Underwater Servo SER-203X Brushless, High Torque

Reliable, affordable, compact underwater servos with brushless motors and ultra high torque capability! With a machined acetal upper and lower case, these waterproof servos are rated to 200 meters. Or choose the anodized aluminum lower case option and you can operate at 400 meters!

• SER-2030: Features the Hitec DB961WP R/C servo with a PWM interface. This servo produces 5.4 Nm of torque and uses a brushless motor. Rated to 200m.
• SER-2031: same as SER-2030 but with anodized aluminum lower case, rated to 400m.

Output shaft is a 6-mm titanium D-shaft. Titanium Servo Hub available separately.

You will need a regular Cobalt 3-pin cable (NOT a 3-pin Power cable) to connect to these servos.

WARNING: These servos do not have internal protection against overheating or overvoltage. They can be damaged or destroyed by:

• driving the servo against a hard stop for more than 5-10 seconds
• running the servo at high torque continuously
• applying more than the recommended voltage to the servo

Users should design their electrical and mechanical systems to avoid these scenarios.

If you are not familiar with how servos work, we highly recommend doing a web search on "servo tutorial" and reading several of the results.

SKUs: SER-2030 SER-2031

Blue Trail Engineering’s Underwater Servos are compact, robust actuators for small marine robotic applications at depths of up to 400 meters. They consist of an off-the-shelf R/C servo installed in a machined enclosure with a titanium output shaft and waterproof connector. This architecture leverages decades of servo development in the R/C industry to provide extremely high reliability as well as almost limitless options for speed, torque, travel distance, and other features, all at a fraction of the cost of other subsea actuators.

We offer four models of Underwater Servos, each available with an all-acetal enclosure rated to 200 meters depth or a combination acetal/anodized aluminum enclosure rated to 400 meters depth.

• The SER-2010 (200m) and SER-2011 (400m) feature the Hitec D954SW R/C servo. This is our least expensive model, producing 2.8 Nm of torque with a brushed motor.
• The SER-2020 (200m) and SER-2021 (400m) feature the Hitec HSR-M9382TH. This servo produces 3.3 Nm of torque and offers an extended travel range (up to ± 3.5 full turns of rotation with position control or continuous rotation with speed control). It uses a brushless motor and magnetic encoder, eliminating the most common causes of servo failure.
• The SER-2030 (200m) and SER-2031 (400m) feature the DB961WP servo, which produces 5.4 Nm of torque and uses a brushless motor.
• The SER-2130 (200m) and SER-2131 (400m) feature the MDB961WP-CAN servo, which produces 5.9 Nm of torque. It also uses a brushless motor and magnetic encoder, eliminating the most common causes of servo failure.

All of the above servos are fully assembled and pressure-tested before shipping. 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 program the servos using the appropriate programmer.

We also offer the SER-2000 (200m) and SER-2001 (400m), kit options that allows users to select and install their own standard-sized R/C servo – including PWM, CAN, or serial servos – making this the most inexpensive and flexible option for underwater actuation. The kits come with the output shaft, bearings, and seal installed, and the user completes assembly with the servo and connector of their choice. Servos must be of the “standard” size (20-mm width) and have a 25-tooth spline. The following servos have been tested for proper fit:

• Hitec D625MW, D645MW, D930SW, D940TW, D945TW, D950TW, D954SW, D955TW, DB961WP, MDB961WP-CAN, HSB-9360TH, HSB-9370TH, HSB-9380TH, HSB-9465SH, HSB-9475SH, HSB-9485SH, HSR-M9382TH
• GoBilda (all models)

If you would like to use a different servo, please contact Blue Trail Engineering and we will help you determine if your servo will fit. You have the option to install a Cobalt bulkhead connector, a Cobalt cable with M10 penetrator, or a Blue Robotics WetLink penetrator (not included).

Output shaft is a 6-mm titanium D-shaft. Titanium Servo Hub available separately.

You will need a regular Cobalt 3-pin cable (NOT a 3-pin Power cable) or Cobalt 4-pin cable (depending on the servo model) to connect to these servos.

WARNING: These servos do not have internal protection against overheating or overvoltage. They can be damaged or destroyed by:

• driving the servo against a hard stop for more than 5-10 seconds
• running the servo at high torque continuously
• applying more than the recommended voltage to the servo

Users should design their electrical and mechanical systems to avoid these scenarios.

FAQ

Q: What is the difference between the SER-2XXX servos and the older SER-110X and SER-120X?

A: The main differences are:

• The enclosure walls are thicker, making the unit more durable and giving an increased depth rating of 200 or 400 meters.
• The surface finish is smoother and tolerances are tighter, making the O-ring seals more reliable.
• The external surfaces are flat for easier mounting from either the side or the top.
• It uses a 6-mm "D-shaft" output shaft instead of a square shaft, making it easier to attach to your device using a simple set screw.
• There is an available kit option, made possible by an easier assembly process.

Q: What kind of fasteners are needed to mount the servo?

A: The holes in the top face of the housing are 16 mm deep and are intended to be used with #6 or M3.5 self-tapping screws like these. The screws should have between 12 and 16 mm of engagement in the plastic. The holes in the sides of the servo go all the way through the servo and are 3.2 mm in diameter, so use M3 screws longer than the width of the servo (which is 32 mm) to mount in this direction.

Q: How do I mount things to the output shaft?

A: The best way is to use our Titanium Servo Hub. Or you can use any type of 6-mm set-screw shaft coupling (including a homemade one), but be aware that the output shaft is titanium and you will get some amount of galvanic corrosion if you put a different type of metal in contact with it. You can also use a hub like these from ServoCity, but again, be sure that the materials are suitable for your application (putting aluminum in contact with titanium in seawater for an extended period of time is not a good idea).

SER-2XXX Datasheet

Need CAD files? Please see the Resources page.