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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Rudder Crack - not the typical

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Jared
1st Mate

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USA
70 Posts

Initially Posted - 09/07/2004 : 08:39:46

Well, this weekend I think I cracked the rudder surfing waves? We ran downwind for half a day with 15-20+ knts and 3-4 foot waves (steep choppy Chesapeake Bay ones and of course every once and a while a big-'un would come up) this weekend and when i got back to the slip, my wife said "Do you know we have a crack in the rudder?" It seemed like I had a lot of stress on the tiller while the boat wanted to turn going down the waves. I didn't get a chance to take a picture, but I will have to go down and get the rudder off the boat to fix it and could take one there. I wanted to know if anyone else has had a crack like ours and how they fixed it.

The crack is a somewhat semicircular crack about 6-9" off the lower pintle that goes through an arc of about 90 degrees or so. It may just be in the gelcoat because it didn't feel soft or anything. Any ideas on what to look for to see how serious the crack is and how to fix it? If the core is still solid (I have that foam core), can I just patch the gelcoat and go? With that shape of crack I would tend to think possibly the core is wet and it started to punch through at the weak spot from the lower pintle? Any other ideas - do I need a new rudder?

Thanks.

Jared Jamison
86 C25 #5354 FK/TR "Saba Rocks" Richmond, VA

Edited by - on

MattL
Admiral

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USA
990 Posts

Response Posted - 09/07/2004 : 09:13:06

To me it sounds like one of those things you treat as if it were a crack all the way through the fiberglass. If it is not that's good, if it is, thank your lucky stars that you caught it in time.
You can sand down along the crack to see how deep it goes. If it stops when you hit fiberglass re paint or get some gel coat reparire stuff from catalina direct. If it goes into the fiberglass you need to grind away to fether off the edges, about 2", and lay a layer of glass. build up succisive layers till you get the thickness up. grind and sand till smooth and re paint. I don't think you'd get away with gel coat stuff from CD here.
Good luck, and if you don't feel up to doing important fiberglas repair, this could be your life on the line, take it to a pro. A good body shop or boat repaire yard could do this for you, it may cost a couple of bucks but that's what boat insurance is for.

Edited by - on

eric.werkowitz
Captain

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USA
283 Posts

Response Posted - 09/07/2004 : 17:29:05

Jared,

I assume it isn't a balanced rudder. The blade-style rudder on my '85 (hull # 4969) broke straight across at the lower pintle. This seems to be the area of greatest stress. Have you noticed the rudder twist when you you are putting "stress on the tiller?" Mine seemed to twist 5 or 10 degrees under weather helm. I believe it is an indication of general material fatigue that is greater than skin deep. I tried to repair my rudder and it failed a short time later. Luckily I had the outboard to get back home. I would take steps to build or buy a replacement.

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 09/07/2004 : 20:16:03

I would want to see how deep the crack goes as well. My guess would be through the glass to the core. If so a major rebuild is in order. Spin out the core in the way of the straps (a bent nail in an electric drill will do it) so that there is solid epoxy there to prevent compression cracks. I've added a fair amount of glass to our rudder in the stressed areas. Dave

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MattL
Admiral

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USA
990 Posts

Response Posted - 09/08/2004 : 03:16:43

If you arn't sure what Dave is talking about here is a little diagram, god I'm getting more and more like my father every day.

Drill out the foam to make a big pocket , step 2 adn 3: fill it with epoxy. Might be good to put a little cloth over this opening step 4; Drill out the correct size hole, step 5, and go to town.
What this does is isolate the foam from any exposiure to moisture and also gives more strength to the whole thing.

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 09/08/2004 : 07:15:00

Not exactly Matt,
Actually what I meant was to leave the GRP skins intact and simply remove the foam from behind them. If you bend a nail about 1/4 inch from the end, cut the head off, and put it in a drill you can open the foam to about 3/4 dia inside the intact skins. A second nail bent about 1/2 inch from the tip will complete the job. Then you tape the bottom hole and pour in resin with coloidal silica. Don't fill it in one pass it will get too hot even with slow hardener. Dave

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MattL
Admiral

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USA
990 Posts

Response Posted - 09/08/2004 : 09:09:39

sounds just about the same to me, just leaving more fiberglass intact initially so you don't have to add it later.

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Jared
1st Mate

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USA
70 Posts

Response Posted - 09/08/2004 : 17:42:55

Thanks. I will try to drive back and take the rudder off to see the extent of damage and try the repair above. I think that it most likely broke the fiberglass as well. May be better to just bite the bullet and order a new balanced rudder.

Edited by - on

Derek Crawford
Master Marine Consultant

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USA
3321 Posts

Response Posted - 09/08/2004 : 18:39:35

Jared - if you can afford the BU's, buy a balanced rudder. The difference in the helm is incredible. I went from two handed to two fingered steering (even in a good wind!) It's like going from steering a tank to a power-steering Mercedes!
Derek

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 09/08/2004 : 23:41:25

Jared: That area around the lower pintle is where the most stress occurs. Many rudders have broken horizontally from that point. One cause is the sideways impact on the blade when the boat pounds on a wave while heeled, such that the rudder is at an angle to vertical, but is thrust vertically into the water.

Gelcoat is generally much more flexible than the underlying fiberglass. It can crack due to shrinkage ("spider cracks"), but yours sound like a stress crack in the glass. The cost and uncertainty in repairing it properly would seem to me to justify an investment in a new, balanced rudder. As Derek says, it's great! But more importantly, you will have a critical component you can trust. There're no guarantees, but patching something where the degree of damage is unknown, is questionable. And the epoxy "plug" for the pintle bolts is not likely to be an adequate repair. It keeps out the moisture, but you probably have structural damage beyond that point.

Edited by - Dave Bristle on 09/08/2004 23:45:34

Greg Jackson
1st Mate

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84 Posts

Response Posted - 09/09/2004 : 22:30:25

Oh yea, it's broken.
I generally recommend against buying a new rudder unless you specifically want to upgrade to a balanced rudder. There are also plans floating around for a homebuild balanced rudder.

The reason I recommend against a new one is that they are just as easy to break. There is not enough strength in the design. The better solution is to repair it but make it better than original so it never breaks again. All you need to do is sand off most of the gel coat and then sand away most of the fiberglass for about 3" on either side of the crack. Lay up either glass or carbon fiber. Regular glass is just a waste here. You can either use unidirectional glass which is made specifically for rudders and centerboards, or use bias weave biaxial glass. The biaxial can be made almost unidirectional just by pulling on the weave a bit, all the fibers will line up. Whether you use glass or carbon fiber toe, get most of the fibers going up and down. Fibers running horizontal will do nothing for strength. Remember that the cord does nearly nothing for strength, even a plywood core. A good broach off a 6' wave can put several hundred pounds of force on your rudder. Lake sailors rarely have to deal with such things, but it can be commmon if you push hard in rough conditions.

Oh, and do the expoxy plug thing around the bolts. No sense in letting the core rot.

G. Jackson

Edited by - on

MattL
Admiral

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USA
990 Posts

Response Posted - 09/10/2004 : 09:35:19

Good reply Mr. Jackson

Edited by - on

Jared
1st Mate

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USA
70 Posts

Response Posted - 09/10/2004 : 09:55:03

I like that idea of trying to repair it so I can learn something new by doing it. I should just throw an extra rudder in the quarterberth in case I break it, right... Only kidding. I have already done that epoxy plug thing repair at the lower pintle connection to the rudder and that thing in bombproof now. I was so proud of my handywork - I would have just sunk her there if it would have broken there since I would not have been handy enough to own a boat. Now, all I have to do is bring that thing home and fix it before the season runs out... Carbon fibre... Fancy pants. I wonder if I could just stick some FRP (fiber reinforced polymer) on it like you do to stregthen in place concrete - then maybe I could get an engineering grant to do it. Is carbon fiber more expensive than glassing it?

Thanks for the advise.

Edited by - on

eric.werkowitz
Captain

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USA
283 Posts

Response Posted - 09/10/2004 : 19:32:29

Jared,

My experience seems to differ with some of Greg's advice. After my blade-style rudder failed I built a balanced rudder as Greg suggested was feasible. That was 4 years ago and it seems to be holding up well with one exception. There are some cracks in the fiber glass running vertically between the pintles. I attribute this to one or more possible causes. First, I didn't put enough of an edge radius on the rudder above the waterline. It's hard to keep the glass from springing up away from a sharp bend as the epoxy sets unless you've vacuum bagged it. I think the numerous patches I did to correct these small delaminations did not leave the assembly as stong and flexible in these areas as I would like. The second, and I believe more serious problem, was orienting the bi-axial glass outer layers in a vertical and horizontal direction (bottom layers were unidirectional and oriented as Greg suggested, along the chord). In the area between the pintles the rudder is subjected to a twisting moment supplied by the tiller. I believe this twisting is best resisted by glass fibers running at 45 degrees to the horizontal. In fact, had I layed up the rudder in this manner the first problem would have been less severe as biaxial cloth drapes much nicer when run on the bias. To sumarize, I believe you need to do a repair in this area with the idea that you need to reinforce against the twisting of the rudder, ESPECIALLY a blade rudder! I say this because the balanced rudder requires much less force from the tiller to control the boat, therefore less twisting moment on the rudder.

Good luck, what ever you do.

Edited by - on

Jared
1st Mate

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USA
70 Posts

Response Posted - 09/11/2004 : 09:54:48

Eric,

I agree that I should reinforce the rudder with a biaxial type cloth. The vertical fibers will experience much greater tension that the horizontal, but the horizontal fibers do need to be there in order to get the load back to the pintles. I guess I don't know that much about fiberglassing and just need to take my wallet to West Marine and let them sell me everything they say I need... On second though, I need to get a book.

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 09/12/2004 : 17:11:34

Jared,
Almost any biaxial cloth in the 6 to 9 0z range placed on your rudder in 3 layers through the high stress area, 1st layer about 18 inches above and below the lower pintle, 2nd about 12 inches, 3rd about six inches, both sides of the rudder of course. This is on top of repairing the broken laminate in the area you damaged. Finish with an overall layer of thin ( 4oz.) cloth and then fair out with micro-balloons. This will be an order of magnitude stronger than the spray layup shell that was on your original rudder. While your at this place a band of biax all around the perimeter to fasten the two halves of the shell together. If you have any questions feel free to ask I do this stuff all the time for a long list of customers most of whom I have worked for for 20 yrs. or more. BTW I striped our balanced rudder and built it up this way 4 or 5 years ago. I also cut off about 3 or 4 inches from the bottom and put an end plate on it so that it did not extend below our wing keel. I highly recommend this be done for all wing keel boats. PS skip the carbon fiber its a complete waste of money in this application. Dave

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