How do I replace the stern gland (shaft seal) on a Hallberg-Rassy 42?

Replace the stern gland with the boat ashore, normally by disconnecting the propeller shaft coupling and sliding the shaft aft far enough to remove the old seal. On a Hallberg-Rassy 42, identify the fitted gland and check withdrawal clearance before dismantling, as the earlier 42E and later centre-cockpit 42F need separate consideration and previous owners may have changed the original installation.

Identify and measure the seal

Start at the inboard end of the stern tube, behind the gearbox. Clean the assembly to identify its construction:

• Moulded rubber lip seal: a black rubber body clamped onto the stern tube, commonly a Volvo Penta type or a replacement such as Radice.
• Mechanical face seal: a rubber bellows with a stationary sealing face and a stainless rotor secured to the shaft, such as a PSS.
• Packed gland: a metal body with an adjustable packing nut or follower, sometimes connected to the stern tube by reinforced hose.

Measure the shaft diameter with vernier callipers on clean, unworn metal. Establish the stern-tube connection diameter, seal length and coupling arrangement too. Do not order a seal simply labelled "HR 42". Both shaft and tube dimensions must match.

Measure how far the shaft can move aft before the propeller meets the rudder or skeg. Compare this with the clearance needed to remove the coupling and slide the gland off the shaft end. Photograph any vent or water-feed connections before disconnecting them.

Plan the shaft movement

Replacing a gland usually does not require full shaft removal. Owners of the earlier HR42E have, however, found insufficient clearance to withdraw the complete shaft because of the rudder/skeg arrangement. On some installations, removing the gearbox has provided another route for shaft and bearing work.

Your gearbox may not need to come out. First check whether there is enough movement to replace the seal. If there is not, have the yard assess moving or removing the gearbox before considering rudder or skeg work.

Have the boat securely supported ashore, isolate engine starting and restrain the shaft against sliding out before releasing the coupling or gland.

1. Mark the coupling halves and record the shaft's position in its coupling.
2. Support the shaft, disconnect the gearbox flange and release the shaft coupling according to its design.
3. Use a suitable coupling puller if necessary. Do not hammer the shaft or use the gearbox flange as an improvised press.
4. Move the shaft only as far as needed and remove the old gland.

Inspect and fit the seal

Inspect the shaft where the seal runs. Fine surface staining can be cleaned carefully, but a groove that catches a fingernail, pitting or scoring needs attention before you fit a new seal. While access is available, check the stern-tube spigot for corrosion and the outer shaft bearing for excessive play.