how much fiberglass to use on deck?? HELP!!

[bayliner198819]

Today i bought 3 gallons of 3m bondo fiberglass resin 6 bottles of hardener and 11 packages of 8 sq ft .74 m2 tomorrow i am going to get 2 4x8 slabs of ply should i get 1/2 or 5/8....i have a 41 sq foot area that i need to replace should i use two layers of these mats i bought on the top and then just spread the resin by itself on the bottom of the ply? i also am planning on filling all the gaps with extra glass then seal. it in with the resin...i have looked at many fourms and really dont know what to do! this is my first boat and my first time and i want to do in right! thanks guys sorry about the pics all i have is my phone to take them

 

[DukesFin]

Re: how much fiberglass to use on deck?? HELP!!

You want all sides of your plywood to have fiberglass on them. You can just spread resin on the bottom of it, but it will crack in short order. Add glass to the plan and it won't.

You really need some thickness to your glass over the plywood to help lateral strength. If it were me, I'd do it this way:

By wrapping the top and sides of your plywood with multiple layers of glass, you are giving it a lot of strength to prevent cracking and excessive flexing. The mat gives it thickness and the fabric give it the strength it needs. If you can lay one layer of fabric and then put the next layer of fabric on at an angle, it will help the strength considerably! One straight and the next diagonal, etc, etc, etc... The bottom just gets a layer of mat so the resin doesn't crack.

I'm sure others will chime in with other suggestions but this is the way I'd do it.

Have you looked at how you have to figure out how much hardender to put in the base resin? It's NOT fun!!! I counted drops one time, put them in an irrigation syringe and marked it.

 

[erikgreen]

Re: how much fiberglass to use on deck?? HELP!!

I'd recommend 5/8 exterior grade ply, that way you only need one good layer of glass on each side. In fact it looks like you're using mat instead of fabric?

If that's the case you're not adding strength with extra layers anyway, just stiffness and abrasion resistance.

If you're using cloth only the best way to do this is one layer of mat with cloth over it. The mat promotes adhesion, and the cloth gives strength. If you were using epoxy there'd be no need for the mat, and you can do that with poly too, but you run the risk of delamination because of poly's adhesive qualities.

Be aware that the bondo resin is thicker than a lot of poly resins and will take some work to make sure it's fully wet out. It also is more gray or yellow than other resins.

Not to poke at your choice since you've already bought it, but good quality boat resin from US Composites would have cost the same or less as the bondo, same with cloth from them.

Erik

 

[noworries79]

Re: how much fiberglass to use on deck?? HELP!!

I have read lately that 2 layers should be enough. Of course one being CSM and the other cloth, etc. I like the idea of wrapping the edges. It sounds like a good way to water proof the edges even more.

Keep us posted Bayliner, I'm in the same boat!

 

[Robert4Winns]

Re: how much fiberglass to use on deck?? HELP!!

What kind of plywood you should use depends. What was there from the factory? If the stringers and other supports are spaced close together you will not need as thick of plywood or as much glass. My boat's deck was only 1/2" with a minimal amount of glass over the top, but it felt very solid because it had expanded foam underneath.

 

[DukesFin]

Re: how much fiberglass to use on deck?? HELP!!

I guess my boat is a little different. In my repairs, I've tried to achieve the same thickness of glass on the deck and mine is almost 1/4" thick! The layers I have shown don't quite get to 1/4", but it sure is strong!!!

Don't mind me... I just play here! ;-) There are certainly more experienced people on here!

 

[kenny26]

Re: how much fiberglass to use on deck?? HELP!!

Today i bought 3 gallons of 3m bondo fiberglass resin 6 bottles of hardener and 11 packages of 8 sq ft .74 m2 tomorrow i am going to get 2 4x8 slabs of ply should i get 1/2 or 5/8....i have a 41 sq foot area that i need to replace should i use two layers of these mats i bought on the top and then just spread the resin by itself on the bottom of the ply? i also am planning on filling all the gaps with extra glass then seal. it in with the resin...i have looked at many fourms and really dont know what to do! this is my first boat and my first time and i want to do in right! thanks guys sorry about the pics all i have is my phone to take them

Hey Bayliner, I'm doing a bayliner restore too. I just finished my transom and stringers. I'm sure the construction of our boat is similar. How much glass you use is up to you. In the book "runabout renovation" a book you may want to invest in... He suggests that you need to minimally coat the deck wood (top, bottom, and sides) in resin and then cover it with a layer of mat, and add roving/cloth around the edge of the deck covering the hull deck joint. This is MINIMUM. Most on here go beyond that. For mine i'm planning to paint (sometimes called a hotcoat) the deck completely with resin. Then apply a layer of 1.5 oz chopped strand mat to the bottom. Lay it in the boat and filet the edges with a fiberglass peanut butter paste made from resin mixed with microballoons (sourced from us composites). Then cover the deck with a layer of CSM, put 12" width of Woven Roving over the hull/deck joint for strength, and then another layer or 2 of mat. If you are applying carpet the finish of the deck isn't that important, if you plan to paint the floor you might want to put a layer of finishing veil or lightweight 3/4oz mat as the final layer.

I'm also applying 2 part expanding foam back underneath the deck which should add strength from below.

I've used both the Bondo resin and the us composites 435 layup resin on my transom. The bondo resin has wax in it, so you need to sand and acetone between each layer if you let it dry (more work). Also the bondo resin is like spreading thick maple syrup, where the us composites resin is much thinner and easier to spread and wet out glass with and doesn't contain wax. The bondo stuff works, but its harder to work with for sure.

 

[bayliner198819]

Re: how much fiberglass to use on deck?? HELP!!

ThanksAlot for all the help guys it's telly seems alot less stressful now!! One more thing though I've been hearing alot about what is required when u add a second mat? So let me get this straight if I let the first layer of mat and resin dry then I need to sand it before I put the second on it or It won't work? Is it better to just sand it down instead of applying the second layer before it drys...what has worked best for all of you?

 

[boatflipper]

Re: how much fiberglass to use on deck?? HELP!!

Im watching this thread very closely!! I am about to tackle my transom this weekend!!

 

[ondarvr]

Re: how much fiberglass to use on deck?? HELP!!

ThanksAlot for all the help guys it's telly seems alot less stressful now!! One more thing though I've been hearing alot about what is required when u add a second mat? So let me get this straight if I let the first layer of mat and resin dry then I need to sand it before I put the second on it or It won't work? Is it better to just sand it down instead of applying the second layer before it drys...what has worked best for all of you?

If the resin has wax in it, then you need to sand and clean it thoroughly before applying another layer, with no wax you typically have few days before this is needed.

Most of the time its best to just do all of the layers at one time, there's no need to do them one at a time and let each layer cure. Of coarse you will need to start and stop, plus as you change from one stage or portion of the job to another the laminates will have almost fully cured before you can get back to work. This is where wax creates a great deal of work, so using unwaxed resin is the best option.

I don't know if the resin you purchased has wax in it or not, I've never read the label on it. I guess I should read it the next time I see a can so I'll know.

 

[mikezohsix]

Re: how much fiberglass to use on deck?? HELP!!

the glass issue as pretty well answered, I'd like to comment on the plywood.

There seems to be a regular disagreement between 1/2" and 5/8", not too many people think 3/4 is the way to go.

I'd say it should depend on the spread between the stringers. In my boat, I have what works out to be four sringers, two actual stringers, and a wide ski/storage area, that runs the length of the deck. I don't have barely a 10" unsupported width. 1/2" is plenty.

I've seen other boats with only a single stringer that runs up thru the center of boat. That leaves 24+" unsupported, and 5/8 would probably be required.

mk

 

[PiratePast40]

Re: how much fiberglass to use on deck?? HELP!!

If it's not to late, you really should take the resin and mat back and get a refund. You're setting yourself up for a lot of extra and unnecessary work.

Believe me, you're much better off with the right materials for the application - especially your first time around.

 

[micks110]

Re: how much fiberglass to use on deck?? HELP!!

There is no wax in the 3m bondo resin.
I will agree though that it is thicker and a little more difficult to work with because of how thick it is.
All in all though I have had no problems using it, and I've been through 2.5 gallons so far.

 

[erikgreen]

Re: how much fiberglass to use on deck?? HELP!!

There is no wax in the 3m bondo resin.
I will agree though that it is thicker and a little more difficult to work with because of how thick it is.
All in all though I have had no problems using it, and I've been through 2.5 gallons so far.

You sure there's no wax in it? Do you cover it with plastic to harden it?

 

[bayliner198819]

Re: how much fiberglass to use on deck?? HELP!!

I finished all the fiberglass finally!! It came out really good I ended up puttin in extra 2x4 for support and now with the glass it's seriously unbendable I used great stuff to fill all the extra cracks and glassed over it and it worked great it was about 55* so it took 4 hours to harden it was extremely difficult to estimate how much to mix at a time so it wouldn't harden so I ended up mixing 1/2 gal at a time it worked for me but I had a buddy of mine helping me...WEAR A MAsK I didn't for the first layer and it really screwed me up fir the day you will need gloves to I also put a coat of the resin on the bottom and sides of every board including the 2x4s I added for support...overall this job was very easy very dirty but very easy anyone can do it so don't be scared to prepare and dive into it I think it's easy if you have two people 1 inside the boat and 1 mixing and preparing... Well now I have to get my carpet anyone have any preferences of where to get it or what type to use?? Thanks guys I wouldn't have been able to do it with out ya!! I'll post pictures tonight

 

[micks110]

Re: how much fiberglass to use on deck?? HELP!!

You sure there's no wax in it? Do you cover it with plastic to harden it?

As far as I know there is no wax in it. It doesn't have the word wax anywhere on the can and I even asked when I bought it to make sure. It was recommended to me by a person on the forum who also said it doesn't have wax in it.
I have multiple layers of fiberglass down now and I have no bonding issues.

 

[boatflipper]

Re: how much fiberglass to use on deck?? HELP!!

Just an idea for your carpet situation-
Have you considered vinyl flooring? I have not used it myself but have heard that it is easy to clean, and it wont mold and mildew.
Just a thought!

 

[lowkee]

Re: how much fiberglass to use on deck?? HELP!!

This thread is in serious need of pictures

Glad you glassed your deck in so quickly. It took me forever to get that far.

 

[bayliner198819]

Re: how much fiberglass to use on deck?? HELP!!

heres some before and after pics

 

[bayliner198819]

Re: how much fiberglass to use on deck?? HELP!!

tell me what u guys think