Dual Pump BALLAST DISPLACEMENT SYSTEM (BDS)

[QuarterMaster]

Due to issues with the previously purchased, single radial (paddle style) pump, I was forced to re-invent the wheel.

Thankfully, my experience with bilge pumps on my 1:1 scale boats, the solution eventually presented itself.

Off-the shelf, SUBMERSIBLE, 12VDC Brushless motors rated at 240l/h. Small enough to fit in your larger boats and as low as $3USD a piece!
Not to mention a MTBF of 10K hours!!
Like the aforementioned bilge pump, they only pump in one direction, but also like them, water flows back through the pump when off.
So you do need two...opposed, and lined up in series.

Preferable for larger boats with high volume ballast tanks. Realistic diving and surfacing, conserving onboard “gas”, and very low current draw.
1:48 scale or larger unless you're dealing with an OHIO, OSCAR or TYPHOON

Dual Pump BALLAST DISPLACEMENT SYSTEM (BDS)

Another in the "Not so reality TV" Series brought to you by.....
INDIVIDUAL ANEMICS
Electric Model Boat Division
...a "sub" Division of MRCSB (where the rent is TOO DAMN HIGH!!)

[type7]

I have a need for a pump system like this. What kind of valve are you using to keep the water from flowing thru the pumps when they are not pumping?

[QuarterMaster]

High-Use Backflow-Prevention Valve with Barbed Fittings for 1/4" Tube ID, Polypropylene Body

McMaster Carr P/N 47245K13

Insure they are lined up BENEATH the tank to insure the "bell jar" effect. Also note directions of flow!