Starting 87 SN Floor/Stinger Repair

I cannot believe this is the first day I have seen this post. I read all through SkiBums' posts and must say I am very impressed with the hard work and dedication (I know what have gone through). The end result looks fantastic and I know will last basically forever. From my experiences, I would like to make a few comments (though they really do not matter to this project, but be of use to others). In no particular order.

1. Polyester or vinylester resin should not be used after epoxy is used. Start with poly or vinyl and stick with it. Once epoxy is used, stick with it (no pun intended). Epoxy is a far superior "glue" and basically that is what is happening on repairs...a mechanical bond rather than a chemical bond.

2. When using epoxy, you have about 24 hours to maintain a chemical bond. After that, each next layer is a mechancial bond and the amine blush MUST be removed as it will inhibit epoxy from bonding to epoxy.

3. Keep epoxy off your skin as it can cause contact allergies after prolonged exposure.

4. Creating a gla$$ surface in the bilge or on the floor is really not necessary as the epoxy gla$$ composite will NOT be effected by standing water in anyway and is just plain too much work as SkiBum can attest to for sure. Carpet on the floor will hide most small low spots.

5. When using styrene to thin polyester resin, it then requires more hardener or MEKP for a proper cure. This applies to gel coat as well as it is polyester resin.

6. Unsupported 1/2" plywood is not strong enough to support people. I do not think one layer of fibergla$$ cloth will help much hear. There is a reason CC used 3/4" for that rear removable section.

The techniques SkiBum used where spot on in relation ot laying up the composite. Good job.

Well, yes and no. Gelcoat is cosmetic and thus a strong mechanical bond is not as critical. But, yes the bond between gelcoat and epoxy resin is not all that great IMHO. To date, I have not had any issue in this regard.

To remove the Amine Blush I first wipe the cured epoxy well with Acetone...several times. I then grind or sand out with 36 grit paper. It is important to wipe with Acetone first, otherwise you simply sand the Amine Blush into the epoxy. Acetone is all that is really needed to remove the Amine Blush. If the epoxy is not fully cured (i.e several days, then it WILL interfer with the curing of gelcoat...again from my observations.

I had good result in using Bondo for the final fairing of my repairs. The Bondo had zero curing issues and since Bondo is Polyester resin putty, the gelcoat had zero curing issues. But, since the Bondo was just in "spots", that is really a moot point.

Sometimes, when spraying gelcoat in small areas, it simply would not cure. The gods conspired against me. No worries, just wiped off with Acetone and tried again. I never really could tell what the main cause was, but suspect humidity.

There are a lot of factors in amine blush. Sometimes it's there and you can't see or feel it but like David F said it must be removed. We use heat lamps to warm the epoxy to about 100* f to minimize it. Most of our repair recipes for room temp epoxy cures call for 1 hour @ room temp then 1.5 hours @ 150*f to avoid amine blush. Bagging the area with a small tarp and a heat lamp works well.Don't use a petroleum fired heater the so2 in the exhaust is a factor in amine blush. If you use an epoxy system and plan on gel coat top coat acetone/sand/acetone/sand/acetone & it should stick OK.
If you use polyester or vinylester resin in the bilge the styrene that out gases is heavier that air and sort of sits on top of the resin inhibiting the cure so use a fan just strong enough to move the air.
Skibum - oo rah !!!

Spent several hours grinding, scraping, and sanding the bilge to remove the remaining vinyl ester resin. Thought I would never get the bilge back in shape. Once I vacuumed all the gunk and dust out of the bilge used acetone all over the bilge. Mixed up epoxy resin, white pigment, aerosol cabosil, and 3M Gla$$ bubbles. Put the first layer in the bilge. Once cured it will get sanded and another layer. Even though I do not need a gla$$ like finish in the bilge, I am going to try to make it turn out that way. Just stubborn like that. The 1/2" plywood removable floor now has four layers of gla$$ with epoxy resin. Both the top and bottom have epoxy mat covered with 10oz gla$$. The bottom has white pigment in the epoxy because I am going to try to make it smooth and shiny too. I will go back to the front floor area and install a brace that connects to the stringers. I still have to tie in the inside of the floor and stringer under that area. On the bottom of the removable floor in the rear I'll add a brace as well. There is still a brace that goes between the main stringers in the back - still need to put it in.

DISCLAIMER:

Probably should have put this out sooner. But I never was good at order.

I learned what I know from this site. Thought it might be of some use for other people to actually see what the inside of a boat looks like. Probably doing a lot of things wrong. That's what I do. Know more now than I did when I started. Learned the hard way. Now, you don't have to.

oo-rah is the marines waterdog, or are you a marine?


I believe you meant to say hoo ah.

Would anyone recomend using polyester fibergla$$ resin instead of epoxy for this job to stop the risk of the amine blush not causing a good bond?

I know epoxy is stronger, but the whole amine blush thing sounds like it adds a whole new factor to the process.

Any down sides to polyester resing besides strength?

http://66.77.200.232/images/company_a$$ets/512F1C7F-0D64-4A5E-9D91-785DC064755F/16cf4_Adv_of_Epoxy_v_Poly.pdf

I went and checked out the differences in epoxy vs polyester. Is the difference that big of a deal when used in a project like this. Or will polyester resin sufface in a 25 year marine environment.

leo0648 wrote: I went and checked out the differences in epoxy vs polyester. Is the difference that big of a deal when used in a project like this. Or will polyester resin sufface in a 25 year marine environment.

When I started work on my project several people advised me to use epoxy resin. The major reason was that it is water proof where polyester resin actually holds or absorbs moisture. The moisture will only transmit to the wood stringers.

Before I found this site I bought a book about how to replace the floor and stringers in a boat. The author not only suggested using polyester resin, but further suggested going to "the big city" to find a plant that makes things from fibergla$$ to buy the resin in bulk cheaper than any other suppliers. The author also said that it was neccessary to sand the fibergla$$ if it has cured more than 24 hrs because of the wax moving to the surface.

As for the horrible amine blush problem, it is really not an issue. Most of the time you are going to be applying epoxy before the magical 24 hours expires. If it were polyester you would have to sand and clean it anyhow because of the wax.

My opinion, use epoxy. I have used about 12 gallons of epoxy without any problems.

When I used filler to level the floor it was so thin that it ran right off the side of the hull not helping to fill the connection of the hull and the floor. Mixed a batch of epoxy with aerosil cabosil until it was quite thick, then used a bunch of fairing compound to make a good filling mix. Went back and filled along the floor to hull connection. Of course only after wiping with acetone then sanding to remove the evil amine blush.

Bill,
First, thanks so much for such a detailed writeup. I'm certain that this thread will be invaluable for anyone with an older nautique with bad floors/stringers. You are doing an amazing job and keeping an incredible pace.

I'm curious about the rear cross support for the main stringers. I see the provisions, but its not in and you appear to be doing finish coatings.

Keep up the excellent work.

-Ryan

Bremsen wrote: I'm curious about the rear cross support for the main stringers. I see the provisions, but its not in and you appear to be doing finish coatings. -Ryan

I have not installed the cross member so I could work more easily in the bilge. I thought I could get the bilge almost done then come back and put that piece in later with minimal mess and an easy repair. Now I have given up on my hopes of a perfectly shiny bilge. I finished sanding today. It is flat and smooth. I have an order in to West Marine for some epoxy paint. You should see the cross support in the next few days.

The floor thickness is 5/16" average. I know there have been several discussions about how much gla$$ and what layup is required to get certain thickness of gla$$ floor. This floor is:

Biaxial Mat
Epoxy Mat
10oz Cloth
Biaxial Mat

All of that makes 5/16". Some spots are just a hair thinner. Some have more filler making them thicker. Just some information that might be useful if you are planning a floor rebuild.

how much would you charge to do the same job to my boat?

Making the rear crosmember out of two pieces of 1/2" plywood. Saturated both surfaces to be bonded with epoxy resin. Added a layer of 10oz gla$$ cloth, worked out all of the air bubbles, then set the pieces in place. Stacked some small weights the length of the brace until it cured. Top layer is epoxy mat with 3M Gla$$ bubbles to make it as smooth as possible. Once that cures the bottom will just be one layer of 10oz gla$$.

Currently the support brace is gla$$ed and cured. It is waiting to be installed. The holdup is that I used 1/2" plywood, not 3/4" plwood for the removable floor. It is sturdy with four layers of gla$$ and resin. However, it came up a little low compared to the rest of the floor. Added two layers of epoxy mat and resin. Once cured and leveled I'll be able to install the support brace and fill all the imperfections. More sanding.