Are you wanting it to look like professional, and brand new or do you want to just make sure it will not leak? Lots of considerations depending on the level of investment ($ and man hours) you want to put into it. Appears that you have a painted deck (light blue) and bottom (dark blue), which is over the original deck skin and gelcoat. A basic understanding of fixing that would be to sand it down to stable material, create a form using cardboard to maintain the curvature of the bow, and then add a combination (depending on how far removed the material is after sanding) fiberglass, epoxy, and the gel coat to match. Another way is to use a product from www.advancedrepair.com called marine epoxy (after sanding it down), should be easy to sculpt to the original shape of the bow, and is water tight. Then paint to match. The good thing is that the bow is pretty stable and thick, and should be easy to fix. Be prepared to spend some hours sanding to prep, and after applying whatever material you use to get the shape you want. Plenty of videos on the web to show different levels of boat repairs. I want to say that there is a Laser video restoration project I saw that had a pretty big bow repair, and it turned out fine. Good luck and post some pictures of your final finish!
I had a similar issue with the same area of my bow and I used polyester resin and west systems filler. Mix up the resin and catalyst and then add the filler until it has the consistency of peanut butter. I used painters tape and cardboard to create a mold around the bow to shape the resin as it hardened in the repair area. The carboard was coated with the painters tape to act as a release agent for the resin. The epoxy resin hardens pretty quickly and you can sand it prior to fully hardening. If you wait until it is fully hardened it is much harder to sand.
It is easier to apply gel coat on top of the polyester resin as well, with epoxy it can sometimes be difficult to get the gel coat to stick. In addition, the boat is a polyester boat so you will be repairing with the same product that your boat is made of.