Trident Search and Rescue water with low visability?


My name is Roger and I work with the Firedept. in Eskilstuna in Sweden. A few weeks ago a young boy drowned in our county in pretty shallow water (about 5 meters). To make our SAR operations more efficient next time we are perhaps going to buy a Trident openROV. All of the videos that I have seen looks great but I haven´t seen any videos when using it in low visability water. Any tips on where I could get samples of that? Will the 6 led´s (right next to the camera) improve the visability or make it worse? Is it possible to increase or decrease the strenght of the leds from the surface via the application? Is there any way to know exact position of the trident when finding something?
Roger in Sweden


Interested in any replies to Roger’s questions as well, visibility in waters around Hong Kong is usually quite limited.


Hey @roger.ehrstedt and @keenmetal,

From our experience, a key factor in visually navigating in low visibility water is the ability to fly very close to the bottom. Basically, the lower the visibility, the closer to the ground one should fly. Trident is designed to fly in transects (long straight lines) and can pitch up and down to follow the contour of ground it’s surveying. These two abilities should help with flying low enough to see while still keeping the ROV off the bottom. Most Trident testing we’ve done so far has been in relatively clear water since we’re trying to learn about its physical performance and want good visibility for that, but it should do well with “lawn mower” search patterns flying very close to the bottom as I’ve described. Lights can help when the area you are looking around in is poorly illuminated from bad water clarity, but they don’t generally help that much with allowing the camera to see further through turbidity. On Trident, the lights are mounted as far to each side as possible and slightly forward of the camera in order to reduce bounce-back on suspended particles, and we hope to come out with extremely bright external lights as an accessory after we’ve started shipping.

In case it’s helpful, here are some videos I found of OpenROVs being used in medium to low visibility situations:



In low visibility search and rescue I have found the fastest. Method to search
And locate drowning victims, is sonar, I personally use and recommend the
Starfish sonar system, many Rov manufacturers offer sonar systems for use on Rovs. In my experience trained cadaver dogs are just as efficient but not always available. Sonar systems are affordable enough for police, and fire teams. These systems have improved remarkablely in the last decade.
The starfish brand is available for around three thousand u.s. And can be deployed in under a minute. When it comes to black water sonar can out perform a diver search every time. In golden hour cases a few thousand spent
On sonar in advance can save a life. Another fast option to locate victims
Quickly is bottom topography video systems, they are however very costly.
Also when hunting drowning victims remember they are usually straight down
From where they went under unless there is strong currents. In moving water
Always factor in for the victims weights, build, body fat index, and clothing.
In child cases diapers or rubber pants can act as floatation and let the body travel further. I allways kept a green laser sight on hand so if there was a witness at the seen they could point the laser to pinpoint the exact site the person was last seen on the surface. What one person thinks is 100 feet
Another person would guess to be 60 feet from shore. Having a hundred
Dollar laser light can take out a lot of the guess work. Don’t use the red lasers they are not very visible in the day light. The green ones however can be seen
In daylight the unit I use is water proof, submersible and available on eBay.
Ty Grabowski Uwcsi, USCG retired


Hi and thanx for the tips! I thought the sonar would be more expensive. Is there any special starfish model you would recommend. Is the image hard to “interpret” for the average user?

The idea with the laser is also great but unfortunately the green lasers are not allowed here in Sweden, not even for us. Just out of curiosity,which laser do you have?


Sounds really interesting and thanx for the video samples. I must say it is truely an interesting device you´ve got there. One thing that im a bit worried about is how vulnerable the propellers are to get tangled in seaweed in these conditions?


Trident would be good in SAR but just as a recovery tool. Also as a search tool to aid police divers.

The clarity of the videos isnt too bad, but I have to agree that Trident/OpenROV would not be suitable for people who have just gone under. Remember, you have the time it takes for the emergency call to be made, your response time, set up time. It all adds up. How long can you hold your breath?


This is a great thread! I agree with @TY_GRABOWSKI_UWCSI about sonar. If you can afford it, a side scan system is a much more powerful tool for finding objects in large areas with murky water. As long as your target is shallower than around 40m, I would also agree that Starfish offers the best capability at a low cost. For SAR, you’ll probably need a higher-frequency version (something above 600 kHz) because lower frequency sonars may not have good enough resolution to spot a body. I’d recommend the Starfish 990F. It’s a bit gloomy to look at these, but if you do a google image search for “side scan search and recovery” you’ll be able to get a sense of what you’d see with the sonar. We’ve also been working on a concept for mounting a sidescan system onto Trident as an accessory, but that is still a ways away since our priority right now is getting Trident out the door on time.

@vidroneuk is also completely correct that Trident (or any ROV) is not likely to be useful for rescue operations as those must be done within minutes of an incident happening. That being said, developing the technology to the point where an ROV could be used to retrieve someone that quickly is something that I am personally very interested in and would really like to pursue.


Hi again!
Today I was together with a neighbor firedepartment and the policedept on a search/recoverymission to check their ROV (a VideoRay). I told them about our thoughts of buying the Starfish sidescan sonar but they told us a sonar looking forward would fit our purpose better. Gemini 720is mounted on a pole was one example (but very expensive) Does anyone have any other ideas on forward looking models (good ones but perhaps cheaper)
ps I know I´m perhaps a bit of topic but I hope you excuse me ds