How do I remove and refit the saildrive seal on a Hallberg-Rassy 31?
I want to replace the rubber saildrive diaphragm on my Hallberg-Rassy 31. What needs to come apart, how do I separate the drive from the engine, and what should I check before refitting it?
Answer
To replace the main saildrive diaphragm on a Hallberg-Rassy 31, haul the boat out, support the engine and drive independently, separate them and dismantle the drive far enough to replace the rubber diaphragm. First check the saildrive identification plate: the kit, dismantling procedure and tightening torques depend on the drive model and serial number, especially if the boat has been re-engined.
Identify the seal and drive
The large rubber diaphragm clamped around the hull opening forms the watertight seal. The thin rubber fairing glued beneath the hull streamlines the opening; replacing this skirt does not renew the diaphragm.
Many HR 31s have a Volvo Penta engine with a 120-series saildrive, but do not order parts against the boat model alone. Record the full drive designation and serial number, photograph the installation and obtain the matching workshop instructions and diaphragm kit.
Volvo Penta commonly specifies diaphragm replacement every seven years; check the instructions for your drive. A sound-looking surface tells you neither the rubber's age nor its condition beneath the clamp.
- Check the replacement date against invoices and any label beside the drive.
- Inspect the steel retaining ring, its bolts and the surrounding engine bed for corrosion, cracking or water staining.
- Check the engine mounts, cooling-water hose, seacock and gear cable while you have access.
Prepare and separate the engine
Ask the yard to position the boat with enough clearance beneath the saildrive for the planned removal route. On the HR 31, access and room to move the engine depend on the installation. Establish the route before undoing any mounts.
Work only with the boat securely supported ashore, the batteries isolated and the engine and saildrive carried by rated lifting equipment or properly secured supports.
- Remove the propeller and, where necessary, the anode and external fairing. Drain the saildrive oil into a clean container and check for water or metal debris.
- Photograph and label the connections. Disconnect the gear cable, cooling-water connection and anything else that would restrict movement.
- Support the engine independently before releasing the saildrive rear mounting or moving the engine off its mounts.
- Support the drive, remove all engine-to-drive fasteners specified in the manual and separate the assembly squarely from the engine.
If the assembly will not separate, check for an overlooked fastener, locating dowels, an attached bracket or load on the input shaft. Corroded splines can also hold it together. Adjust the supports to remove side loading. Do not hammer the aluminium housing or drive a screwdriver between the mating faces.