This is a reply I posted not many days ago about waterproofing this critical and sensitive area. For me, this is the only way to fix a situation like you describe. It is easy to do the second time but the first time will not be very difficult to do at all. The hard part is keeping the bias cut glass remaining at the width you want. It will very easily stretch out and become rather narrow. Take your time with it, there's no rush and mix the resins in a wide flat container like an ice cream container. To stop the resin from setting up too fast, don't have it in a cup shape container. By spreading out the resin in as thin a layer as possible the working time of the resin is very greatly increased. I had some in a coffee cup one day and it went hard in 10 minutes liberating so much heat the cup melted. Before the resin sets, wash the brush in white vinegar and also your hands when finished. The vinegar destroys and removes the gooey resin in seconds.
Check this out:-
"I have mentioned this before (a very long time ago) but I will offer a gentle reminder of how to fiberglass the corners.
I have never used F/G tape more than once to seal an external or internal corner, it was a disaster. The doubled fibers on the outer edges of the tape leave a horrid ridge that has to be sanded and faired back to the original surface. Not fun by any stretch of the imagination. Secondly, only half of the threads are holding the panels together. The threads that run lengthwise offer no strength at all to the joint or edge. A much better way is to cut a strip of cloth, 4 or 5 inches wide from a roll and cut the strip on the bias. That is, cut the strip at a 45 degree angle across the width of the roll. When this is now applied to the corner, both threads of the glass cover the overlap at 45 degrees. This offers vastly superior strength
and is very easy to get the F/G to bend over the outside corner and stay where you want it while the resin is curing. Don't forget to apply a sealing coat of resin before placing the F/G strip on the seam/joint. The sealing coat must be fully cured so you can place the strip easily. You can use two coats to seal the wood as this is where the edges of the strip are sanded down to flair into the panel/s with a minimum of fuss. This method is by far the very best to use for interior corners as well. The glass will push fully into the corners without springing out. The edges of the external corner should be sanded or routed to form a 1/8" or 5/32" radius before applying the glass. This makes laying the F/G around the corner "a piece of cake". If you want a square corner, an extra strip of glass can be applied to build up the edge and then sanded back as needed. If you want/need more than one layer of glass, cut the first strip 4" wide and the second strip 6" wide. This will flare into the panel much better with a minimum of sanding to finish it. This is how I will be building the sides, roof and inside joints of my TD."
A search through my posts will reveal more info for you. However, if you would like more info, contact me via this forum or send me an email. Glassing is not something to be scared of doing, it is quite easy. All you need is confidence and believe in yourself.
Kody
Never be afraid to ask questions here, Prov. 11:14
