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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

rudder vibration

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tackingabout
Deckhand

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USA
13 Posts

Initially Posted - 01/29/2008 : 20:33:18

Hi, First year with my c-25, i noticed a helm vibration/shake. Now with boat on the hard i was looking a the rudder close. it has a high spot in center running veritcal. THe rudder is solid, no cracks or obvious damage, i am sure this is producing the shake. any one have this issue, any suggestions for a fix, i was thinking of sanding down the high spot and re painting, or perhaps laying new glass in the low spots and essesntially re shaping .. any suggestions would be helpfull thanks. I have a rare 1986 with diesel engine, and think the c-25 is a fantastic set up.

scott truhart

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 01/29/2008 : 21:18:46

Take a look at the pintles and gudgeons - there is a good chance those are not a snug fit anymore which could cause cavitation while underway. It is a much cheaper fix. The high spot sounds odd - any pics?

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 01/29/2008 : 21:19:16

Oh, and Welcome!!!!!!!!

Edited by - on

GaryB
Master Marine Consultant

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USA
4312 Posts

Response Posted - 01/29/2008 : 23:03:44

I've noticed my rudder does the same thing. It "wiggles" back and forth. I hadn't thought about the gudgeons and pintles. I know there is some slack in that area. The bushings are probably worn out.

Until now I just assumed I had some mud stuck to the bottom of the rudder. My slip is shallow and the boat sometimes touches the bottom.

Edited by - on

tackingabout
Deckhand

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USA
13 Posts

Response Posted - 01/30/2008 : 08:06:46

thanks for the reply, i am thinking helm wiggle is a better description of the issue, i seem to have the upgraded pintle/gudeons and yes there is some wear and space there, probabbly wouldnt hurt to replace, however i really think that "high spot" in the rudder has to cause turbulent flow across the surface of rudder thus producing the wobble, and perhaps even drag.. i walked the boat yard and saw several much older c-25 and none had this rudder inbalance. i will try to post a pic of the rudder, its not really rediculous looking to the eye but not true . I am a former hobie 16 racer and use to have to tune the rudders to elimante vibration and hummming, of course we flew at 22kts not 5 like on the c-25.

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/30/2008 : 08:31:29

I will bet on galled gudgeons. What year is your boat?

Edited by - on

Derek Crawford
Master Marine Consultant

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USA
3323 Posts

Response Posted - 01/30/2008 : 12:17:01

I had a problem with worn gudgeons which created rudder "slop". I drilled them out enough to hammer in bronze bushings bought from Ace Hardware. Rudder action is now smooth and quiet.

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Ed Cassidy
Captain

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USA
365 Posts

Response Posted - 01/30/2008 : 12:36:30

Is the wiggle noticed only under power or under sail or both? I'm guessing that propwash from the inboard diesel is the cause.
Ed

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GaryB
Master Marine Consultant

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USA
4312 Posts

Response Posted - 01/30/2008 : 13:13:53

Ed,

Now that you mention it I haven't noticed the wiggle while under sail. I have an outboard though.

I'll have to look for it the next time I'm out. Hopefully Saturday, it's supposed to be Partly Cloudy anr 72 degrees.

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 01/30/2008 : 13:29:44

you can get bushings from CD for a under 3 bucks. Talk to Tech support first to make sure the gudgeons you have are the right size to take the bushings...

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/30/2008 : 13:55:32

Gary, you have a balanced rudder, there is a fairly close tolerance to fitting it to the boat. The rudder must be turned and set on the gudgeons while turned. The new gudgeons with bushings fro CD will work for the upper gudgeon but if you use one on the bottom you will not be able to get your rudder back on, you need the non-bushing replacement from Catalina Yachts for the lower. So you will need to buy two pair unless they will break up a set.

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tackingabout
Deckhand

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USA
13 Posts

Response Posted - 01/30/2008 : 15:28:29

boat is 1986, and the issue occurs under motor or sail. after closer look i see only the lower gudeon is the upgraded type, the upper is orginal, apparently to replace this i need to make a hole in front side of transom to access the bolts, CD has a deck plate kit for it, so i will likely replace the upper and lower as a pair , if this works wont bother to try to re surface the rudder, any one know how to post the pictures i took to this site

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 01/30/2008 : 17:32:40

I was able to get to those bolts through the quarterberth in my 78

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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/30/2008 : 20:25:12

I used the embedded brass plate and the old screws on the upper, I have never understood everyone's aversion to the factory method. If they were strong enough that the gudgeon wore out before they came loose then I figure they are ok. I might feel different if I were blue water.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 01/30/2008 : 22:26:17

I felt a distinct flutter with the original, unbalanced rudder. It went away completely with the balanced rudder, which had a very different foil shape with a rounded forward edge--supposedly a NACA foil--compared to the sharp edge on the original (pre-1988) blade. I had no bushings in the gudgeons with either. I can't explain it--just report it.

Edited by - Dave Bristle on 01/30/2008 22:27:21

Jefffriday
Navigator

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USA
198 Posts

Response Posted - 01/31/2008 : 18:42:43

There must be something a little different with Frank's boat than mine. I replaced both upper, and lower gudgeons with the new style with bushings from CD, and had no problem getting my rudder on (She is a 89 with the balanced rudder). As for the vibration, It is probably worth checking the "high spot" for delamination. You can tap the area on and around the spot with a coin an hear if there is anything wrong. I just finished repairing two 4 or 5 inch diameter blister/delamination areas on mine from letting it be exposed to direct sunlight for a few hours.

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Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 01/31/2008 : 18:50:16

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Jefffriday
 There must be something a little different with Frank's boat than mine. I replaced both upper, and lower gudgeons with the new style with bushings from CD, and had no problem getting my rudder on (She is a 89 with the balanced rudder). As for the vibration, It is probably worth checking the "high spot" for delamination. You can tap the area on and around the spot with a coin an hear if there is anything wrong. I just finished repairing two 4 or 5 inch diameter blister/delamination areas on mine from letting it be exposed to direct sunlight for a few hours.
<hr height="1" noshade id="quote"></blockquote id="quote">

Part of what we, as well as any other used boat owner, have to deal with is the fact the the DPO might have made modifications for any number of reasons. Additionally, because we are not a strict one design class Catalina could have made a change mid model year. No reason or explanation required. It's not like they have to shut the plant down for retooling - they just tell Fred and Earl the new process over coffee at the morning meeting. Ergo, there very well could be something different between the two boats.

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jmoritz
Deckhand

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21 Posts

Response Posted - 02/05/2008 : 11:11:29

I have the same rudder vibration and have never been able to figure it out. I also have the inboard diesel and wondered if it contibuted. I get the vib. under power or sail. I even built a balanced rudder from the plans on this forum and still get the vibration. There is a very small amount of play between the pintles and the gudgeons but I have never had a boat do this before.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 02/05/2008 : 20:20:19

John, I'm suspicious your saildrive is creating some turbulence around the rudder, whether the prop is turning or not. My only other thought would be to add nylon bushings to the gudgeons, which might require opening up the holes just a bit.

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.