[DG11] Sonarchart Live, depth offset

[moki38]

Hi,

When using the SonarChart live (Axiom7,RV-200), the depth offset doesn't work as i would like it to do.
The Depth on my DST800/i70s is calibrated to "below keel", offset of 1.7m.
This shows as my current depth, in 2.0m water as 0.3m.

When using SonartChart live, this will show up as "deep red", as it thinks the depth is 0.3m, when i really is 2.0m

The workaround is the to set the offset to 0, so the SonarChart live, shows a "normal" depth. Ofcourse, the depthtransducer is really 0.2m below the waterline, but i am unable to set the offset to -0.2m

The real problem, is that this new depth offset setting (of 0.0), is confusing the Admiral. So either i have a working SonarChart Live or a very confused Admiral.

How to fix this? (Getting a new Admiral is not really option)

[Derek - Raymarine - Moderator]

HI moki38

Thanks for the feedback,

I will have to follow up with Navionics and our engineering team regarding the Sonarchart live issue and will get back to you
Thanks
Derek

[Derek - Raymarine - Moderator]

Hi moki38

I am advised that SONARCHART live will only function with a waterline offset. This is so that the logs recorded can be correctly updated for time and datre to create correct bathymetric information when synchronised with the Navionics Tidal database.

Regards

[moki38]

Following this knowledge article from Navionics:

https://navionics.secure.force.com/kb/ar...t-Settings

Shows that Sonerchart Live, should work with a keel offset..

The advice is good (Working Sonarchart Live)... but will not fix my problem (Working Sonarchart Live, with Keel offset).

[Derek - Raymarine - Moderator]

Hi moki38

The Navionics article indicates that

"Keel Offset applied - SonarChart Live will ignore the Keel Offset so that the contours drawn more closely reflect the true water depth which is the depth below the transducer plus any tide adjustment". They further indicate that "We do not know the waterline depth setting in this case . . . . is the most true depth we can calculate without knowing waterline offset. This is simply the depth below transducer adjusted for tide."

Basically, this provides for an depth which may not be accurate and so in this case Raymarine have decided not to allow Keel offsets and only allow waterline offsets in order to represent a more accurate depth.

regards

Derek

[moki38]

Thanks Derek for your input so far.

The real question is ofcourse, why does it use the depth sensor at all and not the 3D realvision offset settings for depth? The 3D sensor is offset for below-waterline, shouldn't that be enough?

How do people without a depth sensor do this?

[Derek - Raymarine - Moderator]

Hi moki38

I am not sure what you are getting at?

The Sonarchart live needs a depth transducer to measure the water depth,since end users will randomly add extra depth into a keel offset, Navionics Sonarchart will only use the actual depth below the transducer or the waterline offset, it will ignore any keel offset you enter, so Raymarine only allow for no offset or a waterline offset.

Thanks
Derek

[moki38]

Wait, you are trying to explain to me that for the Sonarchart Live function to work, i don't need a Sonar, but just a depth sensor is enough?

[Derek - Raymarine - Moderator]

Hi moki38

No - not at all! Apologies if I misled you!

Sonarchart live is derived from sonar data from a sonar unit, please consider a standard depth system and display as a separate entity.

The Sonar unit has it's own transducer ( which is really a sophisticated depth transducer) and so it will have its own waterline offset that should be selected.

Does this clarify things?
Thanks
Derek

[moki38]

So, this brings us back to my orginal question. As the Sonar unit (which is really a sophisticated depth transducer :-) ) has its own transducer, with its own waterline offset. It should be able to calculate the current depth, without the need of the depth transducer, right?

Then why does setting the normal depth transducer offset to below keel, change the depth massured on the Sonar transducer? It already had its own (below waterline) offset, but seems to ignore this or gets overwritten with the normal depth transducer offset?