Gelcoating Coosa

[JohnV8r]

Guys,

Here's the starboard bulkhead piece in Coosa Bluewater 20.

I want to gelcoat both sides of this piece. What do I need to lay down on Coosa in order to gelcoat? 1.5 oz mat? Matline 2mm? 2 oz glass cloth?



Thanks in advance!

JohnV8r

[Raybo Marine NY]

You can gelcoat right over it, but arent you glassing it into the boat?
Or are you asking about gelcoat AFTER you glass it in?

[JohnV8r]

The particular bulkhead piece above gets mounted in with screws. I may tab it in with fiberglass in a couple of places, but this is an easy piece to replace. The original piece had wood rot on both the port and starboard sides where the piece meets the floorboards. The wood rot coupled with the deteriorated Formica is what made me want to replace this piece.

I want to gelcoat the Coosa, and thought Coosa would need a layer of glass to add impact resistance. I'm not sure the surface of Coosa alone would be gelcoat friendly because it has some holes in it. However, I've only done gelcoat repairs on small patches and old holes. I just trying to make sure I do this correctly the first time.

[Raybo Marine NY]

Ok now i understand, are you wanting this a raw glass finish or will you be fairing it?
2 layers of 1.5oz CSM , dont bother gelcoating it where its going to be tabbed , unless you are doing the gelcoat after its glassed in place

[Tony Meola]

John

Are you rolling the Gel Coat on? I would think that would be tough to smooth out.

[Capt.Frank]

What thickness did you use 1/2" or 1"? Looks good.

[JohnV8r]

I have an Apollo 5 stage HVLP turbine and a 7500QT sprayer with 2.5mm tip that I will spray the gelcoat with. I use the same system with a 1 mm or 1.2 mm tip to shoot polyurethane finish and Epifanes. It works great for the latter. I have not yet shot gelcoat with it yet.

The bulkhead in the picture is Coosa 1/2" Bluewater 20. I am using 1/2" Coosa Bluewater 26 for the rudder shelf per Patrick's instructions in the building tip section, and 3/4" Coosa Bluewater 26 for the deck.

I'll use the 1.5 oz mat and see how that turns out.

Thanks for the help!

[JohnV8r]

OK Guys, I need some advice again on gelcoating this bulkhead please.

I put 3/4 oz chopped strand mat on the outside section of this bulkhead piece to add some impact resistance without adding too much mass. Here is what the surface looks like. I have since trimmed the edges with a trim router.



Here's a better shot of the depth of the surface imperfections.



Question is what is the best fairing material for this prior to gelcoating. The composites guy I buy all my resin and glass from suggested something called qcell mixed with cabosil in a 4:1 ratio with vinyl ester. Apply and sand fair. I've never heard of that here.

Any suggestions on what to use to fill/fair this before I spray the gelcoat?

[ford351c594]

Adding "bubbles" to resin and letting it self level. Then sanding is said to be easier. If that is what he is talking about. IE creating your own faring with resin.

There is a you tube video on it. I'll try to find it. buddy did it on his skiff and worked well.

[JP Dalik]

Peel ply
Nylon shower curtain
Wax paper

Three ways to top coat glass mat and get a smooth surface. Lately I've been using shower curtain from Home Depot

[neil]

The shower curtain is the way to go,Jr and jp have done it several times and it works perfectly every time

[Tony Meola]

Ok guys, I give up, a shower curtain. Anyone care to explain to us novices.

[JohnV8r]

I need a more detailed explanation as well please.

[JP Dalik]

A nylon shower curtain (porous) placed like a last layer of mat on a layup. Wait for cure a peel the shower curtain off like peel ply. Leaving a nearly flat smooth flat surface that can easily be prepped for finish. It cuts faring in half and if using epoxy removes the blush when it crimes off. It also removes the heavy tack formed on the surface of laminating resins when pulled.

[RAWicklund]

Thanks for the info JP, gathering info for some coosa work myself. I googled a couple of YouTube videos on peel ply just for an overview. Lots more videos to look at if interested.
https://m.youtube.com/watch?v=kFAGA4hCEkg I bought a similar product from West to use on a carbon fiber bike repair...879 release fabric ... Used for vacuum bagging release. Obviously lots more dollars then a shower curtain.

John, I'm going to laminate my bulkhead, but please post some finished pics of your bulkhead when your done.

Thanks

Ray

[John F.]

A nylon shower curtain (porous) placed like a last layer of mat on a layup. Wait for cure a peel the shower curtain off like peel ply. Leaving a nearly flat smooth flat surface that can easily be prepped for finish. It cuts faring in half and if using epoxy removes the blush when it crimes off. It also removes the heavy tack formed on the surface of laminating resins when pulled.

I never even thought of using a shower curtain. You guys amaze me. I'll keep that in mind for next time. Thanks.

[scot]

I use visqueen plastic a lot laying glass with epoxy resins. Lay it over the "wet work" and use your hands on the visqueen to shape the wet-out cloth into tight corners, over boards, etc. Visqueen + clamps can form epoxy glass work to practically any shape. Works on large flat areas as well to smooth and reduce fairing time. Once the epoxy is cured, visqueen peels right off leaving a nice smooth surface. Best method I have found for wrapping wet cloth around the end of boards, plywood, etc. I also router the board edges before wrapping the glass to give a nice radius vs a square edge. Haven't tried the shower curtain, but I will now.

[Tony Meola]

JP

Thank You.


One more question, after you lay the curtain on top of the epoxy, do you roll it out or just press it down?

[JP Dalik]

Lay up over the shower curtain.

Product is glacier bay fabric shower curtain.

[JohnV8r]

JP,

I got the Glacier Bay curtain. I want to make sure I do this correctly. Here is my understanding:

1. I'm only going to use this on the final hand lay up with chopped strand mat.

2. I coat the surface of the Coosa with catalyzed vinyl ester, lay down the chopped strand mat, add catalyzed vinyl ester to the surface to complete the wet out of the chopped strand mat, and roll out any bubbles.

3. Lay the shower curtain over the entire piece and rub it by hand or perhaps use a smooth paint roller to ensure even distribution of the catalyzed vinyl ester under the shower curtain.

4. Here's where I want to verify the next step: I then gently pull down evenly from both sides or clamp the shower curtain to something like a 2x4 that will create some even downward pressure by the shower curtain on the surface of the piece.

5. Let the entire piece cure completely.

6. Peel the shower curtain off the piece.

Do I have that correct?

I can't wait to give this a try. The concept seems like it will pre-fair the surface in such a better way than I'm dealing with now.

Thanks!

JohnV8r

[JP Dalik]

Cut the shower curtain slightly larger by 1/4" or so and lay it up like a final piece a mat. Then let gravity do its thing, no clamps. It will peel best in 6" increments and any bits that are left will sand out, leave yourself a tag end.

It saves time and sandpaper.

[JohnV8r]

Here's the first test piece before I go all in on the bulkhead. There were two minor issues that were dealt with on the fly.

1. My metal grooved fiberglass roller was moving the shower curtain around a little too much. I switched to the paint style roller I used to lay the first resin on the naked Coosa. That helped roll everything out pretty well and it sure seemed pretty even to me from the surface after.

2. I could not get the crease on the shower curtain to lay down no matter what I did. I just made sure I rolled that area well and let it come up on its own.









I'll know more in a few hours. Off to my 13 year-old's Little League All-Star game.

More to come...

[Marlin]

Curious, why gel coat instead of Awlgrip or awlcraft painting process. I followed this painting process on finishing 20plus sheets of coosa after applying a coat of mayonese epoxy onto the coosa with a paint roller , covered the surface with cheap polyethylene ,taped the PE down with red tape used by stucco people to a work station, attached a vacuum pump,came back the next morning to process the next piece. I did all inside doors, bulkheads, bunk mattress support sheets, deck support framing,both longitudinal and uprite. I was in a yard that didn't allow spraying so I set up own spray booth in my garage

[JohnV8r]

Game changer! JP, thank you for taking the time to walk me through this.

I haven't trimmed up the edges with my router yet, but I pulled the shower curtain and was just amazed. You can see the minor defect where I couldn't get the crease to hold down, but that's a minor amount of work to sand/fix. I may try ironing the shower curtain prior to laying it down next time. My local Home Depot is going to wonder why they're selling so many Glacier Bay shower curtains all the sudden.





I'll likely start with 180 grit on my Festool Rotax to smooth up the surface.

This has to rank right up there with the best tips I've ever gotten here. It's an absolute game changer for me in terms of time...

[JohnV8r]

Marlin,

I've gone back & forth on Awlgrip/Awlcraft vs gel coat. I guess for me it boils down to my comfort level with my ability to keep gel coat looking good over time and make repairs if necessary. All of my boats have had gel coat that I compounded every year or so to keep looking nearly new. I've also done some minor gel coat repairs and hole filling that I finished with gel coat. It's just a familiarity issue for me even though I have not done anything of this magnitude before.

Also when I called the Awlgrip tech line, they recommended against spraying Awlgrip with an HVLP system. I've got a 5 stage Apollo HVLP turbine system that works great for spraying varnishes and polyurethane. While I've never shot gel coat with it, it's supposed to work fine with a 2.0 mm tip. That was also a big factor.

In the end, I guess I could have gone either way.