Hey blue folks!
You know we’re always out here trying to share information, so we’re back with another comparison chart, and we’re not just scratching the SURFACE 
This time around we are comparing all the details of the small USVs on the market, but we need your help! As usual, prices are difficult to find so if you have information on any of these vehicles, please share so we can add it to our ever-evolving resource!
If it was me creating a rating system. If the unit has a RTKGPS and what brand/accuracy would be it own rating system. The Bathylogger system seem to be the cheapest system with rtkgps. Sorry but you cant say the $5000 Blue robotics is higher rated then $20000 Bathylogger when the gps system accuracy isnt comparable.
Also its no use producing data if its outside your +/- because in the analysis stage this is amplified.
Also a cost of payloads would be great.
Most USV use Hydromagic to log bathymetry data.
This requires a costly subscription.
These addition costs would help the buyer.
I’m the process of building a bathymetry logger that I designed with echo sounded and any RTKGPS that transmits NMEA over usb. Just to keep the budget down.
It also will do a few extra things to increase accuracy of the echosounder.
Hi @cmhopper88
Thanks for the feedback! While it’s true that the BlueBoat does not come with rtkGPS by default, it is possible for a user to install, and we’re working on an upgrade kit product. A rating system will inherently assign weights to things that varying customers/applications may value differently - this compilation tries to stick to the facts rather than provide potentially biased interpretations.
I’m always curious to understand what sorts of applications benefit from the difference in position between a high performance GPS, with an HDOP (horizontal degree of precision) of 0.5 to 0.8 meters, and an RTK GPS with HDOP of 0.03 to 0.1 meters. In the context of a small USV, the potential error sources from the more violent motion of a small platform (and the inertial sensors used to compensate for it), and the dynamic nature of the ocean phenomenon themselves (like bathymetry, plumes, or acoustic monitoring) would seem to make the difference in precision of minimal importance?
Also its no use producing data if its outside your +/- because in the analysis stage this is amplified.
I’m not quite sure I understand what you mean here?
While it is possible to use the BlueBoat with Hydromagic and other dedicated software, it’s possible to produce very similar results without too much additional hassle using free and open source software - albeit with survey planning happening in a different application than the map creation (QGround control and QGIS.) I’d be curious if such an approach has any (other) drawbacks from your perspective?
I do agree that listing costs of common hydrographic survey software would be a useful comparison, if not as a part of this info compilation perhaps its own dedicated one!
You can of course find the cost of our BlueBoat payloads easily, but similar to ROVs and USVs, many such prices are tough to track down, can change based on the customer / configuration / lead time quoted - especially for payloads vs. vehicles!
+Anything to do with hydrology modelling in rivers or estuaries needs highly accurate bathymetry. I’m working on researching the other stuff.
Hi @cmhopper88 -
Understood - my point is that the bathymetry one day may not match the bathymetry the next, as those river systems dynamically shift sediment around!
Single beam sonars are inherently a coarse measurement, with a 20 to 30 degree conical beam (25 degree for the Ping2.) Thus, depending on water depth an average measurement of a circular patch depth is created - this is a much larger area than the GPS precision, especially at greater measurement distances!
Is there a way to narrow the beam with python script or is it based on the hz rate?
bl700 is 9 deg and kogger sonar enhanced 10 deg (out of stock)
Datasets for sediment transport models are exactly what you are looking for.
I’m voluntarily studying a creek at the moment in north Queensland. I can pole out the delta with RTKGPS on low tide (low outflow).
I can not enter the creek because there is a 2.5m crocodile in the murky water and that’s the one I know about.
When the creek was lidar scanned on mean tide the lidar did not see through the turbid water.
There is no use running a fine mesh 2d hydrologic model with not understanding of bottom bathymetry.
Beam width depends quite significantly on the transducer’s transmit frequency, so to have control over the beam width you would need a sonar that supports a range of operating frequencies, and allows you to specify which frequency to use. That’s not a functionality our Ping Sonar devices support, partly because the transducer is tuned to a specific frequency, so runs less efficiently when it tries to transmit at a different frequency, and is less effective at receiving the corresponding echoes.
It may be possible to do some intelligent processing of the response strength profile data for overlapping pings, to determine higher effective resolution data from the combined responses (as is done in synthetic-aperture sonar), but that’s not a functionality we’ve developed and doesn’t seem to be commonly available.
So in 3m of water my calculations say 1.2m diameter scan area. Does the sonar find the mean of this area or how does it function?
Hi @cmhopper88 -
That’s correct, in 3m of water you’re measuring about 1.2 meter diameter circle. The measurement is the approximate average depth of this region, but if one part of the region was more reflective it may contribute to the depth measurement more than other regions within the circle. The Ping2 sonar provides a confidence % value that reflects the quality, you can read more about that here.
I can’t view the doc in my browser. Can’t download either.
OOPS, got it now. Another source is Ocean News July 2024…ONT July 2024 UVBG Page 16
Thanks @bajaMike -
That link does not include prices! If anyone has that information, we’d be happy to add the only USVw listed in the resource, the ARCboat / ARCboat Lite to our comparison.