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Towed Camera Sled


(Nathan Perry) #1

Just came across BlueRobotics and this forum! Great things you are doing here.

I noticed some interest in Drop Cameras so I thought I would share my build, and some videos from the past few years.

I started off building an ROV, but changed gears after realizing an ROV was not feasible for what I wanted to do. There were some areas that I wanted to film that were from 300’ to 1200’ deep. With my boat, there was no way I was going to get an ROV down there easily and accurately, so I built a large towed (very slowly) camera sled that holds 2 GoPro’s, multiple life feed cameras, depth and temp sensors, and a ton of LED lighting. I burn through the 30 amp hour battery pack in a little over an hour with all lamps turned on. All of the data is transmitted over RS485 on one pair, and one channel of live video on the other pair in a CAT 3 style cable. I use amsteel blue for the strength member with the cable. The whole sled is about 80 lbs (on land) and I built an electric winch to reel the 1500’ of cable up and down. Its quite the operation to deploy and retrieve, but the video comes out pretty good. Enjoy some of the video clips I have put on youtube: https://www.youtube.com/user/NPerry8051

A lot of what I learned building the first ROV was used in the design of the sled. Really the only difference is the lack of thrusters and neutral buoyancy.

 

Nathan






Configuration / lessons learned from deep dives?
Drop Camera/ Tow Sled Frame
(Richard) #2

Nice work, Nathan. How do you control depth fast enough with a cable reel to keep from collisions with outcroppings? I notice in your videos that you come quite close at times. I have thought of using a sled in my work instead of an ROV, but with limited visibility I don’t think I can keep from having damaging collisions with the bottom structure.

Richard


(Nathan Perry) #3

Thanks Richard,
Avoiding the bottom, and the rocks is purely visual. There are 4 different live video feeds that I can select from. One looking down, forward, aft, and one very wide angle camera at the rear (facing forward) that gets the whole sled and light boom in the frame. Depending on the viz and other conditions I will use the camera that gives the best view. But your right, in really bad viz you can easily run into things if your not paying attention. Around here (So Cal) we usually have at least 10-15’ viz when your down over a couple hundred feet, provided you have the right kind of lighting, and enough of it. In the shallows is a totally different story.

The winch is 1/4 hp and can move the camera at about 2’/second if needed, so I can move it pretty quickly and with a fast response. I also tow pretty slow and watch the depth finder for large obstacles.

All that said, I have run into rocks, and had close calls with lost nets and long line etc… Its all part of the fun =)

Nathan


(Richard) #4

Great project Nathan. I really like the videos. Knowing what I have been through developing my 11 pound ROV, I am impressed with what you have achieved.

Richard


(Rusty) #5

Nathan,

This is incredible. Your videos are amazing - and I can’t believe all that stuff is in SoCal! I’d love to know where some of those videos were taken and go back with an ROV sometime.

Fantastic work. Please keep it up.

-Rusty


(Kevin) #6

Nathan,

Wow, that is some serious equipment and I know it’s not cheap making things up that can go 1500’. What is your motivation for going that deep? Just curiosity or a science application?

I think you really came through with the lighting and the video looks like what comes off of a larger work-class ROV. Well done!

Kevin


(Richard) #7

Nathan,

Are you using any purpose built “planing” surfaces to provide hydrostatic down force or strictly relying on gravity?

Richard


(Nathan Perry) #8

Thanks Rusty!
All of the video I have posted on You Tube is within about 50 miles of my home port in Santa Barbara. Mostly at and around the channel islands. If you ever make your way up here let me know, I can point you to some good areas, or possibly take you out there. My boat is a pretty good platform for this kind of work.
Nathan


(Nathan Perry) #9

Hi Kevin,
No real science here, just pure exploration and curiosity. I started off with a handful of targets in this area that I wanted to understand better (like what are they?) and the camera project grew from there. 1500’ was just a starting point based on cost, and what I already knew about cable winches and driving video over long runs, etc. There are also many complications you run into while dragging that much cable with a big heavy object attached to the end =)
Nathan


(Nathan Perry) #10

Richard,
Currently the camera only uses gravity. It weighs about 80lbs in air, and maybe 25-30 in water (that’s a guess).
The next version of this camera will be somewhat lighter and smaller (so that I can hopefully deploy it without using the davit to lift it over the side) and will probably use some type of a ‘plane’ that will be used to provide downforce, and also to dampen the up/down movement exerted by the boat. I currently use about 20’ of rubber cord inline to isolate the boats movement from the camera and that makes all the difference in the world, but the addition of a wing should improve the stability/smoothness even more. I am thinking of a wing that can be deployed once at depth, and retracted when bringing the camera up. I am checking out the Blue Robotics brushless motors for this task. With a little gear reduction they may do the trick.
Nathan