Sodablasting reveals "the pits!"

[Fore and Aft]

Tetepare what brand belt sander are you using? My Makita belt sander weighs 4.8kg compared to My Makita random Orbital at 2.1kg. I have big shoulders but still not big enough to hold a Belt Sander above my head for hours.
Cheers

[rslifkin]

Generally if I need something faster than an orbital sander, I go to a rotary disc sander. It's not much heavier than the orbital, but it's much faster (and like a belt sander, it requires careful use as it can make big gouges very easily). Only other downside to the rotary sander is that dust collection doesn't work nearly as well as the orbital, as much of the dust gets thrown off the edge of the pad at high speed and misses the vacuum collection.

[Tetepare]

Originally Posted by Fore and Aft

Tetepare what brand belt sander are you using? My Makita belt sander weighs 4.8kg compared to My Makita random Orbital at 2.1kg. I have big shoulders but still not big enough to hold a Belt Sander above my head for hours.
Cheers

I don't remember the brand, I borrowed it; it was big and metal. It weighed a ton. I don't have big shoulders, and it was a brutal job. But if you have to do it, you get it done.

The mess was worse than the fatigue though, even in a full Tyvek suit and goggles and gloves, the stuff got everywhere. Worst job ever, and I'm dead serious. I'd like to say I'll never do that again but as soon as I do I'll be jinxed and have to do it.

I did it to remove the years of old paint, the bottom itself wasn't pitted, just a very few blisters. Not long after that the paint removal strips became popular; some people say they don't work but I've seen them strip 95% of old paint with zero effort. Soda blast is what the marina uses now for stripping old paint and junk; I don't know that they would take a job redoing a pitted bottom, or that anyone would pay that much.

I will say that my beltsanding work was 20 years ago. Once sanded and barrier coated, an annual touch up with VC17 was all it needed. Never a blister, no other issues, effectively a zero work bottom. When we sold the boat last year the bottom looked as good as it had two decades ago.

[Rightbrainer]

Check out Louie the shipwright's process for fairing the bottom of his new build. Different scale, but some good ideas here.

https://www.youtube.com/watch?v=COYNDOTcouw&t=322s

[Gary Mc]

I have done similar work on an S2 and they do not have issues with blistering.



What you have is uneven blasting resulting in pockets in the original gel coat. Your best bet if you use a random orbital and take most of the reaming gel coat off. If is a lot of work but does the best job.


However if you don't want to put that much into it, fairing it with thickened epoxy then applying multiple coats of Interprotect 2000 will work.


Have fun!

[Celestialsailor]

Originally Posted by Fore and Aft

Tetepare what brand belt sander are you using? My Makita belt sander weighs 4.8kg compared to My Makita random Orbital at 2.1kg. I have big shoulders but still not big enough to hold a Belt Sander above my head for hours.
Cheers

Originally Posted by Tetepare

I don't remember the brand, I borrowed it; it was big and metal. It weighed a ton. I don't have big shoulders, and it was a brutal job. But if you have to do it, you get it done.

The mess was worse than the fatigue though, even in a full Tyvek suit and goggles and gloves, the stuff got everywhere. Worst job ever, and I'm dead serious. I'd like to say I'll never do that again but as soon as I do I'll be jinxed and have to do it.

I did it to remove the years of old paint, the bottom itself wasn't pitted, just a very few blisters. Not long after that the paint removal strips became popular; some people say they don't work but I've seen them strip 95% of old paint with zero effort. Soda blast is what the marina uses now for stripping old paint and junk; I don't know that they would take a job redoing a pitted bottom, or that anyone would pay that much.

I will say that my beltsanding work was 20 years ago. Once sanded and barrier coated, an annual touch up with VC17 was all it needed. Never a blister, no other issues, effectively a zero work bottom. When we sold the boat last year the bottom looked as good as it had two decades ago.

These explains everything...I found a picture of Tetepare online...

[bil56]

I'm surprised, everyone suggests applying epoxy, ok,
but you absolutely have to measure the humidity level first!
locking moisture behind a waterproof barrier is a big mistake...

./.

[OS2Dude]

Originally Posted by MicHughV

I kinda havta agree with you there..some people that West Marine hires to run their stores seem to have dubious maritime qualities or experience...

West Marine is not the old Royal Navy, they don't send out press gangs to the local marinas to get experienced floor people. If you think they need some experienced folks, apply to work there.

[Celestialsailor]

Originally Posted by OS2Dude

West Marine is not the old Royal Navy, they don't send out press gangs to the local marinas to get experienced floor people. If you think they need some experienced folks, apply to work there.

Is that the solution...or is it their model to hire cheap non-experienced employees that are incapable of helping a newer boater? I started using them in the 80's and they would only hire knowledgeable people...usually boaters. They would get a significant discount if they joined up. Not sure they do that anymore.

[Cpt Mark]

If your really want to sand and fair the bottom you want to use a sanding board. A sanding board is maybe 18" long, uses a sanding strip of paper and is flat. You could do it by hand and easily if you look like the guy in the picture or you can buy what's called an airboard. These came out of the auto body world. Makes the job of fairing fast and exceptional results.

some options. I have the Hutchins but there are now cheaper options.

https://smile.amazon.com/s?k=airboar...s_ts-doa-p_2_8

[rls8r]

I was looking at the same thing when I had the bottom of my boat sodablasted. We were calling it "The Great Speckled Bird" for months. I did the following:

1) ground out blisters and filled them, and filled all the little dimples like the ones that you have (without grinding them out), with 3M Marine Premium Filler (46006),

2) sanded the bottom using a DeWalt Variable Speed Polisher, 7-Inch to 9-Inch (DWP849) using 32-grit sandpaper (just to scarify it so the next coat of epoxy would hold - did not remove gel coat - DeWalt is pretty light and easy to use overhead for a while - little trolley made from a kid's wagon helped a lot),

3) gave the bottom two coats of Raka 900 (medium viscosity) epoxy resin using 350 (non-blush) hardener - roll & tip,

4) faired the bottom with the DeWalt using 120-grit paper, and then touched up spots with a 36" sanding board (again, using 120-grit paper - two strokes up-down; two strokes NE-SW; two strokes NW-SE; then move, but have subsequent strokes overlap the previous ones by a bit).

5) finished the base with 2 coats of Pettit Protect High Build,

6) put on two coats of hard copper paint (Pettit Copperguard),

7) finished the topcoating with two coats of ablative (Pettit Hydrocoat ECO).

That was a few years ago - I suspect that I may have overdone things a bit - but things seem to be working OK.

[jamhass]

Some years ago I had to sand off an epoxy barrier coat that was failing. I used a Porter Cable 6-inch right-angle RO sander with a vacuum and 60 grit discs followed by a quick scrub with 80. Easy to handle, captured nearly all the dust and got through the layer very quickly. Very similar to this:
https://www.portercable.com/product/...bit-sander-kit
but mine was rather older ... and still in great shape!