I’m going through a rough period right now. There’s an illness in my family and I’m having a hard time focusing on anything but worrying and trying to take care of health stuff. Everyone is going to be okay, but it’s going to be a difficult four or five months, and I really appreciate your patience and understanding. I’m going to keep putting up comics, but I don’t how much else I’ll be able to work on.
To anyone I’ve been corresponding with, I’m sorry that I may be even more tardy than usual. While davean (the xkcd sysadmin/business manager) monitors the press@xkcd.com address, I know he only forwards to me a fraction of the huge flood of mail that goes there. If you’re trying to reach me personally about something, you can write to me directly at xkcd@xkcd.com, but I’m afraid I won’t able to reply to most of it right now.
I know there haven’t been any posts here in a while. Since most of my projects are on hold right now, I thought I’d share some pictures from one that’s almost done: an underwater ROV. Exploring lakes and oceans has always fascinated me, and while I’ve spent a lot of time snorkeling and free diving, in the end I’m more interested in sending robots than going myself.
I tried to build a couple of ROVs in high school out of scavenged R/C cars and spare parts, but none of them ever worked very well. Last summer, I got interested again and picked up an Inventivity ROV-in-a-Box:
It’s a very basic kit designed to use off-the-shelf parts as much as possible, to encourage people to play with the design or expand on it. I’ve gotten a lot of help and some cool ideas from the company founder, Dr. Karen Suhm, who coaches robotics teams in ROV-building competitions and generally knows everything about ROVs. The kit comes with a good set of underwater motors and a sensitive camera, and this summer I started modifying it to use an Arduino and joystick control, running the whole thing over Cat-5 cable (which significantly lightened the tether). This will also let me add other equipment, like a still camera, depth gauge, compass, and sonar.
It’s very close to being finished—I just have a couple wires to reroute and a leak to seal—but for now, here are some pictures from construction and testing:
I made a coupler so the tether could be detached, and added a chamber to hold the Arduino, Ethernet shield, and motor control board. A Python script on the surface translates joystick values into motor speeds, and the Arduino has some code to listen to commands via the Ethernet and control the motors using three TLE-5206 H-bridges. The 5206s offer more protection than some other H-bridges—I initially used some smaller chips, and managed to blow out a couple. (Thank you to mpanetta of #sparkfun for hooking me up with the 5206s.)
A note to anyone who wants to build something like this: the Arduino isn’t actually capable of processing video, so you’ll need to either put an Ethernet camera and hub on the rover, or—if your camera isn’t digital—do what I did and divert two of the Cat-5’s twisted pairs to carry RCA video, running the Ethernet solely on the other half.
My friend Mike loaned his canoe for depth testing in Walden Pond, which is (according to data from the 1940s) the deepest lake in Massachusetts
At the bottom of Walden, there are close to three extra atmospheres of pressure.
The zip ties double as binary depth markers. This one is 14 meters.
This is the vacuum pump for sealing up wires passing into the sub (it’s sitting atop a draft of the online communities map). If you open up the exterior/water side of a cable and submerse it in a pool of marine epoxy, then apply suction to the dry interior of the sub, it sucks the epoxy through the cable, plugging it up completely. You can also use it to suck all the air out of a wine bottle with random objects inside. It’s fun to see how different materials react to a near-vacuum—particularly if you’ve just drunk a bottle of wine. I didn’t get much more done that day.
Lastly, here’s a clip of the bottom of Walden Pond, about 80 feet below the surface. This was an unpowered pressure test—the sub was just dangling on a rope—so it’s not very exciting, but it was the only test where I could record the video feed:
The Walden lakebed is pretty dead—the material you’re seeing is flakes of debris stirred up by the sub. In other lakes, we’ve found cooler stuff. In Seymour Pond on Cape Cod, we had huge catfish fish swim up to the camera and look at it, and we explored a sunken fishing boat on the bottom of Sheep Pond. I’ve also learned that deck chairs apparently fall off docks all the time—the lakebed 20 feet below the dock on one lake was absolutely littered with them. When I get a chance to send it to some more interesting places, I’ll be sure to share footage.
P.S. A belated thank-you to the NYC Makerbotters; after I posted comic #743, they fabricated and mailed to me an actual tiny open-source violin.
xkcd 
There’s apparently an old submerged jeep in the middle of mirror lake in Devens MA. Might be a fun thing to try to find, the lake is very small and right off Route 2.
I hope all is well in your world soon!
LikeLike
What a coincidence! I was working on designs for an underwater vehicle last night.
My interest is sonar, so I think I will end up with an RC surface ship and a deployable hydrophone. For passive sonar (just recording), I have had good luck with:
http://www.afabsound.com/
A cheap alternative is to build something yourself, like:
http://www.freesound.org/forum/viewtopic.php?p=13253
Both have shocking fidelity. I do sonar for a living, so if you want to talk any of this over, email me. Name above at gmail.
LikeLike
Good luck Randall! I hope the best for you and your family.
LikeLike
Hope everything turns out alright
You might be interested in this: http://www.cambridgeauv.co.uk/
Don’t know how much technical data they’ll give out, but they’re basically a student society that builds underwater vehicles for competitions.
LikeLike
Best wishes for you and your family and your robots. Come back when you’re ready, we will be here.
LikeLike
I work in sales for a company that manufactures and distributes datacomm cables. I’d love to send you out some Cat 5 freebies for your underwater endeavors if you wanted. Just thought I’d offer. Best wishes.
LikeLike
Hope everything gets better, and I wish the best for you and your family. Also, the rov is very, very cool.
LikeLike
Sorry to hear that you’re at the beginning of a rough patch. Your comics brightened up many days during my rough patches, and I’m sure that others would say the same.
All the best to you and your family.
LikeLike
@HJB, I’m working on the Cambridge AUV project for the second year running — let me know what information you’d like and I’ll do my best.
Hugo
LikeLike
Good luck in these hard times! And nice ROV 😉
LikeLike
Tell us if you see Hampture (google it!) down there.
LikeLike
Joining the choir: I hope things get better quickly for you and your family!
LikeLike
Heya
Be well!
Re:ROV: beautiful video, even though it indeed looks a bit dead down there. A beautiful project as well; I mean, it’s really great to hear how you do all that. Especially the Python part 🙂 (a year or two ago I helped write an IRL “lunar lander” game, and also used Python for the joystick interface, it’s very easy)
LikeLike
It that *the* walden pond? of Henry Thoreau fame?
LikeLike
I’ve noticed that not only do ROVs and LocalOVs kick up silt, but humans and other biologicals do as well. The “simplest” solution would be to keep propulsion screws/props (especially ascent/descent drives) as high as feasible. That would disperse prop-wash over a wider area but reduce the energy per surface area of the bottom. You could also try angled prop-wash ports… / but would likely encounter balancing issues.
I wish you(plural) well (even though I find the expression impotent) with the health issues. Try not to feel guilty when the sense of urgency wears off and you tire of dealing with it.
LikeLike
Sorry to hear things are tricky at the moment. I’m sure I join many of your readers in wishing you smooth sailing for the next few months.
LikeLike
Take care. xx
LikeLike
I certainly hope things turn around for you and your family. I think many of us know how that is and I think we would all also be in agreement that if you need to take some time off from doing comics we would be very supportive.
I have always wanted to make myself an ROV, mainly because I have a fear of deep water but an innate curiosity for what goes on down there. This year for my senior design class (mechanical engineering) one of the options was a project for an ROV competition, I think the same one mentioned above, but unfortunately I didn’t get placed on that project. I’ve also wanted to build my own theremin, but just like with the ROV I got no money. The life of a student.
Again, good luck and our thoughts are with you. And the thoughts are in a nice place in my brain, not next to the memories of “my ass hurts in this chair” and “lets fuck with the waitress”.
LikeLike
best wishes for your family! We’ll be here and around for you.
Also, sweet camera. I love it. Can’t wait to see more videos.
LikeLike
Best wishes to you and yours from the far far future…
Well maybe about 18 hours ahead…
LikeLike
@Andrew I think it is Thoreau’s Walden. Pretty sure there’s only one in the state.
Randall’s explorations of Walden are a lovely riff on Thoreau’s own efforts there. Thoreau sounded the pond in part to disprove the local myth that the pond was bottomless.
Thoreau was often using simple but clever DIY science of this sort to demystify the natural world and our place in it.
From Walden:
“As I was desirous to recover the long lost bottom of Walden Pond, I
surveyed it carefully, before the ice broke up, early in ’46, with
compass and chain and sounding line. There have been many stories told
about the bottom, or rather no bottom, of this pond, which certainly had
no foundation for themselves. It is remarkable how long men will believe
in the bottomlessness of a pond without taking the trouble to sound
it. I have visited two such Bottomless Ponds in one walk in this
neighborhood. Many have believed that Walden reached quite through to
the other side of the globe. Some who have lain flat on the ice for
a long time, looking down through the illusive medium, perchance with
watery eyes into the bargain, and driven to hasty conclusions by the
fear of catching cold in their breasts, have seen vast holes “into which
a load of hay might be driven,” if there were anybody to drive it, the
undoubted source of the Styx and entrance to the Infernal Regions from
these parts. Others have gone down from the village with a “fifty-six”
and a wagon load of inch rope, but yet have failed to find any bottom;
for while the “fifty-six” was resting by the way, they were paying out
the rope in the vain attempt to fathom their truly immeasurable capacity
for marvellousness. But I can assure my readers that Walden has a
reasonably tight bottom at a not unreasonable, though at an unusual,
depth. I fathomed it easily with a cod-line and a stone weighing about
a pound and a half, and could tell accurately when the stone left the
bottom, by having to pull so much harder before the water got underneath
to help me. The greatest depth was exactly one hundred and two feet; to
which may be added the five feet which it has risen since, making one
hundred and seven. This is a remarkable depth for so small an area; yet
not an inch of it can be spared by the imagination. What if all ponds
were shallow? Would it not react on the minds of men? I am thankful that
this pond was made deep and pure for a symbol. While men believe in the
infinite some ponds will be thought to be bottomless.”
LikeLike
There’s a lake in Northern Minnesota called Lake Ore-Be-Gone (a deliberate pun on Lake Wobegon, and the fact that’s it’s essentially a big hole in the ground that used to be a taconite mine that has since filled with rain water) that has a tractor, a bus, and a VW beetle all submerged within it. This was done intentionally to provide some points of interest for divers (the water is absurdly clear). I wonder if there’s any such lakes around Mass? At any rate, just thought I’d mention that huge sunken objects in lakes can’t be that uncommon, and should be fun to explore with an ROV.
LikeLike
That is an awesome sub, Randall.
..and my sympathies with the health situation. Best of luck to everyone involved.
LikeLike
Long Pond in Dracut has a cave in the bottom of it.
LikeLike
Stiff upper chin lip up old man, as we say in these parts.
I hate to be so crass as to post a YouTube video, but I couldn’t help but think of the old Condor Tobacco (yes, I know) ad where a suave gentleman with a sub sinks a speedboat….
Please tell me you’re thinking of this as an open source, worldwide comedy munitions platform? You’ve considered the idea of swarming beaches with fake sharks for a laugh? If enough people can build these things, solar powered and satellite linked…well, we can all wander the oceans…little individual, self-sufficient webservers, floating around, each representing one person. Or maybe groups of them, banding together for mutual advantage, harvesting solar power on the ocean, rendering silly amounts of data for money, and beaming the results out.
The pic of the social network map may have been a bit of a giveaway….or maybe just very prescient 😉
Yup, I reckon you’re on to something there.
LikeLike
I’m sorry to hear about the health problems in your family. I hope it all works out.
Maybe this would be a good time to transition your comic and blog to a different format. I can’t speak for all your readers, but I don’t want you to feel obliged to produce three comics per week.
I’d rather see xkcd become a mixture of comics, jokes, observations, clever ideas (that aren’t required to have a punchline), cool data visualization, projects you’ve worked on, etc., all published as time permits.
LikeLike
hang tight my friend — looking forward to seeing where your ROV project leads; maybe answer some questions about marine exploration, who knows 😛
LikeLike
Best wishes to you and your family. Also hugs. *hug* Those always seem to help the most.
LikeLike
Lake Murray in SC has an estimate of 25 WWII B-25s at the bottom of it :]
LikeLike
Your family is dying to get away from you.
Just like Megan.
LikeLike
*huggles* Hope the stress fades quickly. And keep in mind we’ll all forgive you if you miss a few comics.
LikeLike
# thank you
LikeLike
Your comic today made me laugh aloud with glee. Thank you for that, and for sharing that you’re in a tough spot. I know a little of what it’s like caring for and worrying about a family medical situation, so I’m glad you have davean taking care of all that he can, and I hope the rest of your friends and family are similarly supportive.
Please take care of yourself as well. My thoughts are with you.
LikeLike
I hope everything works out for the best, with love and compassion from Sweden. 🙂
LikeLike
Hang in there. Best wishes to you and your family.
LikeLike
I guess I sound like a , but I hope everything turns out well and understand if you can’t do everything.
LikeLike
Hope everything with your family turns out well!
I’ve missed the blog entries, but I was excited and inspired to read this one. Thanks!
LikeLike
Those of us by the big lake in Vermont send our regards… very sorry to hear that things are hard right now. When better times come around maybe you can come find Champ in Lake Champlain with your submersible.
The world is so ridiculously amazing and also drastically tragic at the same time…
~C
LikeLike
Hang in there! Best wishes from Canada.
LikeLike
Best wishes, Randall.
@Matt: thanks for the Thoreau quote! Nice context.
@Rick: easy-to-build theremin kits: http://www.makershed.com/SearchResults.asp?Search=theremin Go live your dreams, man!
LikeLike
@Pokan
I don’t want to start a flame war. But w/e
You’re a jerk. I hope you get punched in the throat by hooker. You’re an embarrassment to society. How dare you say something like that. I hope you get your reproductive organs caught in a bathroom stall door. Who do you think you are? Your dribble doesn’t deserve a response.
LikeLike
Wow! That ROV is awesome! I hate to sound like a fan boy but ….
I love the comic. LOVE IT! It’s really great to see sophisticated humor and know that there are people out there that have a good sense of humor. Watching your video, at the end; did the sub lift and turn around with your controls? That’s wild! I hope you get video from the submerged boats and lawn chairs. Really cool video.
I’m really sorry to hear about the health issue. I hope everything works out for the better.
LikeLike
Pokan seems to think that ‘Megan’ is a real person. I wouldn’t be surprised if they believed in ‘Snoopy’ too. “LOL @ Charles Shultz ur dog hasnt shot down teh red baron yet lol lol!!!”
LikeLike
@ Matt Cooperrider – Actually there is a second Walden Pond in Massachusetts by the Lynn Woods. It’s likely Randall was referencing Thoreau’s pond which of course is the famous one. Thanks very much for the quote.
And best wishes to Randall and his family.
LikeLike
Furthermore, he stole that joke from Dane cook. Unoriginal and stupid in just one sentence.
LikeLike
Good luck and hope all will be well again soon, Randall. Many thanks for all the brilliant and outrageously funny comics and interesting and inspiring blog entries you have shared with us so far. Best wishes to you and your family.
LikeLike
I wish you all the best & all the strength you need to get through this time– hang in there, Randall!
and there’s something both fantastic & tragic about testing in Walden Pond, and finding the bottom pretty devoid of life. eurgh, Thoreau spinning in grave.
Thanks for sharing your forays & delight with the world, with us.
LikeLike