SMC Hull Repair Help Needed

I went under the trailer last night and took a good look at it with flash light and it is exactly as you mentioned. No cracks, it has been evenly sanded down but the fiberglass is exposed.

I will sanded a little more, then use 1.5 oz glass cloth... and maybe multi layer of resin and paint. From what I saw last night 6 oz cloth might be way too much for it.

I was kind of happy to see it was even rather than big gouges or cracks.. Although I see pin holes/porosity here and there but they are small enough that resin will fill them....

I will be working on it this weekend... May get most of it done except for painting... I will do section by section so in case I screw up the first time, I won't have to clean my mess length of the hull.

You guys have been such a big help. THANK YOU SO MUCH!

 

The bond to SMC can be a little tricky at times, the high filler content in SMC is the issue. While polyester will bond to some SMC parts, it may not be the best for all parts, so epoxy is normally recommended. You can tint the epoxy, but don't expect it to weather very well, epoxy and UV rays don't get along all that well.

Don't use tooling gel for much of anything except tooling, it is normally very rigid, so cracking can be an issue, plus it's not designed for outdoor use and typically has poor UV properties.

 

We were typing at the same time.

Did you plan on using epoxy or polyester? There are differences in how each one is used.

 

I picked up SMC Fiberglass Resin, http://www.evercoat.com/productDetail.aspx?pID=16

Should I return it and go to west marine for west system epoxy? I have not opened it.

Thank you,
Reza

 

I haven't used that product, but since it's designed for SMC it should work OK.

With epoxy you don't need to use mat (CSM), with polyester you do, so the repair will be thicker. If you are building up the hull, or just replacing what has been worn away, then either product will work. Epoxy will be tougher and you can use cloth, which will be stronger than CSM.

With polyester, do not use multiple coats of resin alone, polyester is rather weak and brittle when compared to epoxy, the extra unreinforced (no glass) resin will crack easily.

 

Thank you Sir! I am going to take the drive and buy the epoxy.
I want to do this once and forever if I can.

I will use one layer of 1.5 oz cloth with epoxy and then if need be a couple of coats of epoxy on top of it.

All I want to do is protect it from any further deterioration. The amount of lost glass as it is now, is very insignificant so I will just use one layer of cloth.

Great explanation for a rookie like me. Thanks for telling me the difference of the two.

 

how did you make out ??

 

So yesterday I drove to westmarine after work. Picked up 1 qrt Resin 105 and Hardner 206 (slow curing), mini pumps so I don't have to measure, black pigment tube and 403 microfiber filler. I looked for 1.5oz weight cloth but they didn't have anything less than 6 oz. The Gentleman saw the pictures and said I really don't need any cloth and all I have to do is seal it. I had originally picked up the 404 (high density filler) and had me change it to 403.

I have some 1.5 oz glass cloth at home but not enough to do all of the hull. I am going to take off early from work. I even ordered a 3M half face mask for when I sand the fiberglass. He told me the places that have exposed fiber glass with no paint, I shouldn't even sand, just clean with acetone. Is this true? I have 80,180 and 220 sand papers, should I get the 80 to the exposed area?

I will do a foot section and wait until cures to see how I did before I continue the work. I will post pictures if it's OK with you Gentlemen...

Thanks so much,
Reza

 

Hi,

Well I do not know the knowledge of the person yo spoke with at WM. But if it's anything like the ones where I live...... well lets just say not the brightest

Not sure why he had you change filler, 403 most suited for wood and not as strong as 404... but i guess will work

cleaning hull with acetone probably OK but here's the thing, you are introducing another chemical into the smc and between your bond. That being said acetone evaporates but a step not needed. And im sure many will say its fine to use

You have gotten some great advice from people who have done repairs such as yours and in my case much more advanced.

I understand you are nervous but you seem to be making it harder than it really is.
Here's a quick step list to follow

before the list a couple things...

I like resin to be like mashed potatoes, i find it easier to work with.

slow hardener is fine ... I use fast but also i have more experience with it and can work faster

1. rough it up with 80 (when I say grind I only meant a 80 or 60 grit sanding disk
2. apply resin (mixed with 404 or 403... me i'd stick with 404)
3. apply cloth so that it is saturated into base coat of resin
4. apply more resin over cloth
5. let dry
6. rough sand to shape
7. finish sand
8. Paint
9 Go for a ride !!

If you have any questions feel free to ask

 

brker1,

I am nervous and inexperienced in this field. I didn't mean to right off anyone's advise here. I hope people don't think I wasted their time as this thread is the only reason I am doing this myself. It really has helped me.

I can drive and change to 404.

Quick question should I mix the black pigment in the resin/filler as well?

 

I do not think your wasting my time, i am just trying to help. And I see your just looking for as much advice as you can get. Honestly it isn't that hard and no matter what you ca ALWAYS fix a mistake in this type of repair. 403 or 404 either will work, if it's a close drive get the 404... if not don't worry.

yes add color to resin as mixing, with a slow hardener you want to have the pot like i said mash potatoe'e because when it on the hull you want it to stay put, even more so cause you up side down.

The worst thing you could do is mix the resin wrong and even then it's just a mess you'd have to clean. You got the pumps so no worries there, simple sanding to rough up the area... no worries there, If you put too much it just means more work for you to sand off, so no worries there, if you put too little you add more after it hardens and a quick scuff, so no worries there........ All in all nothing you do cant be fixed.

But my guess is you'll be fine. As I broke it down, you see nothing to worry about !

 

Thank you so much brker1! I am going to take the drive and do it right. It's a bit of drive but it just makes me feel better if I use the correct filler. Thanks a million.

Question, is it OK with I work on it until late hours of evening? Since evening gets to 55-60s and maybe a little more moist than day time... Would this be OK?

 

I was going to ask about the temp there. It's the same where I am. I am doing a hull project as well. I would switch hardeners to the fast. you will have plenty of time to work with it... just stir and after mixed spread it out.

But if you're in the 50's -60's for sure fast hardener

 

In that case I will wait until tomorrow morning when temp will go back up to mid 70s to do the glass work. I will do the clean up this evening, will cut the cloth to proper width and length and apply tomorrow morning.

I am mentally ready for this with all the help I got here from you and others... I have the picture pretty clear and I'm excited to break up the epoxy

 

Gents,

Working from under the trailer is a nightmare!!!

But with your help, I think I am making some progress. I only glassed the parts that had more deterioration than acceptable...

I will continue tomorrow... Then sand Sunday and one more coat if possible..

BTW, I am using 406... They didn't have 404 and they told me 406 sands like glass and is not hard... I'll just do multi coat if needed.