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Teleflex SeaStar Stern Drive

Technical Reference Manual

SeaStar Stern Drive Steering

NOTE: When properly installed, this steering system will connect to stern drive engines using application-specific cylinders which use different types of interfaces. Use only recommended type of steering hoses or tubing with SeaStar stern drive steering systems. Do not use SeaStar PRO helms with unbalanced cylinders or power-assisted steering.

SeaStar Stern Drive Steering is the best choice for non-power assisted stern drives and any stern drive boat with an autopilot. The system is based upon the SeaStar helm family, which allows for dual station and autopilot use. Cylinders are specific to drive brands and models.


Ideal for most stern drives, especially non- power-assisted units, SeaStar is suitable for single and multiple drives and dual stations.


  • Best and Most Economical autopilot interface for stern drives! Easy installation.
  • Simple multiple steering station connection.
  • Optional SeaStar 2.0 & 2.4 helms for quicker steering response.
  • Standard 3/4" tapered steering shaft.
  • Fast, easy installation.
  • Meets A.B.Y.C. standards.
  • Meets N.M.M.A. certification requirements.

How to Spec a System:

  • 1. From the application guide, confirm that a cylinder is available for your specific make, model and year of drive unit. Select the cylinder that is appropriate for the drive.
  • 2. From the ordering guide, select the appropriate helm and accessory hardware. Note that three SeaStar helm displacements are available for power steered stern drives (1.7, 2.0 & 2.4 cu. in.) The displacement of the helm affects the number of turns lock-to-lock. Lower helm displacement = more turns = less effort/slower response. Select helm size on the basis of the desired steering response. The 2.4 cu. in. version is not recommended for non-power-steered applications.
  • 3. Select the appropriate tube or hose and fitting kits required for the installation.
  • 4. Confirm that there is sufficient space available in the dash and engine compartment(s) for the steering components. Review helm and cylinder dimensions at the end of this section.

Complete Systems:

System components sold separately. See application and ordering guides to select appropriate components.


  • SeaStar 1.7 Helm..................................HH5271
  • (See Ordering Guide to select helm.)
  • Stern Drive Cylinder..............................HC53__
  • (See Application Guide to select cylinder.)
  • Hose Kit (2 hoses).................................HO51__
  • SeaStar Oil (1 Quart).............................HA5430


Service Items:

  • SeaStar Oil (1 Gallon)...........................HA5440
  • Steering Wheel Locknut.........................747521

Application Guide: Stern Drive Steering

Teleflex Seastar Stern Drive Steering Application Guide


N/A = Not Available.

1. Balanced system - number of steering wheel turns lock-to-lock is equal port to starboard or vice-versa.

2. Unbalanced system - number of steering wheel turns lock-to-lock is unequal port to starboard or vice-versa.

3. Requires additional clevis supplied by engine manufacturer. Reference Quicksilver Part No. B98735A1. See HC5326 cylinder diagram later in this section.

4. Requires cylinder rod end adapter HA5424 from Teleflex Canada. Refer to the HC5326 cylinder diagram in this section.

5. HC5332 replaces HC5326 as of January 2000. If installing HC5326 additional clevis supplied by engine manufacturer required (part number B98735A1).

6. The installation of the HC5332 sterndrive cylinder requires the use of SeaStar Outboard hose only. Do not use 3/8" copper or nylon tube.

7. If engine outdrive is NOT equipped with a torque tab on the underside of the lower leg one must be installed to reduce prop torque.

8. Yanmar Engines using the Bravo III drives require the use of cylinder HC5326.

NOTE: These recommendations apply to factory stock sterndrives only. Modified installations may require a higher capacity steering system. If in doubt, contact our technical service for assistance.

1. SeaStar 1.7 helms are the standard recommendation for both non-power and power steered applications.

2. SeaStar 2.4 helms can be specified for power steered applications where faster steering response is desired. Review the Application Guide on the previous page for recommendations.

3. For SeaStar 1.7 systems, use 3/8" diameter nylon tubing (Part No. HT5___). For SeaStar 2.4 systems or any system using the HC5332 cylinder, use the following option A or B: A. Outboard Hose: hoses must be ordered in standard lengths. They cannot be cut to length. B. Copper tube: 3/8" diameter copper tube and hose kit (Part No. HF5508).

4. For dual stern drives: use the tie bar supplied by the engine manufacturer.

SeaStar Autopilot Interface

SeaStar is the best steering choice to interface with most autopilots. If you are installing an autopilot on a mechanically steered boat, we recommend you upgrade to SeaStar for performance reasons.

If you're upgrading to SeaStar, plan ahead: future installation of an autopilot or extra steering station can be simplified by installing two pairs of shorter hose kits. Connect them with union coupling fittings, part no. HF5530. Tee fittings can be installed with ease at a later date. Bulkhead union fitting kits are available to facilitate hose runs through transoms and splashwells:

  • HF5512 up to 3/4" (19mm) splashwell, 1 cylinder
  • HF5513 up to 3" (76mm) transom, 1 cylinder
  • HF5514 up to 3/4" (19mm) splashwell, 2 cylinders
  • HF5515 up to 3" (76mm) transom, 2 cylinders

For an autopilot installation, a third (compensating) line must be installed and identified. (SeaStar helm Ports marked are for connection of additional helm and/or autopilot compensating lines.) Use HF5501 (outboards) or HF5502 (stern drives and inboards) fitting kits when adding an autopilot to your SeaStar system.

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