Sandblasting vs. Soda blasting

[thereIwas]

I am about to haul-out and have the bottom blasted prior to applying a barrier coat and bottom paint. What should I go with... sand blast or soda blast?
I can hear the gasps! "Don't sand blast it!"... so I thought that I'd open up this debate one more time.
Soda blasting has the cache, and sandblasting has always been frowned on, but the price difference is large: sandblasting is about 1/2 the cost of soda blasting.
I have found two nearby yards in the upper Chesapeake, with good reputations, that do sand blasting on their customer's boats. I have looked at freshly blasted hulls at both yards, and come away very impressed with the quality of the blasted surfaces.
It appears that if they use the "000" grit sand, and the operator has a "light hand", the results are quite good. In both cases, the blasted surfaces had the appearance of egg shell, with the only rough spots being where there were voids from the original gel coat lay-up, or where there had previously been fairing or blister work done with a filler that was softer than the gel coat.
So if there are yards doing this, and they are still in business, and I don't see alarms about it in the forums, and I'm going to put on a barrier coat... then why shouldn't I proceed with having the hull sand blasted??

[puddinlegs]

Sounds like you've made your choice. Good luck!

(soda's still the way to go)

[thereIwas]

Well, the choice isn't made, but it also isn't between sand blasting and soda blasting... mostly because the latter is simply too much $$$. The choice is sand blasting (by the boat yard) or manual (machine) sanding by me. It's not a done deal yet, but I very much don't want to hand sand the entire bottom, and I'm loking for helpful comments or guidance, one way or the other.

[Sabreman]

We did the job by hand last year after we were quoted $3000 to soda blast our 38' hull.

Two of us used 3/4" wood chisels to scrape 20 years of paint to bare glass. The chisels had knocked off corners to keep from gouging. Using chisels is a very fast method to remove paint and not nearly as destructive as many think (try a small test area and the results will be apparent). We also used a carbide tipped paint scraper for difficult areas. We sharpened the chisels every 20-30 minutes. After scraping, I used a 6" random orbit Rigid sander hooked to a shop-vac. Do not use 5". I used 60 grit for the initial sanding, changing disks every 10' or so. Then switched to 120 grit. We had a tarp under the boat and collected about 50# of paint between the chips and dust from the vac. Awesome.

The initial scraping took 2 people 8.5 man hours (17MH total). Sanding took 6 hours. Total job: 23 MH to get to bare glass. If I had to do it again, I'd use this method. Blasting is convenient, but sweat labor is cheaper. I would not sand-blast as it is potentially very destructive. Soda is the way to go.

[tytower]

Having tried both methods on steel boats the soda blasting was pretty well useless. Left a pitted surface but did not remove all the loose paint . I had to come back and re-do it. Sandblast it lightly with used sand gave the best result back to steel .

My glass boat I did with sand blast also very very lightly and glassed the outside of the hull.
Some parts delaminated in about 10 years (above the skeg and keel )

[sailingdog]

I'd point out that what is good on a steel boat may not work on a fiberglass one or even be good for it. It is very easy for a sandblaster to seriously damage laminate on a fiberglass boat. Sodablasting is far more forgiving to the hull and gelcoat, but even that can do damage if done wrong.

[BarryL]

Hello,

If you have seen the results on other boats, and you are happy with the appearance, then go for it.

I can tell that in the storage yard where my boat spends the winter, I have seen a few hulls that were soda blasted and a few that were sand blasted. The sand blasted hulls required hours and hours of filling, and sanding. The soda blasted hulls required a quick sanding only.

If you want to see some pics of before / after soda blasting, go here:

http://www.sailnet.com/forums/gear-m...done-test.html


Good luck,
Barry

[T37Chef]

The link may be helpful to you?

http://www.sailnet.com/forums/322678-post.html

I think his name is Bob Hassellbeck a.k.a. "The Sandman". 410-905-3587

He regularly strips boats in the area (Baltimore/Annapolis), he's very good, in fact he is at the marina today doing a boat. I was very pleased with his work, he is an artist with that thing, really. If I recall correctly I paid somewhere around $600 for him to do my 37' hull, (five years ago).

[thereIwas]

T37Chef
Thanks for the info... I knew that there had to be someone out there that had a successful experience with sandblasting.
You say the "Sandman" is "at the marina today"... could you tell me what marina? I might attempt to find him and chat about the process.
Thanks.

[gtod25]

Very happy with the results. Get an experience person to do it and WATCH the process. Inspect as the process moves along and don't be afraid to call a halt if you are unhappy.

Paint with 7 coats of Interlux 2000 afterward.

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The Incredible Hull: Hull Work