Fiberglass repair of rudder - no space for bevel

How would you guys fiberglass a secure repair for the two damaged patches located at the rudder borders, with no space at the edges to grind a bevel?
Boat is a Wauquiez being prepared for circumnavigation.

From the original design drawings.
Rudder layup schedule:
2850g = Gel/450g/600gWR/600g/600gWR/600g
each side SS web and stock bonded to one side
2400g CSM sides bonded with poly resin
Trailing edge fastened 5 off 6mm diameter machine screws

 

I am a bit confused here (this happens easily with me).
Re the layup schedule, I presume that the 450g and the 600g are CSM laminates in between the 600g woven rovings?
If so, then where does the 2400g CSM come in for the sides - is it just CSM, or has it got WR in between as well?

And I am baffled by this - "Trailing edge fastened 5 off 6mm diameter machine screws" - can you elaborate a bit on this please?

Are you worried about the two areas shown in way of the leading edge at the top and bottom of the rudder, or the two areas on the trailing edge as well - the lower one looks as if a crude glass tape 'band-aid' has been stuck over it.

Which Wauquiez design is she? I am hazarding a guess at a Centurion (maybe a 40 or 47), built in the late 70's or early 80's?

 

Just guessing here,I have a feeling that the zones near the leading edge are indicating where there may be some tangs attached to the rudder stock.That would be a typical technique of the time and hasn't changed too much since and the bulges near the training edge may well be indicators of the location of some of the machine screws,which again may be linked to tangs that connect to the rudder stock.The basic repair technique ought to focus on two things;restoring a good shape to the surface and then applying a coating to prevent water absorption.Materials will have to be selected from what your local suppliers can provide or what can be shipped in to suit your timetable.

 

From what I can see from the pics, those aren't structural, so the bevel is of less importance. Just do what you can and call it good.

 

Standard SS webs welded to the rudder stock.

The damage is 1/8" deep. Normally I would grind out a bevel and layup the repair, but there is no space for that.

Want to avoid just plugging with epoxy and milled fibers.

 

Thanks ondarvr...how would you do it?

 

I would use a good marine polyester, VE, or if let's you sleep better at night, epoxy.

These are relatively minor repairs that will survive a few more decades, or at least as long as the rest of hull does.

 

I like to repair these with epoxy putty and glass, of course. But @Rumars probably knows best.

I’d make patches smallest to biggest and make sure the edges a/o rough spots are filled with putty. So, for 1/8” deep, you can get 3 layers of say db1700 or 400gsm biax cloth, but I kinda like using mat for these with epoxy. Mat can be laid with torn edges. The main thing to avoid is air entrainment.

So, step by step.

Grind ALL loose stuff away. Use a max of 40 grit paper for key. Clean well.

Take a piece of clear plastic and a sharpie and tape to the rudder over the repair area and after deciding how thick to do the repair; draw the size of each patch and move the plastic until you have them all sized. Smallest to biggest, increment backwards and leave a step, say 1/2” around each piece or so…

Cut out the plastic patterns and draw them onto the glass. For glass with strands cut them out and label up on each one. For mat, tear the patches and arrow the orientation as well.

Apply a mixture of cabosil and epoxy. Use a bit more than 2:1 cab to epoxy by volume. If the substrate appears dry, wet the substrate before adding the cabosil. I usually always do it to be careful. Then I paint the putty into the hole to fill voids. It can be hard to do, so I like to use fast epoxy and sometimes let the first coat go hot before I continue.

Then add each piece of glass. I always prewet over putty for biaxial or mat; for light wovens, not need. Then wetout each piece. On the edges of each piece of glass or for odd depressions, I add more putty.

Continue until the patch is done. If you have trouble; you can work on green epoxy, so let it kick some and keep going.

Use a piece of tape or some such to catch the drips or you’ll be sanding for an xtra half hour.

I like wetting out this type of repair with a chip brush and find it does a nice job or forcing any air out.

I do not use milled glass in the putty. It tends to clump and makes it very hard to do without air. If all you have is milled glass~you subtract some cabosil, but it can be harder to work with as clumpy..

 

Turn it hard right rudder and then bevel the expose leading edge.

 

What is the core here? Somehow I read stainless shear web, but seeing none.

If the laminate is damaged thru, you might need to add a core of foam of some sort.

The classic Boston Whaler repair decores the foam behind the repair. Here the original glass in green, the core is yellow, the putty is crudely shown in pink and the new laminates in blue.

Edited: The repair putty extends under the original laminate. I only mention for your edification. I follow if it ain’t broke don’t break it, but if the laminate has cracked or is weak, the putty behind the original laminate makes it very strong.

 

Don't over-think this, it is a simple and relatively easy repair. fallguy's instructions will work, and it will work with whatever combination of resin and marine filler you choose to use.

There are no stresses on these spots other than some rather slow moving water flowing over them.

In general the condition of the laminate is poor, you can see the water absorption in that the surrounding strands of glass have turned white as the water wicks down them. Rudders tend to be poorly constructed on production sailboats.

 

I would really like to know, have you been fixed and started your global plan?