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Old 05-02-2019, 11:21 AM   #1
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Rudder Bearing Block Replacement Help

As the final part of my winter Lazerette project, after sanding and gelcoating the walls and installing new water tanks, I need to re-install the rudder bearing block. The problem is the void between the flat block and the hull shape. The original leaked and rotted the block due to using bedding compound covered with epoxy to fill the void, not sure when it started leaking but it kept the boat afloat for 40 years.

I want a better system for this tricky thru hull. The bronze packing gland extends thru the hull and I would like that to be sealed in the block with compound for maintenance. The void and the block to be permanently attached to the hull.

How should I fill the void? Shape wood and FRP to hull? Thanks.


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This is the hull and hole for the rudder
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The is the top view of the bearing and block mocked up in place
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This is a foam model of the void I made
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Bottom of the block with the packing gland in place
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Mock up of the rudder in the bearing
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Old 05-02-2019, 01:13 PM   #2
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I have seen plywood based boxes do this job. I have also had to make fairly large hole saw cuts to allow access to the otherwise hidden stuffing box. Manytimes, there is bracing to the transom (for instance) to help support the bearing. Note that any external hits to the rudder will be magnified at the top of the rudder post. THese loads need to be supported, and vertical box walls alone are not great for that.

I'm not necessarily recommending wood. I'd likely use FRP sheets, since they are rotproof and can be easily bonded.
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Old 05-02-2019, 03:25 PM   #3
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Hi Greatlaker221,

Now might be the time to consult a marine professional at a local competent boatyard to help with your steering system redesign. Heel-hung rudders, which yours appears to be, typically have not only a hull packing gland, but an upper bearing installed on a substantial shelf, running athwartships or at least tied heavily into the transom. This lends significant strength to the rudder in normal operation, and should a grounding occur with damage to the rudder shoe, would protect the hull gland from damage, and (hopefully) protect against flooding as well.

Your proposed mockup is on the right track, but the metal u-shaped "box" you're using to support the upper bearing is woefully inadequate, in my opinion. And bear in mind your design will make it very difficult to align all three bearing surfaces (the upper bearing, the hull gland, and the rudder shoe) after the equipment's installed. You might give consideration to this alignment, verify your rudder post is, indeed, straight, and perhaps allow for some adjustment throughout the process.

Additionally, it isn't clear that the hull gland you've selected (OEM?) has any method of maintaining the gland. If this is a conventional packing gland, how is the packing installed and maintained (tightened) after installation from inside the boat? I've seen a lot of rudder glands, but never one like yours. If it is a "dripless" gland, and relies on a lip seal, how will you replace the gland without hauling the boat and disassembling the rudder system?

Given you've stripped out the existing setup, now's the time to do it right. And bear in mind, simply because the OEM installation lasted 40 years doesn't make it right. It's just as easy to do a correct rudder design and installation as it is to butch up something that might work. Or maybe not.

Regards,

Pete
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Old 05-02-2019, 05:17 PM   #4
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Thank you for your reply, Everything is original except for the plywood block which I replicated from the original mahogany block. There was no bracing to the transom. The packing gland is standard Buck Algonquin type with rings of PTFE treated packing material and a clamp. (clamp not installed for the dry fit or in the picture). The upper bearing, the hull gland, and the rudder shoe are in alignment with the rudder installed for dry fit. The trick will be to maintain the alignment once final assembly is done.

I was not looking to do a redesign, just replace the rotten leaking block. I may have to consider a stronger upper bearing support tied somewhere. Ill bet most 36' trawlers from Taiwan, at least Albins, Hershines and Jeffersons. (same yard) have the same set up.
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Old 05-03-2019, 06:02 AM   #5
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The best pour in place I have found is Chockfast.


https://itwperformancepolymers.com/products/chockfast
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Old 05-03-2019, 08:30 AM   #6
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Thanks FF, exactly what I was looking for. Thickened epoxy May be too brittle and fiberglass sheets/wood core may not allow for self leveling for alignment. I did not know about Chockfast. Hope they sell it in small quantities I need about 40 oz.
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Old 05-03-2019, 01:42 PM   #7
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"Hope they sell it in small quantities I need about 40 oz."

I have purchased it by the gallon , don't know if its sod in quarts.

Perhaps sharing with another boater?
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