How to Make an Underwater Robot

Reference : Build Your Own Underwater Robot and other wet projects,
by Harry Bohm and Vickie Jensen

First, let me say that the book is pretty neat and a must have if you want to get started on building a robot for underwater research. It gives a nice history of underwater vessels so you can better understand what goes into making a water craft of this type. The book seems a little geared towards a kindergartner at times, but it really is usefully. Now things like transmissions for radio control and brains for the robot are left up to you, but the book does tell you step by step how to build two underwater ROVs, Remotely Operated Vehicles. The one I am going to explain here is the SEAPERCH, the other is more advanced and is named the SEAFOX. The SEAFOX uses tiny bilge pumps to dive and surface.
The SEAPERCH uses DC motors with fan propellers for propulsion underwater.

Parts list:
1 - 60" length of 1/2 inch of regular PVC or plumbing pipe cute in these lengths:
2 - 4 and 1/2 inches long
2 - 4"
4 - 3"
4 - 2 and 1/2"
and 6 that are 1 and 1/2 inches long
10 - 1/2" PVC 90 degree elbows
4 - 1/2" PVC tee's
1 - 10" sheet of heavy duty plastic hardware cloth or 1/4" wire mesh screen
2- 4 1/2" long by 22 3/4" diameter hard closed cell foam fish net floats or you can make your own floats out of two 2" diameter by 10" long PVC pipe with end caps glued on.
3 - film canisters to use as covers to protect the motors

You'll also need three 12 volt motors like the ones from radio shack - # 273-255
and three small propellers that are 1" in diameter model # FP-40 made by Billings Hobby and you can pick them up at most local hobby shops.

You'll also need some fishing weights or balancing leads for the ballast, the book says the weight will be determined by the displacement of the ROV. The idea is to put the weights on the mesh screen and make it so the ROV just barely floats, with the bow slightly higher than the stern.
The wired remote controlled part, I will tells you how to do that step by step also if you need to know that. Just a 12 volt battery, 3 DPDT center off switches and a good amount of wire.




I want to also add that to make the motors air tight the books says to use the film caps (which can be seen on the motors below) and make sure to cover all the motors holes and use petroleum jelly and melted wax to seal up the around the holes of the canisters, just make sure your motor shaft can spin.





Sample of a simple ROV Installation, SEAPERCH

STEP #1


STEP #2



STEP #3





STEP #4

Posted in: Underwater