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USBL Systems Comparison

We are planning navigation for a BR2 used on a small rescue vessel (15m).
After looking at both Water Linked and SeaTrac (X010) they looks to be almost identical in price. Do any have some user experience or inputs?

The Water Linked system looks to be a bit more fragile with the antenna and only cover 180 degrees?

Using Waterlinked without proper GPS antenna on a small vessel is something we wouldn’t recommend. It looks promising only in marketing video. :joy:

I use Waterlinked systems in several setups.
Separate GPS compass for position and heading is recommended.
WL System works 360 degrees around the boat with correct receiver placement, ie free “sight” from all receivers to the transducer on ROV.

I would not go for the WL antenna, but separate receivers.
For each receiver I have a pipe mounted on the boats, some boats permanent, some temporary.
The pipes are 20mm dia so the receivers is telescopic inside pipe.
Apart from sheltered mounting and easy deployment, you also get more distance in the LBL polygon, giving more precision.
I use one receiver in the bow, and one on each aft corner = 3 receivers.

Hi Morten,

I have the same recommandations than Bo Koppel for the WL system. I have tried both Seatrac and WL. I would say the Seatrac is a classic USBL that is easier to install on one pole and required only an external RTK GPS for accurate positionning. I would recommend it if you plan on using it in deeper than 20m WD and choppy waters. The WL which is a SBL system is more stable in very shallow and noise challenging environments (port, breakwater etc) but does not work very well in open seas (no IMU in the hydrophones, VOS configurable only in the 300m version). It also requires a setup harder to install with cables running everywhere on the deck and several poles in the water + a mandatory external compass (the internal one does not work well) & RTK GPS.
So it really depends on what you want to do with it.

Thanks for a great answer! For the rescue vessel the ROV operations will mostly be in ports (hull inspection) and survey in narrow waters so that points a bit towards WL. BUT lots of cables on deck in addition to the ROV and other deck work combined with several poles on the small ship is not favourable. Looks like it might be best to go for the Seatrac for this purpose? Or is it any other systems that might should be looked into?

Hi Morten,

I have not tried the Seatrac for hull survey, you might get some acoustic jumps but it is worth a try, you can still rent it from BluePrint or a reseller to test before you buy it. The best solution for sure would be to combine it with a DVL to get a full INS if you have the budget for it.
For my company we are currently integrating the WL system on a USV (can be a buoy as well if it stays fixed) with a wireless connection to the survey vessel so that we have our WL setup separated with fixed offsets and no more cables/poles etc. The USV will also track the ROV so that we always have the smallest distance between both to improve accuracy. We should release it in a couple of months though in order to run all the tests, not before.

Hi Morten

Take a look at…ROV Locator from ceruleansonar.

Sonar: ROV Locator – ceruleansonar

Best Regards


Looking at adding a positioning system to our unit, between the Cerulean and Waterlinked, what are peoples experience with the units? Cerulean seems most appealing for cost and only needing the single receiver in the water
Do you use both the doppler and the locator at the same time with the Cerulean or are they separate units? I feel like the doppler option would be the least efficient/ accurate?
Any other suggestions for different systems?

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Hey Aaron,

I’m running both the Cerulean Sonar USBL Locator, and the DVL(GPS disciplined). The Cerulean Tracker app does a great job of taking both data streams and passes them through a Kalman filter to output a ‘smoothed’ location. In my experience, running theses for over a year or so, the DVL is my go-to. It requires little-to-no calibration, and is accurate enough for me to find targets of known GPS co-ordinates. As long as the ROV stays up off of sea floor (Min altitude is around 30 cm). The USBL, I find works best when used from a boat. I find it a bit finicky when I hang the receiver over the side of a wharf. Probably too many reflections off of the wall? But from a bout, it functions quite well.

The Locator and the DVL are two independent systems, and can be operated on their own.

The key take away, is how awesome it is to see the ROV location/track on the screen when piloting! Also the feature of placing a waypoint on the screen, and piloting straight to it. Once in the area, I use the Ping3D to guide to actual target!

These are great, cost effect tools for this segment. Thanks to BlueRobotics, and Cerulean Sonar!


It is worth mentioning that a purchase of both the Cerulean DVL-75 and the ROV Locator is still more cost-effective than the cost of our closest DVL (only) competitor. :wink: