Not to disparage his efforts, but this is not unique. There is a nationwide competition for high school student to build ROV’s with the same technologies (PVC and bilge pumps). A great experience, these students come up with very workable craft. They have to prove it in a series of competitions, completing tasks seeing only though the camera eyes of their ROV’s.

http://www.darkerview.com/darkview/index.php?/archives/373-MATE-ROV-International-Competition.html

http://www.marinetech.org/rov_competition/index.php

Posted at 2:57 pm on Sep 24th, 2008 by Andrew Cooper

He mentions using two propellers for vertical travel. I wonder if a reversible centrally-mounted larger propeller would work better.

Posted at 3:17 pm on Sep 24th, 2008 by rivetgeek

Doesn’t RF have really bad range under water
other than that its a cool design

Posted at 3:28 pm on Sep 24th, 2008 by A

cool design

Posted at 3:31 pm on Sep 24th, 2008 by A

rivetgeek: not if he wants to control roll

Posted at 3:45 pm on Sep 24th, 2008 by Man On Fire

am i the only one who read the title as “underwear rov” ??

cool idea, would be interesting what range rf has under water

Posted at 3:46 pm on Sep 24th, 2008 by matt

The article mentions “help from my dad” so i think the writer is still in school.They’re also using cat5 as part of the tether and has hooked up the antenna to one of the wires, i’m intrested in if the increased length works and if it doesn’t suffer lose from the video signal coming up the cat5 too.

Posted at 4:23 pm on Sep 24th, 2008 by Alex ~

Not to discourage you guys, but the term “ROV” generally means a tethered vehicle. Strictly speaking, it shouldn’t, as any RF comms would also constitute a remotely-operated vehicle, but underwater ROVs refer to devices with wired communications.

Posted at 4:25 pm on Sep 24th, 2008 by dax

How does he steer this thing? Does the remote take care of some sort of horizontal mixing?

Posted at 6:32 pm on Sep 24th, 2008 by Abalastow Compendium

rov means “remotely operated vehicle”.

That mean RF, a tether, ir, what have you.

My question is how far the RF is going to penetrate water.
that’s the main reason why tethers are used.
well…maybe that andd getting your rov back. ;)

Posted at 6:44 pm on Sep 24th, 2008 by strider_mt2k

rov means “remotely operated vehicle”.

That mean RF, a tether, ir, what have you.

My question is how far the RF is going to penetrate water.
that’s the main reason why tethers are used.
well…maybe that and getting your rov back. ;)

Posted at 6:45 pm on Sep 24th, 2008 by strider_mt2k

Im building one write now and have all the parts. Its a lot of fun. Once its done I am going to upload pictures and details. Most projects I have looked at are outdated or “high school” projects. I’m taking it to the next level.

Posted at 7:23 pm on Sep 24th, 2008 by vanvreede

you might want to first take your spelling to the next level…

Posted at 11:23 pm on Sep 24th, 2008 by anasshole

The attenuation of RF in water depends on the wavelength. Very long wavelengths were (are?) used to communicate with submarines. The primary disadvantages of such low frequency RF are the low bandwidth and long antennas needed.

Which frequency is used to which RC models varies, but it’s probably 27 or 40MHz, which means a wavelength of 7.5 or 11.2 meters, which is already a bit impractical for using optimized antennas.

Retrieval of a failed sub shouldn’t be that hard, provided it can float up to the surface freely. Just have a separate system act as a watchdog, blowing an airbag with a cartridge of compressed gas if no signal is received for a few minutes. Now if something fails, just turn off your transmitter and wait. If the sub is inside a cave, shipwreck or whatever, retrieval would be a bit more difficult.

Posted at 1:29 am on Sep 25th, 2008 by Sparky

He’s using either 75 or 72 mhz (the two FM frequencies used for model airplanes). Possibly also 2.4ghz, but that would penetrate about six inches.

He’s going to be disappointed – the FM radios penetrate about 5 feet well, IIRC. He’s going to have to tether it for any useful range.

Here is one I helped a team make.
http://pnta.org/engineering/showmedia.php?id=336
http://pnta.org/engineering/showmedia.php?id=344

Posted at 5:40 am on Sep 25th, 2008 by sniper1rfa

I think it is neat that he is using all off the shelf parts and no microcontrollers, that way there is no code for people to always be asking for

Posted at 6:40 am on Sep 25th, 2008 by mike

Hackaday needs to put their favicon back! I miss it and have to see the WordPress W now. :(

Posted at 7:38 am on Sep 25th, 2008 by mike

I mentor a high school robotics team here in Stephenville, Newfoundland, Canada. We competed in the MATE(Marine Advanced Technology Education) International ROV competition back in June. There are two classed, Ranger for high school students and Explorer for college and university teams.

This ROV looks to be about the same as what most of the high school teams had. The ROV competition is usually in a pretty shallow tank or pool so bilge pump motors work great. Most teams used cheap $50 underwater cameras you can get off ebay that are good for 66 ft. Teams from our province had some help getting standard and have slightly nicer cameras from lights camera action. Most teams simply use DTDP switches on the surface to control the motors. But alot of teams have been using PWM motor controllers.

I taught my students how to built a microcontoller(Atmega32) based control system using motor control boards from pololu. It connected to a usb joystick(xbox controller) through a laptop running vb(didn’t have time to teach them something better). The first year they built an oil filed enclosure for the electronics but it was nothing but trouble(leaking oil and it was heavy). So this year I kinda insisted that they keep the electronics on the surface. We had a 33foot tether donated to us with 5 18ga pairs, 1 22ga pair and a 75ohm coax.

They cleaned up at the regional competition but had trouble with the temperature probe at the worlds. Leakage currents were throwing the temperature readings way off. After 3 hours of tracking down cracks in epoxy covering the solder connections they made a second attempt at the mission. They got a perfect temperature reading and then they lost video. They assumed the break in the video was underwater where they had been working on the wiring all afternoon to fix the temperature probe issues. I figured out later that the wire cracked off at the surface on one of the two video outputs. They didn’t even try the other output assuming the problem was under water.

Posted at 12:19 pm on Sep 25th, 2008 by Chris McDonald

@sparky

“Just have a separate system act as a watchdog, blowing an airbag with a cartridge of compressed gas if no signal is received for a few minutes.”

The Trieste had one of the most elegant ‘hacks’ I’ve ever seen to address this problem. It powered big electromagnets that held a large mass of iron shot to the vehicle for ballast. If the vehicle lost power, the electromagnets can’t help but die, the shot drops, and it becomes positively buoyant.

http://en.wikipedia.org/wiki/Bathyscaphe_Trieste

Posted at 12:43 pm on Sep 25th, 2008 by anon

The way the radio control gear is set up in the robot, water attenuation is not an issue – the receiver’s antenna is hooked into the cat5 tether, so that the radio link is through the cable itself, not the water.

Posted at 12:25 am on Sep 26th, 2008 by Thunder.gryphoN

building ROV’s and submarine models is a good hobby for you if you like hackaday.
And, you’re not alone ! have a peek at
http://www.subcommittee.com, http://www.subpirates.com,
http://www.rcboot.de or even http://www.duikboot-vaargroep.nl
for those who speak dutch ;-)
almost every country has his own club by now.

Now, how a about a working obstacle tracking sonar
small enough to fit in the rov or the model ?

Posted at 7:28 am on Sep 28th, 2008 by Ronald

thank you thunder, finally someone reads the whole article before commenting

Posted at 7:35 am on Sep 28th, 2008 by Techball