Picture of Alka Seltzer Powered Bathtub Boat
My daughter had a school assignment to bring a boat that could cross a fish tank under its own power. It was legal for dads to help. Some chose rubber band power. I decided on bubbles from Alka Seltzer mixing with water.

I used a piece of styrofoam about 1/2 inch thick (See the right portion of the graphic.) and a plastic canister from a roll of 35 mm film. Not shown is a piece of clear plastic tube for a fish tank air pump about 3/16 inch in diameter on the outside or less.

Cut out the styrofoam to receive, but still support the film canister. The hole at the rear of the boat is for the clear plastic tube. Shape the styrofoam to resemble a boat hull.

Step 1: Inside the film canister

Picture of Inside the film canister
Make wire support to hold an Alka Seltzer tablet up from the bottom of the film canister near the top of the canister.

The left portion of the graphic shows a cutaway view of the inside of the canister with the wire support in place. The right portion of the graphic shows the wire support.
Kiteman6 years ago
Oh, please re-create this with photos.

Preferably embarrassing ones of your daughter carrying it to school. You have a parental duty to make her cringe in public.
Phil B (author)  Kiteman6 years ago
She was probably about six or seven years old at the time. She is now 36 and lives 2,100 miles away. I think I already embarrass my kids by just being. Thanks, though.
Kiteman Phil B6 years ago
Haha. Still, you should add photos, maybe a video to give an idea of the speed.
Phil B (author)  Kiteman6 years ago
At present I do not have the materials to make one of these, nor do I have the original I described making. I am also not equipped to do and post video. I would say the little boat moves about the speed of an ant migrating across the top of a table, assuming the ant does not stop and knows where it is going.
Karentoo Phil B4 years ago
I'm glad you posted w/o photos, Phil. Photos are nice but the idea is what matters most. I look forward to experimenting with this when I next see my grandson and it never would have occurred to me w/o your photo-less post!
Phil B (author)  Karentoo4 years ago
Thanks. A friend made one of these for the preschool class she teaches. She made the Styrofoam boat much larger than it needed to be. Her boat worked, but the water resistance increases when the Styrofoam is larger than necessary. It will not be very fast, but it amuses small children as it put-puts under its own power. Let me know how your grandson likes it.
hhhttt Kiteman5 years ago
dude honestly leave people alone all 3 of mine dont have fotos get a like you nerd look at that big note that says BE NICE
Kiteman hhhttt5 years ago
Firstly, you're replying to a comment I made two years ago.

Secondly, I am being nice.  That was called constructive criticism.  Look it up.

Thirdly, it is site policy that projects should have original photographs, which you would know if you paid attention.

Fourthly, what "3 or yours don't have photos"?  You only have one project published,  which has photos (of a sort), and it has only had one view since the middle of February.  Two if you count me checking it.

Fifthly, to tell somebody off for breaking the "be nice" policy by insulting them is called hypocrisy.  Look it up.

Bad grammar, lies and an insult.  Way to go with gaining respect, dude.
snoyes Kiteman6 years ago
and a scan of the thank-you note, too
Phil B (author)  snoyes6 years ago
I tried a couple of methods to scan or photograph the note. It is in pencil and very faint on the paper. I could not get anything legible to show.
Phil B (author) 5 years ago
As soon as the water makes contact with the Alka Seltzer tablet, the tablet begins to fizz and also to use itself up.  I needed a way to enclose the tablet inside the film canister with the water, but without the water and the tablet making contact.  I made a wire shelf to hold the tablet above the water until the boat is turned from vertical to horizontal.  Then the water and the tablet come together.  The tablet begins to produce bubbles, which flow through the tube and propel the boat forward.  I hope this helps.
19samman985 years ago
can you explain it better i dont get not bein mean just dont understand
bylerfamily6 years ago
I had only 2 of the ingredients.So I used a bottle with a piece of tubing stuck in a hole in the cap.Then I filled it half full of water and dropped a broken tablet in.I then stuck it in the bathtub and it went across the tub twice.Then I tried baking soda and vinegar.It went across the tub like a bullet,spraying a visible jet stream of vinegar.Thanks for the inspiration.
Phil B (author)  bylerfamily6 years ago
Thanks for the report. I am glad it worked for you. The vinegar and baking soda is a good idea.
Yeah.The baking soda and vinegar produces more CO2 than than alka-seltzer tablets but it runs out faster.