TRIMMING:

Before deep test run you have to trim your boat.

Add some lead to balance the sub. If you do not use the blow tank,  the sub has to be a bit heavy in front in order to use the motor to go down. The ship in this case should be a bit "Positive". 

Instead, if you use the blow tank the ship should be carefully balanced and neutral (with the blow tank empty) or bit positive. I used ca 1.8 Kg for the first version and 1.4 Kg with the BT.

OPERATION:

Without the BT just use the two motor to submerge and no motor to go up. 

Use alternatively one or the other to turn around. That’s all.

With BT just slowly fill the tank and submerge and the motors to turn.