Definitely looks repairable.
First thing would be to remove any damaged (torn) laminate (grinder, hacksaw).
Second thing would be to grind (coarse sand) all the edges to a nice 1 in 8 or better 1 in 12 slope. (I would stay away from the hull stripe, even if it means that corner of the crack may have little weak laminate remaining. The pain of trying to deal with the stripe is probably not worth it, rather, use a patch on the inside)
Third, sand the inside if you want to use a patch (see below)
Fourth would be to first reattach the hull to the deck next to the repair (3M 5200). I would use a compound like 5200 (there are others that also work for hull-deck joints) instead of an epoxy glue, because I think you'll get a better seal that way. However, at the spot where you are making the repair, I would not sweat it, and simply repair the crack in a continuous manner from deck to hull, even if that means that there's one spot that's bonded by epoxy and laminate, rather than some compound. (The PO of my DS1 "sealed" the inside of the hull-deck joint by applying a single layer of laminate at one point. Looks very solid and is watertight, but overkill - using a compound should make this phase of the repair go more smoothly - but, that's really up to you. Perhaps you rather "keep it simple" and limit the number of methods - in that case, thickened epoxy and sealing the crack with a strip of laminate from the inside would work.)
If you do all of this, then your hull should basically almost be strong again, but you now have a gap across which you will need to re-build the laminate.
Fifth, if you can get in from behind, consider applying either a wet or a dry patch to both hull and underside of deck. Generously sized in area, but doesn't need to be very thick (2-3 layers of cloth). A dry patch is just a thin sheet of laminate that you make yourself on a workbench on a plastic sheet. Let it (barely) cure, it will be a bit flexible and conform to the hull, glue in place with epoxy glue (thickened, so it's not runny). A wet patch is a bit messier, again, a few layers of laminate on a plastic sheet, but lifted (with the plastic) and applied to the hull while still wet. No need for glue, but more need for support and even with plastic sheet as backing, prone to a bit of mess.
Sixth, with backing cured to where it's hard (or a dry patch firmly wedged) build up laminate across the gap, using wider and wider patches of cloth (to get a staircase effect that matches your 1 in 12 slope). Dont' build up beyond the level of deck and hull, leave more hollows than bumps.
Seventh. When cured, sand the bumps flat, fill the hollows with an epoxy based fairing compound, slightly proud, then sand flat when cured.
Eigth. Cover up the repair (epoxy doesn't like UV). This is the part that can be infinitely time consuming, or really quick. The quicky solution is to use a good spray paint, designed for "plastic". (You can always sand off the interim cover).
Ninth. go sailing
Tenth. Cut down all trees
OK - this is just the outline. You'll have more questions. There's an
older thread on crack repair where I describe a similar repair I did after I got "gored" by an El Toro (a very small boat). Using a patch adds a bit of weight and you'll be able to see where the repair is from the inside, but it has two advantages: no worries about sufficient strength on your repair. And, an easier time working on the repair, because nothing will fall into the gap. Finally, in my case, once I cut away the broken laminate, the remaining tension in the hull deformed it a bit. With a dry patch and a bit of pressure, I was able to get everything back into alignment.
If you are new to working with epoxy, I would suggest some that is ready mixed for the various purposes (glue, laminating epoxy, fairing compound). My goto brand for these is System Three, but I'm biased because they are well-available locally.
I'm sure you'll be back with many questions, and others may have their own experience / suggestions to contribute.