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

[Oddvark]

First I want to thank all of you here. I'm going through the threads and there's a ton of useful information. It's much appreciated.

Excuse the length. I want to make sure I accurately describe the problem. I have a Oday 27 that I want to experiment with materials, specifically isogrids for reinforcement. fabric interiors and do some sailing. But to do so like I want it would really be opportune to remove the inner liner. Especially the top.

Here's the questions I have after looking at other threads that show rebuilding. In the thread "And so it begins" there's a picture of what I believe to be the roof that he is repairing due to rot. It's a Oday like mine older
but different years. There is a thread "And so it begins"

And so it begins

So begins perhaps the most quixotic endeavor thus far. What might that be? An undoing of 34 years of some mighty absurd ideas of what a boat should and shouldn't be. Finally Yot is sitting along side my home thanks in no small way to Lockview Marine and Boat Transport. Yes, that is the...

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See the pictures of the holes he drilled/made/found? He says,"...The two attached pictures show the deck outer laminate, the rotted core, the deck inner laminate and the inner liner. .."

So my question is this, is it correct? The pictures are not so good. I've been reading his thread but still have no direct answer except for the statement above and the picture which is not so good. I will ask him but the thread is so old the likelihood of an answer is low to nil. What I would like to do, assuming the inner cabin liner is separate from the inner fiberglass to to remove the inner liner. Yes I know there are LOTS of reasons NOT to do this but to be very clear,

THIS IS AN EXPERIMENT.

I notice another thread, I'm wading through them, shows a Oday 272 and it appears the whole interior fiberglass laminate is removed. That's what I want.

272 Headliner Replacement

272 Headliner Replacement

My wife and I have decided to replace the 30 year old carpet headliner in our 272. I am wondering what sort of products people have used. Has anyone simply painted it? Or used filler resin to smooth it and then paint it? The carpet / soft products have their advantages, so I am not against them...

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The second picture looks like to me the whole liner is removed. But this is a 272, is it the same as a 27?

Another,
"Construction question on an O’Day 272" that talks about empty space between the wall liner and the outer fiberglass. This link

Construction question on an O’Day 272

Hi, I recently had to replace the thru-hull connector for the bilge pump in my 1987 O‘Day 272. While the connector was removed I had the opportunity to see both the outer fiberglass hull and the inner cabin liner. I had expected to find some type of insulation material between the two pieces...

forums.sailboatowners.com

And you can see the picture he has of the side of the boat.

So far I'm assuming when constructed they made an outer liner in a mold, added the balsa on the top, more fiberglass, then lowered the inner roof liner on that with some amount of resin and thickener in between. Is that correct?

Has anyone cut out the inner liner and how difficult was it? My thinking is to us a hammer drill with a chisel bit, with the rotation drilling part off. So just hammer, and try to separate them. Sound good, bad, nuts?

Why isogrids? The Air Force did a study on missiles and found isogrids provide a 600% increase in strength per weight compared to normal tanks in missiles. I'll dig up the paper, if I can find it, if anyone is interested. Here's another link to a different type isogrid called a quarter isogrid. The guy makes surf boards from cardboard isogrids.

https://web.archive.org/web/20190517042338/http://www.sheldrake.net/quarter_isogrid//

My boat below. Don't laugh. I wanted a sailboat and this one came up. They had to move it and I got the boat and trailer for $500. Better me have it than to have it cut up in the land fill. I pounded around a little on the roof and it seems fine. I assume it will have a little rot somewhere. Maybe by the stanchions but I don't know that yet. It will likely take me a long time to do this but it's something to really look forward to sailing around.

BTW some parts I'm going to let go. I don't want to go into detail because you're not supposed to sell here but it seems to me the classified is all boats and not specific Oday so I'll straddle the line and hope it's not troublesome. If this is offensive, my humble apologies.

 

[Tally Ho]

We should see some photos to help verify what you are looking at, but my understanding is that the deck is a sandwhich consisting of a layer of glass, then some form of core (balsa), and the. A top skin of glass. The balsa gets wet, and rots, causing the laminate to fail. “And so it begins” details the cutting open the top skin, replacing the core, and reglassing the top skin. I don’t recall if he just laid new glass or reused the top skins somehow.

On the inside of the hull, boat builders have used different methods to cover the inside fiberglass.
- Some boats have ”carpet” liners. My 1988 O’Day 322 uses carpet on the upper half of the hull.
- Some boats use wood or other materials for a headliner or wood slats to cover the walls.
- More modern boats use a fiberglass liner that is smooth and finished to cover the roof, walls, etc. My O’Day 322 has a rigid fiberglass headliner overhead covering the entire ceiling of the boat, and a fiberglass hull liner on the bottom 1/2 of the hull.

Carpet can be pulled down (it is glued on). Here I removed the “carpet” liner from the hull in my aft berth…that is the unfinished fiberglass hull. And you can see the fiberglass liner on the lower part of the hull (Below the teak shelf).

My O’Day 322 has some foam core around the hatches…I found this when I pulled the main hatch out to rebed it…
This photo helps explain the sandwich construction. You can see the fiberglass liner (very thin) at the bottom, then a layer of fiberglass, a layer of foam (the green layer) and then the top fiberglass layer.

Here is a shot of the fiberglass headliner that covers the entire top of Tally Ho. It covers the ceiling and the side decks. You can also see more of the carpet liner on both sides where the side shelves are (a blue/gray carpet).

Hope this helps some. Post some photos of what you are looking at and why you want to chop it up…. Replacing the deck is not for the faint of heart, and requires a lot of fiberglass work. Cutting up a fiberglass liner will be hard to repair back to a finished look. Removing carpet is easy enough, and if you are replacing with cloth, it should e too tough….but I still haven’t refinished my aft berth.


Greg

 

[jssailem]

I have a Oday 27 that I want to experiment with materials, specifically isogrids for reinforcement.

This sounds like fun.
First you might want to understand the way and why your boat was designed. At a basic level is a hull structure that functions as a skin over a skeleton.

In this image the skeleton are the wooden stringers holding the hull skin in shape.


Your O’Day uses some fiberglass ribs attached to the interior of the hull then an interior liner is secured over the hull. This provides strength and interior design function. To the liner are fitted bulkheads and decorative wood / cushions / coverings.

I understand the isogrid benefits, it is not clear how you see those being applied to your boat.

While the hull and liner function to provide a skin and skeleton structure, the salon roof panel provides some stabilization of the deck, but functions more as a covering to hide the under side of the deck.

 

[Oddvark]

roof panel provides some stabilization of the deck, but functions more as a covering to hide the under side of the deck.

That's what I'm getting at. That's what I want to know. Can I separate the inner liner without tearing up the lower inner level of the fiberglass roof. I believe after thinking about it and looking at pictures that I can remove the inner liner. Remember this is an experiment.

 

[Oddvark]

carpet liner on both sides where the side shelves are (a blue/gray carpet).

I like that carpet. Nice.

 

[dlochner]

In general when production boats are built there are 4 main pieces, the hull, the pan, the headliner, and the deck. The pan is attached to the hull in a couple of ways, fiberglass tabbing and/or gobs of thickened polyester resin. Once the pan and hull are one, the headliner is lowered in place, it may or may not be glued to the bulkheads and other internal structures. Next the deck is lowered on to the headliner and hull. Gobs of thickened polyester resin are strategically placed on top of the headliner before the deck is lowered. This attaches the headliner to the deck structure and provides additional support and stiffening for the deck.

Deck stiffness is achieved by building thickness with a core between 2 fiberglass laminates. The most common core material is end grain balsa. It is light and adds bulk without weight. Stiffness is also achieved by adding some camber to the flat structures and breaking up the large expanses with the deck house structure, the vertical sides of the house add stiffness.

High end racing boats, like Open 60s, Volvo 70s etc, do use a grid structure for some panels. Search around for honeycomb panels. These provide very strong and very light panels. They are not used in production boats because of cost. Production boats are built to a price and manufacturers do everything they can do to keep material and labor costs low to be competitive.

Without knowing the specific engineering that went into the design, it would be prudent to avoid altering the basic structure of the boat. There are large forces on a boat that cause the boat to twist and bend. When the boat is designed these forces are considered, hacking away at structure without knowledge of its function could lead to unintended consequences. Consider for a moment a house, there are load bearing walls and non bearing walls. Ripping out a non load bearing wall is no big deal, ripping out a load bearing wall is different story, the house may fall down. Before attacking the structure of a boat it is essential to know the load paths and how the loads are transmitted.

 

[Project_Mayhem]

It will be very difficult and time consuming to remove the good core from a liner. Your lungs and eyes will hate you, especially if it's an enclosed space. I rebuilt the foredeck and part of the stern stern on an O'Day 25.

The composite cores a great until you see the cost. Your boat lasted this long with balsa. New balsa core will outlast the boat.

If you do decide to do this, I would highly advise a full face mask. The double seal helps a ton over a half face mask. It's still far from perfect. You will end up breathing and getting fiberglass dust in your eyes sometimes

 

[Oddvark]

Thanks for all the answers and help. I want to make clear, I'm not sure that it is from some responses. I only want the inner fiberglass liner removed. I'm not interested in new cores. My understanding, so far, is there is a outer fiberglass, balsa, inner fiberglass, then a separate fiberglass inner liner. I only want the inner liner gone. I guess the difficulty is, how much thickened, I assume thickened, resin is between the liner and the inner hull. If it's a lot could be really hard to separate the liner. A guess, it's not all over as resin is not cheap so it will be sporadic spots of resin holding in the liner. I, of course, really have no idea. I know that sailing Uma did this to their Pearson 36.

 

[dlochner]

Thanks for all the answers and help. I want to make clear, I'm not sure that it is from some responses. I only want the inner fiberglass liner removed. I'm not interested in new cores. My understanding, so far, is there is a outer fiberglass, balsa, inner fiberglass, then a separate fiberglass inner liner. I only want the inner liner gone. I guess the difficulty is, how much thickened, I assume thickened, resin is between the liner and the inner hull. If it's a lot could be really hard to separate the liner. A guess, it's not all over as resin is not cheap so it will be sporadic spots of resin holding in the liner. I, of course, really have no idea. I know that sailing Uma did this to their Pearson 36.

Uma's liner was removed and then they invested a ton of time and money to reinforce the deck and hull structures. Dan and Kika both have engineering backgrounds with degrees in architecture, so they did this understanding the loads and load paths.

The headliner is not just cosmetic, it provides structure. Ripping it out means it will be necessary to replace that structure in some other form. Boats that do not have headliners have deck structures that are designed for the loads they will experience.

Frankly, I wouldn't waste the time and money on an old 27 foot boat.

 

[Tally Ho]

Thanks for all the answers and help. I want to make clear, I'm not sure that it is from some responses. I only want the inner fiberglass liner removed. I'm not interested in new cores. My understanding, so far, is there is a outer fiberglass, balsa, inner fiberglass, then a separate fiberglass inner liner. I only want the inner liner gone. I guess the difficulty is, how much thickened, I assume thickened, resin is between the liner and the inner hull. If it's a lot could be really hard to separate the liner. A guess, it's not all over as resin is not cheap so it will be sporadic spots of resin holding in the liner. I, of course, really have no idea. I know that sailing Uma did this to their Pearson 36.

I don’t know that you told us WHY you want to remove the liner. What are you trying to accomplish?

Get to rotten core from the bottom side? Insulate the deck?

Greg

 

[jssailem]

I am sitting here sipping coffee in a rain storm thinking about your boat. Maybe you could take a picture of the area you want to remove.

Is there a seam between the hull and the part your calling the inner liner?

Looking at some O’Day 27 images (this one from a 1978 O’Day 27) show what appears to be to be a solid interior fiberglass ceiling to the salon. The deck hardware is through bolted. This would suggest no liner but a solid sandwiched deck.

Trying to remove this surface will expose the filler (balsa wood, plywood, or foam filler) and affect the deck integrity.

 

[Richard19068]

Just some observations:

I don't have a 27 but on my 1985 O'Day 31the headliner appears to be very securely attached . When I tap on it in various spots around the cabin ceiling it sounds solid as if there is no space between it and whatever (fiberglass) is above it. See Tally Ho's picture of the sandwich around his deck hatch. The liner is securely attached to the bottom of the deck. I think attempting to remove the headliner would be very very difficult and probably leave lots of roughness and pitting in the remaining fiberglass.

As the liner transitions from the ceiling down the cabin sides (around the windows) there may be some space where it doesn't seem as fully attached. Where the liner folds under (below) the deck out to where the stanchions are bolted there is certainly space between the liner and the bottom of the deck. I have had to cut some of this away to re-bed the stanchions. Also. there is space for wires between the liner and the deck.

As Tally Ho posted, it would be interesting to know what you are attempting to do after you remove your headliner. What does your "experiment" entail?

While the hull and liner function to provide a skin and skeleton structure, the salon roof panel provides some stabilization of the deck, but functions more as a covering to hide the under side of the deck.

John, is this a generalization or do you have any information on that specific to O'Day's or O'Day 27's?

EDIT: John, I didn't see your last post until after sending this. I think that post answers my question.