me. They're just a guide.

What I really want is an iPad chartplotter that can display all charts (either format) for North America, is intutive to use, and doesn't erase your charts if a subscription lapses.

[ranger58sb]

Originally Posted by Mike OReilly

Maybe I'm missing something, but I'm not very hung up on raster vs vector, or even which presentation is better. You have to know how to use the tool you have, but I've not found it hard to go from one to the other.

And perhaps my expectations for charts are lower than some here -- but I don't expect them to be perfect. I always use them as a guide, so am always seeking other confirming data (Eye Balls, sonar, radar). ... They're just a guide.

Agree, agree, and agree.

FWIW, I'm finding the switch from raster to vector more "disconcerting" than "difficult." And that's simply because I've mostly ignored vector charts for the last 55 years or so... and that's in turn simply because my first raster usage was about tracking airplanes (and later, other stuff) in a military environment starting way back then.

-Chris

[requiem]

Originally Posted by s/v Jedi

For San Blas we normally use the Bauhaus charts, but I looked the area you show up in iSailor and although I think it’s a bit better than your image, I would still use Bauhaus.

That sounds very wise; I'll see if I can get my hands on those.

I think iSailor may be using the same data; they look nearly identical, and the NOAA data is based on a Navy survey from 1915-17 assigned CATZOC D (>500 m position error). Thus, all the classic warnings about electronic charts in the area still apply!

It's possible the geo-referencing may have been updated. I will need to compare specific coordinates to see if that's the case. My initial check based on a previous San Blas thread here seemed to indicate so.

[s/v Jedi]

Originally Posted by requiem

That sounds very wise; I'll see if I can get my hands on those.

I think iSailor may be using the same data; they look nearly identical, and the NOAA data is based on a Navy survey from 1915-17 assigned CATZOC D (>500 m position error). Thus, all the classic warnings about electronic charts in the area still apply!

It's possible the geo-referencing may have been updated. I will need to compare specific coordinates to see if that's the case. My initial check based on a previous San Blas thread here seemed to indicate so.

The Bauhaus charts come with their cruising guide. I have used them in Open CPN as well as just on paper in the guide. Even on those charts, I have found shallower areas than charted, think 14’ instead of 47’ but for yachts never something posing a danger.

What I really like to do with areas like the San Blas, it to overlay the radar on the chart so as to check if the chart is in the correct position. Many/most plotters allow you to offset the chart to match the radar.

[requiem]

Originally Posted by ranger58sb

Looks like there's a sounding every 23' or so (hyperbole) in the Transas chart; I don't see how they can have so many more data points and so would otherwise suspect those are guess-timates based on averaging and smoothing. Hard to see more important stuff though, with all that clutter on the screen.

I think this is more a case of the app displaying soundings from a large-scale chart too soon (ie before the user has zoomed sufficiently). In this case Transas is repackaging NOAA charts; your screenshot is using soundings from chart US5MD22M, which is 1:25k scale, when chart US4MD81M (1:80k scale) has more appropriately-spaced soundings.

NOAA's raster charts include 1:40k scale coverage so the transition is less abrupt. This particular spot lacks 40k ENC coverage, but NOAA's in-progress ENC rescheming work will add that back in.

[R Hutcheson]

I've been using AquaMaps on rivers, The Bahamas, and along the East Coast for the past two years. I like it and find it to be much better than the expensive RayMarine unit installed in the boat.

[requiem]

Going back to some of the route editing, etc. topics, here's one example of when I might block out an area (South of San Diego, from the most recent LNM):



And one more, to illustrate adding clearing bearings and route editing. One thing I found convenient was to set up waypoints or even stub routes for various harbor entrances, so that they can be quickly inserted into the plan for any new trip. If I later decide to modify them, all routes that incorporate them are also updated.

[ranger58sb]

Originally Posted by requiem

I think this is more a case of the app displaying soundings from a large-scale chart too soon (ie before the user has zoomed sufficiently). In this case Transas is repackaging NOAA charts; your screenshot is using soundings from chart US5MD22M, which is 1:25k scale, when chart US4MD81M (1:80k scale) has more appropriately-spaced soundings.

NOAA's raster charts include 1:40k scale coverage so the transition is less abrupt. This particular spot lacks 40k ENC coverage, but NOAA's in-progress ENC rescheming work will add that back in.

Interesting analysis; thanks for that. Given our iSailor version is running on an older Android opsys, and given Wartsila isn't doing updates to that anymore... I wonder if someone using the iThing version, and a newer version at that, might not have the same experience...

On most of the tools, I don't easily see which actual chart is being displayed at which various zoom level. (There might be a way to do that within each tool, but I haven't really looked...)

My NOAA snapshots were labeled as "1:61,000" (per the sizing gizmo in TZ) and the iSailor/Transas snapshot was labeled "1:60,000" -- but I think those results were simply what a single detente of the mousewheel (TZ) or a single tap on the +/- (iSailor) rendered at the rime.

-Chris

[requiem]

Originally Posted by ranger58sb

My NOAA snapshots were labeled as "1:61,000" (per the sizing gizmo in TZ) and the iSailor/Transas snapshot was labeled "1:60,000" -- but I think those results were simply what a single detente of the mousewheel (TZ) or a single tap on the +/- (iSailor) rendered at the rime.

This is simply the display zoom; similar to zooming in and out on a paper or raster chart. The information displayed doesn't change much, the items on the screen simply get closer or further apart. However, since icons and text on vector charts are always displayed at the same size, they will not shrink or grow but rather pile up as you zoom out.

A qualifier to that with vector charts is the SCAMIN attribute. For example, soundings on the Half Moon Bay screenshot posted above are not displayed because each sounding was assigned a SCAMIN value of 21999 and my display was zoomed out to 1:22000. This is an attempt to reduce clutter by automatically hiding some items when you zoom out far enough. (Some tools like OpenCPN let you disable this.)

As hpeer noted, each chart is optimized for a particular display scale. Attached is a contrived example comparing two vector charts of very different scales (one a harbor chart at 1:20k, the other an overview chart at 1:1200k). Another example might be something created as a point feature on a small scale chart, but created as an area feature on a large scale chart.



On iSailor, if you click somewhere on the chart and tap in the info icon, then select "General information" under "Transas chart" the notes will tell you the scale. Scroll further down under "Explanatory and Cautionary notes" and it will list additional information (vertical datum, sounding datum, etc) including the NOAA chart name used.

[wingssail]

Originally Posted by hpeer

Is there ANY app that will display the Panamanian / San Blas cruiser data?

For Panama we used the Bauhaus charts (scanned and converted most of the 250+ charts before they came with the book). The cruiser data did not come into the OpenCPN but we have the book.

For our world cruise (35 countries and many very primitive and poorly charted areas) we used OpenCPN exclusively. We collected or created our own charts from whatever paper or digital image was available prior to going to each new loccation.

Jon Hacking on sv Ocelot has a very extensive set of tutorials on how to create charts for use on OpenCPN. We used a previous tool IMGKAP which worked but was a bit of a pain.

I think that oCharts is a good way to purchase charts for OpenCPN, https://o-charts.org/?lng=en

[ranger58sb]

Originally Posted by requiem

This is simply the display zoom; similar to zooming in and out on a paper or raster chart. The information displayed doesn't change much, the items on the screen simply get closer or further apart. However, since icons and text on vector charts are always displayed at the same size, they will not shrink or grow but rather pile up as you zoom out.

On iSailor, if you click somewhere on the chart and tap in the info icon, then select "General information" under "Transas chart" the notes will tell you the scale. Scroll further down under "Explanatory and Cautionary notes" and it will list additional information (vertical datum, sounding datum, etc) including the NOAA chart name used.

Yep.

And thanks, now I know how to find the chart info and that helps. OTOH, now I can't figure out how to make the cursor symbol go away; minor detail.

-Chris

[Mike OReilly]

Thanks for all the great info folks. I've been offline the last couple of days, but you've given me a good start on what apps to focus on. I'll report back on what I decide (in case anyone cares).

[sv_pelagia]

Here in Canada, Navionics does not keep up with CHS chart updates! Many months later and rocks etc still not showing on Navionics that are on CHS charts.

OCharts are uptodate.