Frequently Asked Questions for ROVs
Rachel Doornekamp | December 4, 2019
At Deep Trekker we pride ourselves on being at the forefront of innovation and technology. Throughout the years our cutting-edge Remotely Operated Vehicles (ROVs) have inspired many questions. We sat down with ROV expert Cody Warner to answer the most frequently asked questions he’s heard while out in the field.
How deep do the ROVs go?
How long of a tether can I get?
Our base packages come with between 50m (164ft) and 200m (656ft) of tether however there are options available up to 800m (2624ft). The tether reel that comes with the Smart, Expert and Navigator packages accommodates up to 200m and still fits in the carrying case with your ROV. For longer tethers, we provide a slightly larger reel that goes into a separate carrying case.
How strong is the tether?
Rated for 150kg(300lbs), the tether is very strong. In fact, the best method for retrieving and deploying the ROV is by the tether.
How much current can the ROV handle?
This is a common question, however the answer isn’t as simple as just a number or a spec. The answer depends on the application. In general, ROV inspections and surveys can be broken down into two main categories; swimming to a single point or doing a thorough evaluation of an entire area.
When swimming to a single location, an ROV is able to take on more current because the flight path it takes to get there does not matter - as long as it gets to the target. There are tools to help guide you, such as USBL Positioning Systems, Imaging Sonars or even Heading and Depth Sensors, but a DTG3 ROV can fight through up to 2 knot currents and get to a target. The Revolution can fight through up to 3 knot currents.
When performing a thorough survey, the DTG3 has Active Yaw Stabilization, Auto Heading and Auto Depth functionality that help it keep its course and stay on a steady path, however without the vectored thrusters that are featured on the Revolution, you are best to perform surveys with the DTG3 at slack tide, in 0.5 knot to 1 knot currents. With its vectored thrusters and greater power, the Revolution is able to fight against current in any direction and perform thorough evaluations in up to 2 knot currents.
It is important to note that the amount of tether deployed makes an impact on the ROVs ability to fight current. The more tether deployed, the more surface area for water to drag the ROV. Deep Trekker’s battery powered ROVs require thinner diameter (4.5mm) instead of topside powered tether that often is double the size or more, which is beneficial as the drag effect increases exponentially with thicker tethers.
The DTG3 is most effective when it has deployed less than 300m of tether. If over 300m, it is best practice to operate in lower currents. The Revolution is very capable with the tether deployed even up to the 800m amount.
How long do the batteries last?
The DTG3 and Revolution ROVs last for up to 6 hours on a single charge. The DTG3 can be trickle charged during operation by plugging the controller into a standard 110-240 VAC outlet.
The Revolution, while it cannot be trickle charged, the batteries on the ROV are swappable so they can be interchanged with the spare set within a minute and return to operation immediately.
Rated for 1000 charge cycles, our Lithium Ion batteries are extremely durable and long lasting. At the end of the batteries’ operational life, they can be replaced. We are happy to either perform the replacement for you or send you technical guides to help you do it yourself.
How do the ROVs perform in murky water?
The camera will see as well as the human eye in that if the water is extremely murky, it is not going to see “through” the murkiness. However, if you are navigating to a single point, you can still get close to the object and get a look even in murky water. Using heading and depth sensors from your point of operation will allow you to navigate to a propeller of a ship, a dam intake, or other spot that you want to check, even without having good visibility while navigating to the target.
The best way to see through murky water is by using an Imaging Sonar. Sonars can help with getting a visual through murky water. Sonars are not going to find small defects or details that you would identify with a camera, but will give you better situational awareness. This is particularly important in open water applications, where there is a lack of visual cues. In confined spaces, you often have several structures or other visual cues that indicate where you are (a wall, a column, a piling, etc.) Having an imaging sonar as well as a USBL positioning system is extremely helpful for understanding where you are, where you are going and what you are looking at.
How much lighting is on the ROVs?
The DTG3 comes standard with 1000 lumens that track with the camera, wherever it swings. The camera can rotate 270 degrees, allowing you to look straight up, straight down and everything in between.
In confined spaces or greater depths, additional lighting is recommended for getting the best quality picture. The Auxiliary Lights option (included in Expert and Navigator packages) adds an additional 1000 lumens of brightness. The External Floodlights, usually added for professional film crews, adds another 3400 lumens of light to the ROV.
The Revolution is equipped with LED floodlights that track with the rotating camera head as well as additional lights at the front of the interchangeable batteries. This lighting totals 8,400 lumens.
How do I record the video from my ROV?
The DTG3 and Revolution both come with controllers that have micro SD ports. Simply insert the micro SD card into the controller and use either the snapshot or record buttons on the side of the controller to begin recording. When you are finished, take out the micro SD card, insert it into a regular SD card, and upload it to a computer or laptop.
Can I view the video on a larger screen?
The ROV’s handheld controller comes equipped with a 7” LCD display. The high definition and bright display offers a portable yet high quality viewing experience for one operator. There are times however, when you may want a larger monitor to display video to a group of viewers. The handheld controller comes equipped with an HDMI out port, along with Ethernet, SD and USB ports. This allows you the flexibility of connecting to other devices. Alternatively, the ROV records video and photos to an SD card. The SD card can be easily removed and then connected to other devices for viewing.
Why does the ROV have a wire?
Many signals that work through air do not work underwater. GPS, Wi-Fi, Bluetooth, etc. do not transmit through water. In order to have live video feed and control over a vehicle underwater, you need a tether.