PROBLEM - 'What is the simplest way to remove and replace water in the ballast tank, repeatedly'?

There are three contenders for the job!

1. RCABS (Recirculating Compressed Air Ballast System)
2. Pistons
3. GAS

RCABS and Piston systems use power from the main battery to operate motors which either drive compressors water pumps or pistons to move the air or water to alter the displacement of the boat. They employ electrically operated switches or servos and valves to control this.

Valuable space within the watertight cylinder(WTC) is taken up with this equipment. For the novice, these systems are difficult to install and require a high degree of skill to maintain. Electrical understanding, and circuit testing skills are a pre-requisite.

RCABS Systems are not commercially available as a 'ready to run' system. They require many hours building time. These ‘experimenter kits’ cost OVER $450 in parts alone, without costing in the many hours spent on assembly.

Piston Systems are expensive to purchase, but are available commercially as kits. They are large units driving a piston in a tube, using a motor. Much peripheral plumbing and wiring. Many hours needed on assembly.

The RCABS and Piston systems are a plumber and electricians nightmare; plumbing and electrical connections need to be continually monitored for leaks.

RCABS compressors will not create enough compression to fill a bladder a depths of 15 feet or greater.

HERE IS WHY YOU NEED A D&E SUB-DRIVER

1. GAS! We've got GAS! Liquid gas propellant ballast tank operation.
2. Immediate BLOW-VENT operation. Realistic and scale like - No wait for bladder or piston pumps. Does not require a vent above the water-line as does a pump-type ballast system.
3. Low Maintenance - No wires - no pipes - no motors - no pumps - no bladders - no problems! One factory-installed servo does it all!
4. Minimal space requirement - leaves room for torpedoes (coming soon) and other neat stuff like Up-Periscope systems.
5. Gas Empty Indicator - Boat assumes slightly positive trim, changes position in the water when GAS charge is low, telling Commander to return to the Depot Ship.
6. Unique 'Gas Saver' mechanism meters out exact amount of gas to 'blow' ballast tank. (N/a to 1/144 Seawolf & Kilo do to limited space.)
7. Deep Dive Blow Feature. Ballast tank will BLOW at depths of up to 100'. Air pumps only work up to 15-20 feet.
8. Fail Safe. Any gas leaks (unlikely) automatically fill ballast tank and surface the boat.
9. Low Battery Drain. Occasional split second servo use to operate blow-vent- no pumps or motors to operate.
10. Already installed. ANTENNA, MOTORS, GEAR-BOX REDUCTION, BATTERY POWER CORD, PULL HANDLE (to remove end-cap), PUSH-ROD and DRIVE SHAFT SEALS (Buna 8), PUSH-RODS.
11. No assembly required - Ballast system is 'ready to run' & Fully Water Tested.
12. Servo and Electronics Mounting Tray - glue your speed controllers etc. in place.
13. KLIK-ons (magnet connectors) Quickly connect to rudder and dive plane push-rods. No fiddly screws.
14. A D&E Sub-driver is a great investment. It actually holds its price when resold. People 'in the know' will always buy a second-hand D&E Sub-driver.
15. On-line Technical Support - Repair Service Available.

And finally, Mr. Merriman’s take on the subject! “Guys who use other type ballast systems dress funny, have bad breath, don't like girl's, and are chosen last when sides are picked for a ball game”