Sanding, stripping hull to gelcoat - cost/time?

[hsi88]

I own a Catalina 30 that I would like to strip down to the gelcoat so it can be faired and painted with a barrier coat. The quote I got from the marina was about $5K, with $3K of that for blasting the bottom. I got a separate quote for just blasting the bottom at $1500. Boat is located in a boat yard in Deltaville, VA. Have ready access to both electric and water.

Have given thought to doing the job myself. I have several sanders with vacuum attachments. I can also use a chemical stripper and scraper. Or perhaps sand and follow-up with my portable blaster, which is too small for doing the entire bottom of the boat.

The boat is 4 hours away. Don't want the job to take longer than perhaps a long weekend. Using 40 grit to get through the worst of it, I want to clean the boat quickly, basically doing most of the work myself. Any blister repairs and fairing would occur at a later date.

1) Can I sand the bottom to gelcoat in about 12-16 man hours?
2) Is chemical stripping worth the effort? Does it save time?
3) Should I just pay the guy to blast the boat for $1500.
4) Is there a faster or cheaper way to do this I'm not thinking of?

I saw some other threads that talked about doing this for bottom paint, but that is not quite the same as taking it down to gelcoat. I have no experience working with hulls painted with bottom coatings as all my prior experience has been with trailered boats. Any suggestions are welcome.

Thanks!!

[UNCIVILIZED]

You need to clarify what it is that you want to do, as gelcoat is what's underneath of the bottom paint unless a boat's fully built out of epoxy.


I don't know how much bottom paint is currently on your boat, but if there's more than a couple of layers of the hard stuff, it'll take you more than 15hrs to sand it off. Well, unless you're both in shape, & well practiced with a grinder.

[hsi88]

Not sure how many layers, but probably 4-5 over gelcoat. No prior barrier coating. PO fixed some blisters with epoxy. Can see a picture of the boat in my profile. Looking to strip the paint down to the gelcoat. Looking for the fastest and cheapest way to do this.

Previous threads point to soda blasting, which seems to be the norm for marinas and vendors. DIY folks use scrapers, grinders, sanders and chemical strippers. I have not been able to determine which really works best. And I do understand that some things will work better with the type of paints used, age of the paint, etc.

For the most part, I'm just trying to determine if I can do it myself quickly and cheaply. Or should I just spend the money to have someone do it. If I could do this in a long weekend (working 4-6 hour days of actual labor) I would do it myself versus spending $1500+.

[zippy]

Stripped the bottom on my 30 footer quite a few years ago. I found that a long handled sharp paint scaper worked best. Hard work but so is holding a sander over your head, and safer than sanding as you don't hit the gel coat.

[hsi88]

Originally Posted by zippy

Stripped the bottom on my 30 footer quite a few years ago. I found that a long handled sharp paint scaper worked best. Hard work but so is holding a sander over your head, and safer than sanding as you don't hit the gel coat.

Do you remember about how much time it took? Did you use the scraper with a chemical stripper? How did you handle nooks and crannies?

Probably a good way to build upper body strength and I could have multiple people doing this (my son), without much fear of them sanding too deep and causing other mayhem. But if I'm looking at a week of work, probably not.

[cfergu22]

I took the bottom paint of my c&c 30 a few years ago. I would say you're looking at more than 15 man hours. I had a scraper and a RO sander with a vacuum. I found that they worked differently in different spots on the hull. Sometimes I'd be able to get multiple layers off with one pull of the scraper. Other spots it wouldn't do a thing. The sander wasn't nearly as fast as I imagined it to be. It's also heavy over your head. I couldn't sand for longer than 1-2 minutes at a time without a minute break. You're also wearing a respirator which makes you a little hotter and breathing a little tougher. I'm early 30's and in moderate shape. Overall it was very tough and I feel like For 1500 you might be better off paying someone and using that time to do other projects on the boat.


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[Suijin]

Originally Posted by hsi88

1) Can I sand the bottom to gelcoat in about 12-16 man hours?
2) Is chemical stripping worth the effort? Does it save time?
3) Should I just pay the guy to blast the boat for $1500.
4) Is there a faster or cheaper way to do this I'm not thinking of?

1) Maybe, maybe not.
2) No.
3) Maybe.
4) Possibly.

The issue with sanding is that most bottom paint has a high metal content. If you're just roughing it up before applying a fresh coat, no problem. If you want to remove it, even using 30 grit, you can find yourself simply burnishing the paint, wearing out disc after disc and burning up your sander. It really depends on what types of paint are on there and how thick it is. If it's old ablative, it's going to be a real chore. I've seen people successfully sand newer paint off, but if it's years of paint where it's leeched, it's going to be very difficult to sand.

Chemical stripping. Don't even bother. You goop it on a 4'x4' section, cover it with plastic so it does not dry out, and come back 6 hours later only to find that the first layer of paint comes off and you have to do it again. Multiply that by the number of coats and however 4'x4' patches it takes to do your boat. Again, it's subject to what paint is on the boat. YMMV.

Blasting. That's actually a pretty good price for it. Dunno what yard you're in in Deltaville but they all basically use the same guy. It'll be a good job, but one thing about blasting is that it can leave the bottom very rough, like rough sandpaper. It usually or ideally needs sanding afterwards. If the next idea doesn't work, it's probably your best bet.

Scrape it. Get a good quality long handled carbide paint scraper and go at it. Don't be gentle, you want this done. Bring your burly friends, hand out coveralls, scrapers, and beer and put some Iron Maiden on the boombox to set the tone. The paint will usually pop off pretty easily and once you get the rhythm and pressure down it can go fairly quickly. But it's not easy work. The upside is that scraping leaves the gel relatively smooth. There will be some gouges here and there where you *$&%#@-up, but those are easily dealt with. You'll still want to sand just to touch up, but you won't be removing as much material as you would with blasting and then sanding.

If that sounds horrifically arm-tiring, then pay the guy to blast it.

[CaptsWife]

I have to ask, why? Why do you feel the need to do all this work?

[a64pilot]

Originally Posted by CaptsWife

I have to ask, why? Why do you feel the need to do all this work?

Especially with the statement that any blister repairs and fairing would occur later.
I hope that means the next weekend and not next year after putting on a new bottom job?

[toddster8]

It depends on what your time is worth. I did it with a random orbit sander and about two boxes of disks. Tried the chemical stripper - waste of time.
It took me two or three weeks, going at it for about an hour a day, after work. It's a lot of work in the summer heat with a dust mask and coveralls! That's probably including abortive attempts with the stripper, the cheap sander, etc. A drywall screen on a long handle was useful for knocking down layers of soft stuff.

(Hint: Prepare by doing lots of overhead squats at the gym.)

Repairing blisters and other fiberglass repairs took another week, what with waiting for stuff to cure and fairing. Probably could do it faster with practice.

I didn't even consider doing this or other big jobs at a remote yard. I trailered the boat home and dried it out behind the barn. Though the yard fees for hauling the boat, loading it on the trailer, stepping and unstepping the mast, were almost $1000 each way.

[trepanger]

I must of had 15 years of bottom paint on my boat when

[trepanger]

I must have had 15 years of bottom paint on my boat when I purchased it upon initial inspection I thought there was hull damage but was just layers a paint that chipped away then paint again you could actually tap and fear Hollow spots in the paint it had a layer of paint that was over an eighth of an inch thick I power washed it off what is 0 head on a 3000 psi power washer this was on a Catalina 25 took about an hour and a half and then I sanded it quickly and repainted the bottom

[Cthoops]

We did this last offseason on our Bristol 29.9. It took Mr. Cthoops (56 years old) and me (46 years old) 40 hours to scrape it and sand it - I kept track. The hours also included set up and clean up time. Given that we did this over several weekends, I suppose you could subtract 5-10 hours from the total. Compared to paying a professional it was well worth it, but it was definitely hard work.

You might be able to do it over a long weekend if you had at least one or two helpers, but you'll have to go at it all day. For us, half-days were hard enough.

[Frenchfry]

I took 32 hours to scrape and sand my 34'. $1500 is a good rate for soda blasting. I will pay for blasting next time.

[Sailmon]

As noted above, blasting is the quickest method of removing old paint - newest technology is pulverized glass blasting. The bottom will be rough once blasting is finished. Bottom will definitely need sanding and blasting often opens voids in the lay up that will need to be filled and faired. Margins at water line also typically need dressing after blasting - as taping is imperfect. It's a big job - but done correctly, it will be a great improvement.