Tom,
I would highly recommend NOT using Gorilla Glue! I used to be a very strong proponent of this product, but I have had far too many failures with it over the past two years of work on my boat.I think West System is a far superior option in every respect.
My caprails were in horrible shape. I've seen yours. Trust me... there was NO comparison. I'd have traded mine for yours in a heartbeat.
My caprail had been badly damaged through lack of care on behalf of the previous owner. It became even worse from spending 5 years in the Florida sun and humidity, while stored 2,500 miles from my place of residence in Denver.
It was my intention to create a temporary patch that would allow me to waterproof the caprail, until such time that I could replace the entire rail.
This photo shows the state of the damage when I fist began the repair. To say that I had problems with leaks would be an incredible understatement. By this time, the rail was cracking badly and had absorbed so much water it almost never dried.
After picking out the rotted wood, I began the repair using a mixture of Gorilla Glue and teak sawdust. At the time, this seemed like a good approach. As it turned out, it wasn't such a great idea! The general consistency of the Gorilla Glue, made it very difficult to spread into the cracks and crevices. I hadn't considered how much Gorilla Glue expands when it dries. While this can be helpful when gluing/clamping two pieces together, it does not work as a filler!.
t's somewhat difficult to tell in the photo, but the expansion of the glue resulted in a very pourous finish, upon sanding. While the glue might be waterproof, the repair would not have been. It was also rather ugly!
This photo shows the repair as I picked out most of the Gorilla Glue/sawdust filler to start again.
This time I used West System Epoxy, using #105 Resin, #207 Special Clear Hardener, and #405 Wood-Toned Filleting Blend. While the end result was not an exact match to the teak, it was close enough for a semi-temporary patch.
After sanding the patch and applying the finish coats, the result looks good enough that I'll probably leave it for some time... maybe forever. To be honest, it came out much better than I had anticipated.
The other really bad spot on the caprail was within the lamination at the stern of the boat. In this area, the teak had completely dry-rotted through to the inner joint and to the outer side. (I thought I had taken a photo of the top, before beginning the repair, but apparently I did not.) As in the first repair, I only intended to create a temporary patch that would stop further damage, until I could replace the teak all the way around.
Although I did not take a photo of the rail top, this one shows the extent of the rot.
As in the previous patch, I started with Gorilla Glue mixed with teak sawdust. As before, the resulting patch was far too pourous. (No... I'm not dense enought to make the exact same mistake twice. I took the same approach on both repaires, because both were done at the same time.)
This photo shows the patch after removing the Gorilla Glue and then replacing it with West System. It was then sanded and ready for final finish. Again... it's not perfect, but fixed the problem and the concern for further rot.
I had a few sections of the caprail in which large chunks had been removed. Apparently, the previous owner didn't believe in the use of fenders. Though fairly unsightly, I was able to make these patches using nothing but the West System Epoxy. As before, I made a thick paste from #105 Resin, #207 Special Clear Hardener, and #405 Wood-Toned Filleting Blend. This photo shows the epoxy, after hardening.
This one shows the repair after rough shaping...
And this photo shows the rail after final sanding and ready for finish coats. After the finish was applied, you can only find this and similar patches if you know exactly where to look for them!
If you follow Dave's general suggestions as well, and do the work as well as you've done everything else, you should have no problems!
Jack