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 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, 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:

Inventivity ROVIAB

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.

This canoe (and everything else in the shot) travels through time.

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

It's about 90 feet down from here.

At the bottom of Walden, there are close to three extra atmospheres of pressure.

In this shot, read left to right.

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.

664 replies on “Submarines”

  1. Sorry to hear that you’re having a rough time, wish you the best of luck and I really hope things get better. We love you for the comics.


  2. All the best from the UK; saddened to hear your news.

    For me, XKCD isn’t just a wonderful source of humour, it’s a way of telling good people apart. It’s always a great moment when someone references XKCD in a room full of strangers and two or three people go ‘Hey!’

    Much affection and thanks to you, and best wishes to your loved ones.


  3. All the best for you and your family from Finland.

    I just hope that there’d be a way to put some happiness & joy in the jar and send it to you, since you really deserve it. I haven’t been around from the day 1 but, like the others, I’ve read every strip trough and enjoyed each and every one of them.

    If you need a break then take it, if you can’t continue anymore that’s fine as well. You’ve already deserved your place in the history. As many has said before me, if and when you return, we’ll be here waiting. After all, we’re just a bunch of strangers who enjoy your work, you don’t owe us anything, it’s us readers who owe to you. There’s absolutely no need for exuses or being sorry for us.

    And, after all, XKCD is only a comic, an genious one, but still just a comic, atleast to us readers. There’s way more important things than one website, no matter how genious or popular it is. So there’s absolutely no need to be sorry when you focus on the more important things.

    I, among others, am grateful if you share the news and tell us what’s going on, but please, for your own sake, don’t make a big deal out of us.

    Again, all the best and quick and full recovery for you and your family. We’ll wait here until you’re ready.


  4. I hope everything goes well for your family and things get better soon.

    Also, if you’re exploring New England lakes, you simply must try Winnipesaukee in NH.


  5. No prob with you taking time off, I now have a Kinect to amuse me . . .

    Seriously, I’ve been a full-time caregiver to a family member paralyzed in an accident last year and my heart goes out to you, I understand.

    Your site makes me smile, laugh, think, and try my hand at drawing myself. Thank you for all the past smiles and smiles to come.

    Oh yeah, and what those other guys all said . . .


  6. About Walden Pond, if you go near the center of it, there are actually jellyfish. Worth checking out if you ever swim there, although I doubt many people will be doing that for a couple of months.


  7. Just wanted to send good thoughts to you and your family. I’m battling a long-term illness myself and my husband is dealing with a lot of strain. I know how tough it can be, just keep the happiest thoughts you can and you’ll get through it. Thanks for creating xkcd – its been a joy to us since we discovered it.


  8. We just lost our mother two weeks ago after an extended illness, so I can empathize with your situation. All loved ones, as well as the sick individual, take on a lot of strain; please, please remember to take care of *you*. There’s an ancient saying I made up a few years ago: “You can’t get across town on an empty tank of gas.”

    Thanks for today’s comix re: “positive attitude”. Any additional sarcasm you wish to heave in that ideology’s direction would be deeply appreciated! 😉


  9. Today’s comic (“Positive Attitude”) spoke to my heart. I’m a cancer survivor. You captured one of the most frustrating and isolating parts of being treated for any serious illness perfectly. My best wishes to your own ill loved one; he or she is lucky to have someone as genuinely understanding (and funny!) as you around.


  10. Thanks for the last comic “Positive Attitude” and thanks for the mouse over lines. I wish you the best for whatever you are passing through this moment!


  11. Love the ‘Positive Attitude’ comic for Dec. 1. Actually going for my 9th round of chemo this morning and I just *have* to show this to my nurses when I get there.


  12. Glad to read from on the xkcd again.
    I sincerely wish you and your family feel better. And not just for the sake of positive attitude.

    Cheers from Paris, France

    (Hey! if you consider having a global trip all over the globe with halts at your fans places, my couch will be yours.)



  13. Positive Attitude was what helped me feel better through 9 months of grueling chemotherapy almost 10 years ago. I am better, but it was scary; you really do need to know that you’re going to be better; it’s what all the self-help books in the lobby told me!


  14. Wishing you the best. As someone who has a chronic health problem, I can tell you that not feeling like shit for feeling like shit is hard sometimes, but you’re spot on.


  15. I just read your most recent comic, Positive Attitude. It truly spoke volumes to me and I just wanted to thank you for that. I’m one of those people that beat my self up because I feel bad. Like when I’m unhappy, I feel like utter shit because I cant figured out how to make myself happy again.

    Also, I really hope that your family problems get better really soon, especially with the holidays and whatnot…Regardless of whether or not you are religious, I will be praying for you and your family =)

    Best of Luck and Thank you



  16. I hadn’t visited to the website in quite some time… All best wishes from Mexico to you and your family. Thank you for still giving us some time to make us laugh, think and feel. i wish you and yours a speedy recovery.


  17. I just wanted to add my voice to the chorus wishing you and your family luck and strength. You have made so many of us smile, I hope some of this geeky love your way helps you and your family to feel not so


  18. I just wanted to add my voice to the chorus wishing you and your family luck and strength. You have made so many of us smile, I hope some of this geeky love your way helps you and your family to feel not so alone.


  19. Hope things are going better for you and your family 🙂 It’s great to see your new strips! No pressure…I did enjoy the guest strips very much – cool to see different cartoonists’ takes on what you do. Thanks for the laughs and the geek humor 🙂


  20. About « positive attitude »… I’ve heard from medical researcher (I work with some of those guys) that it is well-known that many people dying from cancer feel guilty because they believe they did not fight heard enough, and believe they are responsible for not curing. This is so sad.

    I whish everything will be ok.


  21. I’m so sorry to hear about the problems you’re dealing with. I hope things get better quicker than expected. Fingers crossed over here in the UK for you. All the very best, dear XKCD xxx


  22. you should totally bring that to an old abandoned flooded mine, (i have a few in mind), and see what the inside looks like, some cool history down there and would be stuff unseen for 100+ yrs… cool stuff man…


  23. Sorry about your illness. Hope things get better! Also, does it break the rules of phonetics to assume vowel sounds? If so, I think I discovered the pronunciation of xkcd:
    It’s definitely not very attractive, but neither is the pronunciation of the entire alphabet:


  24. All the best wishes from Turkey. Wish you the strength to smile all the time while coping with the problems -which I hope will get better soon.
    I’ve recently had such a hard year due to serious family health issues, so don’t forget to smile, it is the best cure
    all love – nerd love!


  25. Rooting for you guys! Please know that your work is much appreciated. I have cheered up many a friend by sending them an xkcd comic. You seem to have one for every occasion 🙂


  26. I wanted you to know that I appreciate all of work, art and creativity you have poured into this blag/comic/webzine these last years; it has a precocious humor that has given me needed perspective during hard times past.

    My best wishes to you and your family in this period of turbulence; with the new year soon upon us better days are just around the corner.


  27. You have a webcomic beyond greatness however it lacks a comment section. I would make comments if you made a comment section.


  28. I saw your latest comic, and was worried about what was going on; I hope you and yours are alright. I liked your stuff on the ROV – good luck there (I was working on one myself a while back, but got distracted by other projects). One of the best homebrew ROV sites out there:

    Check out how he does his tether management!


  29. Whoever you feel is responsible for it, let’s give thanks for that p<0.05. Here's hoping that it all works out bitches!


  30. All the best to you and your family. Good luck, man. We’ll be here waiting for good news.


  31. I truly hope your family health issues resolve themselves. I just want to say thank you (not even close to how i feel, but it’ll have to do) for all the laughter you have given me over the years, and especially these last two, which have been horrific. XKCD has helped keep me sane (no mean feat), and made me laugh out loud despite crying.

    You are a truly gifted individual, with a wicked SOH, and your lateral thinking skills ROCK. I would LOVE to have you on my design team!

    Thanks so much, and here’s hoping 2011 is a better year for you and your loved ones. It will be for me – we’re having a “ha ha, I didnt die after all” party for my wife on Jan 9…..

    best wishes,


  32. Well, everything has been said but still,
    Best wishes and Happy New Year 4 u and all your loved ones.


  33. I hope that things are going better with your family. I went through some tough family illnesses as well. It was terribly difficult to get through, but I did. I hope that you’re doing well, and best holiday wishes.

    PS- I love your comic. It always makes me smile when I’m down.


  34. I only stumbled on your site this afternoon. You have one of those sites that makes me look over my shoulder for hidden cameras. My box full of ROV parts is coming out of under the bed tomorrow morning. 15 to 30 feet deep in fresh water is more interesting, more life-giving light. Sorry about your tough patch, it’s mandatory training for when you get older. Why did you leave the kcd’s?

    I’ll go back digging through your art now, thanks for it all, eh?


  35. Not really a comment leaving type, but had to say thank you!! My husband and I love reading xkcd, hope you can hear us giggling from our respective computers.
    As well, my family’s thought’s are with you and yours. Deep breaths.


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