Questions about the roof build of a Oday 27 older model likely 1979 or 78

[Oddvark]

OK, I had a 1976 O'Day 27. FWIW, I added a hatch for ventilation on the roof. It was two layers of glass with a balsa core.

So there is no liner? I have a liner. To be clear are you calling the liner one of the layers of glass? Or is there a layer of glass, then the liner?

It may be two layers of glass and core just on the roof but and extra layer down by the windows??? So assembly would be, glass in mold, balsa, extra glass on the sides but then drop in the interior roof liner so it alone is connected by resin to the balsa on the roof. That seems sketchy to me and a bad way to build.

I "thought" that I had it figured out. Glass, core, glass then a liner with thickened resin to bond in the liner but you say different. I'm not sure of anything at this point. I will have to drill some holes with a small hole saw and see is the only way I see this.

I really wish mine was like the later models which, I think, had carpet or some sort of covering instead of this liner. Another reason I want to get rid of the liner is who knows what sort of musty moldy crap is behind it where you can't clean it. Others on other boats have removed the liner for just this reason. Bad smells and uncertainty about the condition of the hull.

 

[Project_Mayhem]

Do you want a test boat? Then you have the right specimen. If you want a liveaboard, ocean cruiser or cheap boat, then look elsewhere. Cheap boats are the most expensive. O'Days are coastal cruisers at best.

Your O'day has a skin of fiberglass, balsa (plywood in certain areas) and resin core followed by another skin of fiberglass. It's not easy to remove just the skin without damaging the core. It's not easy to remove core without damaging the outer layer of fiberglass. I know this because I did such a repair to my '78 O'day 25. I can say without a doubt it was an awful experience that likely shaved a few years off of my life. Everyone is confirming the same construction techniques on O'days across virtually all of their production history. It's probably the most common technique in cored fiberglass boat building.

People are trying to guide you as they've been down this path. Materials are expensive and there's more work involved than you can imagine. You will encounter both good and bad core. You'll be hoping for bad core because good core is so difficult to remove. You'll need to remove some good core so you can fit a sheet of new core in it's place. I have a very powerful grinder that scares the crap out of me. It still took forever to grind away the core of the foredeck.

Please clearly state your goal. I've read four: live aboard, cheap boat, ocean cruiser and test boat.

 

[Project_Mayhem]

Areas around the windows may differ from boat to boat but the roof and deck is fiberglass/gelcoat, wood and resin core, fiberglass/gelcoat. My O'Day had two layers of fiberglass with no core around the windows. As you can see, @Taly Ho's had core in that area