Fiberglass failure under lower pintle oday 26

[jfschena]

Last season I could hear a creaking noise when moving the tiller. I knew the pintles

were a little loose, as was the tiller. That's what I figured it was.

Fast forward to today. I pulled off the pintles to inspect and rebed them and found a crack in the gell coat. I pulled out my festool ct 22and started sanding. The crack went all the way through the fiberglass, through the filler from what looks like a previous repair, into the foam center.











My initial take on this: fill back to the level of the inside of the lamination using epoxy and cell-o-fill. After that, replace the lamination with fiberglass and epoxy, brush on a thin layer of gell coat or paint.

Any thoughts? Buy a new rudder?

Joe

 

[DannyS]

Last season I could hear a creaking noise when moving the tiller. I knew the pintles

were a little loose, as was the tiller. That's what I figured it was.

Fast forward to today. I pulled off the pintles to inspect and rebed them and found a crack in the gell coat. I pulled out my festool ct 22and started sanding. The crack went all the way through the fiberglass, through the filler from what looks like a previous repair, into the foam center.



View attachment 73463



View attachment 73464



My initial take on this: fill back to the level of the inside of the lamination using epoxy and cell-o-fill. After that, replace the lamination with fiberglass and epoxy, brush on a thin layer of gell coat or paint.

Any thoughts? Buy a new rudder?

Joe

I wouldn't hesitate to reglass that rudder and go back to sailing. I reglass end my delaminating rudder a few years ago on our O'day 35. Here's a link to my repair.

http://forums.oday.sailboatowners.com/showthread.php?p=744783&highlight=rudder delamination

 

[centerline]

repair it.... and save a lot of money.

but when you repair it, do it good the first time so it never fails again... if one of them still looks ok, I would sand it down and add a couple layers to insure it will stay that way.
take the reinforcement out about 4 inches in every direction from where the pintle beds to the rudder...

 

[jfschena]

Thanks guys. Looks like I break out the 6 inch orbital tomorrow. I'll send pictures

Joe

 

[Brian S]

Joe, I'm don't know what cel-o-fil is, but I imagine it is a thickener like colloidal silica or micro balloons. Knowing it was foam under the laminate, at a high stress point, I would consider a beefier cavity fill medium. I have seen colloidal silica mixed with epoxy be somewhat brittle, especially in more of a thinner film [admittedly not what you repair will be.] (Colloidal silica is basically tiny silica beads. And micro balloons are easy to fair, and light, but not terribly structural.) I would consider filling the cavity with epoxy mixed with microfibers. It's not as smooth a mix, but it's good for laminations, and I think it would set up in a stronger matrix than colloidal silica. When I need a strong and smooth matrix, I will use microfibers and the silica. Either way, your repair is likely to be at least as good as the original structure, if not better. But I wouldn't use micro balloons, just not structural enough IMO.

 

[jfschena]

I've started out making a jig so I can get good a alignment when it comes time to put the lower pintle back on.

As you can see, there is a crack that goes through the entire foam center. I'm tempted to take my jig saw and cut out a big notch and replace it with a hunk of oak









Next I'll start filling back in with epoxy and cell-o-fill and some chopped up fiberglass. I'll then start laying in tape and resin

Joe

 

[RichBone]

With the history of Oday rudders breaking it might be wise to sheath the whole rudder in fiberglass.

 

[jfschena]

I gave in to temptation. I'll laminate ply in there to the proper thickness. The foam looks to be in good shape. I'll finish with a few layers of glass as I was before.

 

[jfschena]

This new core is made up of 3 pieces of exterior grade ply. I'll glue them up tonight and make sure the edge grain is well sealed.

So. . . How can this approach backfire on me? I hope epoxy works on foam core; please tell me it does

 

[Brian S]

I think your best bet is to make sure to bevel back the laminate so that when you build up your layers of glass, it makes a good "scarf." Also, the corners of the wood block should be well rounded - fiberglass doesn't like to make sharp bends. Lay your largest piece of glass first, and wet it out, but only just wet it out. Then go successively smaller as you build thickness - it sounds counter intuitive, but you'll need to grind it all down smooth when it's cured. If you had the big piece on last (surface piece) you'd probably grind through some or much of it, and that would weaken it some.

Also, consider taking some firm polyethylene sheet, and wrap it around the wetted out repair area, and clamp it between some boards, to well compact the repair. Remember that resin gives practically no strength. All it does is hold the glass fibers in place so that they become a strong, stiff matrix. Firmly squeezing the works will eliminate any potential voids, and reduce the epoxy in the glass to epoxy ratio, which is a good thing. Hah, my boss has these translucent plastic envelope pocket things for papers. I keep looking at them, thinking how they'd be perfect for fiberglass repairs. I must remember to ask where she got them...

I've been thinking if you should let in a bigger piece of plywood, to support more stress. But, if you can get a wider pintle bracket on the rudder, perhaps you should build up more glass to fit the wider pintle, thus strengthening the whole works significantly. (I'm not too sure on that, as I don't know what the whole rudder looks like, or how it's designed. I only have kick up rudders for my boats...)

After the repair has been able to cure for several days, clean it well with soap and water and a Scotch-Brite type pad, to remove amine blush. You may wish to wait 1-2 weeks before any finishing, as the epoxy will continue to cure even after it gets hard to the touch. Gel coat is rumored not to stick to epoxy, but the guys at West Systems say it will stick fine if the epoxy is fully cured and well cleaned of amine blush. Or, you could just paint it. I found that a Rustoleum Almond spray paint color was a very close match to the sand color on the interior of my Harpoon. It made my mast step repair look very nice.

 

[jfschena]

Thanks, The repair is actually only half the length of the pintle. I left the other half because the core was in good shape plus it leaves two of the original hole to help with alignment. I found a receipt from a marina for a repair previous. They repaired the core by forcing in resin and cab- o- cil. Whatever they did for fiberglassing delaminated.

I hope the new wood core will be more stable

. Joe

 

[Swee Pea 1976]

I like the plywood filler..good idea.

Mine had a hair line crack from top to the waterline of the front edge. I have ground it out and have preped for fiberglass repair. Need warmer weather!!

 

[jfschena]

Added a thin layer of resin and cell-o-fill over wood core. Later today I'll take a rasp and reprofile the area. I'll start glassing after I'm satisfied with the look.





Joe

 

[jfschena]

Spent some quality time with a farriers rasp today. Here are the results. Hopefully I'll get to glass tomorrow.

 

[jfschena]

I found this leftover 6 inch 45/45 directional tape from a ck-17 I built several years ago. After applying a coating of resin, I laid in the tape and saturated. I then rapped with stretch rap and added some weight.

 

[Brian S]

Joe, I would do all of your laminations at the same time, and wet each out with minimal epoxy. I would not do one at a time, unless you lay the next layer of glass on top of "green" epoxy - that is, epoxy which has kicked and started to cure, but is still soft, preferably a bit tacky still. This ensures you get a chemical bond between layers of epoxy/glass, such that it forms up into a unified matrix. If you allowed each layer of epoxy/glass to fully cure hard, you would be getting a mechanical bond between matrix layers. Again, keep in mind that less epoxy is good. Strength comes from glass (fibers) stiffened into a matrix with the resin, not from extra resin. A 60-40 ratio of epoxy to glass is stronger and lighter than 70-30.

 

[jfschena]

Due to the complex shape I'm going to have to lay one side then the other with a 2 inch overlap at the leading edge. I will strive for a chemical bond. However, my schedule may prevent that. If it turns into a mechanical bond I'll give it a real good scotch bright before the next layer. I've had good results with that in the past.

You are absolutely correct, a chemical bond is the way to go.

Joe

 

[jfschena]

I was able to get on 1 layer of 45/45 6oz tape followed by a layer of bias cut 6oz glass. Allowing of a bit more resin to fill the weave, I think that's about all I can fit. Otherwise it will be a tight fit to get the pintle back on.

More pictures tomorrow.

Joe

 

[Brian S]

I was able to get on 1 layer of 45/45 6oz tape followed by a layer of bias cut 6oz glass. Allowing of a bit more resin to fill the weave, I think that's about all I can fit. Otherwise it will be a tight fit to get the pintle back on. More pictures tomorrow. Joe

Joe, don't forget once you get the repair all cured up, you're probably going to have to grind it back smooth, then put one thin coat of neat epoxy on to seal exposed glass, then paint. So don't worry about going too thick, get as much laminate in there as you can. Even if you could keep it exactly the right thickness to fit the pintle bracket with just your lamination schedule, it'll probably be kinda lumpy anyway, and you'd want to address that before final finishing. Just like woodwork, make it a wee bit big, then finish it down perfect.

 

[jfschena]

Drilled over size holes through the portion of the rudder that has wood core. Filled with resin and cell-o-fill. Once cured, will re-drill to proper size. This should keep any water from reaching the wood core--I hope