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Cored deck soft spot repair

57K views 80 replies 41 participants last post by  Hudsonian 
#1 ·
Hi,
I know this has been asked here before, I did a search on this forum and many others but still have a few questions. I’m new to doing work on boats and I just recently moved into my ’76 Catalina 27. I got the boat for a pretty good price and it seemed very solid. I also did have several people in the know (as far as boats are concerned) tell me the same.

I have been noticing a few smaller soft spots on the deck lately (forgive my terminology or lack there of) near the edge of the deck on the side where the mast stays are bolted down. I have one soft spot on the port side that is about 2-3 sqft and another in the same place on the starboard that’s about 1 sqft. I’ve been doing a lot of research about how to fix this. I am a bit concerned with the location of the spots due to the fact that my rigging is bolted there, which is most likely what caused it anyway (water seeping through the bolt holes.) I did notice that it looks like some glass work has been done in that area on the port side before so maybe its possible it wasn't done right the first time. Either way, Im planning on waterproofing all my bolt holes on deck when I figure out what I’m going to do about the soft spots.

I’ve read about the “drill and fill” options where you basically pump epoxy into the core but have found very few people actually advocating this. I know that injecting epoxy into a hole full of wet (Im assuming) plywood isn’t going to solve anything, but I live aboard in a marina in the Tampa area, it rains a lot, and if I start cutting my deck apart to replace an entire section of core, I have no idea (whether being in a boat yard, or in my slip) how I’m going to keep everything dry. Im not even totally conviced I can do it myself. Im pretty handy but Im not completely sold on the idea of tearing into my deck. Is there anyone out there who has done this themselves or who has had success with the drill-and-fill method? Any thoughts at all? I am planning a haul out towards the end of the year (after the rainy seasion) so I could do the work while on the hard but it will all still be weather permitting.

Any advice or comments would be greatly appreciated.
Thanks,
Nick
 
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#34 · (Edited)
Before Dan Pffeifer's PearsonInfo.net website went away, I copied many of the files pertaining to the Pearson 33-2. One group of files was a series of photos of the manufacture of the 33-2 including the deck that one of the original owners of a Pearson 33 had taken. I wish that I knew who had taken the photos because I would gladly credit them here.

Anyway, these pictures show how a BALSA cored deck is built. You can see that the balsa is cut into many 2" squares, and that is how Pearson was able to craft the decks into complex curves.

The deck was built upside down in the mold;

The guys in this picture are laying resin (polyester probably) into the gaps between the little squares of balsa...


The assembled deck curing; (or it was break time)


I believe that the next step would be to cover the entire structure with another, thin, coat of glass roving (or two) and wet it out.

Here is the headliner (built right side up)
 
#35 ·
Great pics!

Only thing I am wondering how they put the deck onto the inner liner and made sure that they have good lamination between them everywhere? There must be a trick to that. I epoxied a few square feet of a shell onto a substrate (a part of one half of a split rudder) and was concerned that I would have air inclusions. I buttered the heck out of both parts (meaning, onto both parts) and then put a lot of weight (bricks) onto the shelf but in the end I am still not 100% sure there is absolutely no cavity hidden. I can't imagine doing this with a whole DECK!
 
#36 ·
Hi
I just finished removing the rotted core out of the cockpit of my 1975 Tanzer 22. I am completely new to the world of fiberglass boat repair but I eventually got it done. It is rock solid now. Its an area roughtly 24 x 70 inches if I remember correctly.
I expect that I will be doing this in other spots as I discover more wet core.

I've documented what I did on my web site.
Christine DeMerchant Repairs the Wet floor of her Tanzer22

Christine DeMerchant Repairs the Wet floor of her Tanzer22

I took quite a low teck approach in removing the rotted plywood because the bottom layer was very fragile. Once stripped out the job went fast and rebuild was easier than I thought it would be.

I use MAS epoxy but any good system will work I expect. I like that it does not blush.

I'm not sure I worked terribly efficiently but I'm confident that my repair is solid and sound.
Have a look, and good luck.
Christine
 
#39 ·
Cored deck spot repair

Over 10 years ago I was asked to repair a trawler with loose teak decking. When I took up the first section of teak, I discovered that the glass deck underneath was very spongy. The wood core was soaked and rotten, on the bow, stern, and both sides of the cabin. I carefully cut away the top layer of glass, removed all the rotted core, which was lauan plywood. I then filled the core area with good quality marine plywood, totally bedded in West epoxy, then bedded the top layer of glass back into place with epoxy. Once it was all cured, I was able to replace the teak decking. The owner kept the boat until a couple years ago, and as far as I know the deck was still solid. Except for fairly small areas, I believe that replacing the core is the best way to assure that the problem will not recurr.

Tom Kenat
The Ship's Carpenter
Medina, Ohio
 
#41 ·
Scotch, clear, Packing Tape does a great job of removing the glass slivers from your hide. Just make a loop of it around your hand, sticky side out, and roll it down your arms. You'll probably lose a few arm hairs in the process as well.

As for the drill and fill process, I'll let you know how things are progressing. I hope to get the Morgan back next week, and I'll be running a hydro-meter over the repair areas to see if they dried out or not. I'll let you know.

Gary
 
#42 · (Edited)
One method of re-coring is to remove the bottom laminate and core from the underside. This leaves the deck non-skid intact. Yes, upside down laminating is not pleasant, but can be done.

After removing the old core from underneath, you can replace it with Balsa or any other core. Core materials are very light and with epoxy, heavily thickened with fumed silica (Cabosil/Aerosil), it is not difficult to stick the new core to the old top laminate. For large areas, you can do a square foot or several square feet at a time and prop in place, if necessary, with a thin sheet of plwood, waxed or covered with Visqueen.

After the thickened epoxy has set up but is not fully cured, laminate over the new core with at least two layers of 1708. 1708 is a biaxial with a stitch mat(no binders). Wet out the semi-cured new core with a good amount of epoxy using a 4" or 7" roller, then apply the glass, wetting out the glass and keeping it in place till saturated. Once fully wet out it will stay in place and not come off. Just in case, keep an eye on it and be ready to catch it before it sags.

One more tip, for better wet out, heat your resin before mixing. I have successfully laminated with US Composites epoxy heated to as high as 120F. I use a cheapo digital meat thermometer, stuck into the epoxy jug.

Obviously, this type of repair only is applicable to boats with a removable headliner.
 
#44 ·
Working from underneath seems very unpleasant.
I think it would be less time consuming than refinishing the top though.
I don't think I have a removable headliner.
I might still be able to cut from the underside. OH that would just be so much fun.
Thanks for taking the time to explain the process. It sounds like it would work very well and might be the way to go for a smaller repair.
Christine
 
#45 ·
Just out of coureosity, has anyone thought of or used the styrofoam insulation panels rather than plywood or balsa? My guess is it would be as strong as balsa, not so much with plywood. But it would never absorb any more water and would be much easier to form to the cavity.

I've made plug molds with it using west system epoxy so the chemicals shouldn't dissolve the panel.

John
 
#46 ·
Just out of coureosity, has anyone thought of or used the styrofoam insulation panels rather than plywood or balsa? My guess is it would be as strong as balsa, not so much with plywood. But it would never absorb any more water and would be much easier to form to the cavity.

I've made plug molds with it using west system epoxy so the chemicals shouldn't dissolve the panel.

John
Foam is used by some builders. While it doesn't rot, any water that gets in travels much easier and the area of delamination is much greater. The advantage to end grain balsa is that any water travels pretty slowly, confining the damage.
 
#47 ·
There was a recent article in one of the boating magazines pertaining to the use of various core materials, with balsa listed as the best wood because of its structural integrity being higher than marine plywood. The same article talked about teak V/S some of the new composite, faux-woods such as Trex, and others currently used for decking material. The biggest problem with any of this is the change in weight distribution over what the boat was originally designed for.

A number of small boat manufacturers, such as Boston Whaler, use a dense form of foam that injected between the inner and outer hulls. The foam is very adhesive, and delamination is extremely rare. For transoms, nearly all powerboat manufacturers have switched to using a honeycomb, fiberglass core that is incredibly strong, it is tightly adhered to the inner and outer hulls and weighs next to nothing. The beauty of this approach is that when screws, through-hulls, etc.. are inserted through the hull(s) if they spring a leak it's confined to one, small chamber and does not effect the rest of the hull.

Cheers,

Gary :cool:
 
#48 ·
Catalina's?????

It's disturbing that so many Catalina's seem to have this deck problem. My 42 Catalina also has a hollow spot. I first discovered it (only owned the boat a few months) when I was washing it and noticed a different tone, when the water hit the deck, in one spot. I'm going to use the technique outlined by travlineasy. wish me luck.
 
#49 ·
It has been several months since I did the drill and fill. A couple weeks ago I had a local surveyor bring his hydro-meter to the marina and check the areas that were treated, and the adjacent areas. So far there is no indication of moisture intrusion and I hope the core remains dry. This nasty, winter weather will be the true test of time. If the core is still dry in early April, I'll be sanding the decks, removing most of the hardware and repainting everything above the hull to cabin joint. All of the fixtures will be rebedded and sealed before reattachment, then it's a summer of fun sailing before heading south to the Florida Keys in October.

Good Luck,

Gary :cool:
 
#50 ·
Hey all,
Its good to see this thread still alive.... I started this thread a little over a year ago asking for advice on recoring the deck of my C-27. I posted pictures of the process in page 3 of this thread, and I used both the drill and fill method as well as the full blown recore with marine ply on two different areas. Everything's still solid, still haven't fixed my dang nonskid though.... Thanks for everyone's input!
 
#53 ·
Go to the West System website. go to projects. download the Fiberglass Boat & Repair and Maintenance manual (free) . It's the bible for this kind of work. chapter 5 deals with cored deck repair. also on the home page click on repairing your fiberglass boat and there's an article in the subject from there EpoxyWorks on line magazine
 
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#55 · (Edited)
I recored 80% of the decks on my old A35. The main problem with production boats is that they often did not use enough resin to saturate the balsa. Water around chain plates is common and IMO unavoidable. There IS no sure way to keep water out and once in, it stays there essentially forever, finding bare wood and promoting rot. It's why I moved my chainplates outside after doing all that work to replace the rotted core.

A larger problem than the core, which is pretty easy to replace, is what the water may have done to the bulkheads below. I wound up replacing one large bulkhead that had turned to mush. Replacing bulkheads requires a some major surgery and a lot more skill to accomplish without doing too much damage. If anyone reading this gets into swapping a bulkhead , I have some valuable tips, just pm me.
 
#56 ·
Looking for a little reinforcement!!! Working on a 1978 Catalina 27.

After a ton of research, I decided to go for the peel the skin option. As sync mentioned, I was able to make quick work of peeling back a 6-8 ft section using a dremel to cut a nice clean line in the skin. As suspected, the wood was soaked (due to years of window leaks & improperly bedded hardware). The good news - I was able to quickly scrape out the wood and clean the whole area. The bad news - is that there is only one sheet of fiberglass underneath the wood. The inner liner is quite thick, but that stops 2" short of the hull. This means that I only have a 30+ year old layer of brittle fiberglass mat for the length of the hull where the liner ends to the hull.

My plan was to cut away a 8ft length on the starboard & port side and let it dry out over the winter - then glass, laminate & glue the skin in the spring. I am worried about the structural integrity now if I cut away an 8ft length on each side and am thinking that I will need to do this in sections to make sure the integrity remains.

Plan A - clean out and dry out a section, add a layer or two of glass, then continue.

Plan B - try and add a layer of glass tape from underneath first, then cut away the rest. My concern with this is that I am glassing in the brittle sheet, need to glass upside down and in very tight quarters.

Plan C - Panic :eek:

I am going to post some photos shortly as soon as I figure out how to do that.

Would love to hear from any C27 owners who have taken on this project. I feel like I have most of the skills to do this job. My plan was to cut away, clean out, re-laminate ply and hire a professional glass person to do the final top layer glassing - either by putting the skin back down or by laying new mat. I was going to paint the top with quik grip so not concerned about the tread pattern.

Thoughts???
 
#58 ·
Injecting epoxy or any other resin into a degraded and probably wet core does not accomplish much but a false sense of security. the deck may feel sound but what you really have is a free floating lump of epoxy that could not possible stick to wet degraded core.

If your deck is truly the structure to which your chain plates are backed then it must be made strong enough to take all the loads of your rigging..... bite the bullet and re-core.

Take a look at "Balsa = Compost" . If your deck is plywood the condition is worse than wet balsa.

PS. The acetone thing doesn't work. I pumped acetone into one spot for 3 years and when I finally decided to do it right and open her up she was sopping wet.
 
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