If I understand your bulkhead problem: The Bulkhead is rotted where one or more chainplates is attached and the Bulkhead is also pulling away from the hull
..possibly causing a dimpling in the hull?
You may need to pull the mast
..if this condition exists on the entire starboard side..?
You'll need to pull the chainplate, knock out the old bulkhead..( if you can get the old out someone intact..you can use it as a template for the new one)
grind down the old fiberglass
tabbing...make new bulkead..and tab it in.
I'd dry fit it 1st and make sure it's aligned properly with the chainplate..slid in.
There's lots of tricks and tips..to doing this.. for example: drilling oversize holes for the chainplate bolts..and then filling them with epoxy
and re-drilling to proper size..so that there's no edges exposed to moisture.
I forget if Casey has a step by step...but this could be a pretty big job..if the condition is typical throughout all the chainplate knees/bulkheads..
The other thing you would want to determine is why..this occured..usually leaks
..through the chainplates or elsewhere
If I didn't understand your problem correctly, I apologize for my assumptions.