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Discussion Starter · #1 · (Edited)
I spent the month of August 2014 working on the rudder on my '77 Pearson 28-1, which had developed a twitch/vibration. After my most recent trip to Cape May, I decided I would rather haul and miss August sailing so I could sail throughout the rest of the year.

Photos:

https://plus.google.com/photos/101935788163929897438/albums/6045893622335987249

Here is a list of the items repaired/replaced/addressed:

1. Replaced missing(!) lower rudder bushing with custom-machined bronze bushing pressed into heel/shoe;
2. Drained, dried and sealed rudder with Interprotect 2000e epoxy paint;
3. Replaced improper, dry-rotted rudder stuffing box hose with new Buck Algonquin and new double hose clamps;
4. Grinded, sanded and cleaned partial skeg rudder housing and laid new fiberglass;
5. Sanded and painted bottom with ablative paint;
6. Re-painted new black hull stripe;
7. Cleaned scuff marks off hull with Fiberglass Solvent Wash;
8. Replaced flax in rudder post stuffing box;
9. Added thimbles to wire rope on eye bolts.

Removing the rudder drive wheel was a beotch. After trying PB Blaster, boiling water, a propane torch, and an impact wrench. I finally cut through the bolts with a grinder. While I wanted to switch to a tiller, my wife prevailed upon me to keep the wheel. My machinist did a great job of repairing the damage.

Upcoming fall/winter repair jobs: replacing wire rope in steering system and replacing cockpit drain hoses.

The boat is ready to splash!
 

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Discussion Starter · #3 ·
It is gratifying to finish the job and to try to do it right. Every time I work on the boat I learn more about particular systems: this time it was primarily the steering system, but I also learned more about wire rope and fasteners, metals, barrier coating, metal corrosion and freeing bolts, and fiberglass work.
 

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Kindly explain exactly what you mean by 'rudder vibration'.

The reason I ask is that Pearson used the quite common "NACA 63A010" type of foil shape profile for their keel and rudder shape. Such shapes if not perfectly 'faired' and kept 'smooth' at the leading edges, can easily develop hydrodynamic 'anomalies' that can be felt in the rudder. If all your work doesnt lessen your 'vibration', perhaps we can discuss in more detail later on how to lessen this - slight changes to the leading edge shape, minor fairing of the leading/trailing edges and the need for SMOOTH bottom paint, etc.

NACA 63A010 AIRFOIL (n63010a-il)
 

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Discussion Starter · #8 · (Edited)
Kindly explain exactly what you mean by 'rudder vibration'.

NACA 63A010 AIRFOIL (n63010a-il)
The wheel wants to turn one way, then the other, repeatedly, back and forth, with a small motion. This was not the normal keel/rudder hum that is enjoyable at top speeds in certain conditions. The boat was fine before several incidents, as described below:

I ran into a poorly-marked gill net adjoining the channel on the Rappahannock this past Spring and was caught for about 45 minutes, before finally cutting myself loose. My wheel pedestal brake broke halfway through the season (a guest manhandling it). Later in the season, I tried an impromptu man overboard exercise to retrieve my son's hat, which fell overboard. The boat backed down on its rudder hard to one side in some chop. After this incident, the vibration became more pronounced. Finally, my boat receives a fair amount of wake from powerboats on the beam in its current slip, so there is more frequent sideways motion and pitching, putting more stress on the rudder fixtures.

When the boat was hauled, I was able to move the bottom of the rudder sideways about 1/8 inch in each direction. The bronze skeg heel/shoe was loose and allowing some rotation. I was surprised by how easy it was to remove the skeg screws and nuts - they were hardly tightened. As you can see from the photo, they are located about a foot deep in the partial skeg - I had to buy an extra long socket extension to each them. It is possible the last person to work on it simply tightened them as best possible by hand, due to their inaccessibility.
 

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I spent the month of August 2014 working on the rudder on my '77 Pearson 28-1, which had developed a twitch/vibration. After my most recent trip to Cape May, I decided I would rather haul and miss August sailing so I could sail throughout the rest of the year.

Photos:

https://plus.google.com/photos/101935788163929897438/albums/6045893622335987249

Here is a list of the items repaired/replaced/addressed:

1. Replaced missing(!) lower rudder bushing with custom-machined bronze bushing pressed into heel/shoe;
2. Drained, dried and sealed rudder with Interprotect 2000e epoxy paint;
3. Replaced improper, dry-rotted rudder stuffing box hose with new Buck Algonquin and new double hose clamps;
4. Grinded, sanded and cleaned partial skeg rudder housing and laid new fiberglass;
5. Sanded and painted bottom with ablative paint;
6. Re-painted new black hull stripe;
7. Cleaned scuff marks off hull with Fiberglass Solvent Wash;
8. Replaced flax in rudder post stuffing box;
9. Added thimbles to wire rope on eye bolts.

Removing the rudder drive wheel was a beotch. After trying PB Blaster, boiling water, a propane torch, and an impact wrench. I finally cut through the bolts with a grinder. While I wanted to switch to a tiller, my wife prevailed upon me to keep the wheel. My machinist did a great job of repairing the damage.

Upcoming fall/winter repair jobs: replacing wire rope in steering system and replacing cockpit drain hoses.

The boat is ready to splash!
Looks so simple, but it's not. Great job and photo documentation. I think thus same project is in my future.

Dave
 
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The wheel wants to turn one way, then the other, repeatedly, back and forth, with a small motion. This was not the normal keel/rudder hum that is enjoyable at top speeds in certain conditions.
Aha! the keel is probably shedding vortexes and the formerly loose rudder allowed the amplification, probably the rudder also is/was shedding the same type of vortexes.
Such foil shapes will do this if the surface is not 'smooth', especially from the leading edges (bow, keel and rudder assy) back to about 30% of the total cord length of each 'foil' segment.
If you have 'rough' bottom paint (typically applied with a roller which leaves 'stipple' bumps) this effect can be quite pronounced. Especially if youre applying an ablative paint ... sand the old 'paint pimples' so that the tops of the pimples are flat, apply the new paint with a roller then immediately follow up with a 'wipe' of plastic trowel (The yellow WEST system trowels are best) and allow to fully dry/cure .... then repeat until you get a mostly smooth surface. The wiping with a poly trowel will fill-in the craters between the 'stipples' and paint bumps.

You can also 'sharpen up' the trailing edges but this isnt as important as to work on the leading edges to about 30% back from the leading edges which will lessen those 'vibrations' (parasitic vortexes).
What will happen is the flow water along the entire length will become less 'turbulent', will create less 'vortices' ... and you should then notice that keel will better 'lift to weather' and the boat will have significantly better 'light wind' performance - a plus on the Chesapeake in mid Summer.

Great job on the 'rebuild'.

regards
RichH
 

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James, thanks for your post and photos. I had not realized that the gudgeon could be removed without dropping the rudder. I have a slight lateral movement in the rudder stock that I can feel at the tiller head, but the last time I had the boat out of the water there was no play in the rudder. I assume (often a big mistake) that the upper bushing is worn. Your photos will help next time I haul out.
Thanks,
John
 
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