Press and move to zoom
Mouse over image to zoom


Product #: 010-0173-00

Castle is excited to return to the boat market after a decade long hiatus. We are pleased to present the Hydra XLX2!

The Hydra XLX2 is based on our popular and powerful Mamba XLX2 ESC. We've removed the air cooled heatsink and added a watercooled heatsink. It is finished off with an aluminum top plate for a clean look. Attached to the top plate are two aluminum, water fittings for 1/8" tubing and uses standard 10-32 UNF threads; package includes optional .17" fittings.

CRYO-DRIVE™, Castle’s proprietary breakthrough technology integrates unique software and dedicated hardware to reduce heat and dramatically increase performance.  Thousands of times per second, the Hydra XLX2 software minimizes the amount of time the electrical components spend generating heat.  The results are more power handling, cooler ESC temperatures and longer runtimes and for ultra-high performance.

NOTE: Due to the high power nature of the Hydra XLX2, you must use appropriately sized batteries and connectors. We recommend a minimum 150 amp connector for the Hydra XLX2; examples include Castle 6.5mm polarized, EC8 and QS8. DO NOT USE XT90, Traxxas, EC5/IC5 or any other connectors rated below 150 amps continuous.

You can easily optimize the ESC for any running conditions. Create, save and download setup profiles through the Castle Link Programming Suite on your Windows™ PC, or wirelessly with the convenience of the new B-Link™ Bluetooth™ Adapter and Castle Link app for Android or iOS.

Additional tuning flexibility awaits you with on-the-fly adjustments from your transmitter via the Auxiliary wire. Simply connect the white signal wire to an open radio channel, and enable the feature in Castle Link by selecting what Auxiliary function you would like to use. Access programming parameters such as Torque Control, Max Brake or Max Throttle. 


  • Input Voltage Range 3S-8S LiPo (33.6v max)
  • Sensorless, SmartSense™  and Brushed Running Modes
  • Powerful Integrated 20A Peak Adjustable BEC (5.25V-8.0V)
  • CRYO-DRIVE™ Technology minimizes the amount of time the ESC’s electrical components spend generating heat, resulting in improved thermal performance during partial throttle operation where the majority of driving occurs
  • ESC is housed in a rugged CNC aluminum case and potted in waterproof epoxy to protect the electronics and promote efficient heat transfer
  • Machined water-cooled heatsink with water fittings for 1/8" tubing.
  • Compatible with S.BUS2 Telemetry Link and Futaba T4PX, T7PX and T7PXR transmitters
  • Mounting holes located in bottom of aluminum case for affixing to your vehicle
  • Data logging capability to capture and record performance data from your vehicle
  • Auxiliary wire functionality for "on-the-fly" adjustments using your transmitter
  • Audible alerts for easy diagnosis of common issues such as motor-over-temperature and low-voltage cutoff
  • Convenient transmitter programming for six common adjustable settings including cutoff voltage and drag brake
  • Castle Link USB programming kit (coupon included with purchase)
  • Optional smartphone-based programming with the B-LINK™ Bluetooth Adapter (sold separately) and Castle Link all available on Google Play or Apple App Store)
  • Proudly designed and manufactured in Olathe, KS USA and backed by Castle Creations' 1-year warranty


  • Hydra XLX2 ESC with water fittings for 1/8" tubing
  • Castle Creations Decals
  • Coupon for free Castle Link USB
  • Hydra XLX2 Quick Start Guide

Hydra XLX2 Quick Start
X-series Drivers Ed Guide
XLX2 Mounting Template
Audible Alert Reference
Hydra XLX2 Product Use Statements

(Based on 3 vote(s))
3 review(s) | Write a review
USD $325.95 /EA
List Price: USD $397.95 /EA
  • Waterproof : Yes
  • Telemetry Capable : Yes
  • Data Logging : Yes
  • Auxiliary Wire : Yes
  • Minimum Input Voltage : 3S
  • Maximum Input Voltage : 8S
  • Sensored Capable : Yes
  • Recon G6 Certified ESC : No
  • ROAR Certified ESC : No
  • CRYO-DRIVE : Yes
  • B-Link Compatible : Yes
    • EA
  • Availability: This item is in stock.
Product Use Statements
  • Individual transmitter signals for neutral, full throttle, and full brake vary. You must calibrate your Castle ESC so that it will operate effectively with your transmitter.
  • Anytime the ESC is powered up with a new transmitter or with different throttle channel settings, it will need to be calibrated to the transmitter’s throttle settings.
  • The ESC may also need to be calibrated after updating to new software via Castle Link.
Input Voltage:
  • Applying voltages higher than 33.6V will cause irreparable damage to your Hydra XLX2 controller.
  • DO NOT RUN HV CELLS (above 4.2v/cell) WHEN RUNNING AT MAX CELL COUNT (8s). This will exceed the 33.6v rating and will damage the ESC and not be covered by the warranty.
Battery Capacity Minimum:

  • The Hydra XLX2 is a high-performance controller; you must use high-discharge cells in your high-performance application to ensure vehicle performance.
  • MINIMUM battery capacity is 5000mAh and MINIMUM of 50C continuous discharge for general use
  • For extreme setups we recommend a MINIMUM of 70C continuous discharge LiPo batteries.We have tested and recommend these brands for extreme setups: SMC True Spec Extreme V2 150C 6400mah, China Hobby™ CNHL GPLUS 6000mah  (white), Power Hobby Pro Lipo 100C 6000mah and Turnigy Graphene Panther™ 75C
  • If the batteries you are using contain input bullets you might consider upgrading to a direct wired pack as the bullets may not be able to handle the currents that the Hydra XLX2 ESC can push out. 
  • If you must disable low voltage cutoff to prevent the ESC from shutting down then your batteries are insufficient for your application. 3.2v/cell is the lowest a LiPo battery should ever be discharged under load. Utilize the data logging capability of the ESC to verify your batteries are not sagging to the cutoff voltage. Exceeding a LiPo batteries capabilities can lead to a catastrophic failure of the battery and/or ESC.
Wiring and Soldering:
  • High strand count silicone coated copper wire is essential with higher power electric power systems. Castle Creations' wire is lower resistance than the same diameter of solid copper, meaning more power gets from the batteries to the motor with less wasted as heat.
  • The ultra-high strand count and silicone coating means the wire is very flexible which prevents work hardening and breakage with use. 
  • Use a high quality soldering station. Soldering stations usually have a variable temperature control which lets you set the right amount of heat to be used. Too little heat will result in a cold solder joint; too much heat can seriously damage a component. The key factors in quality soldering are time and temperature. Our recommendation for the Hydra XLX2 is a temperature setting of 400° C (745° F). You want it hot and as short a time as possible. We use 250W soldering irons.
  • Use a high quality rosin core solder.  The rosin core solder is infused with flux which helps clean the surfaces you    are soldering for better adhesion.
  • Do not exceed more than 18 inches of total wire between the battery and ESC (this includes the wire already on the ESC and battery).
  • Do not solder wires directly to the circuit board. Doing so will damage the ESC and void the warranty.
  • Our wire is available for purchase and this link provides the appropriate wire gauge for your Castle ESC.  http://www.castlecreations.com/wire-application-chart
.Connector Ratings Minimum:
  • The Hydra XLX2 requires the use of connectors designed for 150+ amps continuous. We have tested and recommend Castle 6.5mm Polarized, Castle 8mm Bullet, QS8 Anti Spark and QS10 Anti Spark
  • Do not use Deans, Traxxas, EC3/XT60, EC5/IC5, XT90/XT90s connectors in a Hydra XLX2 setup
  • The Hydra XLX2 is capable of handling incredible amounts of power, your motor must also be up for the task. Always run your motor within the manufacturer’s specs. Monitor motor, battery, and controller temps carefully and never let the motor get above 200° F.
  • Excessive heat in the motor can damage the motor, the Hydra XLX2, and your batteries.
  • The default “Smart Sense™” modes uses the sensors (if applicable motor is used) to start the motor smoothly. Once the motor is running the ESC stops using the sensors and reverts to sensorless operation. If a sensored motor is not used, the ESC reverts to full sensorless operation.
Prop size:
  • When you are tuning a boat, expect some modifications in prop size to get it exactly where you want it.  The goal here is to not overheat the motor, ESC, and/or batteries.
  • Check your motor temps – never let the motor get above 200° F - invest in an infrared thermometer so you can monitor temps easily.
  • You can also adjust MOTOR TEMPERATURE CUTOFF (with Sensored Motors Only) in Castle Link.  When this setting is enabled, the controller will shut off if the motor reaches the specified temperature as indicated by its internal temperature sensor.
  • We always recommend making small changes when propping up.
Castle Link Settings:
  • During the optimization of your setup it is critical to check motor and ESC temperatures after making adjustment.
  • The heat limit threshold for Hydra XLX2 ESC is 200° F and Castle motors is 200° F. 
  • We recommend the use of the data log as you progress with the feel and power of the vehicle. You will be able to record real-time data such as motor RPM, battery current and voltage, ESC and motor temperature, throttle input, and more.
  • Download and analyze the collected data via Castle Link and make adjustments to maximize both performance and battery life.
AUX Wire:
  • The AUX wire allows you to adjust a setting “on-the-fly” using an auxiliary channel on your receiver.
  • The AUX wire function is disabled by default and is programmable via Castle Link. Plug this wire into the auxiliary (#3/#4) channel on your receiver.
  • You MUST connect the AUX wire to an open channel on your receiver even if you are not using the Auxiliary function.
  • You MUST disconnect the AUX wire from your radio before connecting to Castle Link. Failure to do so may result in damage to your Castle Link and/or computer.
Operating Environment
  • Although Hydra XLX2 is waterproof, it is not intended for operation while completely submerged in liquid.
  • Always rinse the ESC and motor with clean water after exposure to corrosives or dirt.

Technical Specs
Application Guidelines:
RC Hobby boats up to 50"
Input Voltage Range:
MIN: 3S LiPo, MAX: 8S LiPo 33.6V
Running Modes:
Sensorless, Brushed and SmartSense™ when paired with a Castle 4-Pole Sensored Motor.
Brake: Available, but disabled by default.
Reversible: Available, but disabled by default.
On/Off Switch: Yes, waterproof
Water cooling fittings
Two fittings, for 1/8" tubing installed. Optional .17" fittings included. Uses 10-32 UNF threads.
Size: Length: 3.98” (101.2mm),  Width: 2.49” (63.3mm),  Height: 1.34” (34mm)
Weight (with wires): 12.8 oz (362g)
Continuous current rating*: (SEE NOTE BELOW)
Burst current rating*: (SEE NOTE BELOW)
Motor Connectors:
8mm female bullets on circuit board, matching 8mm male bullets for motor required (not included)
Items Needed for Operation: The Hydra XLX2 requires the use of connectors designed for 150+ amps continuous, such as Castle 6.5mm polarized or CC BULLET 8.0MM, QS8 8mm Anti Spark or QS10 10mm Anti Spark. You will also need 8mm male bullets for the motor connections.
Operating environment:
Waterproof design for all weather conditions (See Operating Environment Considerations)
Fully programmable Castle feature set using Castle Link USB adapter (coupon for free link included in package) and freely downloadable Castle Link Windows software, or the Castle Link App and a B-LINK Bluetooth Adapter (sold separately).
Telemetry Link Capable:
Yes, with Castle Creations Telemetry Link for S.BUS2 and Futaba T4PX, T7PX, T7PXR, and 10PX transmitters.
Tech Tips:
The Hydra XLX2 has threaded mounting holes on the bottom of the ESC. There are four M3 mounting holes with a maximum depth of 5mm; they are spaced 46mm wide and 40.2mm long. Use this template for assistance in alignment and screw hole positioning.

If replacing the water cooling fittings, it is recommended to use Loctite® 545 (or similar) on the threads. This will ensure a watertight, 25+ PSI strong seal.

For support, frequently asked questions, technical documents, and more, visit our support site.

Castle Creations, Inc. warrants this product to be free from manufacturing defects for a period of one year from date of purchase.

This is a high power product with the potential to be very dangerous. Please read the safety information before use. This product may contain chemicals known to the State of California to cause cancer and or birth defects or other reproductive harm.

*RC HOBBY CURRENT RATING: Castle does not generally publish amperage ratings for surface ESCs. There is no standardized industry method for testing and rating ESC current capabilities. Castle's testing methods tend to result in much lower numbers than our competitors; we feel our numbers better represent the products actual capabilities. But due to the difference in testing and rating methods, our ESCs can look weaker in comparison to our competition. Please keep that in mind.

The continuous current rating is for 5 minutes with proper cooling, adequate connectors, and batteries. Using improperly sized components can lead to ESC stress and failure that is not covered by the warranty. Controller temperature must never exceed 100° C (212° F). Exceeding current or temperature ratings may damage components and may shorten the life of the ESC. Always verify system current draw at full-throttle. Decrease load to decrease the ESC's operating temperature. Many users have pushed MUCH higher numbers, but Castle makes no guarantees on the long term reliability of the product or on the warranty.

The burst rating is for short, momentary periods lasting no more than 2 seconds. The time between bursts, how long the burst lasts, and water temperature will affect temperatures. Make sure all components in the system (battery, connectors, motor) are capable of handling said current. Closely monitor ESC, motor and battery temperatures and review ESC's data logs.

U.S. Patent # 7400103, 7492122, 7579796, 7740516, 8287328, 8678875, and 8905814 B2 - Other patents pending.

Controller designed and circuit boards manufactured, in Olathe, Kansas USA.
Controller assembled in Olathe, Kansas USA.

Product Features
  Castle’s newest software technology, CRYO-DRIVE™ minimizes the amount of time the ESC's electrical components spend generating heat by optimally controlling which components are being used while driving the motor. This is happening thousands of times per second, which greatly reduces the rate at which the ESC heats up.  This results in significantly improved thermal performance during partial throttle operation where the majority of driving occurs. Your setup will be able to handle higher gear ratios, in heavier vehicles, with longer runs.

When paired with a Castle 4-POLE 12-SLOT SENSORED MOTOR SmartSense™ software, enabled by default in the Castle Link Programming Suite, will use the motor’s sensors to provide smooth starts, excellent torque, and low-speed drivability.  Once the motor is turning, it seamlessly transitions to Castle’s ULTRA-EFFICIENT sensorless mode with electric timing. Smooth sensored startups and high-efficiency sensorless running makes the Hydra XLX2 system produce more power and less heat. QUIETSENSE™ is an innovative advancement in the design of sensored motors to deliver the highest precision and most efficient startup.

The Hydra XLX2 allows “on-the-fly” adjustments to be made through the AUX wire once enabled in Castle Link. Once you have selected an AUX wire function, that setting can then be tuned from your transmitter while driving. Torque control, max throttle, max brake and drag brake adjustments are a sampling of the available modes. This real-time tuning allows you to quickly and easily fine-tune your system. . Click here for additional information.

Enabled by default, the Hydra XLX2 captures and records performance data from your vehicle. This allows you to view a detailed turn-by-turn record of what your ESC actually experienced during the run. You will be able to record real-time data such as motor RPM, battery current and voltage, ESC and motor temperature, throttle input, and more. Download and analyze the collected data via Castle Link and make adjustments to maximize both performance and battery life.

For over 20 years Castle engineers have been setting the bar for industry leading software functionality. The Castle Link Programming Suite is your ticket to creating the perfect setup. To gain access to the host of tuning parameters, simply redeem the coupon for the Castle Link adapter included with your Hydra XLX2 purchase and download the simple to install software from our website and you are ready to personalize your controller's settings. You can now wirelessly program your ESC with the free Castle Link Mobile App and the purchase the B-Link Bluetooth Adapter. Click here for settings overview for the Hydra XLX2 ESC.

You can now WIRELESSLY PROGRAM settings with the free Castle-Link app available on the Apple App store or Google Play for Android devices and the Castle B-Link™ Bluetooth™ Adapter (sold separately). It is compact and lightweight installed in your vehicle, for anytime programming!

Hydra XLX2 is telemetry ready, which means owners of Futaba 4PX, 7PX, 7PXR, and T10PX transmitters will be able to purchase the Castle Creations Telemetry Link for S.BUS2. Real-time data such as ESC temperature, voltages, and RPM can be monitored to ensure performance advantages and spare you the “unknown” parameters that all R/C enthusiasts experience at some point. Telemetry data provides another level of protection and can increase performance.

Housed in a rugged CNC-machined aluminum case and then potted in waterproof epoxy. This not only protects the electronics but ensures any heat generated in the controller can easily be dissipated through the case.

Hydra XLX2 features Audible Alerts that will notify you via audible chimes of possible issues with calibrations and error conditions to help diagnose problems .

The Hydra XLX2 is proudly designed and manufactured in Olathe, Kansas USA and is backed by Castle Creations’ 1-year warranty and unparalleled "make-it-right" customer support. Call us, email us, or walk in our front door – we’re here to help. Click here for additional information about our Tier 1 and Tier II warranty.

Optional Accessories
B-Link Bluetooth Adapter supports iOS and Android App
Telemetry Link S.BUS
Castle Link Quick Connect (or Quick Connect Duo)
6.5mm Polarized Connectors-Male/Female Single Pk
6.5mm Polarized Connectors-Male Multi-Pack
Polarized Castle Connectors - 6.5mm Female Multi-Pack
6.5mm Male/Female Connector Set (3ea)
8.0mm Male/Female Connector Set (3ea)
Castle Capacitor Pack, 8S MAX (35V)

Service Parts
WIRE, 36", 08 AWG, BLACK                                  
WIRE, 36", 08 AWG, RED
WIRE, 36", 08 AWG, WHITE

Average rating:
(Based on 3 vote(s))
Rate this product:
Emil Wilkens From Denmark
The Power House!
July 14, 2023
I just resently finished my 41” mono build using this esc. Pushing the boat on a time trial type national race, it managed to stay cool to the touch, despite pulling more than 300amps consistently during the race. Im very impressed and can’t wait to start pushing this esc with some speed runs by the end of this season. Highly recommended.
Stay tuned!
2 of 2 people found this review helpful
Was this review helpful to you? (2) (0)
Kenny Pro From FL
Beast of a ESC!!
July 14, 2023
I run castle in all my race boats and Saw boats. They by far are the best ESC!! Love the data log feature. Helps so much with setting up a boat and prop choice.
2 of 2 people found this review helpful
Was this review helpful to you? (2) (0)
Moonie From United States
Return of the Hydra
January 17, 2023
The new hydra has incredible hardware with equally impressive software. It works as good as it looks. I have not seen a motor it hasn’t been able to drive with incredible precision. I’m waiting for the return of the Hydro HV.
2 of 2 people found this review helpful
Was this review helpful to you? (2) (0)

Recently Viewed

  • USD $179.95 /EA
  • List Price USD $268.95 /EA
  • USD $209.95 /EA
  • List Price USD $254.95 /EA
  • USD $76.50 /EA
  • List Price USD $121.95 /EA