The Submarine Project

**Update** There are a lot of people finding this page using web search tools. Congratulations on your use of research to solve this problem. As a result there are a lot of valuable comments and possible solutions in the comments below. Please take the time to read the comments from others. I’m unable to provide any individual help on this project but I hope you find some useful information here. Please do not use the comments to complain about the project or chat with each other. If you have found something that works for you or another useful website please take the time to carefully write it up and submit it as a comment for others to read. Off-topic comments will be deleted. -Ben 2/26/2006

My 7th grade sister came home for winter vacation with a science project to do. Nothing simple like we used to do in school, she’s supposed to build a working miniature submarine. Naturally, I was asked to help with this project, but at the moment I’m quite busy with a number of other projects, so I’m wondering if anyone in the vast world of the internet has any ideas regarding how one would go about doing this? Remember, and this is important, this is still a 7th grade project and as such should not be overly complicated, we are going for the simplest solution to the problem, not the most technical one! You can find a copy of the project requirements below, any help would be greatly appreciated!

PS 14 The Submarine Project

Your Mission: Design, constuct and demonstrate a
submarine device that will float, sink and float again OR sink,
float and sink again in a tank of water 30 cm deep. This mission also includes
writing a "Captains Log" of your design process.

Procedure:

  1. Design and construct a subnmarine device that will operate in a tank of
    water 30 cm deep.
  2. Captains Log – write a report about your device and include a log
    of your design as you work
    .
  3. Demonstrate your device to the class

Restrictions:

  1. Sub must be more than 2 cm long and not larger than an average shoebox.
  2. You will only have about 5 minutes to get your submarine to complete its
    mission
  3. You may not touch (or drop things onto) the sub once it is put in the water
    – it must be completely self-operational
  4. Presentations will be done in our class fish tank. All materials must be
    contained inside the fish tank, not clinging to the walls or connected to
    anything outside the tank. (No hoses)
  5. Chemical reactions are not recommended unless it is designed
    to happen inside the submarine and not released into the aquarium. Only gasses
    can be releases into the tank, not the "chemicals".
  6. The density of the water in the tank must remain unchanged after your sub
    has completed its mission. Things that dissolve in water are not allowed.
    Kleenex and paper dissolve in water and can contaminate the tank
  7. Restricted materials: NO Funnels (or funnel-shaped objects), NO golf balls,
    NO tops to Tupperware and NO sponges may be used as the main body of the submarine.

Submarine Report must include the following:
Helpful Hint: Start each section on a fresh page and title the page with
the section

  • Creative Cover Page (Color picture, your name, submarine name, date, science
    hour)
  • Salty Captain and vessel name (ie.:Science Stein of the S.S. Density)
  • Log of design work – Each time you work on the submarine, keep a log of
    the date and time you worked, discussing what you tried including drawings,
    frustrations and successes. You need to do this each time you work!
  • Final materials list: List all materials needed to construct your final
    design.
  • Vessel Operation: Explain how the submarine works in detail. How does it
    change density? (It should change density twice)
  • Design Plans: At least 3 drawings or pictures of your sub: floating sinking
    and then floating again (or vice versa). Be sure the pictures show changes
    in your sub.

87 Comments.

  1. alka seltzer and pennies in a film canister or plastic egg
    hope i gave you some ideas
    (once the water hits the alka seltzer it will rise to the top

    GOOD LUCK!!

  2. What if you aren’t allowed to use chemicals like Alka Seltzer that will go into the water?

  3. John Mulholland

    Greetings!

    Did you ever figure out how to make a “working” submarine for your then 7th grade sister?

    My 4th grade son has to do this project, and we are stumped.

    John Mulholland

  4. MY DAUGHTER WAS GIVEN 1 WK TO DO THIS PROJECT…1 WEEK…AND NO CLUE ON HOW TO EVEN START. THIS SUB HAS TO FLOAT, SINK AND RESURFACE. ANY HELP OR IDEAS WOULD BE GREAT. THANKS!!

  5. Has anyone figured this out yet? My son is going through the same project. I don’t want to give him the answer but it would be nice to be able to guide him someway.

  6. I believe there is more than one solution to this problem. I don’t want to give everything away but the solution we came up with involved a weighted flexable container that had a small hole in it. The type of container is important as is the fact it was flexable. On its own the container would sink but was light enough so gas created by a chemical reaction would make it rise, we also found a way to let the gas escape slowly making the container resink. Best of luck!

  7. Alyssa Campbell

    This is how you do it, you take a yoplait container stick ten pen holes in the bottom of it add 8 marbles and 1 big marble plus 5 key and put those in the yoplait container and then you get a ziploc bag and add 2 1/2 Alka-Seltzer tablets in the bag, but dont close the bag but fold it and put it halfway into the yoplait container!

  8. OH my god same prodject too!I think U could make a fan that will make it float then fan stops it sinks again I dont know?thats what I think.

  9. i THINK YOU COULD TAKE SAND AND CUT A LITTLE HOLE IN A PLASTIC BOTTLE THEN THE SAND WOULD LEAK OUT THAT WILL MAKE IT FLOAT. haha THEN u COULD NAME IT THE SANDY SUB!!!! :)

  10. I have to do this stupi Experiment too and I have no idea what I am DOING!!!! Mr. Leslie gave us like 2 weeks to do it and I can’t even start. this is really difficult. I don’t know how I’m gonna do this. ne one wanna help me??

  11. To-Tomiko From Killer Ninja Shinaku

    R u stupid????!! If u put sand on to it, sure it would sink. If u cut a hole in it, sure, it would float. But with no sand, how r u gonna make it sink again HUH?

  12. Killer Ninja Shinaku

    For all those people who need some help out there, use this, use one of those water guns. Take it apart and use the pumping air thingy.

  13. To-Tomiko Killer Ninja Shinaku

    P.S. Don’t use a fan and burn the motor. lol

  14. I felt that this project is completely ridiculous. I have to find a way to make it sink, rise, sink and then rise once more! A complete waste of my valuable, intellectual time, I say! If any well-educated, creative-thinking mind can help a young woman such as myself, it will be duly appreciated. ADIOS! HASTA LUEGO!

  15. I just did this project and got 100%! Anyway, if you only have to float sink float, take a Dixie Cup and cut the top off, so that you have a shoter cup. Then poke 3-5 pencil tip sized holes throught the bottom. Then, poke a pencil through the middle, so that it sticks out throught the bottom. Then, put marbles in as necessary. It will should gradually sink because water will seep in through the holes in the bottom. The pencil will hit the bottom, tip the cut and marbles over, and make the marble fall out. Then, the cup & pencil will rise to the top.

  16. I have almost the same project except nothing can be leaked into the tub so I cant use the Alka-seltzer or marbles! we have to finish it by the end of spring break so we dont get help from the teacher. HELP!!!!

    P.S. to make it corny our teacher says we have to make it yellow. as we try them out we will listen to ‘yellow submarine’ the yellow cant leak either HELP!!!!!!!!!!!!

  17. I had to do this same project- it is due tomorrow – this submarine had to float for 45 seconds, sink for 30 seconds, then float for another minute.

    This is what I did:
    Supplies needed:
    2 Water bottles, one slightly larger than the other
    Two Balloons (you will need more, due to trial and error)
    1 rubber band
    marbles (amount depends)
    1 small empty container. (i.e. – empty prescription bottle – empty 35mm film canister)
    alka seltzer tablets (recommend buying the biggest box you can find!)

    Take two water bottles. Mark it approx. 1/3 of the way down. Cut at that point. disgard the bottom half of the bottles. Keeping the halves with the original water bottle opening.
    Take the two ends of the bottles and slide one into the other so, the original bottle openings are facing outward.

    Take some marbles and place them in the empty prescription bottle. close bottle. take the rubber band and place, around center of the two bottles, then take the container with the marbles and slide it into the rubber bands. poke two holes in the water bottle creation (not prescription bottle) one hole on each side ( you may need more it will depend on the size of the holes) take one tablet of alka seltzer and place it into one balloon, then do the same to the other. Suck the air out of a balloon then slide the opening of the balloon to the opening of the bottle, then do the same on the other side. twist the balloons around in a clock wise motion to prevent water entering the balloons too soon. As the body of the “submarine” starts to fill with water, it will slowly sink to the bottom. when the water fills the cavity and hits bottom, the balloons will start to untwist and fill with water. Then the alka seltzer will react with the water, causing the balloons to blow up and make the submarine float again.

    I would have gotten bonus points if I could get it to sink again, but this was hard enough to design.

    It took several attempts several hours and a lot of patience to get this to work, the weight of the marbles, the size of your holes – ect – will affect the outcome. Good luck!!!!!

  18. the marbles? did you use jumbo ones or reegular hazerdous kinds?
    definitly doing that one now after talking to my partner. still, we would like help;we need it!!!

  19. I have to make a submarine that floats sinks then rises. how can I make this. I’ve tried so many things and it’s not working for me. can you help me.

  20. Lauren^^^^^same person from before

    ok. I can’t use any chemicals. how can i do this project now?
    please help me.
    thx
    Lauren

  21. this is so hard

    i heard from sum people that u take a film canister and poke holes in the bottom.then u put an alka-seltzer wrapped in a tissue in side it.then the tissue will fill w/ water as it sinks from the holes in the bottom of the canister.the canister will sink.after its sunk the alka-seltzer will dissolve turining into bubbles…..the canister will sink.i dont no if itll work or not (it didnt work 4 me but it worked 4 a girl in this other skool that i no).u should all try it it could work 4 u.(if any1 has a different idea 4 me then please add another comment onto the site…..this project is due in like 2 dayz!!!!!ill be checkin it evryday!!!!help me

  22. this is so hard

    *sry i meant afetr the alka-seltzer dissolves the canister will FLOAT!!!sry

  23. this things retarded and has nothing to do with the real world

    all that alkselser didnt work because for mine it has to be 50% above water when it floats for 15 secs anbody know how to do that

  24. if you use: plastic water/soda bottle, marbles, vinegar, and baking soda.

    It will take several tries to get the right combination(exact number of marbles, baking soda, etc).. best bet is to wrap the baking soda in a small piece of paper or tissue and put it in first, then add the marbles. Fill the bottle with vinegar, close it up. Open it right before you out in the tank of water. It will float, sink(the marbles weigh it down), then slowly rise as the baking soda creates gasses…

  25. im doing a submarine project. Its due on May 312005!
    It has to propel itself underwater a minimum of 1 meter ..1)The vessel has to be atleast 5cm below the surface of the water & 5cm above the bottom of pool. 2)Not 2 b operated by remote control. 3)No pre- prep ared propellants 4)NO longer than 30cm by 10cm by 10cm. CAN YOU PLEASE HELP ME!!!!
    EMAIL ME!!!

    -ANNETTE, CALIFORNIA

  26. this things retarded and has nothing to do with the real world

    2 ltr bottle
    plastic tubing connected to a ballon that is through the cap.
    3 holes on bottom
    1 hole on top ( for air to get out)
    pennies duck taped toghether and taped to the bottle

  27. HOW DO YOU DO THIS PROJECT????
    my idea-a sponge in a high diameter ottle which will accumilate water w/a piece of paper on the bottom of the bottle. will float, sink, sponge fall out, float again.

  28. Try this=
    take 1 water bottle. fill it with 12 regular size marbles (my marbles are from the Ker-Plunk Game).Take 1 balloon and fill with 1 alka seltzer. Next, fill waterbottle halfway with water.Put balloon where the cap should be.Being Heavy, ur sub should sink, then the water will leak into the balloon, it will fill up, and float. Then it will slowly deflate, and sink. i haven’t tested this yet, but i am now. when it works i’ll re-post a comment. Adjust water and marbles accordingly. =]

  29. You guys are hilarious…
    i figured it out!
    yay.
    you git a dixie cup, poke 4 holes in the bottom, poke a penicl thru the middle of the bottom, and put it in water. if the cup falls over, than the marbles will fall out and the cup will float. if the cup doesnt fall over there are some adjustments you need to make. good luck!

  30. well this is what i thought up, wrap up two alka selzers in two different towels (1 for each) and stick them in two different balloons put both balloons on eahc end of a two liter bottle, next poke a bunch of holes in the bottle for that the water can get in, next duck tape a bunch of marbles on just one side of the bottle for that it can sink. well thats all i got for you right now, i’ll try to see if i can make it float-sink-float, wish me luck….(havent tested this out so tell me how it freakin works!!) =)

  31. same progect. take a cork and glue a weight on it with glue that will disolve in water. the cork will sink, and when the glue dissolves the cork will unstick and float again. too bad my project has to sink again. won’t work for me, but good luck everyone else.

  32. Using the comment about the dixi cups:
    “I just did this project and got 100%! Anyway, if you only have to float sink float, take a Dixie Cup and cut the top off, so that you have a shoter cup. Then poke 3-5 pencil tip sized holes throught the bottom. Then, poke a pencil through the middle, so that it sticks out throught the bottom. Then, put marbles in as necessary. It will should gradually sink because water will seep in through the holes in the bottom. The pencil will hit the bottom, tip the cut and marbles over, and make the marble fall out. Then, the cup & pencil will rise to the top.”

    It worked! except, using a cheap Bic ball point pen works better because it is filled with air. The pencil wasn’t working becuase some of the trials I did at home didn’t work, because the marbles got stuck in the cup.

  33. My daughter has to do this, too. We’ve been trying for several days. The teacher demonstrated the pencils/dixie cup/pennies method and said, “Isn’t this great? AND YOU CAN’T DO IT FOR THE PROJECT.” Thus, the kids have to think up something else. No contamination of water is allowed. The captain’s log is the easy part. It’s trying to find something that can sink taking another floatie object with it and then having it ‘release’ down at the bottom of an aquarium to come back up. Tough, tough, tough! Luck to everyone.

  34. Well, I have the following that can float: orange peel, styrofoam pieces from cartons in the fridge, anything plastic in mom’s kitchen drawer, candles, plastic toys, aluminum foil (sometimes), prepackaged candies from Burger King/ketchup packs/soy sauce packs, etc. As for sinking, I can tie two plastic spoons together with rubber bands/hair bands and weight with paper clips or metal objects in kitchen drawer….but how to ‘break’ the seal open to ‘release’ an object ‘trapped’ in the sinking object is the part that we can’t figure out yet. I can weight anything down and cause it to sink. But how to ‘break’ one of the floaties loose? Also tried ‘sinking’ an object with paper towel but if wrapped incorrectly the float (sub) can’t break free to resurface.

    We are stymied. Have spent about five hours on this so far. Frustrating!

  35. “I just did this project and got 100%! Anyway, if you only have to float sink float, take a Dixie Cup and cut the top off, so that you have a shoter cup. Then poke 3-5 pencil tip sized holes throught the bottom. Then, poke a pencil through the middle, so that it sticks out throught the bottom. Then, put marbles in as necessary. It will should gradually sink because water will seep in through the holes in the bottom. The pencil will hit the bottom, tip the cut and marbles over, and make the marble fall out. Then, the cup & pencil will rise to the top.”

    okay well i did all that and i must have did something weird with it cuz instead of tiping over the pencil tip hit the bottom of the floor and it went up so that was the floater part. so it worked and i think i used like 15-20 marbles. so good luck and ill see what grade i get in a couple of days! thanks so much dude!

    goood luck.

  36. The dixie cup was already done BY THE TEACHER in front of the class. The teacher gets an “A”/100% but none of the kids can use it.

    Got any other ideas? The cup/pencil/marbles (the teacher used pennies) is NOT ALLOWED in classroom demos.

    You’re lucky you have the teacher you have!

  37. i have figured out how to do it!

    you need:
    *1 pop bottle
    *non drying clay (knowen as “sculpy clay”
    *wood object (floater)

    cut about 3/4 of an inch off the bottom of the pop bottle. take the scuply clay and put a 1cm layer over the bottom of the pop bottle (should look like a round boat with a layer of clay on the bottom).Poke holes into the clay and the plastic “boat” (this allows it to sink). take the wooden object and lightly stick it on the clay. then put it in water it will float for about 2 seconds, sink to the bottom, and then the wooden object will dislodge and float up to the top.

    PS. you can get the clat at almost any crafting store. and the clay DOES NOT contaminate the water

  38. there are many ways to do this now that we have played with so many household objects. What’s ‘working’ right now is a dixie cup with holes poked into the bottom, weighted down with marbles. Then we have a plastic floater (like the kind that comes from vending machines with little toys inside, minus the toy) and hold it into the cup with a rubber ring from yes, the blender…..and if it is done just right it fills w/water, sinks, and the pressure or something makes the rubber ring get loose and the plastic container floats to the top of the aquarium.

    We’ve also played with ice cube trays (not much luck), pencil grips as the floater, corks put together with toothpicks….so keep trying and don’t give up. Make a sub where you drag the ‘floater’ to the bottom and then it falls off/pushes out/releases somehow.

    This is it for my blogging, but I have enjoyed reading everyone’s quest. Luck to all.

  39. If you just have to make it sink and then float, then I would suggest freezing something that floats into a block of ice. Then the ice will melt at the bottom of the tank and the object will float up. I am doing this same project, and its really hard, but my teacher gives extra credit points for putting lots of entries in the ‘captains log’ Good luck everybody, sorry I couldn’t help more!

  40. I have one that works regarding the submarine. I used a balloon filled with hot water and I dropped it in cold water. It sinks to the bottom and floats back up. My teacher said it was really good and I got an A+ on it.
    P.S. I hope it works for you!

  41. I see:
    1. poked dixie cup w/marbles +pencil
    2. alka seltzer in different containers (water makes gasses that make sub float)
    3. baking soda and vinegar
    4. floaties/weights combinations

    I haven’t tried these but I wonder if you can keep the soda/vinegar or water/alkaseltzer separated just long enough for container to sink and also keep them contained without escaping into the tank. Maybe put a little vinegar in a balloon, put it in a soda bottle with enough weight in it, don’t let go of the balloon neck untill you’ve put a little baking soda in a piece of paper towel and quickly stuff it in the balloon, tie the balloon, drop it in the bottle, cap the bottle and put in the tank of water. Will the expanding gasses in the balloon help the bottle float?
    I guess the most important thing is to write down everything you try and say what happens whether it works or not.

    I guess I’ll have to go try my idea.

  42. well i cant make it subsurface but i took a film capsule poked a pen hole on all sides + bottom & top. then took a nickle + penny and put 2 tablets of alkaseltzer in then it floats 3sec. sinks 3sec. and resurfaces.

  43. Lil Miss Smarty Pants

    This project was really annoyingly hard! But I figured out how to do it!! Here’s what you do:

    Ingredients:
    -3 1/2″ tall Dixie Cup
    -Pen
    -31 regular marbles
    -1 shooter marble
    -1 ball of aluminum foil (should fit into top of cup)

    Poke 2 holes in the bottom of the cup with the pen and then put all 32 marbles in the cup. Stuff the ball of aluminum in the cup over the marbles. Water will seep in through the holes, the cup will sink and the aluminum will dislodge and float back up!

    This worked for me- I hope it works for you!
    If not, alter the weight of the marbles or something.

    Good Luck!

  44. An idea I had (but failed to work, thus given me an F) is to glue pennies on the bottom of a film canister, with water-soluable glue.
    The density would pull it down, the water will dissolve the glue, and the lighter density of the canister will force it to surface.

    btw, we learned the density formula (mass/volume for 1 month in this science class!!!)

  45. okay, i think i have an idea of what to do……first, take an empty sour cream container(or one about the same size) and fill it with marbles. Then put the lid on and poke a few small holes into the lid, and at the bottom. Then take 3 or 4 balloons and put 1 or 2 alka seltzer into each one. then put the balloon ends into the lid holes. When you put it in water, it will sink at first because of the marbles and the water filling it up, when it’s all the way under water, the alka seltzer will activate, and make it float back up. (you can use more balloons at the top if it doesn’t work)
    hopefully this works for you
    let me know if ti doesn’t so i can find a new way
    goodluck!!

  46. i did the submarine project 4 months ago and i did it with a 3onz dixie cup cut in half poke 4 holes on the bottom of the cup then a pencil through the middle of the cup wit the eraser pointing down and then put 3-4 normal marbles

  47. Right I Did This A While Ago And It Took Me Ages To Figure Out How You Do It ….. All You Have To Do Is :

    Get An Empy Film Case .

    Poke 1 Hole In The Top And 2 in the bottem .

    Put 2 1p Pennies At The Bottem .

    Put In Any 2 FIZZY Tablets Of Yur Choice On Top Of The Pennies

    Place In Bowl Of Water And They You Go .

    Your Submarine Should Now Float For Around Sink And Float :D ..x

  48. CAN’T USE DIXIE CUP?

    Try taking a film canister and making one hole at the top, and many smaller holes around the bottom. This will make it float because it is filled with air, but then it will slowly fill with water from the holes in the bottom, and sink. Once it has sunk, the water pressure coming down on the top of the canister will push all the water out of the holes, it will become filled with air, and it will float to the top. This might work, but I have not tested it yet. Thanks for the dixie cup idea!

    -Marquel-

  49. get a mini pepsi bottle and duct tape the whole bottle. put 2 alka-seltzer tablets in the lid. then duct tape them in the lid. tape the lid on the bottle then put 6 holes in the bottem. put it in the water. when the water gets to the alka-seltzer the gas bubbles should lift it up.email me at dalton@blake.net with results. GOOD LUCK!

  50. Use alka seltzer and a sponge so it can only escape through the sponges holes this will make it rise

  51. The best solution that i came up with was the alka seltzer idea.

    1 poke holes in film canister, approx. 4 on each side
    2 put in 3 small washers, or 2 medium/heavy bolts
    3 wrap 2 tablets alka seltzer in a paper towel and put in to canister
    4 put it all together and stick into water

    for some reason this concoction managed to do the float sink float cycle 4 times!

    for the other idea, go to this site

    http://www.submarinesafaris.com/kids-uk/build.htm

  52. we arent allowed to use the pencil dixie cup thing. or a balloon one. i was confused. what i did was i got two little small gerber bottles. taped the sides together with one upside down, preferably clear duct tape. and once it hits the bottom, the tape will have been there so long it cant hold anymore. and they come apart. my science teacher told us at least some part of the submarine should come up. i tried it with alka seltzer, it didnt work. hope this helps :)

  53. My son has the same project and we are lost as to how to make something float after it sinks. He has put some taped pennies in a plastic bottle and poked holes in the bottle taped some batteries to the outside of the bottle and it sinked but what can we use to make something float off of it?

  54. Okay, so I FINALLY got my submarine to work. My assignment was to make a sub that would start on the bottom, float, then sink or start on the top, sink, then float. I did the following after getting inspiration from here:

    Materials:
    1 film canister (may need more for test runs though…)
    Alka seltzer (loads of it)
    A nail
    Pennies
    A sink or something in which to test it

    I filled a sink with cold water to test my sub since I’m assuming my teacher will use cold as well. I took my film canister and poked five holes in the canister itself with the nail: one in the bottom of the canister, two on the side of the canister about 1/4 of the way from the bottom, and two on the side of the canister about 1/4 of the way from the top. I also poked a slightly smaller hole in the cap of the canister. I then filled the canister completely with water and placed 4 pennies in it (you may need more or fewer depending…) I then took an alka seltzer tablet and broke it into two pieces, one only SLIGHTLY bigger than the other. I quickly dropped it into the canister and snapped on the cap. It sinks because the weight of the pennies and water pulls it down. The alka seltzer then reacts with the water and it will rise eventually, although bubbles will escape from the hole in the top. It is difficult to get the size of the hole to the amount of alka seltzer ratio right, but this worked for me. It will rise, and then when the alka seltzer is gone, water will come in through the holes in the side and air will go out through the hole in the cap and it will sink again.

    This will work if your teacher doesn’t allow pencil/dixie cup/penny contraptions, but not if he/she doesn’t allow chemicals or contamination of the water.

    Good luck — don’t procrastinate with this one! =]

  55. u will have the answer if u go search youtube,search “how to make a submarine”
    and click on 7/8th grade project (i forgot).

  56. Some of you parents need to stop asking people how to do the project and actually do some problem solving. Quit complaining and try things out!!

  57. I did this project and i got an A. You can take a piece of bread and toast it. Then after it’s toasted put a good amount of toothpaste in two opposite cornors. Then put a quarter on top of both globs of toothpaste. You can put it in the water with the quarter side face down. Hope it works!

  58. my class did this project. u can use a film canister, and put alka selter init, and let it rip. orone of those medicine bottler, ans majke sure th ecap isnt too tight. another one is inside a ballon, put vinegar, and in a little bottle, put bakiing soda, and put it in water. thye all work

  59. dakota so easy g

    take a water bottle poke wholes in it with a knife, then cut top off with knife, place a few marbles in it then tape them to the bottom, then place some more in, tape a thin peice of paper over the top, place it in the water upside down it will sink the marbles will drop through the wet paper it will float back up and flip over with the opening to the sur face then the marbles that are taped to the bottom will make it start sinking again

  60. I’m in 8th grade and I have the same project. What I did was:
    1) Cut a carrot in half lengthwise,
    2) Cut a hole on the flat side of the carrot in the middle,
    3) Fill the hole with baking powder and pack it in tightly,
    4) Break 3 toothpicks in half and place a half of the toothpick in each of the 4 corners of the carrot,
    5) Place the remaining 2 halfs in between the toothpicks already on the carrot.
    (THE TOOTHPICKS ON THE CARROT SHOULD BE SYMMETRICAL IN LENGTH AND IN HOW IT LOOKS WHEN ALL THE TOOTHPICKS ARE INSERTED IN THE CARROT!!)
    Ta-Daa! You now have a submarine that can float-sink-float at least two times in a row!!

  61. I had the same project, and I know this one works great. (I tested it 5 times in a row).
    Items needed:
    -1 film canister
    -A box of 12 Alka-Seltzers
    -3 Nickels
    -2 Pennies
    -Tissues
    -1 Nail

    1.) Poke 2 holes in the bottom of the film canister (not too small!)
    2.) Put the nickels and pennies in the film canister.
    3.) Wrap 1 Alkaseltzer tablet in tissue (2 Layers works best)
    4.) Put the Alka-Seltzer in the canister and fill the canister with water.
    5.) Drop the canister in the water and it will sink to the bottom right away, and stay at the bottom for at least 5 seconds.

    I hope this was a big help!!
    Thank you to all the other comments-they gave a lot of ideas! :-)

  62. just so u all know some teachers wont allow any of these cheesy ideas and if u choose to use any of them u should try custimizing it and using different but similar objects that work the same becaus e when i was in 7th grade i did this exact proj. and i flunked because the idea wasnt origanal enough. so i hope anyone with a mean or strict teacher that knows of the past/original ideas takes my advice and make ur project unique

  63. We have this project too. We think if you put 2 holes in the bottom of the suba nd let ir sink and then attach a straw to the lid of the bottle. when you blow into the straw thje water will be forced out through the holes

  64. that one awesome girl

    I had to do this project, and it was SUPER hard!!!! Anyways, what I did was take a black with gray lid film canister, and used a SCREW (NOT nail!) to poke TWO holes in the LID! Then, I took a regular, small, nail and put 3 holes in the bottom, four in the top. Then, I put 3 REGULAR marbles and one nickel inside. I then put two alka-seltzers inside, put the lid on, and put it in water! Water comes in through the holes on the bottom, sinks, then the alka-seltzer reacts and brings it to the top! It takes a LONG time sometimes, so be patient! It works, trust me! I couldn’t get mine to be yellow, so points were deducted. If this won’t work for you, keep trying! It’s a hard project, but all these projects are supposed to make you think! My mom helped me a LOT through this project, so ask your mom or dad for help, too! If it won’t work, keep trying! You’ll get it. Best of luck to you all, and Merry Merry Christmas!

  65. same person from above!

    Oh, and get the biggest box of Alka-Seltzer you can find! They cost only about $5, and there is a TON of trial and error involved with this project! And off-brand (I used Hy-Vee brand) tablets work just as well. Good luck and Merry Christmas, Hannukah, and Kwanza!

  66. hey u can use a funnel & marbles.
    All u do is put the marbles on the funnel and let the funnel sit with the tube down then u wait and the air will flow thru the tube and over flow the funnel. When the funnel hits the bottom of the tank it will let all of the marbles out and float to the top again! good luck!

  67. We have this project too, but our teacher used the funnel with a golf ball to demonstrate it, so that’s why we can’t use a funnel and golf ball like the rules say. Where do you get film canisters? We have a digital camera and no film anymore. We can use alka-seltzer so maybe that’s what I’ll try.

  68. okay… so you take a big plastic egg, 10 tablets of alkaseltzer, 10 pennies, and you put them in the egg, and it floats and sinks and floats ok there got it

  69. so i just did this project and i found a way that is pretty simple.
    what you need for it is:
    -A plastic bottle or tube
    -three rubberbands
    -24 pennies
    – a knife or sharp scissors
    -a straw(s)

    what you do is take the knife or scissors and poke a small hole in the cap of the bottle and then insert the straw into the hole.
    then you make three holes on one side of the bottle one should be near the bottom one in the middle and one near the top.
    after you have done that split the pennies into three groups (4, 8. and 12) then use a rubberband to attach the group of 4 in an area above the top hole then use the group of 8 and attach it above the middle hole and then attach the group of 12 to the bottom hole.
    then put the cap back on and place it in the water. it will float for a minute and then start sinking when it sinks all you have to do is blow in the straw to get it to come back up.

  70. Variation on the film canister theme.

    Take a standard film canister, drill 2 small holes in bottom (off center), one in lid (center). Place 3 quarters at bottom of canister. Drop in 2 alka seltzer tables. place 1 penny on top of alka seltzer tablets. Place lid on canister, place in water. Sinks in 7-10 seconds, resurfaces, sinks, resurfaces, etc. up to 5 times.

    This, of course was after hours of trying to balance the ballast on a two-bottle technique with balloons on either end. Weight ratio and air movement during submersion are challenges I’ve yet to figure out.

    Good luck!

  71. here, get a dixie cup tape alka seltzer to the inside bottom of it and but pennies or marbles in it or somehting and but a small baloon at the top of the cup…idk if that works but i think it would? maybe it can give you some ideas :)
    ps
    this project is SO frusterating!!!

  72. Ok so my sister is in 7th grade, and she is dieing to find this out. I’m gonna try this in just a second.

    Anyway, if you only have to float sink float, take a Dixie Cup and cut the top off, so that you have a shoter cup. Then poke 3-5 pencil tip sized holes throught the bottom. Then, poke a pencil through the middle, so that it sticks out throught the bottom. Then, put marbles in as necessary. It will should gradually sink because water will seep in through the holes in the bottom. The pencil will hit the bottom, tip the cut and marbles over, and make the marble fall out. Then, the cup & pencil will rise to the top.
    :{)

  73. Haven’t got a project to do like many, but my son is fascinated by submarines.

    I used a very large syringe as a type of pump. A length of tubing, a ballon and a small plastic bottle with holes and weigths as ballast. The syringe has to be full and the ballon empty. The syringe inflates the ballon and displaces the water in the bottle. Pull back on the syringe to remove the air and the bottle sinks. I can get this bottle to rise and sink as many times as I like.
    I was going to experiment with a foot pump only I need some way to release the air once the pump has filled the chamber. Hope this helps someone.

  74. By gosh I think I’ve got it!!

    Get one of the small plastic easter eggs. Take a heated knife and put small hole on both the top and bottom of egg. Place 13 pennies and 4 alka-seltzers inside. It floats sinks floats and repeats several times. We’ve tried them all. This was simple cheaps and really works.

  75. Hi i am Olushola I had to do this problem and i found a solution try using a 20 oz
    bottle cut it in half from center
    across. then spray paint a DIET pepsi
    can and the slide that into the 20 oz
    bottle then glue Triangular magnets to all the sides of the 20 oz bottle the drop it in water. DONT put it in a pot that is metal because then it wont work try in a laundry tub and in 4 seconds it will drop and in 17 seconds it will come back up

    Enjoy!

  76. people, this isn’t as hard as it seems. I was given a month to do the project, and my group has been working on it for 3 days, and we’re half way done! it’s fairly easy with the right materials and research.

  77. 8th grade student

    what my teacher did was use a medicine bottle thingy and fill it with some pennies so it would sink and one alka seltzer pill, then he put a little bit of water (so it would activate the alka seltzer) in the container and closed the lid so it wouldnt contaminate the water and put it in the tub..

    the results were that it went down, then back up, then down again.

  78. it was so stupid and easy! it took me almost the two weeks to figure it out, but when i did, it was so simple! you only need 2 things: a paper plate and a few rocks(I’m not sure what they have to weigh, just experiment,) Take the plate and swish it through the water a few times to make it really weak. Fold one end together like a burrito, it should stay that way. put in the rocks and shake it towards the bottom to make sure they are all there and the plate stays that way for a while. place gently, NOT DROP, the plate in the water. It will fill up with water and spin rock end down towards the bottom. when it hit, the burrito will unravel and the rocks will fall out. Some take a while to come out, but they all will eventually. The plate floats up to the surface! Yes, you make thank me 4 saving you! HAHAHAHAHAHAHAHA!
    -yes, I know I’m weird.
    MEEEHHEEEHEEE!!!!

  79. The experiment that worked for me was… I took a large pill container with 5 large 1/16″ holes in the bottom that let the water enter the capsule. Then one small 3/16″ hole in the lid to let out the air. Then you put a tablespoon of salt in the capsule. As the salt combines with the water and disolves out the bottom of the vessel. It creates salt water which is less dense the fresh water and that combined with the density of the capsule makes it float back to the surface, but you must be patient it takes about two minutes to resurface. This worked for me, hope it works for you. This for all you kids like me that r freaking out because this is the dumbest project ever. Good Luck!

  80. For the dixie cup with the marbles and the pencil through the middle… is the dixie cup 2 inches long? Because If it isn’t, couldn’t you just use like a regular plastic cup and it would use the same effects?

    Well I will try because we don’t have any dixie cups :)

  81. I found out another cool way to make a submarine. All you need is a carrot, toothpicks, and baking powder. It’s really simple. So it shouldn’t take too long. I have the same project to. It’s due friday. The only thing I need to find out is why does this work? Any ideas? If so, then could you post it on here? PLease and Thanks!

  82. tWO iS BEtteR ThaN OnE By Tay SwiFT RoX!

    btw. the idea for the paper plate and rocks, DOES NOT WORK!! so dont do that for your project. I didnt do it mysely, but my friend did. And it didnt work for her. It only sinks to the bottom and floats back up, but is doesnt sink again!! So sadly, I’m stuck with the Alka Seltzer and film bottle. :-( which is actually harder than it sounds. I’m STILL working on it. Hope this is useful info. <3TAYLOR:-)

  83. this is gonna be kind of complicated, but you can use a strong metal water bottle filled with air. the hook a small but strong pump to it. after the pump(oh, yea, since its gonna be submerged all the electronic parts gotta be water tight)put an electronic sprinkler valve at the end of the pump. wire it so the valve will be closed when the pump is off and the valve will be open when the pump is pumping either way. when the pump brings water in, it will compress the air and eventually there will be too much water in the water bottle(the water bottle acts as a ballast) sink. when the pump brings water out the air will decompress and it will rise again!!!

  84. I just did this with my daughter. We used the film canister, 2 quarters, 1 penny, and 2 alka seltzer tablets. The only difference from the above scenario’s was I left the alka seltzer’s in the foil packet. I poked 4 or 5 holes in the packet, folded it up and stuffed in the film canister.
    Worked the first time! Yeah!

  85. make a aluminum boat and put a hole in the bottom of it and sit it in the tank then it will float for 5 seconds and then it will subsurface float and then it will sink.

  86. get a plastic bottle poke three holes
    in it and put an eraser in it it works perfectly!!!!!!!!!

    you’re welcome