e-charts for san blas

[maldhorror]

in a few days Im planning to sail to the san blas islands in Panama.
I've been told that the navionics charts are not faithful there
does any body has some personal experience sailing there and can recommend me a guide and charts that I can download in a Ipad or if not, in an android tablet or if impossible in a laptop
thanks
maldhorror

[s/v Moondancer]

Navionics are out by large margins and dangerous to use as evidenced by all the boats on the reefs.

https://www.amazon.com/Bauhaus-Panam.../dp/B00RWTR76C

The Bauhaus is mostly accurate but it really is a place for 'good light' visual navigating.

Google earth overlays on Open CPN work to some extent but I have not used them in San Blas but they work in the Pacific.

[phiggins]

I used the overlay function of GE2KAP to compare the Navionics charts from SasPlanet with Google earth and yes in some places the Navionics charts are not correct.
The Bing satellite Maps from SasPlanet are clearer than Google earth for that area.
GE2KAP can create charts from SasPlanet that can be used on OpenCPN on Windows or Android.

[robert sailor]

The Bauhaus charts knit right into Open CPN and are very accurate charts, everywhere We sailed in the San Blas those charts were dead on. Forget Navionics charts in the San Blas, they are a total joke, not to be used.

[Paul L]

Originally Posted by robert sailor

The Bauhaus charts knit right into Open CPN and are very accurate charts, everywhere We sailed in the San Blas those charts were dead on. Forget Navionics charts in the San Blas, they are a total joke, not to be used.

This is what we used along with the eye-balls. The Bauhaus charts were very good . I think we only had one anchorage in the East end that was slightly off.

[Hobie_ind]

Here's a shot of our tracks into one of the San Blas anchorages on our Navionics charts (shown in iNavX on the iPad).

Actually, the accuracy of the Navionics charts for this anchorage was actually better than most in the San Blas...... As Phil on Moondancer noted though, even with the book, it's certainly a place to plan moving around in good light. It's good, but we didn't rely on it solely.

Mark

PS. I really recommend getting a copy of the book, but if you just get a copy of Eric Bauhas' charts electronically for free from somewhere at least look him up in Panama City when you're there and give him something for his efforts. His dad (Allie Heise - also a welder if you need one) lives on a red steel boat usually anchored in the bay north of La Playita. Eric spent a lot of time surveying the San Blas and truly deserves some compensation for his efforts and the service he's done for cruisers in the area.

[belizesailor]

Do NOT depend on any electronic charts in the San Blas...except a known good georeferenced version of Bauhaus (unfortunately he does not supplies these, so the versions you find were done by cruisers). More than one boat has been lost in the San Blas due to relying on electronic charts.

Both Navionics and CMAP are inaccurate to varying degrees and areas. For example, Navionics is absurdley off in the far E San Blas...not even a vague fascimile of reality, but CMAP is much closer.

My suggestion is enter the Bauhaus way points and routes for the areas you plan to visit then follow those and not pay so much attention to the non-Bauhaus charts. For example, my old Raymarine chartplotter runs CMAP, but I have entered Bauhaus' routes and way points. I also have digitized versions of his charts on my tablet using OpenCPN. So, I can follow the routes/WPs from the helm on the chartplotter and not rely too heavily on CMAP, then bring the tablet up to the helm if eyeballing thru a new area and directly use Bauhaus charts for the detail.

After several years of cruising the San Blas with Bauhaus' charts, I only know of one minor error. Both CMAP and Navionics by contrast are chock full of errors...many of them quite dramatic. (I actually contacted Navionics about some of the more aggregious errors...they were not interested).

Another helpful aid is Google Earth chart overlays, this allows you to at least confirm land mass positions and some shoals.

[phiggins]

I just recreate my charts of the San Blass using GE2KAP from the Google Earth, Bing and Navionics Maps from SasPlanet. You can get them from this link and drilling down to the Panama Charts:

https://1drv.ms/f/s!Ahv3fXEZ5SzkjRTcnfNuiHWgtQKa

They were created at Z16 zoom level which is about a scale of 1:17000

[phiggins]

Hobie_ind your chart seems to put you on land. Here is what your position looks like on Bing and the Navionics charts creatd by GE2KAP from SasPlanet.
Notice on the satellite image you can see the channel.

[Hobie_ind]

Originally Posted by phiggins

Hobie_ind your chart seems to put you on land.

I know..... that was the point. :-) Like I said, that was probably one of the anchorages where it was closest.

Navionics isn't of any use in the San Blas

[chuckr]

we used a combination for Navionics and Bauhaus together along with OpenCPN - the problem is the narrow channels in some locations and you really do need a good eyeball - but as long as you are careful and NEVER EVER move at night you can be ok - we had a great time but were very careful and more than once had our heart in our throats

[roland stockham]

I have fond Cmap to be accurate in Panama but did not go to San blas. They are not free but if you download plan2nav (free app) they are only a few bucks.
If worried about any chart I take a fix by radar or visual observation and compare it to the GPS position on the chart. Gives an idea of the error. Even if charts are off relative to GPS the error is usually consistent across the chart.

[Hobie_ind]

Originally Posted by roland stockham

....... Even if charts are off relative to GPS the error is usually consistent across the chart.

This would be a wildly dangerous assumption in the San Blas.

We found the error was incredibly variable, with even the most commonly travelled areas having errors varying from 100's of feet to over a 1/4 mile, plus the underwater detail was often completely wrong or missing whole reef structures, so cross referencing to radar feedback off of land references was useless. This was across all three separate platforms of the electronic charts we had onboard.

One fun detail that I haven't seen noted here is that, in the anchorages closer to the mainland, the water was often so murky that even eyeball navigation in good light was challenging. This is where Eric's waypoints and charts really came to the fore. I put waypoints separately into the chartplotter and the iPad or OpenCPN so that I could minimize the risk of incorrectly inputting a waypoint. My daughter then checked the waypoints..... and we still only moved around in good light even if the water was murky.

[belizesailor]

Originally Posted by Hobie_ind

This would be a wildly dangerous assumption in the San Blas.

We found the error was incredibly variable, with even the most commonly travelled areas having errors varying from 100's of feet to over a 1/4 mile, plus the underwater detail was often completely wrong or missing whole reef structures, so cross referencing to radar feedback off of land references was useless. This was across all three separate platforms of the electronic charts we had onboard.

One fun detail that I haven't seen noted here is that, in the anchorages closer to the mainland, the water was often so murky that even eyeball navigation in good light was challenging. This is where Eric's waypoints and charts really came to the fore. I put waypoints separately into the chartplotter and the iPad or OpenCPN so that I could minimize the risk of incorrectly inputting a waypoint. My daughter then checked the waypoints..... and we still only moved around in good light even if the water was murky.

Second that. The errors are not just GPS offset, much of their cartography is just radically wrong.

[Paul L]

Originally Posted by roland stockham

I have fond Cmap to be accurate in Panama but did not go to San blas. They are not free but if you download plan2nav (free app) they are only a few bucks.
If worried about any chart I take a fix by radar or visual observation and compare it to the GPS position on the chart. Gives an idea of the error. Even if charts are off relative to GPS the error is usually consistent across the chart.

Outside of the San Blas up todate CMap was very good. Inside the San Blas it was hit and miss (no pun intended). Adding the Bauhaus info was required for safe navigation. The chart errors are not consistent datum shift problems. More changing, missing reefs and land.
The San Blas takes an amazing number of cruising boats each year. For many cruisers this is the first place where eyeball navigation is required, the charts are inconsistently way off and the conditions are variable. We were there one year when a cruiser decided to enter a narrow pass to an anchorage under high sun. A thunderstorm popped up and they lost the view of the coral. Hit the reef on the side of the channel and lost the boat. Another boat did a late arrival from Colombia and thought they could get into a relatively open anchorage. Hit the surrounding reef and lost the boat.