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to blast or not?

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rclift
Navigator

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USA
152 Posts

Initially Posted - 01/20/2005 : 01:06:44

I need to remove the bottom paint from Buzz. Looks to me like there have only been 3 previous applications but the last one didn't adhere well at all and the bottom is very rough. I used Petite Trinidad bottom paint last time. There is a local sand blaster who does quite a few boats using walnut shell and charges around 5 bu's for a c25. He's experienced but I don't want to ruin Buzz's pristine bottom. (no blisters) On the positive side I could have him work on the boat asap and have plenty of time for painting the bottom and putting on a barrier coat when the weather improves. The other alternatives look to be either extremely time consuming, hazardous to the environment and applicator or can only be done when the temperatures are above 60 degrees which means later in the spring in Oregon. (I think it rains only 50% of the time in the spring here)

Any advice, warnings or personal experiences with walnut shell blasting that I should know about.

Thanks

Ray Clift
Buzz 1361 sk/tr
Oregon

Edited by - rclift on 01/20/2005 01:09:14

Ben - FL
Admiral

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880 Posts

Response Posted - 01/20/2005 : 05:44:36

I've never heard of anyone blasting a fiberglass hull, much less with walnut shell?

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/20/2005 : 08:56:22

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Ben - FL
 I've never heard of anyone blasting a fiberglass hull, much less with walnut shell?
<hr height="1" noshade id="quote"></blockquote id="quote">
HUH?

Remember, I soda blasted mine last winter.

You should ask the guy if he is willing to try soda. It will broaden his buisiness, (Corvettes ask for soda) If he is willing to try then he should give you a discount for being the guinee pig.

Edited by - on

Mark Loyacano
Navigator

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USA
247 Posts

Response Posted - 01/20/2005 : 09:05:04

Walnut shells are often used to clean jet engine parts. These shells work well because they are a very hard and sharp edged material. I have no idea what they could do to fiberglass, though. Blasting with sand isn't a good idea either. It leaves the fiberglass too porous resulting in water intrusion (read .. cultivating osmosis). Auto body/paint shops sometimes use "plastic media" blasting. Little plastic "bits", selected from different shapes, "chisl" paint off without causing the steel or aluminum to overheat and warp.
One of our Catalina 25 members cleaned his hull with the "soda and water" pressure blast. That is probably more fiberglass compatable than any other method - but it creates an environmental "mess". West Marine markets "PEEL AWAY". It is a non toxic chemical and paper system that eliminates messy environmental disposal problems.
Ray, what methods are your local marinas using to prep fiberglass boat bottoms for paint?

Edited by - on

Ben - FL
Admiral

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880 Posts

Response Posted - 01/21/2005 : 23:46:09

Sorry Frank. I've got CRS disease.

Edited by - on

Gloss
Master Marine Consultant

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USA
1916 Posts

Response Posted - 01/22/2005 : 11:13:33

How much did the soda blast job cost?

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 01/22/2005 : 13:13:40

Didn't Val B. get "blasted" a couple of years back? Seems like he had some issues with the results...

VAL?

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 01/22/2005 : 13:43:17

Dave's right I sand blasted

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 01/22/2005 : 13:53:35

Well I don't know what that was all about. The post happened in the middle of a sentence....Blizzard perhaps.

I was about to say that my hulls bottom was sandblasted and at $300 was a bargain. Dave's memory serves him well. The issues that I had had to do with a s^&t load of tiny blisters that the blasting uncouered. And that led to a deblistering with a Dremmel tool and several burrs followed by puttying and barrier coating and you know the rest.

Val on the hard DAGNABIT

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/22/2005 : 14:48:08

My soda was about $400. I cannot imagine any environmental issue resulting from it. First none of our paint has any real toxins in it any more, I am not sure why we even use the stuff! (I was really ticked to see my bottom when I hauled out, back in the day if you sailed as much as I do there was never anything there at the end of the year, this year it looked like astro turf. I'd kill for some tin!). Another guy had it done in the boat yard at the club this year, no big whoop. It was funny though, he has a 22 or 23 ft Hunter and for some reason there was no gelcoat on his deck. Why he had the guy blast his deck is a mystery to me, but he did and there was nothing left but raw fiberglass. nice Hunter, nice.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 01/22/2005 : 15:09:15

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by fhopper@mac.com
 It was funny though, he has a 22 or 23 ft Hunter and for some reason there was no gelcoat on his deck. Why he had the guy blast his deck is a mystery to me, but he did and there was nothing left but raw fiberglass. nice Hunter, nice.
<hr height="1" noshade id="quote"></blockquote id="quote">
The mystery to me is why the guy went ahead and did it if it was taking the gelcoat off.

Maybe he'd never done a boat...

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/22/2005 : 15:43:37

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave Bristle
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by fhopper@mac.com
 It was funny though, he has a 22 or 23 ft Hunter and for some reason there was no gelcoat on his deck. Why he had the guy blast his deck is a mystery to me, but he did and there was nothing left but raw fiberglass. nice Hunter, nice.
<hr height="1" noshade id="quote"></blockquote id="quote">
The mystery to me is why the guy went ahead and did it if it was taking the gelcoat off.

Maybe he'd never done a boat...
<hr height="1" noshade id="quote"></blockquote id="quote">
He is the same guy that did mine. New to boats but big in the hot rod circuit. They were both standing there the whole time. I really think the deck had no gelcoat and was only painted, no doubt one of Hunter's experiments. This is the early Hunter with a centerboard and all the ballast in lead in the bilge. A very tender failed design that was the precursor to their WB.

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 01/22/2005 : 16:07:41

Dry ice blasting is another commonly used method for cleaning hulls... even though the frozen CO2 is expensive, it simply evaporates when the job is done and all that's left is the material that came off the boat. Saves lots of money in the long run.

I think walnut shells would work fine too... If you were nervous about it, I'd set up a test run. Have him do a small patch and if it doesn't look good have him stop... give him $75 for his set-up time.

Edited by - on

rclift
Navigator

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USA
152 Posts

Response Posted - 01/22/2005 : 19:58:36

Thanks for the advice! The soda blasting isn't very popular in our area yet but the guy I'm working with is interested. I like the idea of having him do just a small section and seeing how it goes.

Mark, the local boatyard usually just uses 80 grit and industrial sanders and rarely takes off all the previous paint. They're mainly into roughing up the surface and reapplying a new layer.

Thanks for your help!

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 01/22/2005 : 22:13:43

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rclift
 Thanks for the advice! The soda blasting isn't very popular in our area yet but the guy I'm working with is interested.
Thanks for your help!
<hr height="1" noshade id="quote"></blockquote id="quote">
Google it, I bet he only needs a diferent orifice.
Here is one place
http://www.sodablasting.com/index.htm

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 01/23/2005 : 08:51:01

I saw a new one this year...an applicator wearing a full body suit was using a tool that looked like one of those oldie badger shaving brushes except it was all steel bristles (air powered). It worked well except that it took forever to do. He was working on a Pearson '36 and it took about 10 days...can't imagine what he was charged for the work. Just know I couldn't/wouldn't afford it. I'm not much when calculating this kind of thing but a quick guess gives me, $75 per hour X six hours a day X 10 days and I come up with OUCH. Perhaps he owned the yard.

Val on the hard DAGNABIT

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 01/23/2005 : 11:00:13

"like one of those oldie badger shaving brushes except it was all steel bristles (air powered). "

I've heard them called called 'needle gun' or 'scaler'. The business end of the tool is a bunch of blunt-ended small-diameter steel rods that are rather vigorously vibrated against the surface you're de-scaling.

I spent many hours using one as a young man (I was tasked with re-painting all the equipment in the machine shop where I was working)

I don't think it would be my tool of choice on fiberglass.

Edited by - ClamBeach on 01/23/2005 11:01:50

Buzz Maring
Master Marine Consultant

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USA
1772 Posts

Response Posted - 01/23/2005 : 14:59:02

I need to remove the bottom paint from Buzz ... the last one didn't adhere well at all and the bottom is very rough ... There is a local sand blaster who does quite a few boats using walnut shell ... but I don't want to ruin Buzz's pristine bottom. - Ray

The way this thread started out I figured I was going to get it ... y'all are just too kind ...

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 01/24/2005 : 09:21:21

Hi Clam,

Needle gun hey, never saw a workman so willing to stop what he was doing and pass the time of day. Povera bashta

Val on the hard DAGNABIT

Edited by - on

frankr
Captain

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256 Posts

Response Posted - 01/24/2005 : 12:46:12

The Dry Ice CO2 method will also pop blisters by freezing the water within them. Supposedly one can apply the barrier coat shortly after the blasting is finished.

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 01/24/2005 : 13:17:40

Dry ice, what next? We might consider making a list of what hasn't been tried yet. Could be interesting. I've wondered where my old sneeks have gone to, stranger things have happened.

ya know YA NEVER KNOW

Val on the hard DAGNABIT

Edited by - on

John Mason
Admiral

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USA
687 Posts

Response Posted - 01/24/2005 : 14:53:57

"The way this thread started out I figured I was going to get it ... y'all are just too kind ..."

I was going to suggest Ray clear it with you first before he just starts blasting your "pristine" backside, even if it is just with soda, but I figured others would be chiming in plenty.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 01/24/2005 : 15:08:24

I have to be honest, when I first read...

"I need to remove the bottom paint from Buzz..." "but I don't want to ruin Buzz's pristine bottom. (no blisters)"

I wanted so badly to chime in on this

, but,..with great difficulty,..I restrained myself!

)

Edited by - on

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