RebelHeart - you will probably find it easier that you had expected it to be once you get started. Wood is not that hard to work with. Here is a little project that I am doing on our Ingrid:
Head knocker From Deck on Flickr - Photo Sharing! Not Anymore! on Flickr - Photo Sharing! Head Knocker From Below on Flickr - Photo Sharing!
Don't look too closely at the quality of my work - its not pretty. But it's not finished yet either. Even at this point it is water tight - I know for sure because of the amount of rain that we have had in the last few weeks since I did this part!
You will do just fine with your repair. Sounds like a good time for a new hatch