balsa core repair

[mikehoyt]

I just completed recoring sections around several stanchions. I have photodocumented the process at this address J27 #150

Four areas required approximately 30 hours of work. This includes cutting, cleaning, layering, recoring, fairing, sanding and refinishing

Mike

[Gary M]

I have an S2 9.1, which all have deck coring issues. I cut out one section around my starboard chain plate when I was replacing that bulkhead and had a professional come down and do the final work on both.

I cut out a section of the side deck from the bottom about 1 foot square. What the pro did, and it looked pretty easy, was to set the new coring in place and hold it there with a slightly larger piece of 1/4 " plywood which was held up with a 1 by 1/2" board kinda wedged in. He put waxed paper over the plywood so it would not attach to the underside. Same support for the two layers of glass that came next.

I have 4 more spots to do in the main cabin area and I plan on doing them all this fall from the bottom, using the same method. I wil be removing the carpet that S2 is famous for in the entire main cabin and covering with a nice marine foam.

Good Luck
Gary

[Maine Sail]

Having done a fair number of core repairs and re-done previous owners "drill & fills" I can assure you of a few things:

#1 Working from the TOP is the ONLY way to avoid voids!! It's called gravity!

#2 The water took years and years to penetrate and rot the deck you will NOT dry it sufficiently in even a month or more. you need NEW balsa!

#3 These "Ginsu" equivalent "penetrating epoxies" are BS!! Period and end of story! As I stated before it took the water years to penetrate that much core. Epoxy begins to kick in as little as an hour or two at which point it begins to thicken and or NOT penetrate!! Having cut open my fair share of "drill and fill" short cuts I can assure you the epoxy penetrates balsa all of about 1/16 of an inch if that!!

Try this experiment. Take a piece of balsa and drill a 1/8" hole. Now inject that hole with "penetrating epoxy" and let it kick. Now chip away the balsa around the hole until you find it solid and hard where the epoxy "penetrated" it. I've done this and I think you'll be amazed at the snake oil BS you've been sold!! Again, years for the water to penetrate but an hour or two for the epoxy?? Can you say "Ron Popeil salad shooter" ten times fast..



Unfortunately, there is NO easy way to do this job and going at it from underneath will get you a sub par repair unless you have serious vacuum bagging experience and remove the entire inner skin then completely rebuilt the lamination schedule for the inner skin..

Unless your deck is soggy at a key structural location like a mast step, chain plates or stanchions sail it until winter then tackle this job from the top..

[CrazyRu]

Originally Posted by halekai36

Having done a fair number of core repairs and re-done previous owners "drill & fills" I can assure you of a few things:

#1 Working from the TOP is the ONLY way to avoid voids!! It's called gravity!

#2 The water took years and years to penetrate and rot the deck you will NOT dry it sufficiently in even a month or more. you need NEW balsa!

#3 These "Ginsu" equivalent "penetrating epoxies" are BS!! Period and end of story! .... Epoxy begins to kick in as little as an hour or two at which point it begins to thicken and or NOT penetrate!! .

Having done a fair number of wooden boats repairs I would say that penetrating epoxy ARE NOT BS. They will not set three to 7 days, they have very good penetrating properties, they are great product.

And they are not designed to fix large structural panels, as balsa core.

First of all - roted wood mast be dry before applying penetrating epoxy. It is not possible to dry out wet roted core, period.

[Maine Sail]

Originally Posted by CrazyRu

Having done a fair number of wooden boats repairs I would say that penetrating epoxy ARE NOT BS. They will not set three to 7 days, they have very good penetrating properties, they are great product.

And they are not designed to fix large structural panels, as balsa core.

First of all - roted wood mast be dry before applying penetrating epoxy. It is not possible to dry out wet roted core, period.

With all due respect I think you are confusing "working time/pot life" with "full cure time".

Smith & Co's CPES is the most widely known of the penetrating epoxies. At 68 degrees it has a max pot life of 8 hours! That means it essentially STOPS penetrating at about 8 hours many have shorter pot life time. With epoxies the longer the pot life the longer the full cure. Full cure and workable pot life are totally different.

For a truly dry rotted piece of non-encapsulated wood, like you referenced, CPES works ok. Encapsulated balsa is NOT dry rotted it's wet rotted and CPES or similar products don't work well for THIS application. I've torn it apart many times and seen it's failings and lack of penetration..

[mangomadness]

ttp://mangomadnessj30.blogspot.com

ttp://sailrattleandhum.blogspot.com/search?updated-min=2007-01-01T00%3A00%3A00-08%3A00&updated-max=2008-01-01T00%3A00%3A00-08%3A00&max-results=27



add the "h" to the front of the links

[mikehoyt]

Mango

Nice job. Looks similar to my process on Nut Case (J27)

Intersting similarities. My first section I cut out too large an area because I thought the wet would have spread further. (of course the next sections I had to cut out more than I originally intended because it has spread).

The deck appears flat but is actually sloped and to different degrees as you move fore or aft. The pain would be with what I called the levelling coats. thickend epoxy (I used West 407) which would sag downhill. This meant the next layers there were always small areas to build up from this. I found after glassing in the new core material that two layers of thickened epoxy that I called levelling layers were required followed by two skim coats to fill in holes from bubbles, etc.... Always one more skim coat than expected and usually when running out of time.

As for rain. I have found that so long as the epoxy has kicked and the area is sealed to keep water out of the core it usually is OK if the rain is light and several hours later. I found the biggest pain with rain would be during refinishing process. It seems to always cloud over and start to spit just as i am about to roll on new paint.

I love the interior pic of the J30. When compared to J27 it is a castle.

Mike
J27 #150
Nut Case

[rvrdgn]

Three years ago I had to replace a 3'x3' section of my cabin top due to rotten core. I cut through the top and dug out as much rot as I could find. I cut 1/4" x 2" strips of marine grade ply and lay them fore and aft and the second layer port to starboard. I pored epoxy over each layer filling in all of the gaps. After the epoxy hardened, I epoxied fiberglass matte over the plywood to match the rest of the deck. I haven't had a leak or any visible problems since. This project took about 2 weeks. If you want to see the pictures I took during the project, let me know.

[sailingdog]

RVRDGN-

Not a big fan of marine plywood as a core material. it's a lot heavier than balsa or foam and has the worst characteristics of both. IMHO, you would have been better off laying in balsa or foam, rather than putting in two layers of plywood.

[fredmole]

I am going to be soon joining the recore group and it is always interesting to see how others deal with this problem. For my 2 cents worth, unless you are very good with resin and fibreglass, I would recommend going in from the top. Gravity works with you not against you, you have a fraction of the fumes (even if you do have a double cartridge organic vapor mask). Even from the top i would recommend vacuum bagging as it inevitably makes for a better cure and helps eliminate any trapped air or voids. Drilling, nope, not going to work, it needs to be DRY in there. I would take a zip disc and cut around the rotten area to expose the rot and remove the surface laminate. my question is ---- if one can get the surface laminate off in one or more pieces (obviously there would be a size limit), and if it is not compromised, can you resin it back on to the new core and then only be left with a seam to fill?? And under the mast step would I be best to use just laminations and no core? Will that give it more strength in that area or will it compromise the flex (I think that it would work) Also I would think that an iso formula of resin might be stronger and/or better than the general purpose or layup resins. The general purpose of course would also have to be sanded before each layer of glass to remove the curing wax.
Glenn/fredmole