The sealing system was devised by Whitlock Europe as a solution to the problem of a rudder tube terminating just below the water line in order to accommodate the bed above it. It is an aluminium housing glassed in to the hull, and containing roller bearings at the base and a pair of seals above that. They are held in position by a nylon locating ring which engages in a slot in the inner face of the housing just above them.
The rudder shaft itself is 60mm diameter. Just above the rollers in the housing it is turned to a smaller diameter, and then restored to 60mm with a glued on plastic sleeve. This provides the bearing surface for the sleeve. The seals are 80mm OD, 60mm ID and 10mm deep.

The procedure I adopted for replacement was as follows:-

1 Support rudder underneath before releasing the top bearing.
2 Remove rudder position sensor. Free grub screw holding the shaft to the ball race at the top of the shaft, then remove the whole assembly to reveal the steering quadrant.
3 Cut away the top 30-35 mm of glass to ensure that the leak could not be from water seeping between the housing and the hull.  It seemed OK so I replaced the glass with epoxy glass on the grounds that it has better adherence than polyester.
4 Chopped away the filler from the rudder heel bearing, and removed the bearing. ( I was shocked to find that Conyplex had used aluminium for this, and that it was already showing signs of surface corrosion. It was painted before re-assembly.)
5 Lowered rudder on a jack by about 40mm. This was to allow clearance to remove the locating ring and to ensure that the mating surface with the seals was not damaged in the process of seal removal.
6 Used hot air blower to soften the locating ring before prising it out.
7 Used services of heavy-engineering friend to provide the necessary brutality to get the old seals out. Cleaned out the housing interior with scraper and vacuum cleaner, checked for cleanliness and absence of scratching.
8 Smeared waterproof silicon grease over assembly and raised rudder sleeve to the level of the seals. Greased and slid in the two new seals and pressed them down evenly using a short length of plastic drain pipe, about 70mm diameter. I Warmed the new locating ring in boiling water and pressed into position. Only then raised the rudder to its full position and completed re-assembly of remaining gear.

Whitlock in this country are not familiar with this system (Jefa Denmark make it for Whitlock -Webmaster). A similar sized seal to the original is available locally fromBlue Diamond of Chandlers Ford for much less than a Conyplex spare; £3.54 plus vat each, or a superior 80 X 60 X 8mm which looks attractive. Being thinner it has the advantage that the seal will bear on an unused portion of the bearing sleeve. These cost £4.80 plus vat each, Stock code BBD7622 . (BUT NOTE THE HUGELY MORE EXPENSIVE JEFA SEAL IS TO A TOTALLY DIFFERENT MATERIAL SPEC AND IS THE ONLY ONE NOW RECOMMENDED BY CONYPLEX - WEBMASTER)