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LAMP Hosts ROV Launch

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This past Friday LAMP deployed a new instrument to recover data from the 1764 shipwreck of the Industry.

Loading in the Nickerin early Friday morning on the 8th of August, LAMP volunteer Mike Gates, Lighthouse employee and LAMP volunteer Shaymal (Sam) Patel and LAMP archaeologist Brendan Burke were setting out to reconnoiter the 18th century wreck using some whizbang technology. Using a remotely operated vehicle (ROV) designed and built by Sam we attempted to record video footage of the sea floor with intact wreckage.

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On the way out we cruised by this beautiful Danish-built sailboat in the middle of its rebuild. Peter Grundvig, of Grundvig Woodworks, is the proud owner and restorer of this classic and historic hull.

As mentioned the ROV is Patel’s own design and is made from a mixture of PVC pipe, bilge venting blower fans that have been waterproofed, underwater halogen lights, a submersible video camera, and assorted electronic control components. The control box is made from a cigar box with holes cut to allow switches to protrude from the top. An umbilical cable is made from bundled wire which handles the 24 volt power supply to the motors and lights, plus the coaxial video cable. All in all, it’s a very sleek package compared to some of our other remote sensing systems.

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Here is the control box along with the laptop used to capture and control the video feed. Sam was very flattering when he applied the LAMP sticker to his creation.

This particular ROV is version 2.0 of Sam’s original model and has the ability to swim vertically as well as horizontally, illuminate its path with two powerful halogen lights, and record its progress with the compact video capabilities. Friday’s trip was the maiden voyage for the ROV in open waters as well as a depth test since it had never traveled to the moderate pressures at two atmospheres (electric motors hate salt water intrusion)

We took LAMP’s vessel Nickerin out to the Industry site and buoyed the site with a marker ball to pinpoint the wreck location. The coordinates used were recently refined by cross checking them to sonar imagery recovered in July. Next we dropped anchor and drifted back down on the site so the boat hovered directly over the wreckage. The Industry site was chosen particularly for its profile characteristics. Other wreck sites we have worked with such as the Centerboard Schooner Wreck and the Steamship Wreck have wreckage standing proud off of the sea floor which, while interesting to look at and study, create snag hazards for a trial run with an ROV. The machine moves using water thrusters created from four bilge blower motors that Sam waterproofed for marine usage. Despite being built to move air, they move water at a pretty good clip and two are used for each plane of travel. Thus, two motors in the forward position can move the ROV forward, if you reverse one while keeping the other in forward then the machine spins on its axis. The same is true of the vertical thrusters and this feature allows you to control the pitch and yaw of the machine.

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Note the blue thruster motors in the center of the vessel. The two blue cans flanking the yellow video camera is the halogen array.

Upon arrival at the site we had noticed that the seas were not as clear as could be. Trying to avoid afternoon thunderstorms we were subjected to tidal conditions which were not optimal. Low tide that morning was right about 8:30 and so the muddy river water had been flushed to sea with the outgoing tide to create a ‘blanket’ of turbid water around and near the St. Augustine inlet. Thinking that the lights on the ROV may help to overcome this we began a launch sequence. This entailed performing a deck test of all circuits while onboard the boat and then putting the ROV in the water and performing the same test again to ensure its waterproof integrity and check its buoyancy. We had to add a couple small weights to the ROV body to counteract its use in salt water since it was designed and tested in fresh water. Salt water imparts greater buoyancy to objects floating in it due to its increased density, thus the ROV needed additional weight to make it neutrally buoyant.

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Sam launching the fish.

The fish was ready to go down. I use the term ‘fish’ endearingly for all remote sensing instrumentation we put in the water, the terms ‘towfish’ and ‘fish’ being interchangeable. We placed it right over the downline on the buoy and after accounting for the angle of the downline, began to swim the fish downward. The video was up and running and the halogen lights ablaze. At first we really didn’t expect to see much since there wasn’t anything to see except the downline, which the camera picked up a couple of times to help verify out position.

The ROV doesn’t have a depth sensor and so we had to rely on the amount of umbilical payed out to approximate our depth. One person was assigned to tend this cable to make sure it didn’t snag on the boat engine or too much cable was let out and was acting as a vane in any water currents. The ROV also doesn’t have a navigational suite installed to provide the user with a compass heading to help direct the fish or be able to monitor the attitude and yaw of the fish to help direct the camera angle. Unfortunately, had the water been clear then we would have been able to overcome these obstacles by ‘flying’ (a term used by ROV operators who use joysticks or switches to remotely fly their machines) the ROV around the wreck area in a search pattern. We knew the seafloor had been reached after a while when enough cable was out and the fish was taking no more. We also knew it because the visibility, while extremely limited on the way down had gone to zero when the ROV hit the seafloor and the thrusters created a cloud of sediments.

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ROVs can be very complex, as is this one pictured here. Capabilities include biological or minerological sampling, underwater repair such as welding and cutting, materials handling, and pipeline inspection. (Image courtesy of Wikipedia.com)


We stopped all thrusters with the hopes that the sediments would clear and we would be able to identify the sea floor. However, it appeared that there was a sufficient ground swell that was either moving the ROV back and forth across the sea floor or else it was swirling around the base of the ROV and creating a cloud of sediments that would never settle. I knew from prior experience scuba diving on the wreck that with the exception of the rare day of good water clarity a cloud of sediment commonly hovers over the wreck. This is caused by ground swell raising the muddy deposits held by the wreck structure which accumulate in the shallow scoured-out area around the cannons and other wreckage debris. This commonly occurs around wreck sites since they can cause changes in water flow and trap loose particles suspended in the water column, often precipitating their buildup around the base of the wreck. Our fish was in this cloudy haze and we needed to re-position the fish and try again.

All thrusters were put in the ‘up’ position and soon the yellow mechanism was bobbing on the surface right by the boat. We double checked the buoyancy and re-deployed it right over the wreck site. This time we let the fish descend very slowly so it would, with any luck, settle gently onto the wreck site and provide and image of some part of the wreck from which we could gain our position and navigate the wreckage based on our knowledge of how things are situated in relation to the cannons.

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This ROV was used by a partnership between the PAST Foundation and a group of partners to identify and recover imagery of the 1941 wreck of the gasoline tanker Virginia, sunk by Nazi submarine U-507. (Image courtesy of www.pastfoundation.org)

A third attempt was made and with similar results. We were never able to see anything firm on the video and so we decided to wait for a better day with better conditions. The waves had built so the boat was a little unstable, causing some of its passengers to take on a greenish cast. Moving to Salt Run and its peaceful waters, it was decided that we should examine the ROV’s maneuverability in a non-pool setting while being able to observe it. Beaching the boat on Conch Island we put the ROV in the water and ran a series of maneuvering tests on it to ascertain its strengths and weaknesses. It was determined that the port horizontal thruster was slightly more powerful than the starboard thruster and it caused the ROV to swim in a broad circular manner, not in a straight line. It was also discovered that the thrusters were a little underpowered given the wave and current conditions. In placid water the ROV is able to maneuver deftly and with agility but once the rocking motion of a rolling surf and ground swell are introduced and compounded with the drag and sail-like effect of the umbilical, the ROV becomes unwieldy and unreliable in its accuracy of position. For a final test we took the ROV back to the boat launch dock for some testing at depth. I got into the water with the ROV and observed it as it descended and maneuvered. Just our luck though, dredging around the boat ramp had been going on that morning which reduced visibility to about two or three inches. With that sort of limited visibility we needed an acoustic wave like sonar, not a light wave. This was finally figured out when we turned off the halogen lights. Although they had certainly not prevented us from seeing anything, with all of the suspended particles in the water, the strong halogen beam had been reflected by the particles ending up with a condition known as backscatter. This is like trying to shine a flashlight through a maze of mirrors. Some of the light will get through to the target but you can’t see it because of the blinding reflection from all of the mirrors. The particles in the water act as those mirrors and were in effect, blinding the video camera to a degree.

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Testing and analyzing the ROV in Salt Run.

All in all, we learned a great deal about this prototypic machine. Sam is extremely talented and has built a very nice machine. With more field testing like Friday, he will be able to develop and mature the ROV into a very useful tool. Thank you Sam and I certainly look forward to going out again with some clearer water!

Comments (1)

Great job, Sam (Patel)!

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