Bottom painting Driftless

[tribologist]

What a messy job! The bottom paint on Driftless was in terrible shape. Since she is trailered its not that important but after sanding and blending for the bowthruster we ended up with a huge bare spot in the bow so the Admiral decided it was time to fix it so she scraped it down.

Scraping is done now and i sanded the starboard side. I'm a bit annoyed by someone thats been grinding with an angle grinder at some point making divots in certain areas but where its smooth the Festool Rotex cut it wicked fast. Its probably 5x faster than a DA sander (lol!)

I never heard of a blistered albin so i'm not planning to put barrier coat on it. The gelcoat is thick and there are no cracks. This boat was always moored until we got it so if no issues until now i would thinks its fine, right?

We jacked the keel and trailer to get room. Next is to drop the trailer back down and leave boat on blocks to get under side bunks.

[WillieC]

Yup, it's a mess. I did mostly handscraping once I discovered how poorly the fifty previous coats were adhered. Got it down to just-released-from-mold fiberglass. Smooth, shiny even and apparently nobody thought to remove the inherent wax before the first coat. Thank you very much.

Nary a blister to be found anywhere. I went ahead and put two coats of two-part epoxy barrier coat under the whole thing to cover a few areas where I was a bit aggressive and to make a good base for bottom paint. That job won't need to be redone for a while.

[tribologist]

About thanks to previous owners. Look at the pattern aft and above the thruster. Someone went bouncing with a angle grinder.... The other side has it to. I'm going back to that area and sanding them down. If gelcoat is getting thin then I will add a high build epoxy primer there. I need to do that around the thruster hole anyway. It also looks like it was repaired in the bow so that need a skimcoat of filler and some white primer too.

[ssrig]

Hate to tell you this but you have a hole all the way through the bow! I can see right through!

[tribologist]

Hate to tell you this but you have a hole all the way through the bow! I can see right through!

Them Festool grinding machines are fast... u blink and that happens

[Bob Noodat]

Hate to tell you this but you have a hole all the way through the bow! I can see right through!

I'm surprised you don't know that this is called a fishfinder. With those holes you can find the fish very quickly.

[WillieC]

I just dropped the dremel for a second!

[nebulatech]

In preparation for painting Carolina Wren's topsides, I sanded down to gelcoat on some of the bottom paint. The reason is the old boot stripe followed the chines all the way to the bow, and that doesn't represent the waterline on my boat. Plus, after removing a 650lb engine and planning to install a 150lb outboard on the stern, the bow will probably be a bit higher, but I digress.

I'm posting just to say that I had some blisters and some chipped gelcoat that would soon develop blisters if not treated. I had to grind out some spots, which I filled with vinylester resin thickened with colloidal silica. One blister was readily apparent, but the other few, along with the chipped gelcoat, didn't reveal themselves until I actually sanded off the bottom paint to bare hull.

Also FWIW, I found that my 80 grit kept clogging and falling off the sander. Once I replaced the backup pad with a new one, the paper stuck much better and lasted longer. I also switched to 40 grit for some particularly tough paint, I think it was a non-ablative paint. The 40 grit left some deep swirl marks, but bottom paint will cover that up pretty well anyway.

I'm interested in your choice for bottom paint. I heard Sherwin Williams has some good stuff in their industrial stores, can't remember the name now...

[tribologist]

Interesting! How much of the area and how big were they. Did you take any pictures? In our case its on a trailer most of the time so its a non issue. I got a gallon of Sea Hawk AF33 its a harder ablatable that comes in a nice blue. The Festool Granat paper does not clog a bit. I get it in 50 pack and change as soon as edges start to fray a little. A pad cost more than a box of paper....,

[WillieC]

I went through at least one velcro, sorry, Hook and Loop manufactured by Kleenex who brought you Q-tips but I digress, backplate on my cheap random orbital sander. The good, readily available discs are the adhesive type for the six inch common air sander. I prolly should have bought a good compressor and the truck load of new airtools to accompany it, but I tend to wait until the job is almost finished before slapping my forehead. I used the cheap RO sander to finish clean after all the scraping was done.

Air is the way to go, as soon as your 3D printer spits out a big enough compressor to handle it.

[nebulatech]

Everything Festool is top quality. We used to be a distributor, but only sold 2 tools because they cost a lot, and most of our customers didn't have extra cash back in 2009. My former partner kept our demo sander. We never sold their abrasives, but I looked up the Granat paper. I like that open mesh stuff! I posted pictures of the blisters in a different thread earlier today.

WillieC, I agree air sanders are the best, but you have to have a big compressor. Mine is a stand-up type, looks like R2D2's big red cousin. I can't remember its specs, but it can't run an air sander, even a 5" one.

[tribologist]

Shiny!!!!!

[nebulatech]

Looks great!