Building an Underwater self propelled detector

Peg Leg, if thats all the depth and in fairly calm inside waters, why dont you just get a Whites Surfmaster PI Pro, which will automaticly ground ballance, and comes with quite a bit of cord, and is completly waterproof. Then get a piece of PVC and extend the coil out(down) much further. Then get a rubber raft or something like that a canoe-not aluminum,anything to float you around. Then just go over the area and check for sounds. When you get something, stick a marker like a float with a weight or a thin PVC sticking up. One of those PIs will go quite a ways on a large object, but with the supplied amount of wire you could stick it on the bottom at all tides. And still have the ear muffs on and be dry. But remember, aluminum cans last forever, and there are millions of them stuck in the mud. You should be able to find something big by just pulling it up to say if its small or large. I do that for rings and stuff, but I did it all. I can at least tell if its small or real big. Out of the water (air test) it will go 6' or more on a metal trash can lid. In salt water it will go even further, so you should be good. I dug an anchor(just a small 2' rusty modern anchor,)out of a beach that was 4'+ feet down. It was funny, I started to dig the day before and got a huge hit even before I got to the area, and a guy with Minelab Excaliber 1000 gotnot a beep. He thought I was crazy. I came back the next day and dug up the anchor with a shovel. I know I got off track, but it should be a lot easier and quicker that way. What are you going to do when you get a big hit? If you need a diver let me know, Steve.
 

I meant dig it all.
 

Timeline,
I must say that the ROV you show is very good and gives me more ideas. I would never have thought of using PVC tubing for the unit frame work.
To keep the device on the bottom you could pack the tubes with sand. The placing of the lights is also a great idea.
What is the stuff in the middle?
Peg Leg
 

Hey Peg leg

That is not my ROV, (wish it was). This is really a Yahoo group. You need to register and login. There is a wealth of information in the database (over 30000 messages). There are several files and photos of all kind of ROV that are being built. Mine is a square, has a camera, and has a 100-foot umbilical cable.
I read all the stories here and only dream of diving in the ocean. My spot of the world is the lakes of northern Indiana. I figure this is the last frontier for finding treasure and keeping it. It may be cannon, Al Capone boat, or a covered wagon that fell into the lake when it was crossing in the winter. I have been diving since I was 16. Only made it to the ocean once to dive. A few other times I was just checking the shorelines. Not many predators in the lake would hurt one. The main ones are the boats and skidoos.
Most of those 31 years I just look and felt in the muck for thing, mostly bottles. Got me a Fishers Pulse 8x about 5 years ago. Man was that ever a dream come true. Haven’t found much. Only get to go on weekend. Got a job, wife, and three kids. Started building the ROV at the beginning of the summer. Almost done, just need to check that my camera is sealed and then it time to put it in the bathtub to work on the ballasts. I figure I’ll spend a lot of time in the fall winter and spring locating things and then dive down to them to do further investigation in the warmer months.
Lot of advantage diving in the lakes, no mean sea creatures, no current, some things get well preserved in the muck, salt is not a factor, untouched in the deeper water (most of the metal detector only go as deep as there chest), not to many people interested in salvage, most divers want clear water and dive to object put down there by divers to dive to. Lot of disadvantage, probably won’t find any Spanish gold (maybe some gold coins), water visibility is from zero to 3 ft most of the time, a lot of muck, branches and beer cans, may find a few things I don’t want to find, boats always getting to close just see what going on.

timeline
 

Timeline, have you considered pulling a side scan sonar around the lake to locate the wrecks? I'm diggin the ROV forum and all the cool ideas over there. I bought the little Humminbird 987C SI Side Imaging Fish finder for $1,600 on Ebay and it works very well. Might save you some time by finding things and marking the GPS coords for you, then you could return to the spot and send down the ROV to see if it's worth diving on or not. It's a thought anyways...you'll probably see me asking questions on the ROV forum as soon as I learn enough to ask them :D

Jason
 

Jason, I have thought about getting one of these Hummingbirds too. I would love to check one out in action, but still have not even seen one mounted yet. If you ever get down near Sarasota, West Coast Florida, stop in. Yes I know you are working a wreck on the other side, but you probably didnt bring your boat right? How do you like your Hummingbird? I may have asked last year, I think someone said they had one. Steve.
 

Steve, I think one of the Robert's has one (Robert in N.C. or Rgecy, can't remember) that we discussed a while back. That was what prompted me to try tone. I got the transom mount version, and am in the process of building a towfish for it and extending the cable. Humminbird was a little tricky to get info out of...they kept saying "you want to do WHAT?" :D On the lakes around here I get very little distortion from the pitching and rolling of the boat, but I'm not sure what the images would look like on Atalantic or Gulf waters. I like mine quite a bit, very good images for the money! It's on my uncle's boat right now, we are going out to look for a fire boat that went down in an area lake several years ago. Once we locate it and get some eqwuipment brought up for the local fire department, I can tear into it and start the conversion.

I wouldn't hesitate to buy another one, it's neat even on Texas lakes and the resolution is better than I expected based on the price and its intended use.

Jason
 

Very interested in the towfish-would take the rolling and moving out some. Keep me informed, Thanks, Steve.
 

HI Cornelius, Excellent idea, I would suggest that the attacment of the rigging be located in such a manner so that any upward pull wuld be at right angle to the center of mass on the disc. othewise it would merely tilt the disc to point of min resitance.

Tropical Tramp
 

Thanks Cornelius, I was planning a 100 foot cable because I thought it would take "most" of the pitch out...with a long cable and a version of your pitch eliminator, I bet I could get pretty close to no movement at all. Thank you kind sir.
 

Jason, apparently the Hummingbird company said with the supplied cable not to go over 30' in length for an extension over stock, because of image and sensitivity degradation. Probably because of thin wire. But I have found some people have gone up to 90' of just stock extensions(30'), and had no problem. So I would get another cable and transducer( save one for you transom mount) and extend it with heavier wire size, same type though, just thicker conductor, same shielding etc. I extended my underwater tow behind video camera (Sea View)that way. I just brought the cable - with the insulation cut away, to the electronics store. He fixed me up with a cable and shrink wrap, the low temp solder etc, and I did it myself. Works like a charm. I used to be a boat rigger and had to solder the ends on transducer cables after pulling the cables through the boat and up towers etc. Piece of cake if you can solder small wires and keep it clean and insulated. On my UW video camera I used 3M 5200 in the cable, smeared it on the shrink wrap where the splice was(the individual wires were soldered and shrink wrapped too) and let it dry. This was about 6" long and I smoothed it out. Then I slid a shrink wrap over and shrunk the whole thing. I have towed it and no problem. I also extended my 3' x 5' coil cable out 125 feet with co-axial TV cable, no problem there either.
 

Thanks Steve...I've had a soldering iron in my hand since I was 14 years old, this will be nothing new. I'm talking to hummingbird about putting a small repeater inline inside the towfish to boost the transducer signal up a touch to cover the longer and heavier gauge cable.

Do you tow by the cable alone, or do you also some steel cable for added strength? I'm planning to have a 1/4" steel braided cable tied to the data cable, but I think this may be overkill, especially considering the $25 PVC towfish and inexpensive transducer. What do you think?

Jason
 

Jason,
The commercial tow cables on the marine sonic I've got are 7mm twisted pair with a Kevlar jacket and a PVC jacket, thats for a 100 meter cable dragging a 35lb fish. I think they are rated at about a 1200lb breaking strength, hence no other tow cable required. Its built so one could crash it into something and get it snagged, and with a shear pin and a rear tow point it will allegedly unhang. My point is that for something homemade with someone using some common sense you can get away with much less.

I built a transducer and towfish years ago it was all straight forward. I still don't get why the Hummingbird is using multiple frequencies (I wonder if it really is) you'd have to have two piezo elements for each separate freq that the thing is using. How big is the thing? My point is how hard would it be to make a custom transducer for it.

If anyones got a no s*$@ project they like to try it on let me know, I love playing with it. Be advised I come with it, sorry no loaner deals I've got too much $$$ invested in it.

I hope this helped.

Brad
 

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