Rudder repair or replace?

[Runaway#23]

As Runaway slowly gets back into shape, I have now noticed that the rudder head is hooked to port. The leading edge of the foil has a series of hairline cracks that can be ground out and glassed over to seal properly. That still leaves the head out of alignment.

Has anyone had to deal with fixing this or is it just better to replace?

I found the reference to Phils Foils, who have made rudders for other 7.9's. Can replacement rudders be purchased from Tiara as well?

[Stef]

Sounds like it's ready to break!
This is a weak point with these rudders. I had some water in mine after the first season I owned the boat. I found the crack and drilled 1/4" holes all around into the core and put it under a heat lamp 8 hrs a day for a few weeks. After it dried out I carefully examined the head and found lots of crack here too. I then proceeded to cut a slot from above the pivot hole down the rudder about 17". I tried not to break through the other side. After, I installed a 1/4" x 2" piece of stainless steel and buried it in the slot using 2 part Interlux filler (blue stuff) for above and below waterline. Reglass and it seems better than ever.
I found just digging out the cracks on the head didn't hold up well, you will need to add a few layers of glass cloth over the whole thing to keep them away. This was also another water entry point for mine. Although just rain, it would add up over the season.
I have some ugly pictures of a rudder that snapped at the head, real ugly!
I priced a new one, it was around 2K. With Tiara building more 7.9's (someday) I would think you could get a better deal with them.
Don Smith in NJ had an extra rudder in his garage.

[dave]

My rudder is the same way, LOTS of stress cracks. My plan is to grind the whole area out: that is to say, grind all of the original glass down to just this side of the core, with the ground out area going 9" or so past the highest and lowest stress cracks, and then rebuild with biaxial glass and a few carbon stringers running top to bottom, using MAS epoxy. Make sure you do a long taper on the grind to get a great bond and spread the load.

[Runaway#23]

Thanks for your comments (or welcome to my nightmare!). The crack(s) along the leading edge of the foil should be the easier repair. I ground the entire edge back about 3 inches on each side and will retape with fresh resin and biaxial 1708. Have used this before with much success.

The challenge is really the head - since it is out of alignment with the axis of the rudder - and hooks to one side when upright. This means that one side became too long (or the other is too short). The head has lots of crazing in the gel coat, so I will grind it all off to see what lies beneath. But fixing it will require more than adding some cloth and resin since the hook will have to be straightened. I can't imagine that whichever side get adjusted will take more than adding or subtracting 3/16 of an inch - maybe only 1/8.

Dave - you mentioned ( and several other past posts ) adding a stainless steel square rod - perhaps as large as ?? 3/4 x 3/4? Do you put one forward of the pivot bole and another aft or will just one do?

I did a repair years ago on a skeg, and had an engineer design the repair. He used a steel rod with several 1/4 inch holes drilled to accept steel rods creating a webbing effect. At the bottom of the skeg, the 1/4 inch rod was maybe 3-4 inches long. Put them three inches apart and each rod (moving upward) was an inch longer than the previous one. We used 3 or 4 rods, but remember it was just a skeg and the idea was to transfer the load at the bottom of the skeg through the 30mm solid bar (an old prop shaft) up into a reinforced bulkhead in the boat.

The same thing could be done with the S2 rudder by drilling 1/4 inch holes every 6 inches and adding 1/4 in rods of various lengths. Question is - how long shoud the square tube be and do you guys recommend using one or two?

the rest should be easy - just grinding the cloth off one side and making a trench in the foam core, fill in with blue filler and reglass. Also, what material did S2 use as a pivot bolt guide? What's left of mine looks like corroded aluminum. Perhaps replacing with stainless would be a good idea while it's apart.

Thanks in advance for all the comments from our experienced group of unintimidated glass and engineering experts!

One last comment- GO Wings!

[dave]

Stef mentioned th steel, not me. A few carbon strips in the laminate is WAY stronger than steel and adds no weight. The whole setup is crazy heavy anyway, I would do whatever I could to make the whole shebang the minimum weight allowed by the rules.

On the foil. If the blade is so warped/crocked/bent that it can't made perfectly true with some simple grinding, filling and fairing, I would go with plan B, whatever that is. Having a blade that isn't at LEAST close to perfectly fair, straight and centered hurts the program WAY more than most folks care to admit. The bottom of the boat and all that goes with it suffers form the "out of sight, out of mind" thingy in spades. Fresh water is 833 times as dense as air at sea level and saltwater denser still. The lift and drag that is made or CAN be made and/or fine tuned [lift to drag ratio] is enormous!!!!

[Runaway#23]

Dave;

I had a chance to do a little research today and found some 6 inch wide carbon fiber tape rated @ 3K. The advantage of this tape is that it is unidirectional -not woven. I would tend to think that this ( similar to biaxial mat) has advantages over woven carbon fiber fabric.

It would appear that using your idea is certainly easier to implement ( beats cutting a 2 inch groove in the skin to insert a stainless beam). So a few questions about carbon fiber: would you make two 3 inch wide strips on each side, double over the 6 inch tape making it double thickness or just use the 6 inch wide piece as it comes?

Or do something different?

Next question: how long a piece to install? - measuring from just above the pivot bolt to the fwd tip of the blade - it seems that 4 ft is a good dimension, maybe 4 1/2 if you want to go the whole length of the blade. I spoke with someone from Ontario (frank, former owner who built a few rudders) who told me that the quality control of the blades were irradic at best and that warping of the heads was common. The other tidbit was that the foam of that generation absorbs water. Not good. Store your blade indoors during the winter. Also, that a considerable amount of filler/gel coat is on each side of the head and could possibly be sanded off to correct the warp - and beef up the opposide to correct the thickness issue. Lots of good information to be sure.

Thanks for all the pointers. Maybe you should give an online seminar!

[Runaway#23]

Stef:

Do you know how to get in touch with Don Smith? If so, please send PM.

[tuctdls]

Hi all!

Well yes my boat came with two complete tiller assemblys. That is the good news. Bad news is I am mixing and matching now to put the least used or worn parts together. Few years back someone was looking to buy my extra assembly. So where I sail down on Barnegate bay there is an unused S2 up on the bulk head at the south end of duchman's point. From what I hear the boat was sailed 2 or 3 times. It now sits filled with water. Other then weather the rudder is unused. Boat with inboard is a lawn ornament.

Don

[dave]

Runaway, use the stress fractures as your guide, as I said already. I would go at least 6-9" on either side [top and bottom] of the last stress fracture, and yes, for this repair the unidirectional is the ticket. Don't fold it though, if you want double thickness just cut to size. Some uni carbons have so much sizing on them to keep them together that they are hard to wet out. Vacuum bagging the whole patch, one side at a time, would make sure that you had the highest fiber to resin content and take care of any issues with the carbon not wanting to lay down completely. Of course you don't HAVE to bag it, but I would take a small piece of your chosen carbon and wet it out first and then see how it lays down.

On the core thingy, yes, they do absorb water over time...................................

[Marionete]

Don;

Thanks for letting us all in on your secret - two rudders may be better than one. But you open up another can of worms with that poor abandoned "yard ornament" S2. But the good news is that it probably has a keel, hatch, mast and rudder that can find better homes with the 7.9 members. Let me know if you can find the owner and if they might want to sell of the parts -

After speaking with Frank the other day, I decided to grind out the warp in the head to see what was going on underneath. There is a 1/2 inch ID copper pipe as a pivot bolt bushing that goes completely through. In addition, it looks like some glass work had previously been done, but there were no cracks visible going from the head down into the blade.

I ground off about 3/8 of an inch - well into the foam core and it was noticibly damp. Dave probably has a few ideas on what to do next - like let it bake in the hot summer sun, poke the copper pipe out, grind off the gelcoat. Then check the head - blade alignment after more grinding and reglass the whole thing to get it true. Glass cloth will extend into the blade with carbon fiber inserts possibly between the laminate.

Fair and gelcoat, sand more and paint.

Ugh. Just what I needed, another full time job. Maybe I'll ship it to Little Rock and let attend Dr. Dave's clinic!

[Marionete]

Dave;

I ground off all the gel coat and old fiberglass on one side of the head - no stess fractures to speak of, just damp foam underneath. Interesting to find the copper tube for the pivot bolt. What's up with that?

Probably means this rudder was repaired once before -

I gound off enough foam to make the head alignment with the blade and will have to build up the other side ( inverse mirror image) Not quite sure what weight cloth to use sealing the head up again.

The place I found for carbon fiber only charges $7 a yard, so the actual dollar investment for the fix will be low. Would you recommend replacing the copper tube with stainless? Thanks for the advice on the unidirectional 3K tape. 6 feet should do the job.

What do you recommend to dry out the rest of the foam core?

[dave]

Getting moisture out of foam or any other core material is a time consuming and not always completely successful.

I think that I would drill many holes all the way through the rudder, from skin to skin. Then place the blade in a spot that gets plenty of sun for as much of the day as possible and build some kind of quick frame to support it and keep it from warping. Put down black visqueen under everything to act as a moisture barrier from the ground, put a couple of containers of Damp Rid or something similar in with the blade and then cover and seal the whole thing with more black visqueen. A heater would keep things working after sundown.

Vacuum bagging would work too but most folks don't have access to a powerful vacuum pump and it would still take much time. Remember; warmer air can hold more moisture than cooler air, hence the heat needed to make this work. The moisture needs to be allowed access to the air and the Damp Rid gathers it so that the air in the tent doesn't get saturated to the point that it can't or won't hold any moisture! Check it after maybe a week or so to see if the Damprid containers are full and if so replace them until you see no more activity.

[Marionete]

Good recommendations as usual Dave. I think that I will first try to make some determinations in the hole drilling process to see if there are areas where the core may still be dry and then choose not to over drill those areas, and focus the drilling on the sections where the core is obviously wet.

Escept for the head where the copper pipe exists for the pivot bolt, only the leading edge of the blade had any visible cracks. How far water may have penetrated into the remainder of the core remains to be seen.

Sailing this old thing would be preferable to glass work any day!

[dave]

I just assumed that you would start drilling outwards from the wet to see if you ran into not wet................................ SOP.

On the bearing: Make a quick jig to relocate the hole exactly when needed. I would suggest knocking it out and over drilling the hole, then refill it with some epoxy filler. After you get your new skins on, redrill for the original bushing size and reinstall with the old one if not worn too badly, or something new. This way, when the bond between the metal and the FRP weakens or cracks as they always do, the area around the hole is still waterproof and sealed by the outer skins too.

Don't use gelcoat. I would spray a few coats of Interlux 2000/2001 on it when done, sand smooth and then finish the top with Awlgrip and the bottom with Interlux Performance Epoxy for dry sailing or bottom paint for other. The egdes where the two skin halves meet are the main problem. Until those are both ground down and then taped with glass they will continue to be areas of water ingress.

[Marionete]

Dr. Dave's Fiberglass Repair Shop:

Good advice. Probably have to buy more 1708 now in addition to the carbon fiber. Eastern Burlap in VA Beach area is a good source for glass, resins and other stuff.