Water Bottle Submarine

I came up with this idea after reading this article on this website:

https://basic-mechanics.yolasite.com

I have made the following water bottle submarine from a water pump that I purchased on the Amazon website:

I used connected the rubber tubes with plastic fitting from eBay:

Step 1: Seal the Pump Electric Input with Blue Tack

This step is needed to prevent water from entering the pump motor. You need to use soft sticky clay that does not harden. Blue tack is a good example: 

This step might not be necessary if you are using the correct pump. However, motors in most typical pumps (not to mention low-cost pumps) are submerged in the water anyway.

Step 2: Connect the Pump Hose to Bottle

This plastic bottle is from an old Scott's Hand Sanitiser:

You can remove the plastic lid and seal it with blue tack, you can see in the first photo of this article.

Step 3: Make a Hole in the Bottle

You will need to make a hole in the bottle to allow air to exist in the bottle as it is pushed out by incoming water when the submarine is sinking. You can use an art compass or hole puncher.

You can see water coming out of those holes (at the top of each water bottle) in the video.

Step 4: Build a Rectifier for Water Pump

Do not connect the water pump to the power supply/batteries in reverse polarity. It might fail immediately.

You need to make this Schottky diode rectifier:

Conclusion

If your motor runs on 3 V or 6 V you can make a submarine that does not need external power wires for the water pump. You can attach batteries.

However, the batteries will need to be well sealed to prevent water damage.