Attempting to push epoxy into such a tight crack (delamination) is gonna be fraught with near failure.
What I would do is similar to what what you did to the tip of the rudder. If you have a table saw, I would saw into the delaminated area to a bit wider than the width of the G10 (for the G10 AND thickened epoxy). Be sure to cut as deep or deeper than the delamination. A large band saw might be better yet. The multi-tool that you used for the tip repair might be ok,too, if you can saw deep enough.
Thoroughly coat the sawed surfaces and G10 with neat epoxy to provide for the best secondary bond, then fill the sawed crack with thickened epoxy (something like West Systems High Density filler or Colloidal Silica), then slide the G10 into place, allowing the excess thickened epoxy to ooze out. Be sure that the overall thickness of the rudder head at the repair is approximately the same thickness as the other good rudder's head. Use clamps very carefully. You could measure with some calipers.
Trim and finish after cure.
The other option would be to try prying apart the split rudder head enough to inject epoxy far enough down the crack to effect good enough repair. It might work, but you'd never know if the epoxy would fully fill the bottom of the crack, and therefore the crack may propagate further with a load on the rudder.
I would warm the slow-cure epoxy to lower it's viscosity and warm the rudder head as well so that there would be a better chance of capillary action helping to suck the epoxy deep into the delaminated fissures. I wouldn't use fast-cure epoxy for this method. It could get too hot during it's cure and actually harm the rudder core materials.
I think the main problem with this method is that the rudder's core and delaminated fissures likely have crud on those surfaces, so 'gluing' them together might not work well if those surfaced aren't perfectly clean. From plenty of experience in failures and successes, I'd do the first method with the G10.
Or.... if you can ensure that the fissure is perfectly clean, maybe with the help of the multi-tool and sandpaper, then prying open the fissure slightly and slathering-in a coating of neat epoxy along with thickened epoxy might be just fine and more expedient.
If that area of the rudder is solid glass (or at least reasonably thick glass skins), you might be able to inject some low-viscosity resin down into the crack and then also drill and countersink a couple holes across the width of the rudder, close to the edge. Then install some stainless steel flat head wood/sheet metal screws. This would give you an adhesive bond down into the crack plus mechanical clamping.
Otherwise, inject resin into the crack and the wrap glass/carbon around the edge so that you have fibers running perpendicular to the axis of the crack
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Thanks for the recommendations. I'm going to sand into the crack with some nail file emery boards
and see if I can clean it up enough to go with the simple fix. The G10 project on the rudder end took some time and I am out of patients with the repairs!
You talked me into the G10 repair. The inside tip of the rudder has crack that traveled farther than I thought. Hopefully this will hold for a summer!
The inside tip of the rudder has crack that traveled farther than I thought. Hopefully this will hold for a summer!
Yup... cracks will always surprise you/me. Think they're only a couple mm deep.... Ha! Think again!
I'm fixing 'gelcoat' cracks within the Mystere 6.0's centerboard well casings.... what a pain! They're not merely gelcoat cracks. Sand-blasting is a great way of cleaning/abrading hard-to-reach areas and exposing more problems! Oh yay.
Yeah... sometimes I have to pull back and complete something else just to keep on 'keeping on.' Hay the pastures.... sew a few more lines on the trampoline.... Work on the Sauna foundation.... continue fairing the F18 C2 hulls.... oh the list keeps growing.
Something that keeps me going on these boats..... the goal of racing them.... not only in round-the-cans races, but in long-distance races that require a robust craft. I was looking at the Texas 200 website this morning.... dreaming. That kind of thing keeps my goals in sight.