I have a 91 Mystere 5.0. The rudders are intact and look to be in good shape except they are roughed up along the bottom from hitting ground/beaching etc. They appear to be constructed of two halves (plastic I think) bound together at the seam with adhesive and hollow inside. One already has what appears to be an old epoxy repair in this area. They both get some water leakage into the center cavity when I sail. One will drain out when I leave it standing up but the other does not. I want to repair the bottoms and seal the seams to keep the water out. What is the proper way to repair these plastic rudders, with expoxy, other? Do I need to do anything special since they've already had water leaking into them? Any ideas would be appreciated.

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Steve - Texas Gulf Coast

91 Mystere 5.0 (sold)
04 Nacra 570 (sold)
08 Hobie Wave
00 Taipan 4.9
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Steve, good to see another Mystere owner on the board. Yours is definitely vintage! The rudders are gel-coat & glass, filled with foam and Mystere's own mixture of glass-reinforced putty. Water penetration is never good and if you have one draining then there's a void or the foam's getting soaked. You could try injecting epoxy once it's dry, but the reality is once foam gets wet delamination is likely to follow. Check out products from West System.

Other options are to take the better of your two blades to use as a plug for a mold, then building your own blades. Or swap to a different manufacturers blades/castings/gudgeons.

Thanks for the response. I was able to remove a silcone plug on the side near the top and get all the water out. The rudders seem rigid and sturdy so I am going to attempt a repair for now and see how it goes. I'm thinking of using Marine Tex gel epoxy to repair the bottom edges of the rudders where they have some wear from dragging the bottom. Then I think I will use a thinner marine grade epoxy to seal the joint/seam all the way around. If someone has experience and tips for working with Marine Tex or knows of a better option to use for this purpose let me know.

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Steve - Texas Gulf Coast

91 Mystere 5.0 (sold)
04 Nacra 570 (sold)
08 Hobie Wave
00 Taipan 4.9
--

marine tex is not the preferred product.

depending on how much you need to add back to the shape ...

use the same materials (glass and/or gel-coat) and add something to strengthen up the glass (mill fiber, fiber glass strands, cut up glass cloth, etc) so you add "rebarb" to help hold it together while you are sanding down at the beach (every time you hit bottom)


then will fair down the new gel-coat to the correct shape.... (wrong shape means trouble)

all products can be purchased at your local marine store.

Thanks Andrew, I guess you caught me trying to take the easy way out! Actually, one rudder has no wear at all on the bottom so I think I just need to apply something to seal the seam on it to keep water out. The other is worn down about about 3/8" max at the peak of the bottom tip radius compared to the other. It has been repaired previously (and not very well) with what to me appears to be epoxy (yellow and ugly). My thought was to sand this down and use the white Marine Tex to build it up slightly and reshape it. Do you think the Marine Tex will not do the job or is it more that it is not the "correct" way to do the repair? Keep in mind that for now I am not worried about cosmetics. I just want to seal it up and prolong the life until I get more time on the water and decide whether the boat is a long term keeper for me. Also, can you expand on the "wrong shape means trouble" comment? I appreicate the input as I am a rookie when it comes to marine fiberglass repairs.

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Steve - Texas Gulf Coast

91 Mystere 5.0 (sold)
04 Nacra 570 (sold)
08 Hobie Wave
00 Taipan 4.9
--

From the Marine Tex site
"-Applying polyester resin (like gelcoat) over epoxy is very tricky and must be done extremely carefully. The smaller the repair, the easier it is to coat epoxy with gelcoat. The larger the area, the polyester will be more difficult to work with and more likely to malfunction (not cure)."

without gel-coat you have no UV protection and your epoxy will degrade much quicker

As per the fairing.. if you don't match the optimal shape you can have lea/weather helm issues (i.e. lea helm at one speed and weather at different speeds), you can create drag (slows you down), etc

I am no expert on glass/fairing either. Last year i built up my rudders with gel-coat only to fair it ALL off 3 times. i now have unmatched rudders that behave slightly differently.