As this is a job I have done (with some satisfaction) on my boat I will comment. We have a B 38 (2004). I knew I was in for a job when the helm started going stiff after an idle period. This was a couple of years ago so the bearings were 8yrs old or so. We keep the boat in the (salt) water all year round as is common in this part of the world, only coming out for maintenace. I researched a bit and it seemed the problem would be
either the nylon plasticky thing had swollen
or the alloy bearing housing had corroded creating pressure on the bearing, which being somewhat flexible was transferring pressure to the rudder stock and creating resistance to movement.
I was hoping it was the plastic thing as the housing is resined into the hull. After reading daunting stories of sledge hammers pounding for hours on the rudder stock to try and get it out of the bearings I had worked up a dread for commencing the job. I don't recall much of an issue about digging into the boatyard surface to allow the rudder to come away cleanly. I know that we did some scratching around in the gravel but it wasn't significant. If you allow so much from the rudder stock through the top bearing (say 130mm guessing from memory) and a little more for the bottom bearing (say 150mm) the complete length of the rudder shaft can be measured from the inside the lazarette access in the aft cabin. Then measure down from the bottom of the rudder and you will know how much to dig. If digging is not an option then either make arrangement to hang for a minimum of two hours to be safe or have it placed on hard at appropriate level.
My biggest fear was damaging the top of the rudderstock from hammering it to get it moving. Admittedly mine was not seized completely just getting very stiff and way too much work on the auto pilot and the rest of the gear. I was forewarned the rudder is quite a hefty piece so set up a rope sling to take the weight as it started to come free and slide through the bearings after removing the locknut affair on top. After some thought I figured the best way to avoid damage to the top of the stock was to take advantage of the weight of the rudder and the flexibility of the fibreglass hull. So the secret method to my madness is this: Instead of belting the hell out of the top of the stock I got a rubber mallet (no sledgehammer by any means) and tapped upwards around the bottom bearing housing on the hull bottom. Being tens of kilos heavy, the inertia of the rudder is such that every tap upwards acted like a ratchet on the rudder stock and it inched (or should I say millimetered) down as I tapped up. The flexibility of the hull allowed the bottom bearing housing to rise a fraction as I pounded, while the weight of the rudder resisted that movement up. It took maybe an hour but seeing it move fraction by fraction was worth it as no damage to either the hull or the stock was done. No heavy gear at all needed. I even managed with a straight back to carry the said rudder and lay it down without popping any discs.
After getting it out the next issue was getting out the nylon-plastic (whatever) bearing. Actually have just realized this has all been covered before on this forum. Here is a link that will show a great series of photos that highlight the way to remove the offending bottom bearing which is virtually the same as the Dufour pictured:
https://www.flickr.com/photos/41315554@N07/sets/72157622026477419/ In the pictures shown, the guy is using a piece of galvanized pipe to swing on the siezed bearing from side to side. Being round it needs to be rotated to a certain angle before it can be removed. This was by far the hardest part of the job. From memory my pipe lever was at least a metre long, perhaps 1.2 metres and i used every inch of it with all my weight and lots of different lubes to try to get movement. It was quite a while before it would move at all and I got quite rough with it, but at last it started a little. It definitely puts a strain on the resin to housing bond but it held well and there were no leaks when back in the water.
I disagree with whoever complained at the type of plastic used for the bearing, while it may be inferior on some boats or models, the problem was not swelling of the bearing due to absorbing water or whatever. It was the corrosion of the alloy bearing housing. Perhaps anodes attached would stop this. Once I cleaned up the housing with emory paper and applied liberal quantities of marine grade grease I replaced the same plastic bearing with no problems. No tightness and no wear either- just smooth finger pressure to turn the helm again. Brilliant. And I hardly had to open my wallet. It's been at least a couple of years now with no recurrence.
P.S. It should not be forgotten that once the rudderstock has cleared the top bearing- if the bottom bearing has any movement at all this can be used to advantage. The whole rudder can be pivoted to some degree to help clear the ground beneath, it can swing away with all the quadrant and cable off and auto pilot gear off, which may lessen the height necessary to clear the ground.
