R/C Paradox - a Pair of Radio Controlled Duck Decoys

After driving my friend's R/C boat on a duck pond one day, I was inspired to build an R/C duck.
I ended up buying a pair of duck decoys at the local flea market for $10. These are intended to be used by duck hunters to lure unsuspecting water foul within blasting range. When researching what kind of cheap R/C boat I could find to tear apart and reassemble into the duck, I found the yellow 10" submarine at RadioShack on sale for $20. They are available in two different channel frequencies, so I bought one of each, (excited now that I might be able to make two!). So now all I had to do was figure out a way to connect the ducks to the submarines in a fashion that would allow them to look and float like real ducks.

below are som links i found along the way:

R/C duck with a vengeance and rocket launcher

RadioShack R/C submarine

DuckCam Decoy Intructable

commercially prebuilt R/C ducks

I had a hard time with the first version of the project, making a good seal between the duck and the sub.
It sank.I decided then, if I filled the duck with foam, it wouldn't matter if it leaked.
Also it would be easier to change the batteries, or add a different accessory, like shark fin.

duck decoy - hollow hard plastic, not wood or rubber.
spray foam - this stuff is messy and hard to clean up
submarine
heat gun
utility knife
(not pictured)
drill, holesaw, all thread stud, hex nut, hot glue gun

This where I should mention a missing step.
Notice in the picture I have used a hole saw to cut a circular hatch in the duck's back.
go ahead and do this first.

I used a utility knife. depending on the hardness or thickness of your duck you may want to use a dremmel tool or a saw. It did help a little to heat up the blade with the heat gun. The ballast is what makes the duck float upright. This will also create the hole that we need for the periscope and upper part of the submarine to fit inside the duck.

The top of the submarine isn't completely flat like the bottom of the duck. To make the duck contour the submarine, I used a heat gun, to warm up the plastic, and pressed the submarine into place. You may need to hold the sub there until the plastic cools. different plastic have different memory properties, so you may need to exaggerate the indention to have it fit properly when it cools.

I suggest using rubber gloves, because this stuff is really hard to get off your hands.
After allowing the foam to completely cure, carve out the space for the periscope section of the submarine.

The submarine already has a small hole in the top portion behind the periscope. I simply drilled it out a little bigger with 5/32" bit. Then I used the heat gun to heat up a 3/16" all-thread stud, and drove it into the hole. This will stick out through the ducks back, and be our connecting point.

Using the same method as the previous step, I drove a machine screw into the top of the periscope.
The periscope happens to be the power switch for the submarine. I chose a screw with a large head.
it will be concealed inside the duck, but accessible via a hole, in the ducks back. You want it to come close the the duck shell with out touching it, so you can push it with a key or a small screwdriver.
(yes I'm and old school Mac user)

you may want to take some measurements, with the duck pre-assembled to get the screw length right.

here I have hot-glued the circular hatch back in place and drilled a hole in it that matches up with
the stud allowing it to penetrate the duck shell and accept the nut that hold the whole thing together. through the hole on the left you can see the machine screw head. this is our power button.

Duck is now seaworthy. Now repeat steps 1-7 for a second duck.

I took the duck for a test swim in Golden Gate Park, next to the DeYoung Museum. Currently there is a large neon sculpture there that is part of the Dale Chihuly exhibit.

here's some pictures I took of the Saffron Tower

and a short video clip of the other duck in action