19xx Kobra 12ft. transom/stringer/floor restoration.

[Woodonglass]

Re: Glass stringers

Re: Glass stringers

Oops! I misunderstood.
This will give you what you need. I found this in an article online.

There are three situations that cause gelcoat to not cure over epoxy... all related to the hardener chemistry. Epoxy hardeners are basically a blend of amines, which can terminate the chain reaction of the radical molecule that is the basis of polyester (and vinylester) cure chemistry. So by carefully mixing, curing, and preparing of the epoxy so that there are no unreacted amines to interfere with the gelcoat cure, gelcoat bonds quite well to epoxy.

The first situation is undercured epoxy. Gelcoat applied to undercured epoxy will be in contact with unreacted amines and the cure will be halted.

The second situation is if the epoxy is mixed off ratio so that it is hardener rich, again leaving unreacted amines free to interfere.

Third is the issue of amine blush, commonly called blush. Blush is a surface phenomena that is a reaction of the amine molecules at the surface with the carbon dioxide in the air. It forms easiest in the presence of moisture, so working in cool, humid environments will maximize the formation of blush. Any amine hardener has the potential to blush, but it can be minimized by careful choices of amines in the formulation. In fact, WEST SYSTEM 207 Special coating hardener is one of the lowest blushing hardeners on the market and still maintains structural properties on par with our other hardeners. Regardless of chemistry, blush is very easily dealt with because it is water soluble. A simple wash with clear water removes the blush. No soap, no solvents. Then sand that washed surface with 80 grit paper to provide the gelcoat with sufficient key so it won't run. Be sure to use non-air inhibited gelcoat that has a paraffin wax added.

Gelcoat is applied over epoxy on a routine basis everyday in boatyards that are aware of these issues.

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

Great, thanks ! Excellent infos. Should be all good when following this strictly.

 

[ondarvr]

Re: Glass stringers

Re: Glass stringers

looks like a quote from West Systems.

We make gel coat, to a person every chemist we have says don't do it, the bond is poor. This goes along with every attempt I've made to get a good bond to epoxy and 99% of the other people in the industry that have tried it too.

I have tried to bond gel coat to epoxy on well cured (many months) and well prepped (36 grit) epoxy, it would appear to bond well unless you tried to remove a bug, drip or other defect. If you tried you could easily pop chunks off, they would have a perfect matching surface of the 36 grit grinding marks on the epoxy.

I also called West Systems on this, and while they said it did sort of work, it may not be the best thing to do

 

[Woodonglass]

Re: Glass stringers

Re: Glass stringers

Well, there ya go, ondarvr, IS our resident EXPERT, and been in the Industry FOREVER, and he is Correct about where I got the info, SOOOOOOOOOOO.... If I were You, I would take his advice and NOT what the article said. Sorry I mislead you. NEXT time I will direct you to the experts.....:facepalm:

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

Ah damn.. Well thanks for letting me know, I am not going to risk it then. Any recommendation on alternative UV resistant paints that can be used on epoxy? and maybe end up looking like gelcoat ?

 

[Psiclown]

Re: Glass stringers

Re: Glass stringers

If I shot at your boat with my 45, the bullets would turn around and head for the hills screaming.

 

[petermarcus]

Re: Glass stringers

Re: Glass stringers

There are two-part epoxy-based paints that I think are UV-resistant (otherwise why sell an epoxy paint I guess?) I've also heard some good things about Rustoleum brands of paint.

I'm tossing these ideas out purely for selfish motives, as I'm using epoxy in my decking, too, and I'd like to hear someone endorse or shoot down these options Good thing about this forum is that a lot of people are in the same situation and five or six projects can be helped along by one post!

 

[Yacht Dr.]

Re: Glass stringers

Re: Glass stringers

Hello Peter..

There are reasons why Gel should not be applied over Epoxy ( which I will not debate in this thread ).

There are also some "tie coats" that can be applied to the epoxy that will accept gel ( kinda like an epoxy/poly primer ).

I would not recommend them unless there is a Good reason of necessity of gel application.

So.. getting beyond the gel over epoxy issue lets talk Paint..

Awlgrip or Imron is my only advise for proven durability and long lasting. Now I havent had much experience with Brighside or Perfection..or Rusto or any other XYZ paints .. so Its not that Im saying NOT to research or use other products its just that I cannot give personal experience with XYZ paint systems..

YD.

 

[petermarcus]

Re: Glass stringers

Re: Glass stringers

Long before I was an iBoats member, I tried to put gelcoat over epoxy during my first boat renovation (and, again, I'll sing the praises of this forum -- I did a ton of things wrong, which I now know from reading tons of iBoats threads).

From personal experience, I can say that gelcoat over epoxy sucks. I couldn't quite scrape it off with a fingernail, but I certainly could with something harder, in big chunks and strips. I could say that maybe I was too much of a novice to attempt a tip and roll gelcoat, but then again, the epoxy/glasswork that I did as a pure novice actually turned out pretty good. I could take a hammer to my stringers with no problems. My amateur problems were more structural and theoretical, like not attaching the stringers to the transom.

Not trying to threadjack, though (I hope). I'm thinking of putting deckodot or some similar vinyl, non-skid flooring over my deck, but I'm curious to what other options are there for epoxy, because I haven't made up my mind yet and CP here is asking some of the same questions I am.

 

[ondarvr]

Re: Glass stringers

Re: Glass stringers

We make tie coats, but they go the other way, it allows you to use a polyester gel coat in a mold...then tie coat...then an epoxy laminate over it.

We also make epoxy gel coats so no tie coat is needed, but these are inmold products.

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

Thanks guys for your replies and inputs.
Been researching a bit on google and it seems Awlgrip, Interlux, Imron etc are 2 part Polyurethane paints. - I also read it is recommended to apply an epoxy primer before the 2 part Polyurethane.
So that's the current plan, unless someone here tells me it's a bad idea. I haven't decided on the brand yet, as not all of them are available over here, so I will see what I can get my hands on.

On another subject, the weather isn't the best here today, so I will probably not be getting any glassing done as planned, unless it clears up later :/
Perhaps I can get some good old grinding done

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

Yesterday I managed to get the remains of stringers glassed.

So today I only had a little preparation to do before I could glue back the floor. Meaning grinding a cleaning with acetone.

The floor and the stringers were pasted with epoxy and put together with distributed pressure, to follow the bending in the floor, basically the middle stringer is about half an inch lower than the side stringers.


Next up is glassing the floor to the hull, most preparation is done (grinding!) . Then I need to look for appropriete paint for the entire inside of the hull. I think it'll be epoxy primer followed by 2 part polyurethane.

Outer stringers got their final glassing on the outside.

Floor grinded and cleaned for the touch down on the stringers and sides of the hull.

Epoxy applied to floor, stringers and sides of the hull and weight distributed to get full contact.

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

After the epoxy cured, the weights were removed and the boat now feel rock solid I noticed even when putting the weight on that the hull (before the epoxy was cured) it would not bend/flex on the trailer supports, it did when I first got it without any weight on (just lifting the boat and putting it down). When I glassed the hull and stringers I had to add support directly under the transom to avoid re-shaping the hull.
So I am taking it as good sign.
Yesterday I filled the joints between the floor and hull with epoxy mixed with microballoons and today after a quick grind up (and the neighbours complaining about the dust/smell :/) I glassed the joints to the hull with overlapping layers of woven roving. Also grinded the splashwell end that connects to the transom.
Next up is grinding the gelcoat inside the hull and paint it with 2k epoxy primer. I'll try to get the remaining grinding done aswell (outside of transom) so I can have peace with the neighbours after that, as from then on it will only be minor grinding

Happy easter guys.

Joints filled with epoxy putty and glassed with overlapping layers of woven roving.

Another angle.

Overview. Next up grind the grey gelcoat and excessive epoxy then paint with 2 component epoxy primer.

Splashwell prepared for glassing to the transom when the top goes back on (soon!)

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

Got the grinding of the outside transom and inside hull done, quite happy as this was the last major grinding needed.

After vaccuming and cleaning the hull with acetone 3 times, it was time to paint with epoxy primer. I used a foam roller, unware it would detoriate after awhile, luckily I had two and made it to the end (barely). 1 Liter (0.26 gal) of epoxy primer was used, and I think it covers pretty well with 1 layer.
Now I have to let it cure for about a week, before I can paint on the (grey) 2k polyurethane after a light sanding.

Inside hull grinded and ready to be painted.

1 layer of epoxy primer applied.

Another angle.

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

Just a small update.
Finished applying 2 part polyurethane over the epoxy primer inside the hull. It went really well. Some really nice paint to work with, I applied it with mohair rollers, it was easy and it kind of ran together.
The result is far from perfect, due to the rather rough grinding I did, which can still be seen some places through the paint, however its acceptable to me.
Also put the top back on, tomorrow I will permanently attach it and glass in the splashwell and add two layers to the outside of the transom aswell.
Will post an update tomorrow if everything goes as planned, starting to see the end of it!

First layer of polyurethane (with a 48 hour window to the next layer).

Second layer, no point in adding more layers imo, it covers everything good.

Yay the top still fits

Next up final glassing of the splashwell and outside of the transom.

 

[Cadwelder]

Re: Glass stringers

Re: Glass stringers

Looking good, you're about there......

 

[cp2009]

Re: Glass stringers

Re: Glass stringers

Thanks Cadwelder. I'm getting there, two more weekends is my goal

Another sunny day, and a little more work getting done.

Top was attached to the hull using rivets, as that's how it was attached when I took it apart and it was easy to deal with.
Splashwell got attached to the inside transom with 4 overlapping layers of woven rowing (1 layer going over the top to the outside). Then two additional layers going from inside of splashwell curving over the transom and covering the entire outside of the transom aswell. All 10 oz woven rowing with epoxy. I wanted to get a few layers on the outside due to all the former holes I closed with epoxy putty earlier, so I got a completely closed and strong surface.

For those who likes numbers, here's some on the materials I used so far:
4.7 gallons of epoxy (18 litres) resin and 236 square feet of woven rowing 10 oz (22 m2, 300 grams).
1 gallon of polyester (4 litres) and 50 square feet 20 oz matt (4.8 m2, 600 grams).
0.26 gallons of epoxy primer (1 litre)
0.52 gallons of polyurethane paint (2 litres).
0.26 gallons of prefab epoxy putting (1 litre)

More to come

Next up wait for epoxy to fully cure, then grind and paint with 3-5 layers of epoxy primer (on outside transom), paint with polyurethane above waterline.
While waiting, I have seats to finish, new steering and other small stuff.

All fabric cutout and ready to go on (left, middle, right side of transom/splashwell and the big ones for complete overlap).

Splashwell epoxied, with 3 layers inside and additional 3 layers from the inside to the outside.

Outside transom got two complete layers. Used foam roller to even out the excessive epoxy well, so hopefully when I grind and paint there will not be much print through from the fabric.

 

[boaterinsd]

Re: Glass stringers

Re: Glass stringers

Please advise me how post super pics in a reply like you just did. Thanks for the info in the thread.

 

[cp2009]

19xx Kobra 12ft. transom/stringer/floor restoration.

Hi boaterinsd,

This is how I do the photo's, they are shot with a 10 mpix camara, I then load the pictures to paint, reduce size to 40% (they are huge jpegs originally). Then I upload the pictures to photobucket (create an account first there http://www.photobucket.com).
When viewing your pictures in photobucket, you have on the right side "share this photo", click the IMG code one, it will say copied to clipboard.
Now in your iboats thread/post you can right click and paste the photobucket link. That's all you need.
Quite easy and works well, let me know if any issues.

 

[Bob_VT]

Re: 19xx Kobra 12ft. transom/stringer/floor restoration.

Renamed thread at OP request

19xx Kobra 12ft. transom/stringer/floor restoration.