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Catalina/Capri 25/250 Sailor's Forums

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Rudder modification-repair

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vipermagic
1st Mate

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USA
69 Posts

Initially Posted - 01/07/2013 : 15:27:04

I know this topic as been discussed ad naseum here, but I've been kicking this around in my head for a while now. I figured I should probably run it past you all before my cheapness and youthful invincibility combine to prove me much less invincible than previously believed.

Anyway, my new boat came with a rudder that's pretty severely cracked (Figures 1 and 2 below), certainly compromising the core despite the POs efforts with the tube of silicone. And as we know, the lower half of the rudder is nothing but a cantilever that is prone to snapping in half when under load, aka when you absolutely positively do not need a broken rudder.

My thought, before I spend the $600 on a new rudder, is to open the old one up and put two steel rods right down the lateral center of the rudder (figure 3), to stiffen the lower end and transfer some of the load to the top half between the gudgeons.

I haven't done any of the calculations - is the force on the rudder so high it'd just bend the steel and snap the rudder off anyway? Or is there something else I should be concerned about?

Thanks guys!

79 C25 #1433 SR/FK - 'Carina' - Destroyed by Sandy
84 C25 #3817 TR/SK
Cleveland, OH

Edited by - on

islander
Master Marine Consultant

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USA
4024 Posts

Response Posted - 01/07/2013 : 17:32:05

In my opinion that is the way the rudder should have been built, With a backbone. By the way that seam isn't a crack, Its how the rudder was made. My 87 balanced has the same seam. I'm not sure but I think newer ones have the seam glassed over. As far as forces on the rudder? Well lets just say there is enough to do this.

Edited by - on

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 01/07/2013 : 18:16:53

Looks normal to me, mine looked like that and I did go ahead and put some cloth and resin along the seam just to make it look nicer.

Edited by - on

putzmeister
Navigator

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100 Posts

Response Posted - 01/07/2013 : 18:20:50

In my novice opinion - unless you make the straps out of material that would be overkill - you're still going to have flex.

Is the seam open? Many here have opened the seam and filled it with epoxy.

These (by Schaefer Marine) are pretty bulletproof:

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 01/07/2013 : 18:54:18

Mine looked like that so I ground out the seam a little bit then filled it in with epoxy. That was about ten years ago.

Edited by - dlucier on 01/07/2013 18:56:19

Stinkpotter
Master Marine Consultant

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Djibouti
9081 Posts

Response Posted - 01/07/2013 : 20:51:49

If you grind the seam, before you fill, do some probing into the core, especially around the lower pintle straps. I believe it's wood in that vintage, and although it's above the waterline, it is subject to rain water and such leaking in at the bolt holes for the tiller and pintles, even if not through the seam. If you detect rot in there, you're risking a break at the lower pintle, regardless of what you do to the shell.

BTW, the balanced fiberglass blade I bought from CD had no evidence of a seam--at least not as long as I had it.

Edited by - Stinkpotter on 01/07/2013 20:55:07

JohnP
Master Marine Consultant

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1520 Posts

Response Posted - 01/08/2013 : 06:55:12

I think that the time and money you spend rebuilding your rudder would be equivalent to much more than you would spend simply buying a new one. After you open the rudder up, you will find a mass of rotten marine plywood that is partially attached to the fiberglass shell. You will need to remove essentially all of that old core and then you may need to connect your planned steel rods firmly to the shell with epoxy plus roving plus fiberglass mat.

Alternatively, you could cut, shape, and attach new, marine plywood pieces to replace the original core.

Finally, closing the seam will involve more fiberglass work which would likely increase the final cross-section of the rebuilt rudder. If you don't reinforce the outside of the shell, you would risk more cracking later. An increased width would affect the fit of the pintles. The original pintles would be too narrow. So you may want to not reinforce the rudder shell around the pintle attachment areas to keep the width the same.

After all this you will have a lot of experience with the West System and the safety issues involved with fiberglass work. If the project extends into the sailing season, you will start missing day after day of sailing.

I reinforced an old, split, original rudder on my C-25. I ground out and added 8 layers of fiberglass to each side, sealed up the edges and painted it. It looked like new. The rudder lasted 2 more years until one day I was sailing with friends in some good, 25-knot winds when half of my "beautiful project-rudder" fell off and sank to the bottom. I was 40 miles from my marina and the fun weekend trip was over!

These days I'm happy with my new foam-core, balanced rudder. I really like fixing things, but I never should have tried to fix the old, rotten rudder. I prefer sailing to fiberglass work!

The core of the rudder is essentially a spacer that maintains the shape of the hard fiberglass shell. The shell experiences large, vertical, compression force and horizontal torque on the leeward side, as well as vertical expansion force and horizontal torque on the windward side. I think that a steel rod would need to be firmly attached to many points along both sides of the rudder to actually reinforce the fiberglass shell as well as some new plywood or plastic foam. If the steel rod were loose inside, the shell would be able to bend and crack.

Good luck with your work on the rudder! If you sail on Lake Erie, you will want a reliable rudder to bring you safely home every voyage, that's for sure.

Happy sailing!

Edited by - on

islander
Master Marine Consultant

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USA
4024 Posts

Response Posted - 01/08/2013 : 14:19:22

John, I believe his intention is to remove one of the shells(If that's possible), Rout out a channel in the foam, lay the SS rod in the channel and pour epoxy in the channel to fill it. Then re-epoxy the shell to the foam... I think

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Stinkpotter
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Djibouti
9081 Posts

Response Posted - 01/08/2013 : 19:58:59

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by islander
 John, I believe his intention is to remove one of the shells(If that's possible), Rout out a channel in the foam, lay the SS rod in the channel and pour epoxy in the channel to fill it. Then re-epoxy the shell to the foam... I think<hr height="1" noshade id="quote"></blockquote id="quote">...except from '84, it's wood--not foam. That's in the head of the rudder where the pintles are mounted--I believe the thinner section that goes below the waterline is solid fiberglass.

In most big-boat rudders, there's a stainless steel grid welded to a rod that is the rudder post. The steel grid adds strength pretty much from corner to corner, rather than just along the leading edge in the rudder head. That might be overkill for a C-25, but a single rod on the leading edge might not be a satisfactory solution if the wood core is shot.

Edited by - Stinkpotter on 01/08/2013 20:07:12

vipermagic
1st Mate

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USA
69 Posts

Response Posted - 01/09/2013 : 09:06:18

My idea was indeed to remove one of the shells, (assuming the inside wasnt *too* bad) mill a slot in the wood and replace any of the core that needed, epoxy everything in place and reseal the beast back up.

I didn't realize the bottom half was solid fiberglass. That's a pretty big kink in the plan. Its good to know that larger boats have a SS grid inside- the idea made a lot of sense to me, but I hadn't really heard of it elsewhere.

I also didn't realize that the crack might not be a death sentence for the rudder. I'll have to clean it up and do some inspection and see how the core is, and then make a decision how to proceed.

I did a little modeling of the rudder, the maximum force is around 750lbs! And a bending moment at the lower pintle of about 1200lb-ft.

Edited by - on

JohnP
Master Marine Consultant

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1520 Posts

Response Posted - 01/09/2013 : 09:40:30

Your plan sounds like it would yield a very strong rudder. The main question may be how to remove one side of the fiberglass shell without ruining it. Perhaps you could saw straight down the middle of the rudder with a hand saw (or a big band saw) in line with the crack all around. When you stop producing sawdust and hit solid fiberglass, then try to take off one or both sides. You might have to cut off that shell portion and plan on re-attaching it with its refurbished core and the steel bar in a later step.

I am not aware of a discussion on this Forum about removing part of the original C-25 rudder's exterior shell.

Anyone have info on that?

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 01/09/2013 : 10:38:39

Bronze is far superior to SS in an application like this.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 01/09/2013 : 10:44:34

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by vipermagic
 I also didn't realize that the crack might not be a death sentence for the rudder. I'll have to clean it up and do some inspection and see how the core is, and then make a decision how to proceed.<hr height="1" noshade id="quote"></blockquote id="quote">

I believe someone around here used a table saw to make a 1/8" or 3/16" kerf in the seam to a depth of maybe 3/8", then epoxied/glassed in the crevice.

Edited by - on

islander
Master Marine Consultant

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USA
4024 Posts

Response Posted - 01/09/2013 : 14:05:13

It might not be that hard to remove one of the shells. Over the years it might have delamination in spots anyway. Tap on the shell all over and listen for the hollow sound.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 01/09/2013 : 15:01:44

I wouldn't remove the skins unless you are simply doing a post mortem inspection.

If it were my rudder, like I did ten years ago, I'd clean up the crack, fill/epoxy/glass it, then put it back on the boat. Since I did mine this way, it's seen a lot of nasty Lake Erie conditions.

Edited by - on

putzmeister
Navigator

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100 Posts

Response Posted - 01/09/2013 : 17:21:57

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dlucier
 I wouldn't remove the skins unless you are simply doing a post mortem inspection.

If it were my rudder, like I did ten years ago, I'd clean up the crack, fill/epoxy/glass it, then put it back on the boat. Since I did mine this way, it's seen a lot of nasty Lake Erie conditions.
<hr height="1" noshade id="quote"></blockquote id="quote">

Ditto - I ran mine on a table saw with the blade set at 1", glass and resin then gel coat over the entire head - looked new.

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9081 Posts

Response Posted - 01/09/2013 : 21:30:00

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by putzmeisterIf it were my rudder, like I did ten years ago, I'd clean up the crack, fill/epoxy/glass it, then put it back on the boat. Since I did mine this way, it's seen a lot of nasty Lake Erie conditions.<hr height="1" noshade id="quote"></blockquote id="quote">I'm glad Don's is still working for him, but we have several stories from this group about doing similar restorations of the wood-cored rudders, without checking the core, followed by the rudder snapping completely off at the lower pintle (which is attached through the wood core) in conditions when they really wished they had a rudder. Depending on the point of sail, this can cause anything from a momentary scare to an actually dangerous, out-of-control situation.

If the wood core in the rudder head isn't sound, I'd replace the rudder.

Edited by - on

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