[SVAuspicious]

In certain places along the interior of the hull, there is a cheap, vinyl liner with a woven pattern. It's literally just a thin sheet of vinyl, glued to the hull to prevent you from seeing the raw glass. The weave pattern is awesome at holding mildew spores and requires constant scrubbing with bleach. It looks cheap and dated.

For removal a heat gun and a set of putty knives should get most if not all the old vinyl off. 3M makes a great adhesive remover that will get must of the glue off after that. You'll probably want to run a random-orbital sander over the glass before starting the new installation.

My thoughts for a replacement are a veneer of some kind which could be either wood or something like Formica. Here is one place to look Wood Veneer, Veneering, Veneer Plywood, Sheets & Tools at Woodcraft .

On general principles I would go for a light color (maple or birch). It should be something that doesn't clash with the wood you already have. Although I like to think my sense of the aesthetic is pretty good, when I was choosing finishes and upholstery for my boat I tortured nearly everyone I came across with samples. The input was helpful and made me think about things differently. Ultimately I made the choices myself but they weren't what I originally made. Eight years later I'm still happy.

 

[SVAuspicious]

When you have everything clear you might consider a layer of solid insulation on the hull before you put the covering on.

 

[SVAuspicious]

I thought about insulation but wondered if it was worth the effort because I can't access much below the waterline due to the cabin liner.

Is there any point in insulating portions if you can't get to everything?
If so, what kind of insulation should I use? I don't want to install anything that is too bulky.

It is worth it. Remember that the water (other than surface ice) won't get below 32F. The air on the other hand gets 1. really cold and 2. moves, increasing heat transfer.

I'm thinking the thin pink or blue stuff used under house siding. You just need to be very careful not to allow voids between the insulation and the hull or the insulation and the cover.

I like the strip idea someone suggested above. That looks great. You just want to match colors and textures.