Ultraflex GoTech Outboard Hydraulic Steering Kit

The Ultraflex GoTech-OBF 42634G is a packaged hydraulic steering system for compatible single outboard engines up to 115HP and boats operating at no more than 45mph / 39 knots. The kit includes an UP18 18cc/rev intermediate-mount helm, UC81-OBF balanced front-mount cylinder, two litres of OL150 hydraulic oil and a 6m / 19.7ft cut-to-length 1/4in hose kit. The system provides approximately 4.5 steering-wheel turns lock to lock. The steering wheel is not included.

Product Identification

• Brand: Ultraflex
• Product range: GoTech
• Full system name: GoTech-OBF
• Product category: Outboard hydraulic steering kit
• Model: GoTech-OBF
• Manufacturer part number: 42634G
• Supplier catalogue code: 4-48120
• Store SKU: AF-4-48120
• Helm model: UP18
• Helm part number: 43182C
• Cylinder model: UC81-OBF
• Cylinder part number: 42654N
• Hydraulic oil: Ultraflex OL150
• Oil part number: 42398X
• Oil quantity: 2 litres
• Hose-kit model: KIT OB-GT/M-60
• Hose-kit part number: 42669C
• Hose length: 6m / 19.7ft
• Hose internal diameter: 1/4in
• Approximate wheel turns: 4.5 lock to lock
• Maximum engine power: 115HP
• Maximum boat speed: 45mph / 39 knots
• Engine configuration: Compatible single outboard engine
• Cylinder mounting: Front mount
• Steering wheel: Not included

What Is This Hydraulic Steering Kit Used For?

The Ultraflex GoTech-OBF converts steering-wheel rotation into hydraulic pressure, moving the UC81-OBF cylinder and turning a compatible outboard engine.

It is intended for:

• Compatible single outboard engines up to 115HP
• Single-station hydraulic steering installations
• New installations replacing mechanical steering
• Replacement of a complete compatible GoTech-OBF system
• Outboard boats operating within the stated speed limit
• Engines listed as compatible with the UC81-OBF cylinder

The GoTech system can reduce the direct steering load transmitted back through the wheel compared with a conventional mechanical cable system.

The complete installation must still be checked for engine compatibility, transom clearance, tilt movement, boat speed and steering load.

Which GoTech Version Is This?

This listing covers the GoTech-OBF front-mount outboard package.

It includes:

• UP18 intermediate-mount helm
• UC81-OBF front-mount outboard cylinder

It does not cover:

• GoTech-OBS: Separate package using the UC68-OBS side-mount cylinder
• GoTech-I: Separate inboard or side-cylinder configuration
• Other Ultraflex hydraulic packages using UC95, UC128 or UC130 cylinders

Confirm that the required system is the UC81-OBF front-mount version before ordering.

What Is Included?

The Ultraflex GoTech-OBF package includes:

• One Ultraflex UP18 intermediate-mount hydraulic helm
• One Ultraflex UC81-OBF balanced front-mount cylinder
• Two 1-litre bottles of Ultraflex OL150 hydraulic oil
• One KIT OB-GT/M-60 hydraulic hose kit
• Two 6m / 19.7ft high-pressure flexible hoses
• Fittings preassembled at one end of each hose
• Two separate reusable fittings for the cut ends
• UC81-OBF cylinder mounting and link components supplied with the cylinder
• Helm dashboard-fixing hardware supplied with the UP18

Not included:

• Steering wheel
• Optional Suzuki KIT SU adaptor
• Additional hydraulic oil
• Autopilot connection kit
• Second steering helm
• Second hydraulic cylinder
• Twin-engine tie bar
• Boat- or engine-specific components not included with the standard cylinder
• Installation labour

Which Outboard Engines Are Compatible?

The GoTech-OBF is designed for compatible single outboard engines up to 115HP.

Compatibility depends on:

• Engine manufacturer
• Exact engine model
• Engine horsepower
• Engine model year
• Tilt-tube dimensions
• Tiller-arm arrangement
• Engine-cowling clearance
• Splashwell and transom clearance
• Required cylinder orientation
• Spacer arrangement
• Maximum boat speed

The UC81-OBF is used with compatible engines from manufacturers including:

• Mercury and Mariner
• Evinrude
• Johnson
• Yamaha
• Honda
• Suzuki
• Tohatsu and Nissan
• Selva

This brand list does not confirm every engine model. The exact engine must be checked against the current Ultraflex UC81-OBF Application Guide before ordering.

Suzuki 1998–2008 Installation Note

Certain Suzuki outboard engines manufactured from 1998 to 2008 require the optional:

• Accessory: Ultraflex KIT SU
• Manufacturer part number: 41954W
• Supplier catalogue code: 4-48130

The KIT SU adaptor is sold separately.

The requirement depends on the exact Suzuki model and year. Confirm compatibility before ordering the steering kit or adaptor.

Maximum Engine Power and Boat Speed

• Maximum engine power: 115HP
• Engine configuration: One outboard engine
• Maximum boat speed: 45mph / 39 knots

Do not use the GoTech-OBF:

• With an engine above 115HP
• On a twin-outboard installation
• On a boat exceeding 45mph / 39 knots
• On a racing or competition boat
• Where the UC81-OBF Application Guide does not approve the engine
• Where the cylinder or hoses interfere with engine steering or tilt movement

The boat manufacturer's maximum engine and speed ratings must also be observed.

How Many Steering-Wheel Turns Does It Provide?

The GoTech-OBF combines:

• UP18 helm displacement: 18cc per wheel revolution
• UC81-OBF cylinder volume: 81cc

The approximate steering-wheel movement is:

• 81cc ÷ 18cc/rev = 4.5 turns lock to lock

Because the UC81-OBF is balanced, the number of turns is the same from port to starboard and from starboard to port.

UP18 Helm Pump Details

• 18cc / 1.1cu.in displacement per revolution
• Five-piston pumping mechanism
• Built-in lock valve
• Positive rudder lock
• Integral over-pressure relief valve
• 55-bar / 800psi relief setting
• Standard 19mm / 3/4in tapered stainless-steel shaft
• Corrosion-resistant composite housing
• Two 1/4in NPT hose fittings
• Accessible lock valve and shaft seal
• Maximum steering-wheel diameter of 508mm / 20in
• Maximum steering-wheel dish or socket depth of 115mm / 4.5in
• Dedicated compatibility with the UC81-OBF cylinder
• Optional K18 autopilot connection kit

The K18 autopilot connection kit is sold separately.

UC81-OBF Cylinder Details

• Cylinder volume: 81cc / 4.9cu.in
• Maximum theoretical thrust: 222kg / 489lb at 55 bar
• Internal diameter: 27.4mm / 1.08in
• Stroke: 186mm / 7.3in
• Maximum operating pressure: 55 bar / 800psi
• Hydraulic-hose connection: 3/8in
• Bleed fittings: DN5 quick connect
• Approximate overall width: 574mm / 22.6in
• Approximate vertical reference: 77mm / 3in
• Cylinder type: Balanced
• Installation side: Configurable for approved port or starboard installations
• Cylinder end caps: Replaceable
• Tilt-tube rod: Split design for installation access

The 222kg thrust figure is a theoretical limit calculated at 55 bar. It is not the cylinder's normal continuous steering output.

Hydraulic Hose Kit

The included KIT OB-GT/M-60 contains:

• Two high-pressure flexible hydraulic hoses
• 1/4in hose internal diameter
• 6m / 19.7ft hose length
• Fittings with rotating nuts preassembled at one end
• Two separate reusable fittings for the unassembled ends
• Cut-to-length installation

The hoses can be shortened to suit the installation.

Before cutting:

• Measure the complete hose route
• Allow for connection to both helm and cylinder ports
• Allow sufficient movement for engine steering and tilt
• Avoid sharp bends
• Avoid hot engine components
• Avoid sharp edges and abrasion points
• Leave enough length for fitting installation and future servicing

Once cut too short, the hose cannot be extended by pulling or stretching it.

Which Steering Wheels Are Compatible?

The UP18 helm uses a standard 19mm / 3/4in tapered stainless-steel shaft.

Before choosing a steering wheel, confirm:

• The wheel has a standard 3/4in tapered hub
• The wheel diameter does not exceed 508mm / 20in
• Wheel dish does not exceed 115mm / 4.5in
• The wheel seats correctly on the shaft taper
• The shaft key and retaining hardware are serviceable
• The wheel clears the dashboard, instruments and controls
• The wheel can rotate through the full steering range

The steering wheel is sold separately.

Cylinder Orientation and Clearance

The UC81-OBF can be configured for approved port- or starboard-side link-arm positioning, depending on the engine and available clearance.

Before installation, confirm:

• The correct orientation for the engine
• Engine cowling clearance
• Transom and splashwell clearance
• Full port and starboard cylinder travel
• Full engine tilt movement
• Hose clearance during steering and tilt
• Correct spacer arrangement
• No contact with wiring, control cables or rigging hoses

The cylinder orientation must follow the Ultraflex installation manual. Do not reposition the cylinder components without following the prescribed procedure and replacing seals where required.

Construction and Design

• Five-piston UP18 helm
• Built-in hydraulic lock valve
• Integral 55-bar over-pressure relief valve
• Corrosion-resistant composite helm housing
• Stainless-steel tapered steering-wheel shaft
• Balanced UC81-OBF cylinder
• Equal port and starboard wheel turns
• Replaceable cylinder end caps
• Reversible approved port or starboard cylinder arrangement
• Split tilt-tube rod
• Front-mount cylinder configuration
• DN5 quick-connect bleed fittings
• Two litres of OL150 oil
• 6m cut-to-length hose pair
• Components designed for the marine environment

Standards and Operating Range

Ultraflex states that its hydraulic steering systems are designed in conformity with:

• UNI EN ISO 10592
• ABYC P21
• Recreational Craft Directive 2013/53/EU requirements

The stated ambient operating-temperature range is:

• Minimum: -18°C / 0°F
• Maximum: +77°C / +170°F

The helm, cylinder, hoses, fittings and hydraulic oil must be installed as a compatible system. Certification does not validate an installation using an unapproved engine, incorrect hose, unsuitable steering wheel or incompatible component from another system.

Installation, Filling and Use

Installation should be completed by a qualified marine technician.

Before installation:

• Confirm the engine against the UC81-OBF Application Guide
• Confirm the engine does not exceed 115HP
• Confirm the boat does not exceed 45mph / 39 knots
• Check the engine tilt tube and tiller-arm condition
• Confirm the required cylinder orientation
• Check splashwell, cowling and transom clearance
• Confirm dashboard space for the UP18 helm
• Confirm steering-wheel diameter and dish
• Inspect the hose kit before cutting
• Confirm whether an optional Suzuki adaptor is required

During installation:

• Position the helm with the oil-filler opening correctly orientated
• Use the supplied dashboard fasteners
• Install the UC81-OBF using the correct spacer arrangement
• Route hoses clear of heat, sharp edges and moving components
• Maintain suitable bend radii
• Cut hoses squarely and fit the reusable connections correctly
• Keep the hydraulic circuit clean
• Use Ultraflex OL150 oil
• Do not use PTFE tape where fragments could enter the system
• Do not modify the cylinder, link arm or tilt-tube components

Fill and bleed the system until the oil leaving the bleed valves is free from visible air bubbles.

After installation, check that:

• The engine moves fully to port and starboard
• The cylinder reaches its complete permitted stroke
• The steering wheel turns smoothly
• Approximately 4.5 turns are available lock to lock
• The engine tilts through its complete required range
• No cylinder, hose or fitting contacts the transom or cowling
• No fluid leaks are visible
• No excessive wheel free play is present
• The helm remains securely mounted
• The steering wheel remains securely seated
• The hydraulic-oil level remains correct

Marine steering is safety-critical. Do not operate the boat with hydraulic leakage, trapped air, damaged hoses, loose fittings, restricted engine movement or abnormal steering-wheel travel.

Frequently Asked Questions

Is this the front-mount GoTech kit?

Yes. This is the GoTech-OBF package with a UC81-OBF front-mount cylinder.

Is the GoTech-OBS side-mount cylinder included?

No. GoTech-OBS is a separate system using the UC68-OBS cylinder.

Is the steering wheel included?

No. A compatible wheel with a standard 3/4in tapered hub is required separately.

Can it be used with twin outboards?

No. The package is specified for one compatible outboard engine up to 115HP.

Can the supplied 6m hoses be shortened?

Yes. The KIT OB-GT/M-60 hoses are designed to be cut to the required length, with reusable fittings installed on the cut ends.

Is the system suitable above 45mph?

No. The UC81-OBF manual limits the installation to 45mph / 39 knots.

Does every Suzuki outboard require the KIT SU adaptor?

No. The requirement applies to specified Suzuki applications, particularly certain 1998–2008 engines. Check the exact model and year.

Key Features

• Complete Ultraflex GoTech-OBF steering package
• Manufacturer part number 42634G
• Supplier code 4-48120
• Store SKU AF-4-48120
• Suitable for compatible single outboards up to 115HP
• Maximum stated speed of 45mph / 39 knots
• UP18 intermediate-mount hydraulic helm
• 18cc / 1.1cu.in displacement per revolution
• Five-piston helm design
• Built-in lock valve
• 55-bar / 800psi relief-valve setting
• UC81-OBF balanced front-mount cylinder
• 81cc / 4.9cu.in cylinder volume
• 186mm / 7.3in cylinder stroke
• 27.4mm / 1.08in cylinder bore
• Equal port and starboard steering turns
• Approximately 4.5 turns lock to lock
• Port- or starboard-compatible cylinder arrangement where approved
• Two litres of Ultraflex OL150 oil included
• 6m / 19.7ft cut-to-length hose kit included
• 1/4in hose internal diameter
• Standard 19mm / 3/4in tapered steering-wheel shaft
• Maximum steering-wheel diameter of 508mm / 20in
• Steering wheel supplied separately
• Exact engine compatibility must be checked before ordering