Rotten core at the bow

[bigd14]

Stop leaks, then recore.

First order of business is to stop the leaks. Then it looks like you will need to replace some core. It's a messy business. But I think you will be thankful you did in the end. I did this and found that almost the entire foredeck was saturated (not all was rotten, though). Lots of good advice at www.plasticclassicforum.com.

I have a bunch of pics and details of my recore experience (and other repairs) at:http://www.plasticclassicforum.com/viewtopic.php?f=37&t=4431

http://www.plasticclassicforum.com/download/file.php?id=96&mode=view

Contact me back channel if you need details. Good luck!

Doug

 

[Emerald]

My experience has been that if you have a truly wet core and try to dry it by drilling holes, it is going to take weeks, not days to dry it out, perhaps even months depending on ambient humidity and temperatures. If you really have a saturated area, I think in the long run you will do much better to cut it open and replace the core and rebuild a deck skin. The links to the Epoxy Works Magazine articles and West System information Loren posted early on in this thread (don't miss the .pdf download which has good pictures) provide a great blow by blow description of the process and other good epoxy working information.

 

[bigd14]

Sorry, I missed a bunch of your questions above. I agree with Emerald, holes in the deck could take a long time to dry and you still have to patch them and paint. And you still have a bunch of rotten core left inside when you are done. I think your best off replacing it. I would be wary of doing it with the mast up unless its just the very tip of the bow. Once you start moving back with repairs I would start to worry that removing the structure would cause the boat to change shape in weird ways. Doing the job in the water is possible, but you'll lose a few tools and risk electrocution from your power tools.

Steps (do one side at a time to maintain deck structure unless it will just be the small area in the bow):

1. Cut out top sheet with circular saw (you probably can't save it). Keep a center strip (if its a large area) and two inches around the edges.
2. Dig out balsa core. A Fein Multimaster or Dremel Multimax will help removal.
3. Dig out balsa core from under the edges and the center strip.
4. Mash epoxy thickened with a mix of finely chopped fiberglass and colloidal silica under the edges and the center strip.
5. When this hardens, cut balsa core to fit.
6. Soak both sides of balsa core with epoxy prior to step 7.
7. Bed balsa in thickened epoxy.
8. Place 2-3 layers of 1708 Biaxial fiberglass fabric over the balsa and soak with epoxy.
9. Fair surface with epoxy thickened with microballoons and colloidal silica.
10. Paint.

These are the major tasks and there are additional steps within each task. Do your homework, have all your materials at hand, and go for it.

As for time, it took me about 5-6 days (before painting, which I have not done yet).

Step 1 is the scariest . Once you get past that its ok.

Doug

 

[ki1025]

I would be wary of doing it with the mast up unless its just the very tip of the bow. Once you start moving back with repairs I would start to worry that removing the structure would cause the boat to change shape in weird ways. Doing the job in the water is possible, but you'll lose a few tools and risk electrocution from your power tools.



Doug

Doug,
Thanks for your link, I've read your process a couple times, great job with it. we just shipped this boat from jacksonville fl, and had alot of interior work done as well as the bottom painted, so demasting it and taking it out of the water is outta of the question financially at this point. 3 years from now it may be possible but im afraid of letting the deck sit and rot even more causing a much worse issue. seeing as how some say it could only take months to cause further rot. We are going to rebed all the hardware the correct way(right now a little silicone is keeping the deck mostly dry)

a small triangle seems to be the only soft area. and the PO did a 2'x2' repair mid foredeck where he removed balsa core and put in foam-so id like to keep the repair to just forward of that. the repair would start just aft of the cleat in the picture i posted earlier in this thread.

Do you think that size area can be done with the mast still up if we do it side by side? how do you fill the centerstrip you left with epoxy if you left the other side intact. Does it matter if we replace it with balsa core or foam core to match the PO repair? I know balsa has its advantages, and I read a few places that foam can rot also is exposed to water and air but doesnt keep the rot area contained like balsa does.

we have dock on three sides of the bow so working on it while in the water would be a little easier than if just by one side.

We will surely post pics of our progress all the way to show our progress. Is there a certain temp that fiberglass work is best done? thanks again.

 

[bigd14]

I would imagine it would probably be ok with the mast up if its just a small area, but I am not really sure. I would definitely loosen up the rigging as much as I felt was safe to take as much tension off the bow as possible. If your just doing the very tip of the bow, I would not bother with leaving a center strip. If you were to leave a center strip like I did for a larger area, I just excavated out the balsa core from underneath and filled it with thickened epoxy. I wouldn't worry about using balsa or foam: if you keep it dry it won't matter. I think the core thickness is 3/8, but you should measure it before you start. You should be able to work with epoxy in temps above 45 or so. Depends on the hardener. If its cold, use a fast hardener, if its hot use a slow. Follow the manufacturers guidelines. And you'll probably burn up a pot or two before you get a feel for it, especially if you are using thickening agents. Just don't panic when it starts smoking! All part of the fun Its good to practice a bit first on some home projects. Maybe even do a mock up to practice wetting out the fabric and getting bubbles out, etc.

Oh, and I wouldn't use silicone at all on a boat. Its IMPOSSIBLE to remove effectively. I had nightmares removing a small amount of silicone contamination from around a fitting. Sanding just drives it deeper into the surface, and then you have to use all sorts of nasty chemicals to remove it in order to paint or epoxy over it. Its truly evil stuff.

Oh and I forgot to add as a major step to sand a bevel in the edges around where you cut out so that the layers of fiberglass will match the deck level. I put a 2-3 inch bevel in.

Doug

 

[ki1025]

Doug, <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" />
Thanks for the advice, We had to use some kind of sealant cause the boat was leaking when we got her and we haven’t had the time to put into her yet to fix her. The type of silicone we used is:
West Marine’s “Marine Silicone Sealant”

• Formulation: One-part silicone sealant
• Recommended Usage: Can be removed easily. Bonds to non-oily woods, metal, fiberglass, glass, plastics
• Material Incompatibilities: None.
• Compatible with acrylics. Not as strong as polyurethane
• Cure Time: Tack free: 1 hr; complete cure: 24 hrs.
• Cleanup: Soap and water
• Removal: Mechanical removal

Think this will be difficult to remove? We have to do the overdrill/expoxy/countersink method on all the deck hardware. I was thinking we would chip and pull out what we could, then clean it with acetone, then overdrill it.

Do you think that will take care of it enough to then fill with epoxy and drill new holes? Anything you recommend using to get it off so the epoxy can form a strong bond?

We are going to take the cleat off of the middle of the deck. And replace the two rope holders on each side with cleats. Its in the way and I imagine some of the water damage is coming from it due to the headliner being in the way of the bottom of it. I don’t think it was ever sealed correctly.

Do you remember what is under each stern pulpit and lifeline stanchion? Is there wood under there? I’ve read a few places there is plywood. We are planning on redoing the soft spot in the bow and rebedding all the deck hardware on the bow at the same time. I suppose we could remove all the hardware first then when we are digging out the balsa wood, we could dig out the plywood as well and fill with epoxy under everything around the edges, then we wouldn’t need to overdrill those hardware in the bow area.

Thoughts?

 

[Lucky Dog]

Chris McKillip

How did you re produce the tread on the deck?

ml

 

[Glyn Judson]

Reproducing the nonskid pattern.

I watched several of my buddies do that up in Vancouver BC when we lived there. They'd slather common silicone sealer, hardware store quality in the caulking tube, all over a piece of cardboard slightly larger than the repair in question. A location with a good pattern, adjacent to the repair would be selected and Vaseline applied to it. The silicone/cardboard would be placed over the Vaseline area and lightly weighted from above and when cured, the silicone would have taken on the new pattern. After cleaning the Vaseline off, the repaired area would get the last glass layer with a little mold release on the pattern and it would be applied on the wet glass and left to cure. The cardboard with silicone would be removed, the repair cleaned up and gel coat applied. I saw it done several times and it always worked like a charm. Just be sure that the template area you select has the pattern as close to what the old area would have looked like. Even if the repair area were not to have been flat, the cardboard would bend enough to make it all come out right. It was so cool when the silicone pattern was laid over the patch and then some around the periphery, it would clock into position guided by the surrounding intact pattern and you then knew you were right on the money. Glyn Judson, E31 hull #55, Marina del Rey, CA

 

[CSMcKillip]

Chris McKillip

How did you re produce the tread on the deck?

ml

Glen has the basic idea and there are several different ways to tackle this. I will list what I did.


The Mould
First the gelcoat non skid area on our boat was colored about 1/8" thick. I brought the final coats of gelcoat right at the existing level of the non skid. I used PVA and found an area flat and had not been too worn from traffic. I rolled on the PVA onto the deck then I mixed a good amount of gelcoat and painted 2 to 3 god layers onto the deck covered with PVA. This will be the outside of the flexible mould. I let this kick for 20 min. then I took three layers of cloth and applied this to the gelcoat, let this kick, then 2 layers of thick chop mat, let this kick then several layers of polyester resign and layed a thin 1/4" plywood on top to make my base. This gave me a mould I could use to pattern the non skid.

The Prep.
I then took a countertop router and set a flat bit at a 1/16, I ran the router over the area and removed the gelcoat around the existing non skid area, I removed the center being carefull no to let the bit dip into the new glass layup. I then champhered the outer edge with a dremel tool and cleaned the area with ascetone. I then applied PVA around the outside edge this will allow the extra gelcoat to seep out from the repair area and you can just pel this up after it cooks.

The Layup
I color matched the gelcoat on the inside of the boat so no UV damage was in the color, after about 1 year the new gelcoat started to match the old. I mixed the gelcoat with the MEKP and poured this onto the 1/16 hole in the deck allowing there to be more gelcoat then not enough, I made sure to take a small brush and get all of the low area and any air out of the mix, I then took the new mould and appied PVA to the gelcoat side and layed this ontop of the reair area and moved the new mould around to seat it into the pattern, I then took a battery and placed it ontop of the plywood and let the gelcoat kick.

The Cleanup
After about 30 min. I pulled the mould of of the fixed area, I then cleaned, and peeled the extra gelcoat that seeped onto the PVA off of the old non skid, I took a small blade and carved a small slit between the old and new gelcoat, making a thin area for final gelcoat. I then taped off the entire non skid area old and new areas from the white finish.

Final Repair
I then mixed another batch of gelcoat, and with a small roller applied the entire area old and new patch with gelcoat, with the roller it was putting enough gelcoat down to fill in the small slit area, and fill any voids from the mould. The new gelcoated non skid was then covered with PVA to cure, I let this sit over night and the next morning I washed the PVA off and lightly compunded the non skid area to knock off the shinny new gelcoat to match.

I got the idea of doing this from a company that sell rubber non skid moulds to do this kind of repairs, it worked rather well and after mounting some hardwarefor my spinnaker twings in the ruff areas I was very pleased with the results.

 

[bigd14]

Great ideas on matching nonskid.

As for silicone removal, I used acetone, followed by soapy water followed by acetone, etc. soapy water, etc. It worked eventually. When the water no longer beads off you're ok. You should be ok with your technique.

There is plywood for core in the size of the deck pads under the stanchions. I don't remember there being plywood under the back two stern rail supports.

Doug

 

[ki1025]

Received Quote-Opinions?

Ok,
So I just wanted to see what some local people had to say about the repair and how much it would cost. I put an ad out on craigslist asking for someone with core repair and fiberglass work. We got a response from a young guy who has a boat building business with his father. He came and looked at the area and this is what he said:

cut the top skin off of the small bow triangle leaving a 1 inch edge. get all old wood out, then replace with regular 3/8 inch treated plywood. In doing this we would overdrill the holes where the deck hardware would go back then lay the plywood down to fill the whole area, under the 1 inch edge and everything.

Then we'd reattach the skin and sand everything and make it smooth.

Doug you had suggested we leave a 2 inch edge and fill under the edge with epoxy. How do you fill the edge with epoxy when the consistency is like honey? If you have to make the consistency thicker, how do you assure that all the voids are filled.

Lastly he said this work would take the better part of a day. His labor is very cheap seeing as how he is so young and basically seems like he just likes to do this kind of work.

Any thoughts on why this wouldnt work? why it would? plywood choice?

Thanks so much

 

[Mark F]

I wonder how the epoxy would adhere to the treated ply. I would ask to look at something he has done and then hire him!

 

[bigd14]

Couple comments here.

Plywood vs. balsa or foam: the balsa or foam is cut into sections and held together by a lightweight fiberglass scrim. This allows it to drape over the contour of the bow. You would have to cut relief kerfs in the plywood to get it to drape similarly, and even then it would still be tough to get it to match up.

Edge thickness. The two inch edge is so that you can sand a bevel into the top skin and lay fiberglass over the seam. If you leave an exposed seam, it will be a weak point in the top layer.

To fill the area under the edge, you first thicken the epoxy with colloidal silica (and I would add a little chopped fiberglass), to the consistency between thick ketchup and peanut butter. Then using a putty knife you mash it back into the area under the edge. You also use this mixture to bed the core material to the bottom skin (like using mortar), fill in any gaps using your putty knife, and then bond the top skin back on.

Much of this could be done in a day, but I'm not sure all of it. You could remove the top skin and core material, bevel your edges, then put thickened epoxy under the edges, bed the core material and replace the top skin, and also put the fiberglass over the seams all in one day. If you are VERY skilled with the fiberglass installation, you could also put the fairing compound on (I couldn't have done this with my fiberglass skills). But then you have to come back, sand the fairing compound, and probably put in another coat of it. If you are not VERY skilled with fiberglassing, you would have to come back next day when its cured to sand it smooth, then fair it, sand it fair it, etc.

In my opinion I would be cautious about hiring this guy if he thinks it can be done (correctly!) in one day. Definitely get some references.

I think this is something that anyone who is at all handy with stuff could do. I know it sounds intimidating, but once you get all the steps planned out, its not too bad.

I would be happy to walk you through it, send me your # on the private message feature if you like.

Doug

 

[ki1025]

Thanks for that advice.

Doug I'll give you my # this week when i get the chance to sit down and write your instructions down. One question I have off the top of my head is, is it easy to create the bevel on the 2 inch area when nothing is supporting it underneath? like the core you just took out?

Someone local suggested cutting out the top layer but then leaving an edge, and the wood that is under the edge, if its not rotten to leave it and let it dry under a tent if wet, then just install the new core material and finish with the steps you described, as for the deck hardware in that area we would just do the overdrill etc through the old wood like we will with the others. See any issues with leaving the wood under the edge in place instead of removing and filling with epoxy/fiberglass?

And lastly When you fill the 2 inch edge with epoxy and fiberglass, can you just drill through it for the deck hardware? The four bow pulpit bases and the two rope things (soon to be cleats), We are removing the middle cleat for sure and replacing the two port and starboard rope holders in the picture with cleats. Other area than the bow we are doing the overdrill fill with solid epoxy through the wood, where the 2 inch edge if we are putting epoxy and fiberglass, does it matter the bow pulpits will be drilled directly into that mixture? or is it better to overdrill through the epoxy/fiberglass the and then fill with solid epoxy?

I have attached a picture of the entire bow so you all who are giving opinions can better see what I'm talking about. The PO's repair is bigger that i thought and it looks to be a 3' x 3' square. He put foam there. The repair we are going to do will be from the fore seam of the old repair forward to the tip of the bow. One good thing about he repair being so big is that I think it would isolate the rot to the bow. If for some reason couldnt fix it now. I think we are going to tackle this though in the next few weeks, while the weather is getting better, and before its 150 degrees outside!

 

[Emerald]

See any issues with leaving the wood under the edge in place instead of removing and filling with epoxy/fiberglass?

Get out all the old stuff. It sounds like your deck really has been solidly saturated with water. I think you'll find that you will never get the old wet wood, be it balsa or ply, to truly dry out, and epoxy will not work properly in the presence of moisture, and you need to get a good bond on the edges here. Another issue you are fighting is that severely water saturated plywood is going to be delaminating, and saturated balsa can easily go to garbage with no strength. Here are a couple pictures of balsa core I cut out under snaps for my dodger that were not bedded properly when installed. I've also included a close up off one of the worst hole where you can see how the surrounding balsa was totally shot. I dug this out and packed the areas that extended beyond my cut outs with thickened epoxy. Ultimately, I bedded plywood plugs in thickened epoxy and then layed up new fiberlgass over the whole thing. The holes I cut out were about 1-1.5 inch diameter, and it took about 4 months to dry out the surrounding balsa before I could finish the repair, and this was a scenario where I had sealed the snap holes at the deck side and was able to leave the exposed holes in a controllable environment - the cabin.

As others have pointed out, if your systematic and careful, you can do this type of work, even though it may seem intimidating. Here's a link to redoing the core under my mast step. Similar to your deck but on a smaller scale.

http://home.comcast.net/~independence31/core/looksbad.html

Hope this helps.

 

[Loren Beach]

Thanks for that advice.

Doug I'll give you my # this week when i get the chance to sit down and write your instructions down.

When it comes to preserving the text of any thread, there is a useful feature at the top of the thread called Thread Tools. Click on that and then on Show Printable Version.
Now you have the text stuff you can save to the desktop or print out.

Best,
Loren

 

[bigd14]

I agree with Emerald, better to get rid of all the nasty stuff and do it right first time. You only want to do this once!

I have a couple concerns about the PO's repair. First of all it sounds like in an earlier post that there is water coming down one of the seams around this repair. If that is the case it would indicate that there was no fiberglass put over the seams to stabilize them (if the top sheet was reused). If this is the case these seams are weak spots. They may also be leaking water into the sides and aft of the repair. Have you sounded those areas with a hammer or back of a screwdriver? Sound them out and if any areas sound dead (e.g. not a sharp report when rapped), then something is wrong. If they are suspect I would recommend re-doing the whole foredeck. If that is the case you might want to sail the boat for awhile and then do it while hauled out. I hate to sound alarmist, but I have found that damage is often more widespread than originally anticipated. For example, during my recore experience I found that wet core was much more widespread than the rotted areas. In fact only a hand-sized portion of my foredeck was dry! About 1/2 of the foredeck was rotted, the other portion wet and on its way towards rot.

The area under the tip of the tool in this photo was dry.

Here is a photo of the carnage on the side decks. I didn't get one of the fore deck but it was similar. Notice how much of the top sheet was still adhered to the rotting core and peeled up totally unsalvageable...

As for your other questions, the beveling of the edge can be done before you pull out the core material from underneath, or I just did it afterwards. The top skin is pretty robust, the bottom skin is not.
Here is a photo showing the bevel, and the core material in place with thickened epoxy.

Also, I think the stanchion bases have plywood in them so you would want to do the drill out method with those. The cleats on the sides of the bow do not go through core material. If you go through thickened epoxy, you don't need to do anything except drill straight through.

Doug

 

[ki1025]

I reread my previous post. What I was saying about the water leaking through from a crack in the seam, is that in the vberth storage area on the port side on the cabin top there was a place where water was getting through. a little area about 1/4" appears to be cracked, but when you go on the top surface there are no visible or feelable cracks. We were thinking maybe the water is coming through that seam from whatever is rotting the bow. nowhere else along the visble seam is there any water coming through. I suspect most of this is caused by that cleat in the middle.

The PO did the repair about 4 years ago and the sides of the deck dont seem soft at all. I havent done a sounding test in that area yet, but i will.

Do you think we could wait to do the repair then? We wont be hauling out the boat for another 3 years or so. We just got the bottom repainted etc. if we rebed the deck hardware, do you think we could just let this repair wait for a few years. If its only rotting in the bow area and not into the sides then the rot would be isolated by the PO's repair that spans across the deck. we definitely only want to do this repair once. We would prefer to wait as long as possible if its going to be major.

Do you think the boat will sail just fine untill later when we can do the repair? Do you think its dangerous to leave the spot soft? (I've read alot that says its not). Thanks so much again for all your advice, its been so very helpful!

 

[ki1025]

Oh yeah one more thing i forgot to say about the PO's repair. He took out the rotten wood, then set the foam up and then fiberglassed the new foam into place, Then he refiberglassed the top skin he had removed back on. so there the is top skin as well as new fiberglass underneath that. To give more info on the possible weak seam.

I called him to ask him more about his repair but he hasnt gotten back with me..I imagine we have used up all of our "contact the PO and get answers about the boat" reserve. We are on our own now!! lol

 

[bigd14]

You could probably sail it like it is its held up this long...

As for waiting, I would immediately re-bed all hardware up front especially the pulpit and hardware on the very tip of the bow (the tip of the bow was where all the water was coming from on my boat I think). With no more water coming into the boat at least things should stay pretty much the way they are.

Then be prepared for a major haul-out!

Doug