Im going to revive this thread because I just finished my recore and I figured I would share my experiences and a bunch of pictures with everyone. I really couldn't find very many people with definite answers on how these things were done and I got a lot of mixed opinions from people who had never done it. I did find a lot of good information both on and off this site, and I figured I would give a little back. I did learn that a lot of people would consider soft decks to be a reason to write off an old boat. After actually doing to work and seeing exactly how involved it is, I really think it can be very practical for someone with reasonable handyman skills to do themselves (barring situations where the entire deck needs to be done). If a 3-5 foot section of soft deck is the only major thing standing between you and the boat of your dreams, its very doable. So, with that being said, heres the story:
I had a soft deck along the starboard side between the windows and lifelines which was approx. 1 foot x 8 feet stretching all the way along the side involving the areas where the chain plates went through the deck, as well as the area where the lifelines were mounted. I figured out that my portlights, which leaked every time there was a heavy rain, were the reason the water was getting into the deck. I also suspected the chainplates so I also dealt with them, noted below. Dealing with this area was extremely complicated by the rigging and lifelines so I was forced to have the boat hauled and blocked, I also had the boat demasted. Fortunately, I already had other reasons for having the boat out and demasted so it was easy to justify spending the $$. So, after removing the chainplates, (which needed to be replaced from water damage) I took a hammer, marked the dull areas, and took my 4 inch angle grinder and carefully cut through the top laminate only and set it aside. (I was careful not to damage it because it was going to be glued back in place instead of reglassing the whole area). This was pretty easy because the area was completely delaminated and mushy. Heres what I found:
The plywood (1/2 inch plywood FYI, to the other 70's Catalina 27 owners out there) was completely soaked and had a nice dirty rot smell to it. It was quite lovely. It then took me about an hour or two with the same grinder and a very course wheel to grind all the rotten wood out down to the smooth lower laminate. Catalina, I found out, likes to skimp on the lower laminate, using one single layer of 1.5 oz matt as a lower laminate. So naturally, I ground right through it to the headliner, which only extended to within an inch or so of the deck to hull joint. Momentary panic led to an easy fix where I took 1.5 oz glass mat and extended the headliner to the hull. It can't be seen on the inside unless you lay on your back on the counter top, and even then, it looks pretty good. At this point, I had created a lower laminate of the deck that would hold water, or the laminating resin I was going to use to glue to the new wood in (important if you dont want to clean up a mess of resin seeping into the cabin.) Heres what it looked like when I was done cleaning it up:
After doing this, I realized how easy it is to accidentally grind all the way through the bottom layer. Expect it, it will happen. Just be ready with something to patch it so you can continue with the job and pretty it up later.
At this point, I had completely gutted an 8 foot section of deck in a little less than 3 hours, (not including removing all the deck hardware).
The next step would be to let dry if necessary, clean with a good degreaser and make sure you have a good surface for bonding.
For the new core, I bought a grade A-B 4x8 sheet of marine ply (1/2"), which was about $70! (Didn't see that one coming). They only sell it in 4x8 sheets so take that into consideration. I used less than half of it for the project...
I then took the top laminate pieces which I cut out earlier and, with a pencil, used them as a stencil to cut the new core to fit.
I bought all my supplies from Fiberglass Coatings Inc in St. Petersburg, FL. They are very knowledgeable and have absolutely everything you need for a fiberglass project. One of the reasons this job was successful was there are several people there that used to work for big name boat builders. It was a huge help to have those guys for advice. He had advised me to use a bonding putty for the laminates, however, after trying it, I found it too hard to work with and went to a polyester resin thickened with cavacill (Spelling??). I thickened it to a toothpaste consistancy and spread it as thick as I could on both the lower laminate and the core material, mushed it down, placed sand bags on top for weight, and sunk wood screws through the bottom laminate into the wood to draw it down. I then covered the project to protect it from the morning dew, and let it cure overnight.
In the morning, I mixed some more thickened resin and poured it into the voids between the cracks where the new core and old core joined, and anywhere else it needed.
At this point, the new core was still square and had a bit too much thickness in some places, and had to be built up in others. This was one of the things that originally worried me about a project like this. Think about it, you have a boat with many curves, concave and convex areas. If you ask for core material at the supply store, they give you a completely flat, 4x8 sheet of ply. This is probably the hardest part of the whole job, making everything fit naturally.
I once again got out my trusty angle grinder with the course wheel and started grinding down the wood in the places where the upper laminate needed room to sink. I had the top skin set aside within reach so I could dry fit it every so often to make sure I don't grind too much in any particular area.
After I ground down all the areas that needed to sink, I then started marking all the areas that needed to be built up. I mixed about a qt of thickened polyester resin (a little thicker than before) and spread it with a large putty knife and a paint stirrer as a squeegee, smoothing it out as much as I could. After that dried, I took the angle grinder and ground it down smooth, dry fitting the skin and grinding some more until it fit snugly. I actually had to do this step twice before I got it completely right, mixing a second batch of resin and grinding again. Heres what it looked like after that:
After all that is done, It was pretty easy. Clean the under side of the top skin, make sure the core was sanded smooth and clean, mix another batch of resin, same as before, slap on a thick layer on both sides, and mash down. Put down plastic and sandbags and let it sit overnight.
After letting it cure, all there is to do is glass in the seams. I took the grinder and ground a 2 inch wide gutter along the entire seam of the project. This gives you room to take strips of glass mat and reinforce the seams for strength.
I then cut 1 inch wide strips of the 1.5oz mat and glassed in the seams with two layers, came back with the grinder to smooth it out, and followed up with a thickened epoxy and put a layer over the seams with a squeegee. This helped as a final step to smooth out the seams and fill any last minute voids. One last go over with the grinder and it was ready for paint. I used the epoxy as a last step instead of polyester because it is a lot stronger and harder and it readily bonds to just about anything, including cured polyester resin. However, I was careful to make this my last step because, once I used the epoxy, I could no longer go back and use polyester in that area. (Epoxy sticks to polyester, but polyester doesnt stick to epoxy).
So here it is:
After this picture, I spend several hours with a sander to smooth out any remaining bumps and some acetone to clean up stray drops of resin. It cleaned up much nicer but I dont have a later picture. During the project, I also found it a perfect oportunity to make epoxy beds for my chainplates. This gave me a lot of peace of mind that it wont destroy my deck again if they start leaking in the future. I would really recommend everyone do this. Over the course of the last year, I've done this to pretty much every piece of deck hardware I have.
This entire project cost me just $250 in supplies and 3 days. It only really took me that long because of curing times, and I could have done it maybe $30 cheaper if I new what I know now about the putty.
Also, there is a huge debate on this site about what is better or more cost/benefit effective: Drill and fill options like CPES or just recoring. After this project, I also decided to use a product called Stop Rot on another, much smaller soft spot on the other side of my deck. Ill keep you posted on the longer term results of both.
Well, this has been extremely long winded, and I'm not the greatest at explaining things, but I hope this helps everyone else thinking of taking on a project like this... Feel free to message me with any questions. I really have been wanting to put this experience down in writing because I don't think there are enough people out there speaking from experience on this topic. I really found it hard to find pictures of actual recore jobs or people who had successfully done it before. I hope this answers some questions.