Welcome to the club.
I guess that Herculon material was popular in the 60's. It reminds me of Archie Bunker's recliner. (if you dont know how Archie was, you are too young).
I removed my first piece by pulling on it. That was the starboard side of the forward cabin.That left the foam attached to the hull. I had to go back and scrape it with a putty knife, brush and other assorted implements.
I attacked my second piece , the port side, with my new Dremell multy tool. I had just used it to install 30 strike plates on doors and loved it. I changed the saw blade for the scraper blade. By pulling on a corner of the material and introducing the blade, I was able to strip both material and foam in one downward stroke. Just like skinning a rabbit. (I have never skinned a rabbit, but I guess that's how you do it with a knife).
I had the rest of the boat skinned in no time. I actually looked for material to remove. The nastiest was behind the electrical panel. (See picture) Some of the foam has deteriorated and will crumble as you peel it. You may still have to go back and hand scrape. I had to by another scraper by the time I finished. I had worn it to nothing.
Harbor freight and other import tool companies offer similar tools for about $40.00. Well worth the investment. If you are going to use it more oftent, the Dremell if about $95.00. If you are a pro or tool hound, then the original Fein multy master will only do. About $300.00.
Good luck.
P.S. I keep a Tyvek disposable suit and wear it when I work on the hull. Otherwise, I itch for days. I planned to use berber carpet to line the closet and storage areas ,however I think I am going to use white marine vinyl with 1/4 inc foam attached. I think it will clean better and not keep smells.