Castle’s legacy of overpowering the surface doesn’t stop at land — it goes full throttle into water. Our Marine Product lineup is purpose-built for high-performance RC boats that demand brutal torque, thermal control, and bulletproof reliability. From the proven Hydra X 8S to the next-generation Hydra Cobra 5 HV 12S, these ESCs are highly capable and designed for high-RPM water-cooled action.
Pair your ESC with our precision-machined 15 Series Water Jacket for maximum heat dissipation and consistent performance during long pulls and hard turns. Whether you're racing, bashing, or building a custom watercraft, Castle’s marine gear is ready to make waves.
High-Voltage Sport and Racing
Push your boat to its limits. The Castle HYDRA COBRA 5 HV is a next-generation marine ESC designed for RC hobby boats up to 50 inches. Built on the same proven technology as the Cobra 5 HV surface ESC and re-engineered for water, it delivers uncompromising 12S / 50.4 V power, data-rich performance monitoring, and bulletproof protection.
Sport and Racing
Based on our proven Cobra 5 architecture, HYDRA COBRA 5 8S is a marine-focused ESC features a custom water-cooled heatsink for efficient thermal management and an aluminum top plate with dual anodized water fittings (.17" OD, 10-32 UNF threads). The ESC is housed in a rugged CNC aluminum case and potted in waterproof epoxy to protect the electronics and includes an upgraded current-sensing and thermal protection system actively mitigates the risk of failure in aggressive or high-load setups.
High-performance Monohulls
The HYDRA X 8S is based on our popular and powerful Mamba Monster X 8S. We've removed the air cooled heatsink and added a water-cooled heatsink. The final touch is an aluminum top plate that gives it a sleek and polished appearance. Attached to the top plate are two .17" aluminum water fittings and uses standard 10-32 UNF threads. The HYDRA X 8S is the ultimate enhancement that propels high-performance monohulls, up to 36 inches in length, to new heights.
CNC Aluminum Cooling Jacket
Designed with precision and engineered for durability, this cooling jacket is the ultimate solution for RC boat enthusiasts seeking optimal motor performance.