Update to core rot and removal.

[Jackie]

[Fishcatcher907]

I’d suggest watching total boat works on YouTube. I just finished my first ever core replacement and fiberglass job ever. I leaned a lot just from watching that channel and a few others. At least you’ll know kind of what to expect.

[thataway]

Hi Jackie,

When I re-read my last post, I realized I had left out a quote on 1708. IT is laid bundles of fiber, it is laid at 45*. it is stitched together. It is not woven as usual roving is. We used to use woven roving alternate with mat. The 1708 is lighter and as strong. It does not have the "print thru pattern" that the heavy bundles do. The cloth is smaller twisted "threads" of fiberglass woven, and the mat as is you described, with a sizing compound.

The Core Bond is basically thickened polyester resin--and applied with a trowel as I described. You can either use something like "Poly-Fair" which comes in one gallon cans, (talk it over with the supplier--you would waste most of a 5 gallon container). and is also made by ATC. I just mix up my own. using Cabosil and low density filler. I am not sure what makes the ATC Corebond "elastic"--But that can be a feature which is not essential with the C Dory.

Another way to go is 945 Vinylester Bonding at $50 a gallon. It seems to be as good as the CareBond, and comes in gallon containers--stronger resin bond. I have not used it, and I would do the initial hull laters with the vinyl ester then polyester on the top of the balsa, and between the layers of the two 3/4" layers of balsa.

You want something which will adhere well to the bottom inner side of the hull, and to the balsa, filling the voids between the hull (you want to weight the balsa to give best adherence) and voids in the kerfs of the balsa. It is cheaper, and in this iapplication probably sensible to use polyester resin. The issue between the resins is the secondary bond. Initially when the boat is newly built, there should be a primary bond--that is all of the hull and core is laid up wet, before the layer below is fully cured. The reason that vacuum infusion is superior, is that it assures that all is laid up at once (as well as saving weight and resin). Hand layup may mean that the hull got partly laid up on Friday and then finished on Monday--Thus giving an inferior secondary bond, rather than a primary chemical bond. This happens occasionally--and may lead to hull failure. There was a new very expensive spot fisher where this appeared to be the cause of total hull failure.

Epoxy resin gives a considerably stronger secondary bond, but is also far more expensive. (we are fortunate to have a wholesale supplier of all of these items only abut 8 miles from my home). There is a huge markup to by places like West Marine. Vinyl ester resin is about half way between in strength between epoxy and polyester. See above about using the 945 Vinylester Bonding.

Yes,you will tab in the sides--basically filling any voids where you cannot get the balsa, with a thickened polyester or vinyl ester compound. It can be thicker than the bonding material used for the core to the hull. You will dry fit the balsa. Then see how much filling you will have to do along the sides. I probably would put that in just before you put in the balsa. Leaved this highly thickened resin slightly concave, and us the bonding agent between the balsa edge and the filler along the sides.

I would probably sweep on layer of 1708 up the side, and then fair and sand smooth as you do the finish work. Tabbing can be done with cloth tape and mat or the 1708 and mat. How much fairing and sanding at the end, depends on your aesthetic sense...not a crime to leave a line of tabbing. But I have the impression that you do very nice work and would want it to look as near to perfect as possible.

[Jackie]

Thank you, Bob, that is very helpful and leads to a couple of questions. I wanted to lay in the layers of mat and 1708 against the hull maybe several days before putting in the core. I don't know how much cure time there is between layers, but I assume there is some and that it is okay to get that part all ready to receive the core? I would be using just a vinyl ester resin for that with no thickeners or anything, wouldn't I? Then the 954 vinyl ester bonding compound would a new layer that beds the core to the hull I just laid?

At this point I had thought to do the bow with the two layers of 3/4 inch, and then later go back and finish the rest with the 1.5 inch. Will that be a problem? If it needs to be all done at the same time I could put in one layer of the 3/4 inch along with the rest of the floor, and then go back with the final 3/4 inch. I'm assuming they need to cure in between, or do I just lay both 3/4 inches at once? One of the reasons I was interested in the pre-mixed bedding resins is that I read the open times are longer. I have a big area and, since I've never done this, may not be the fastest worker. But I've laid a lot of tile so I'm fairly fast with a trowel.

I'm pretty sure (from walking through the one place in town with any fiberglass supplies) that I'm going to have to order out. I planned to enter a few of the items in the online order forms of the various company names that have been suggested here just to see how the shipping shakes out. That's kinda how I decide when I have to order, and once I do I can call the store and I'm sure they will be able to guide me in the right direction. I just wanted a rough idea of what I'll be needing in advance.

Thanks for all your help. I tend to be look with a more critical eye at work I pay for, but can be tolerant of my own errors For the boat though, I do want it to look good, and it needs to be sound, so I'm trying not to let any laziness take over! I blame it on being a Gemini!

[Teufelshunde]

Jackie,
Below is a link to boatworks today. He has a bunch of videos on boat fiberglass repair and worth a look.
Another video series that is helpful is “west system epoxy” on YouTube.

https://youtu.be/JAtjHjJhBV0

Fish on!

[Jackie]

Thanks for the link Teufelshunde. I just watched his series as well as others pertaining to core replacement. It is easy to fall down the YouTube rabbit hole!

Fishcather907, I looked at TotalBoat and those seem to be mostly wooden boats? I haven't searched through all of them yet, but YouTube videos are a great help. I will go to the West System videos as well and see if there are videos from the makers of the products I'm thinking of using.

Thanks all.

Jackie

[thataway]

[Jackie]

Once again, thank you for the resources. I will look them all over carefully. The reason I said I wanted to put layers down under the balsa was because of something you said when I first posted about this in April. That thread was called something like cracks around seat boxes and v-berth flexing. You said

[thataway]

Hi Jackie.

For that limited area, I would grind down the glass very carefully to get into good glass. 'for that area, then I would go ahead and feather in some mat and 1708. You will have to taper this out to the sides and forward, so there is not a "lump". When putting in this type of "patch", a ratio of 12 : 1 is commonly used. instead you can lay the two layers of 1708. near the center, then some mat out a bit further, then the second layer of 1708 further out, and finally some mat out round the area. Then this will be allowed to harden, grind to feather it in.

Yes, my original post was assuming that you were only going to take out a limited amount of core. But if the boat seem floppy now, I would go ahead and put in some re-inforcement.

How big an area do you think you need to re-inforce?

[Jackie]

Well, It’s been forever it seems but I am finally making headway. When I ordered my balsa I was told it would be about 5 weeks before it arrived in Homer and then it would be mailed on to me. It took a bit longer than that, but I used the time to sand and get ready…and procrastinate. When the balsa finally arrived in Homer I was told it would be $237 to send it UPS Next day air to Ketchikan! Yikes. I asked about the good old post office and that brought the price down to $86. It was supposed to be 7-10 day shipping. I figured it would truck to Anchorage then be put on a plane, but apparently it got barged from Anchorage to Seattle then back up to Ketchikan. It took 5 weeks! Everything about this job has taken longer and been even harder than I expected. But I’m doing it.

It took me three days (but I'm not putting 8 hr days by any means) to cut out the balsa to fit my space. When I finally had it ready and numbered for ease of actual installation I got my sons to help. I was in the boat spreading the bedding compound and laying in the balsa, they were outside coating the kerfs in the balsa and mixing the two solutions as needed. It was quite the ballet but we got 26 square feet of balsa laid in about an hour. Definitely not my favorite job ever. I’ve spent the last few days filling small gaps and resanding to get ready for laying the cloth skin which I’m going to tackle tomorrow.

This has taken sooooo long and if this had been a nice summer I’d be really annoyed. As it is we have had near record breaking rains so I haven’t been missing any good boating weather. I'll post pics soon.

[Jackie]

Well I finally got the fiberglass laid on the floor. It was not fun. Not even a little. I posted pics in my album. I still cannot get them posted inline here. I've tried to follow the directions offered but they just aren't working on my MacBook. Could be OHS...

I bought ¾ oz CSM and 1708 biaxial glass to do the floor. It came packaged in tall boxes that I didn’t bother to open until I got ready to do the job. When I looked at it the stuff seemed so thick that I thought perhaps I’d said 3 oz CSM? But it was correct so I made a small test patch to see how thick it would be when done. My lamination plan was mat, 1708, 1708, mat. That kept it symmetrical and I laid the 1708 in different directions in between. The small test was pretty thin and taught me a bit about the art, but I really wish I had had more experience. I learned a lot as I went but that means I made some mistakes.

My biggest mistake was underestimating how really flat the surface should be. My sections of flooring had some spots where they didn’t meet up perfectly height wise for some reason. I fared them out, but maybe not far enough, so I really had to work at getting the air out. Because my area was so large, almost 10 ft long and averaging 3 ft wide, I cut each layer into 3 sections, varying the seams. I had a section of the back deck that I could get on and had set up for resin mixing and had my glass pieces rolled up and marked sitting in the transom. My plan was to lay bow to stern, cover the back sections with plastic so that I could crawl forward on wet glass and start the next layer. It wasn’t possible to do such a large area without getting on the wet layers.

The first layer of course went OK, but when I started the second I found that the plastic REALLY sticks to the wet stuff and wants to pull it up. After fixing a huge mess and redoing a bunch of my work, I decided to lay down all the sections of each layer, back to front, so that the dry fabric was under the plastic. Of course the resin soaked through in spots, as it should, but that stickiness was easier to deal with. Then I would coat the front with resin, work out the air, get off the excess move back a little and repeat. Wherever I placed a hand, knee or foot, the pressure when I moved would bring the glass up so I spent a lot of time really trying to get out air that was introduced by me having to get on the surface. I’m not sure I was 100% successful, but I promise to keep the boat forever.

I also had trouble keeping my layers staggering away from the edge in the section nearest the stern so I have a pretty nice line that is going to need more sanding than I’d like, but all in all I think it will be okay. Still a lot to go. I had to cut out the vee berth bunk so it has to be replaced. And I had to cut the ‘fins’ off it in order to make it narrow enough to remove from the cabin so there is repair work there. Plus putting the seats back in: those were also cut away from the sidewall unit. But I’m going to do those repairs with epoxy. They don’t touch what I just did so I don’t think bonding will be a problem. I feel like I’ve gotten through the worst, but, hey, it’s 2020 so there will probably be a new worst just around the corner.

[thataway]

Great job Jackie! I made a comment about tabbing back in the seats and V berth platform. Only grind the surface to give good area to put tabbing--3" up on side and 3" on th v berth, and second of 1 1/2 to 2" on top. That can be smoothed and painted.

I wondered how you were going to do the "bridging." I can understand the struggle! Also the delay to get the materials was difficult to say the least. Hopefully there were other great things for you to do during this period.

[Marco Flamingo]

Too late for this suggestion but I talked with somebody the other day about how they did a deck repair with three layers of glass over a large complex surface. They told me that they had used 6 inch wide fiberglass mesh tape. Cut the first strip into a 2 inch and 4 inch. When you start laying them right, all the remaining joints are staggered using full width 6 inch tape (which has a finished edge) and he could work backwards like tiling a floor. Only the ends needed to be cut. Much easier than working with sheets.

I couldn't see any of the seams in the top layer of 6 inch mesh strips even though there would have been about 20 of them. I think the secret in that is KiwiGrip deck paint. That's what I used to make my deck repair disappear. $40 a liter and you'll probably need two. It goes on really thick, so it doesn't go very far. It is easy to get a "professional" look.

http://www.c-brats.com/modules.php?set_albumName=album2402&op=modload&name=gallery&file=index&include=view_album.php

Mark

[Jackie]

Thanks Bob and Marco. I did the work yesterday and left it alone today to fully cure (and to recuperate!) But I went to check on it and it was so nice to walk around on a nice firm deck! My daughter was surprised that it is clear. I had numbered the sections of fabric 1A, 1B, 1C, 2A, 2B, etc and all the lettering showed through the various layers. I can't see my seams, but maybe because I was concentrating on the areas I need to touch up.

I did spend my wait time grinding down the area I need to apply tabbing for the bunk and also ground the matching areas on the bunk itself plus the spots I'll make my repairs to the fins that surround the porta potty hole. We had literally 4 sunny days so far since May and I used them to get the stuff outside for the grinding. I am not going to tab back in the roughly trapezoidal piece that sits on the bunk right in the nose. If I ever need to get to the hardwear up there (nuts holding the cleats in and bow roller and something else)I want to be able to. I figure I'll use some 5200 or something to stick some blocks of wood in toward the bow that I can screw into.

When it comes to tabbing in my seats, I'm afraid I'm going to break your heart, Bob. I've decided to screw them in unless you can all convince me otherwise. It will be awkward since the rest of the sidewall is tabbed down, but I firmly believe that the design as it was is what allowed water to get under the seat tabbing and crack it when it froze. That was completely unrelated to the core issues.

My seats had tabbing inside the box on all four sides so that the interior was closed off. But underneath, between the inside tabbing and the outside tabbing, was a large groove that allowed the water coming in from the open front of the seat box foot rest to flow all around the box underneath its tabbing, the sidewall tabbing, and between the sidewall and the hull. There was no exit for the water at the back by the transom which is why, on the port side, my sidewall and seat box separated all the way. As I laid the glass I sealed the places where water could go down along the side wall. I will obviously have to glass back in my seats where I cut them away from the wall, but I'm not going to tab the front inside of the boxes and I'm going to overdrill and fill (really well) screw holes for the flange on the outer part of the seat. Then my seats will look like Marco's: open in the front all the way and screwed down so water can actually escape. Putting the seats back will require me to work with gel coat. Expect more questions then!

Marco, I really like the deck paint in your album. Nice job. I talked to the owner of our marine store here and he has a product he uses a lot. I'm not sure if it is the same, but due to shipping times I'm going with whatever he carries. I'll let you all know what it is. The part that isn't grippy though, just the paint like for refinishing the vee berth - how do I get it to match what is already there? Is there a particular color C-Dory uses?

I'm leaving town on the 8th and really hope I can finish everything in time to at least go for a spin.

[thataway]

If you must screw the seats into the bottom, be sure that you over bore the holes, put in a thickened epoxy plug and then screw into that. If you screw into the balsa core, you will have the problem down the line. I am not sure where putting in screws will serve you any better than tabbing. If you wish you only have to put a few 1" to 2" tabs in, and you can leave a space under if you want.

If there is an area where water has pooled, I would be sure to put a "limber hole" there to allow the water to freely exit. If you tab all around there will be no way for water to get into any of the core.

I probably would just paint the interior. "Hatteras white". is very close to the gel coat used on the C Dory color wise. If you use white gel coat, you have to tint it, just a little yellow, a little brown and maybe a splash of blue....We have a gal in Pensacola who is a real artist doing gel coat and 2 part paint spraying. She has a devil of a time matching the C Dory gel coat--but when she gets it right--it is perfect--even if she has to do it over a few times. This reminds be I have a ding made by the anchor late one night this spring--and I have to get the pigments out and do a "match".

I am not quite sure what the blocks of wood are for. But I usually use epoxy and hold in place with hot glue unit the epoxy sets up.

Also I would make some fiberglas "Pilars" where the SS tubing supported the berth. They will be as strong, and give a much better support, with no risk of water intrusion.

Go with what ever paint is available. Do they already have a "grit" in it, or do you have to add the grit? I like glass beads over sand or walnut shells. Another way is to make a thick gel coat with Cabosol and roll it on. This is how some of the hull inner surface are done in many of the factory boats. We did this on the cockpit of the 25 when we replaced the floor. You want the gel coat to 'stand up" in little tufts.

Your boat is better than new now! You don't have to finish everything before going for a ride--just get the rigging back up, a seat and away you go. Heck even a lawn chair would work if you don't have the seats tabbed in yet....(in calm water).