New Ceiling on Coronado 25

[Xander]

I am looking for advice on installing a new ceiling in my Coronado 25 sailboat. The original ceiling was 3/4" plywood glued to the underside of the fiberglass deck. I had originally planned to glue in a few wooden stiffeners and glass over them with several layers of new fiberglass. After removing the original ceiling I noticed that the deck was very soft and I'm now thinking that I should probably reinstall 3/4" plywood to be safe. Has anyone out there done anything like this before? I would love to hear any advice that you might be willing to offer. I found a thread somewhere in the past that described how I should prop up the new plywood with 2X4s from underneath and place some weight on deck to bring the two tightly together while the adhesive sets. I've been advised that "good-one-side" fir plywood would be fine to use instead or marine grade plywood because the "not-so-good" side will be sealed in adhesive. I'm on a very limited budget so I'm hoping that this is true. Am I overlooking other possible options? Would fiberglass and stiffeners be good enough? Should I stick with the original construction style? Thanks in advance for any advice or suggestions.

[SkiprJohn]

Aloha Xander,
I think the term you want to use is cabin overhead. A ceiling on a boat is on the inside of the hull.
Just my opinion but I'd use two layers of 1/4 inch with a layer of mat in between installing it using bracing from below unless the existing 3/4 was in an extremely flat area. If the area you are talking about is under the mast step then you have more problems and may need to reinforce or replace a bulkhead too.
As far as strength goes the doug fir ply will be just fine but if you want it to last in a marine environment more than a couple of years I'd go with the extra money involved in getting good marine ply. Don't ever use any ply with a luan exterior. It'll rot in a couple years for certain and termites love it.
Good luck,
JohnL

[David M]

...additionally to what John says, I would apply a layer of epoxy to both sides before installation. Marine ply is horribly expensive but in an environment which flexes and where the humidity is high and subject to direct contact with water, it is worth the money. A couple of years ago I spent just over a hundred dollars for a 4X8X3/4 sheet of mahogany marine ply. I hate to see what it costs now. A clear epoxy coat over mahogany ply actually looks pretty good!

[SkiprJohn]

Because I always use epoxy I assume that most everyone does. I do recommend it. It is a very good adhesive mixed up with microfibers so that's what I normally use to install patches.
JohnL

[Xander]

Thank you for the advice gentlemen - much appreciated. Cabin overhead - right, I'll remember that one! A couple of quick questions just to clarify: By "a layer of mat" do you mean fiberglass? And by "epoxy" you mean that two part fiberglass resin and catalyst (10:1), right? I'm obviously new at this and I just want to make sure I'm understanding the lingo. This is my first boat (I'm still in my 20's) and I don't want to screw it up too badly. Thanks again for you help!

[SkiprJohn]

Hi Xander,
Mat is fiberglass that has short strands going every which way. Epoxy is usually a resin and hardener that you mix together in a 5 to 1 or 4 to 1 mixture. Epoxy has better water resistance and better adhesion qualities than polyester in my opinion.
I recommend you do some reading in "The Fiberglass Boat Repair Manual" by Alan H. Vaitses that is probably in your public library.
Good luck on your repair.
Kind Regards,
JohnL

[David M]

Originally Posted by Xander

Thank you for the advice gentlemen - much appreciated. Cabin overhead - right, I'll remember that one! A couple of quick questions just to clarify: By "a layer of mat" do you mean fiberglass? And by "epoxy" you mean that two part fiberglass resin and catalyst (10:1), right? I'm obviously new at this and I just want to make sure I'm understanding the lingo. This is my first boat (I'm still in my 20's) and I don't want to screw it up too badly. Thanks again for you help!

No, dont confuse polyester resin with epoxy. Epoxy is more expensive but it is better for your application. The first place that comes to mind that sells good epoxy resin is West Marine. They sell West Systems epoxy resin. You have a few different choices of epoxy catalyst (Part B)...quick drying, slow drying and part B with a UV filter for varnish that will be exposed to the sun. The epoxy has hand pumps you can buy separate that screw into the container that give you an exact pre-measured ratio. They are worth buying rather than risk screwing up the A to B ratio.

I don't think applying a layer of fiberglass is necessary for your application, but then all I know is what you have described.

Do you have some pictures of your project?

[Xander]

I just reserved that book at the library, I will read it from cover to cover I'm sure. Thanks for the suggestion. I don't have any photos at the moment but I will take some the next time I get down to the boat. I am living a little ways inland right now and only get to visit my baby once in a while on weekends.

She's a 25' Coronado and not worth that much (compared to most of the other boats at the marina) which makes me wonder if I should cut a few corners to keep the cost down. I am not interested in seriously compromising quality or safety but if, for example, polyester resin is "almost" as good as epoxy and less than half the cost - could that not be a viable option? I have priced out marine grade plywood in the past and it also is at least double the price of "good one sided" fir plywood. If I'm coating it in epoxy or polyester anyway - could this be another potential compromise? Again, I don't want to take any big risks but I'm thinking of her as a Volkswagen, not a Porsche. What do you think?

[theonecalledtom]

How long are you planning on using the boat? If its several years you might want to invest in higher quality components for your own happyness (we won't talk about the person you eventually sell the boat to happyness ). There is also the experience factor. I would probably err on the side of doing it properly, thereby learning skills that can be re-utilised on boats you care more about. Of course this does depend on the overall cost/time - benefit ratio going in!

[Xander]

I plan to have the boat for several years and when I eventually sell it I don't want it to fall apart for the new owner (although by then it will quite possibly have outlived the original owner). I'm only thinking that I don't want to "over do it" on the repairs. If I were totally rebuilding her I'd feel different but I'm just wanting to fix what needs to be fixed. I would think it's silly to have such expensive and extensive repairs on a boat that wasn't built to such a high standard in the first place. To me it would be like putting a new $100,000 roof on an old shack. Don't get me wrong - I'm not wanting to just slap a band aid on the problem. But, for example, the original cabin overhead was a slab of 3/4 inch standard construction $25 per sheet plywood - a far cry from marine grade!

I borrowed "The Fiberglass Boat Repair Manual" from the library and it states that, "Polyester is used in the vast majority of boat laminates - probably 99 percent of the fiberglass boats built to date." In my opinion, if the boat is made of polyester - why not repair her with polyester? I accept the fact that epoxy is better than polyester, I'm just wondering if polyester isn't good enough for a boat from the 60's and an owner on a budget.

[Allan S]

Hello Xander, I just bought the same boat very cheap. I figure it will be a fantastic learning tool for the family without incurring huge debts. We have a lot of cosmetic work to do AND we have to replace the overhead ply also! How did it go? Appreciate any tips you have learned. Thanx...Allan

[Xander]

Hi Allan,

It's going well. I have learned more than I could have imagined over the last few months. Since I posted these messages (nearly 5 months ago) I've read about a dozen books on the subject, taken a few brief courses and got a full time job with a very reputable boat builder. It turns out that I really like this kind of work!

I've finally admitted to the scope of the project that I've gotten into with my own boat and pulled her from the water. She is now "on the hard" in my back yard. It's the only way I'm ever going to be able to finish the project properly.

I have since discovered that the "cabin overhead" that I thought I was removing was in fact the core of the deck! At the time of writing these posts I believed that it was more of a deck liner of sorts. Unbelievably, the CORE was INTERIOR GRADE 1/2 inch plywood. This is VERY unusual from what I understand (at least for American built boats) and the reason for my assuming that it was a liner. The inner skin of the deck was just a SINGLE layer of fiberglass cloth. The outer skin is much more substantial but not strong enough to stand on it's own. To my horror, I also discovered that the entire fore deck had the same problem. Every square inch of core throughout the boat had become saturated and de-laminated! A nightmare but not at all surprising considering the material used for a core.

So once I finally had the boat in my yard I got to work. Seriously got to work! I have gutted everything from the boat. Galley, head, bulkheads, absolutely everything. I am sure that I am going to extreme measures considering the value of the boat. I really don't think it's worth all the effort and money that I will be putting into it but I don't care. It's a learning project and I will have one solid boat when I'm done. After stripping her down to a bare shell, I started grinding. And I've been grinding ever since. Upside down. Call me crazy but I'm doing it anyway. After the inner skin was removed (most of it peeled right off after grinding around the edges of cored sections) the core came out quite easily. The plywood had de-laminated from itself as well as from the laminate so it mostly fell right out. The layer of wood closest to the outer skin required some encouragement with the use of a chisel and hammer. Once the core was completely removed I continued grinding. I'm nearly done grinding (hopefully by the end of today). When I am satisfied that the only thing left is good quality laminate, I will start fiberglassing. My plan is to layup at least 2 or 3 layers of alternating mat and woven roving to the underside of the original outer skin. I will then glass in a couple of significant stringers that will run the length of the main deck on either side of the companion way (the larger portion of the fore deck had two of these originally on either side of the forward hatch and I will also replace them with new ones). I'm fairly convinced that this will provide enough strength and stiffness to function as well or better than the original cored construction.

Let me know what you decide to do about it if you find that your problem is similar to mine.

Best of luck.

Xander

[Allan S]

Holy cow! Sounds like I might have a big job ahead of me. Looks like a winter project! Thanks for the heads up. It sure doesn't look like it should be that involved but I guess that old saying you can't judge a book by its cover is very apt in this case. Later......Allan

[rgranger]

Hi Xander: I have a 1970 Coro 25'. Sounds like you are well into restoring yours. I wanted to share a few quick tips

1: (cosmetic) I also replaced the cabin overhead in my boat. It looks like someone dropped the mast on the cabin top. They had done a bad job of repairing the fiberglass and did not bother to replace the shattered plywood at all. So once I fixed that I cut out a piece of nice blue marine carpet and put some waterproof glue on the back of the carpet. Use a staple gun to hold the carpet up while the glue dried. Two years later it still looks great.

2) If you are going to do a lot of fiberglass work (I've restored 3 boats far) you should know that epoxy will adhere well to polyester but not vise versa. Also the plastic sheeting you can buy at Lowes or Home Depot for paint drop cloth (the thicker plastic) will not stick to polyester. so you can use that to make a nice backing while you lay up multiple layers of cloth. For instance if you want to repair a hole you can lay the plastic over the hole... use a sharpie to trace the hole onto the plastic then cut out 4 -6 layers of overlapping cloth and place them all on the plastic. Pour on your resin and make sure it wets out the cloth thoroughly. You can do all of this on your work bench... then roll up the plastic and go into the boat and unroll it and place it over the repair. Let the resin harden a bit and then remove the plastic and fair up the job as much as you can before the resin cures. This technique is especially useful for those hard to reach places.

Good luck,

Rob

[Allan S]

Damn Rob, sure wish I read that tip of yours about the plastic 2 weeks ago...lol It would have saved me some grief.

Allan