I used to make these all the time with my dad when I was a little girl and we would "race" them in the tub. They are super easy to make and tons of fun to play with.
This is my daughters cucumber that she chose.
Next you cut the top off you want it wide enough that you can get a small spoon in it to scoop out the seeds but not too wide that it can easily get water in it.
This is what it should look like after taking the top off.
Next scoop the seeds out.
You can leave it like this if you want, or make a sail. We use to used pencils as our masts, but this time we had some kabob sticks laying around so we broke one in half. If you do decide to make a sail be careful poking it into the bottom of the boat so you don't poke a hole in it and spring a leak. :)
This is how my husbands boat turned out.
We took them out to the river and raced them. It's kind of hard to see them but there are there in the middle, one with a sail and one without. Have fun making your own!