Starting 87 SN Floor/Stinger Repair

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.

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?

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.

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.

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 !!!

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.

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.

Here's some pictures for a local MA marine restoration shop. They did an interior and new stringers on an '87.

Ski Nautique

Ken

I bet the plywood is twisted. Not your excellent stringer/floor repair/replacment.

Thats how I feel most nights and mornings.

And you still find time...

This is the removable floor. The origional was made of 3/4" thick plywood. There was no resin, gla$$, or water proofing of any type on the origional floor. In reality, it did not have a lot of rot. However, it was heavy and somewhat saturated with water.

My concept is 1/2" untreated plywood. Applied epoxy mat then 10oz cloth on one side today. Will do the same on the other side when it cures. Also will make certain to saturate the edges very well. This will make the floor very strong and very water proof.

I did notice a problem with the stringers. With the floor laying in place the corner on the back observer side is higher than the front driver side. No worries. Just need to finish the removable floor piece. Then I'll set it in place and make the adjustments to the stringers.

I remember working with a level, dial caliper, and hand plane for hours on end. I really thought everything would turn out in the end. But, I have more work to do.

Thanks for the encouragement Alan.

Used just under a gallon of epoxy resin with fairing compound on the floor. First I sanded off the little bumps that mysteriously appeared. Tried to get the fairing compound where it was thick enough to fill properly but thin enough to run into the low spots to make the floor level. I think I mixed the compound a little thin. If you remember back, I made the floor a little higher at the hull so water would run into the bilge. Yeah, resin does the same thing as water. Most of the resin and compound stayed behind so the floor should be quite level. Just one more piece of the floor to finish now.

leo0648 wrote: What is the reasoning for the different width tapes (2" 4" 8")? Is it to build up a slope?

When attaching a stringer to the hull or floor to the hull I use sequential widths of tape starting with the 2" centering it along the joint. This is followed by the 4" tape and then the 8" tape. Each layer doubles the first. Where the three layers overlap there is a large concentration of resin and gla$$. This helps to "bed" the stringer.

Don't be so hard on yourself Bill, I can't wait to see it colored and finished. Better than original by a long shot, awesome work man.