sanding and preping for paint

[ElkySS]

This is the same spot before sanding it down as much. I sanded off the bottom paint then used a dremel with a grinding stone to only clean up the cracks and remove anything that was seperated. Took me a long time. But any black you see here are spots where a crack alowed the gel to seperate. Im just not sure how to fix it. The boat sat in the water for a long time before i got it so most of the bottom is cracked like this.
https://goo.gl/photos/pPBytu1MsnuUDG2EA

[Russ]

Im pretty sure somebody painted it and did a crap job of it. I am trying to fix it all but since everything on the bottom has seperated from the glass I was aggressively sanding. I can chip at it with my fingernail and chunks will come away and leave raw glass. How should i fix it if not to sand it off?

I'll let the experts chime in. But the "chips" and "chunks" could be gelcoat. Again, you are sanding too far. You should never see the raw "dark" fiberglass.

[Herschel]

Again, you are sanding too far. You should never see the raw "dark" fiberglass.

It is so hard to tell from just a photo, but judging that the boat is a 1969 and has been in the water a long time, I am wondering if the gelcoat below the water line is mostly toast already and the material that is peeling off in chunks is actually a "layer" of the glass. I am far from an expert in fiberglass repair (even though I have stayed in a Holiday Inn Express on occasion ), I did do a lot of restoration on my 1959 O'Day dinghy. I think at some point on these old boats you can get to a point where the original finish is so worn off and degraded, you have to get the old stuff sanded/ground down to something solid and smooth. Then it might be necessary to build back up with more cloth and epoxy before going with primer and paint. Just thinking; not sure at all.

[seahouse]

This is the same spot before sanding it down as much. I sanded off the bottom paint then used a dremel with a grinding stone to only clean up the cracks and remove anything that was seperated. Took me a long time. But any black you see here are spots where a crack alowed the gel to seperate. Im just not sure how to fix it. The boat sat in the water for a long time before i got it so most of the bottom is cracked like this.
https://goo.gl/photos/pPBytu1MsnuUDG2EA

I have never done a repair where this type of damage is this extensive, so I'm no expert.

In the right part of this photo it looks like some blister ("osmosis") repair has been done at some point in the boat's past. Hopefully that is still sound. Sand down as far as you need to go to reach solid material, anything that is loose has to come off to give your repair something solid to adhere to. There are repair systems on the market (eg West System) and you can build up areas where you needed to grind deeply with layers of fibreglass cloth. After that there is a two part skim coat that gets applied before the gel coat. There are lots of Youtube videos on it, check them out.

Do you see any sign of water that has penetrated into the surface, or is everything bone dry? Be sure it is dry.

The top looks like it has been painted. I would remove the caulking around the window (looks like it was painted over) before sanding, mask, then finish it, then finally re-caulk it.

Good luck.

[ElkySS]

Once i get the flaking chips out of the way it all looks solid and dry. Not sure if these will help show anything new but they are two chips i just pulled off with my nail. The one on the left has paint side up. The one on the right has paint side down. Everything below the waterline is like this. i may just have to take it to a place and have them do the bottom of the boat.
https://goo.gl/photos/iifpLzH3F3PxiBkS9

[Herschel]

In the right part of this photo it looks like some blister ("osmosis") repair has been done at some point in the boat's past. Hopefully that is still sound. Sand down as far as you need to go to reach solid material, anything that is loose has to come off to give your repair something solid to adhere to. There are repair systems on the market (eg West System) and you can build up areas where you needed to grind deeply with layers of fiberglass cloth. After that there is a two part skim coat that gets applied before the gel coat. There are lots of Youtube videos on it, check them out.

Yep, I agree with this. It fits my experience with my old O'Day. I think you are into a layer of glass. Good news is that it CAN be fixed.

[ElkySS]

so if i am understanding this video from interlux, I can take it down to glass, roll on some epiglass, then interprotect 2000e, and finally paint. That (again if I am understanding) should build it back up and provide a water barrior. Any input on if I am understanding that right.

[ElkySS]

And I have not said this yet but thank you all for spit balling this with me. I appreciate all the input.

[Herschel]

I can take it down to glass, roll on some epiglass, then interprotect 2000e, and finally paint. That (again if I am understanding) should build it back up and provide a water barrior. Any input on if I am understanding that right.

I watched the video, and, including the washes that they discuss, I think you have the right idea. Notice the use of filler powder with the epoxy to even out the gashes and dings. In my reconditioning of my dinghy I had areas that I wanted to strengthen. That is why I used the West System epoxy and fiberglass cloth to build bulk/strength in several areas. If you don't have to that, then you shouldn't need cloth, just filler powder. I did learn that each epoxy and paint product has recommended thinners, and they are different for each product. Not to use just any thinner/mineral spirit product lying around. And, these products are a little pricey, but, I think it is important to use the best products. You don't want to have to do this again for a while. Some people on the forum have good reports with products they get at Lowe's and Home Depot, but I think it is important to stick with marine grade products that are from the main providers of those products. One last item. Most cans have a telephone number you can call for advice if you have a question. I use those numbers when I need to. They can be very helpful.

[Jimmyt]

Looks like you've made good progress. From the pics, it looks like everything but the glass is shot - at least in spots. A disc sander works fine, as long as you are very patient. I typically stick to 120 grit and go very slowly. Some of my buddies use 60 grit for what you're doing, but it's a bit aggressive for my taste. Looks like you might be through the glass in spots on the bow. Don't be afraid of cutting the loose crap off and adding a layer of glass back on the really bad spots - if you have any. Don't leave anything loose on there. You can put a skim coat of filler on to facilitate getting the surface smooth again. Abandon the disk when you're going back with new stuff (after you cut off the really high spots) and go to a long flat board or pneumatic longboard. Gelcoat is an interesting experience the first time, but it looks like you've got the skills and the nerve to pull it off if you decide to. I've done about a 6 square foot area repair on the bottom of my boat and went back with gelcoat. Not pleasant, but resulted in a repair that I can't even find. Lots of wet sanding and final polishing with a machine. Other marine coatings will probably work fine, just find a supplier you like and get them to recommend the products you need, for the complete job. Just to ditto what Herschel says above, probably ought to get all of you products coordinated before you start putting stuff back on to avoid compatibility issues. Nothing worse than having the new layer of stuff take off the previous two layers!

I'm sure you're wearing a quality respirator that's rated for the products you're using, and the crap you're grinding off. Some bottom coatings can be pretty nasty. Good luck - you're doing great.

[seahouse]

Yeah, good advice above, and good video. I used that family of products (Interlux) including Interprotect 2000 on my boat when new. It spends ~5 months per season in fresh water, and no blisters after 4 seasons. It is highly rated in tests.

If you work carefully and follow the steps exactly (don't skip any of them, and ditto above about using the exact recommended solvents) you will end up with a job at least as good as if you paid someone to do it, and will have money left over in your pocket.

It's lucky your hull is dry, that can extend the job. When exposed, the glass fibres act as moisture wicks and can draw and hold water deeper into the hull, so you need some thickness of material on top of any exposed fibres. Years ago I used a heat gun to speed the drying of some moist areas I was grinding, and, remarkably, you could feel the humidity coming out of the surface with your hand.

Good luck.

[ElkySS]

Thank you all. I will just keep at it and hope that one day it will be done. Lol

[Herschel]

Thank you all. I will just keep at it and hope that one day it will be done. Lol

And we will buy YOU the pizza when you finish!

[ElkySS]

I know this is sort of a dead thread but figured i would post an update. I have gotten most of the bottom paint off back to the axle (port and starbord) of the trailer. I have only had about 6 hours to work on it so i think it is decent progress. There are still a lot of cracks but with the paint out of the way i can go back with a smaller grit sand paper and get them.

https://goo.gl/photos/9PPVwERcxFJamP887

https://goo.gl/photos/n2VmAJfnLMzy7FW2A

[Jimmyt]

Making great progress!