Re: 1958 14' Fleetform
Climbing aboard for this one.
First off...my hat is off to you. 13 and wanting to restore a boat? Wow! I can only hope my son follows with your kind of ambition.
Next, I'm no expert and I don't play one on TV
With that being said, there's been a lot of advice to slow down and develop a plan of attack. This is good advice from people who have been there before. So after that, the next step is to get that boat of yours supported correctly - as good as the cinder block is, it's not the correct way of going about things.
Now to answer your question about the interior, I don't own a boat just like yours but I did own a '56 MFG at one time. I think you have all the answers you need in this pic here:
If you look at it in layers, the closest one to you is the newest. That's definitely powder blue paint. That paint stripper can remove. However, when using paint stripper you need to know that any little trace that you leave behind will cause problems later on down the road. The better approach would be to sand that paint off as the residue can be vacuumed out with a shop vac and the remnants left behind can be picked up with a tack cloth and subsequent cleanings.
The next layer in is what appears to be either white paint or gelcoat. Usually gel coat is fairly thick. Going off your pic, it certainly looks like gelcoat which means its definitely time to break out the grinder.
That final layer underneath the white looks to be fibreglass cloth. I'm saying this as it has a grid like texture to it which, when you view other resto threads, is exactly like the cloth they're using.
Now, with all this sanding you are doing on fibreglass, its imperative you use the correct PPE (Personal Protection Equipment). Failure to do so will cause long term, long lasting health problems. So Tyvek suits and a respirator are in order. A $1 dust mask from your friendly hardware store will not cut it for this application. Please, please heed this advice. I didn't when I was younger and my hearing is suffering because of it - a summer job was cutting apart 55 gallon drums with an air chisel and NO hearing protection. I have ringing in my ears constantly. So learn from my mistake!
Now as for your cap, it looks like someone painted it dark blue.
I'm saying this as in one of the cracks it appears as if a lighter blue is under the darker blue. If that's indeed the case, then the upper layer of dark blue paint could be stripped off. If it were me, I'd be using a grinder again for the same reasons as not using paint stripper on the inside of your hull.
And one thing I have learned going through a number of these threads - take LOTS of measurements before you pull that cap off (and after the boat is properly supported). Keep them in a notebook so that you can refer to them later. Ratchet straps can help you reshape the boat if it springs out of shape once you pull that cap. You want the hull in the same shape as when the cap was on it otherwise you'll be expanding your vocabulary 10 fold when the cap doesn't fit right when you're ready to reattach everything.
Good luck and keep posting!