Saturday, November 6, 2010

I Love my Sonar

It is true. This summer, and especially fall, the Blueview sonar and I have developed what I think is a special relationship. Like any good relationship, it is based on open communication and always telling the truth.

The Blueview sonar, for those of you not yet lucky enough to witness, is a digital imaging sonar that is mounted on the VideoRay ROV (see photo to the right, the Blueview sonar is under the front dome/lights). It is integrated into the system so it uses the same tether as the ROV and tells me everything that is ahead of the ROV for around 100' and a 45 degree field of view. The images, when used correctly, come out incredibly clear and the information they give invaluable. Being able to see so far ahead, even when the best I can get out of the video camera is 2' or less (Charles River), means I have a chance of avoiding obstacles (trees with lots of twisted branches waiting to grab the ROV), navigating successfully (knowing that there are pilings under a dock so I can avoid weaving the tether in and out of them) and most importantly, finding and identifying marine debris.

One of the biggest marine debris problems on the East Coast is derelict fishing gear, especially lobster traps. They get disconnectedfor a variety of reasons from storms and big weather to boaters (props, rudders, etc.). The problem with a disconnected trap is that it can keep on fishing. That means that animals are dying for no reason, they will not live to reproduce and they will not end up on your plate (see photo right, a crab is stuck in a derelict trap). They are also clogging up the sea floor habitats and can be a everything from a nuisance to dangerous to boaters (catching anchors to fouling props/rudders, etc. if too shallow).

A few weeks ago, at the end of October, we went out for one last debris s
urvey with the equipment. This time the venue was Sail Newport an incredibly busy, diverse and successful community sailing organization in Fort Adams, Newport, RI. It is in Breton Cove which even the charts show as heavily trafficked and the users range from the 8 year olds in Optimists to some of the biggest and most beautiful sailboats I have seen to the modern and incredibly cool foiling Moths to working fishermen. I was very eager to get the gear in the water and have a look at the bottom. There is also a relatively strong current in this area which can mean trash is taken away on each ebb tide.

Just throwing the ROV off the dock showed that even the strongest ebb tide was no match for the volume of beer cans we found. Both the video camera and the Blueview showed multiple targets (mostly cans) which we easily discovered just flying around. And then, just as I expected the Blueview fulfilled its mission. In vibrant orange on black, 30' from the ROV (27' farther than we could see with the camera), we found our first trap. And from there, they kept on coming. I knew that the gear we had would be excellent for finding DFG (derelict fishing gear) but the clarity and detail was a welcome confirmation. Above image shows the detail we get on the sonar viewer. That is a lobster trap and you can even see its line lying on the sea floor to the left of the trap.

Since this discovery, I have been hard at work planning the Trash Tour for next summer (more on that in another post) and am very excited that we will be going back to Sail Newport to rev up the VideoRay and Blueview, add the Starfish sonar (for an even bigger sonar picture of the bottom) and get that trash out of the water.

I have to say, I have found it very exciting to see the gear working as promised and even better to know it will help us fulfill our mission: to find and remove marine debris.

More soon.

Think snow (summer is over so bring it on),


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