Underwater servo with corrosion-resistant titanium shaft

Waterproof High-torque Servo SER-120X, multi-turn, BLDC motor

SKU: SER-1207

Digital, waterproof servo, submersible up to 100 meters.  Programmable rotation up to 7 turns or continuous rotation.  Brushless motor and magnetic encoder.


SKU: SER-1207

Blue Trail Engineering’s SER-120X is the ultimate underwater servo for small robotic applications. Unlike any other servo in its class, it can be programmed to provide up to 7 turns of rotation with position control or continuous rotation with speed control. The SER-120X features a brushless motor and magnetic encoder, eliminating the most common causes of servo failure. Ideal for Autonomous Surface Vehicles as well as Remotely Operated Vehicles, the SER-120X provides reliable, long-term actuation at depths up to 100 meters.


The SER-120X is based on the Hitec HSR-M9382TH digital servo. Blue Trail integrates a modified HSR-M9382TH into a corrosion-resistant, depth-rated Delrin® housing with a ball-bearing-supported titanium output shaft and nitrile quad-ring shaft seal.


  • Submersible up to 100 meters
  • Programmable up to 7 turns of rotation or continuous rotation*
  • Brushless motor
  • Magnetic encoder
  • Compact size
  • Low power draw
  • Engineered for months of exposure in seawater or fresh water
  • Corrosion-resistant titanium output shaft, Delrin® enclosure
  • Standard R/C PWM interface
  • Servo arms included
  • Square output shaft for easy integration

The SER-120X utilizes the compact and reliable Cobalt 3-pin dry-mate bulkhead connector, compatible with Cobalt Series cables from Blue Trail Engineering.  Custom connection options are also available.


* By default, this servo travels approximately 1/2 turn.  If you require increased travel or any other changes to the servo's programmable parameters, we will happily program the servo per your specifications for free.  Simply email sales@bluetrailengineering.com after placing your order.  Alternatively, you may use a DPC-11 programmer with the BLDC_HSR User interface_Ver 3.1 software (download here).