This Ultraflex NAUTECH hydraulic steering system kit for outboards up to 300 hp is the NAUTECH-3 variant with an UP25F helm pump and a balanced UC128-OBF/1 cylinder. The complete kit also includes two 9 m hydraulic hoses and 2 liters of hydraulic oil. The steering wheel is not included.
The front-mounted UP25F helm pump has a displacement of 25 cm³ per revolution and provides 4.8 turns lock-to-lock together with the included cylinder. The pump features five pistons, a ball-bearing piston race, a built-in lock valve, and overpressure protection with the valve set at 70 bar. The lock valve prevents kickback in the steering system, while the steering shaft is a tapered 3/4" stainless steel shaft. The pump can be used with steering wheels up to 710 mm in diameter.
The UC128-OBF/1 is a balanced, front-mounted cylinder with a straight link arm positioned on the starboard side. The balanced design provides the same number of turns in both steering directions. The cylinder has a volume of 120 cm³, an output force of 450 kg, an internal cylinder diameter of 35 mm, and a stroke of 185 mm. The total cylinder length is 544 mm, and the height is 76.2 mm. The cylinder rod, link components, and ULTRABOLT connection bolt are made of stainless steel, and the cylinder heads are replaceable.
The hydraulic connections are 3/8", and the cylinder has DN5 quick-connect couplings for bleeding as well as adjustable fittings. The two included 9 m hoses can be cut to length and feature removable, screw-on couplings. The cylinder mounts to the outboard motor's tilt tube. The required mounting space for a single engine is 540 × 152 × 152 mm. For twin engines, the mounting space is 1110 × 152 × 152 mm, and a minimum of 650 mm center-to-center distance between the engines is required, along with additional connection parts not included in this kit.
Compatible engine models
The UC128-OBF/1 variant is documented for select engines from Mercury/Mariner, Yamaha, Honda, Suzuki, Tohatsu, Selva, and Johnson, as well as OXE, Neander, and E-MOTION. Compatibility includes, among others, Mercury/Mariner Optimax, Verado, and FourStroke models, Yamaha F115-F200 L4, Honda BF75-BF250, Suzuki DF100-DF200 L4, and Tohatsu TLDI, MFS, and BFT models within the specified model years. The cylinder's /1 link arm is engine-specific and should not be confused with the /2, /3, or port variants.
The system is not intended for racing. In a normal single-cylinder installation, use at speeds above 48 knots is discouraged. The limit is 56 knots for a documented dual-engine installation with two cylinders and counter-rotating engines. Always verify the engine make, model, year, horsepower, and correct link arm variant before installation.
Components and accessories
The UP25F pump corresponds to item no. 45.280.00, and the UC128-OBF/1 cylinder corresponds to item no. 45.282.00. The LA1 link arm has item no. 45.282.21. The pump can be mounted partially flush using the X64 square flange or X57 round flange, and the X72 tilt mechanism provides 60° of adjustment across five positions. These mounting parts and steering wheel are not included.
Key featuresComplete hydraulic steering system kit for outboards up to 300 hp
NAUTECH-3 system with UP25F helm pump and UC128-OBF/1 cylinder
4.8 turns lock-to-lock
Balanced, front-mounted cylinder with straight link arm on the starboard side
Two trimmable 9 m hydraulic hoses
2 liters of hydraulic oil included
Built-in lock valve and overpressure protection
3/8" hydraulic connections and DN5 bleeding couplings
Steering wheel not included
The UC128-OBF/1 cylinder is CE and UKCA marked
