wow, that’s unfortunate.
i have made some mistakes in the past of similar consequence.
that said, i continue to be impressed with the ability to fix things in strip build construction or even in stitch and glue. the main thing in any repair at this stage is more about can you get the shape you want vs any concern about structural issues. appearance may be important as well…and that can also impact your approach.
the reason i mention, at this stage, not to be overly concerned about structural issues, is that the strips are acting as a core, and its the glassing on the inside and outside that really makes for the struture…so we routinely have glued edges of signifcant length on any strip built…and as long as they are reasonably glued and then glassed, you will be fine from a structural perspective.
so the focus is really about how do you sift between different approaches to ensure you get the shape/profile of the wood where you want it so that you have a fare surface and avoid things like a flat spot, a bulge or a divot.
if you test fitted and simply glued the piece back and in that process, got it close enough to the the shape it supposed to …where you can sand and fare it in, and no flats spot, bulge or divot, then you can do that. (i have made this type of repair in my long experience)
if that doesn’t give you the shape you need, then you need to cut the stips out of the piece you are going to keep and restrip it kind of like the way you would repair a wooden floor. (and i have also make this type of repair)
from a looks perspective, if you want a ‘natural’ (unstained) look you want to push towards the second option (restripping) becuase the crack might not look nice even if it’s not a structural issue. for unstained light colored wood, cracks like the one you have will show. that said, if you stain the boat dark before glassing, you can make a lot of defects ‘disapear’. if you intend to paint the hull…then you don’t have to worry about any of this becuase you won’t see the strips.
as mentioned i have, through the school of hard knocks, used both approaches succesfully… and more frequently than most people would imagine. there was somebody, I can’t recall the exact reference, that told me the mark of a great builder is how he hides or corrects mistakes, not the absence of making them.
all of my craft have had that as part of their process, particularly this one and the next one which had similar damage to yours in their build process where they languished in garages for years before i picked them up as garbage and restarted them…they came out ok.
the first one here was handled with restripping the bow after tediously cutting out the strip edge to make a wood floor style repair (just ensuring all the edges were not lined up)
the second one here was handled by reversing a panel (switching it to the other side of the boat) so the crack (which did not go all the way through the panel) was on the inside of the boat vs the outside of the boat.
hope that helps.