Remove Bottom Paint - Wet Sandblasting

[Joker757]

I've started to remove the bottom paint on my 1999 Maxum 2800SCR. I started out with Aquastrip which works ok however due to the many layers of paint requires two applications, is very messy and expensive. My neighbor did his Trophy last year and said he used a 4000psi pressure washer with a sandblasting attachment and the finest sand he could find. He said that the water helped cut down the agressiveness and it turned out fine. He cautioned not to try to go all the way down to the gelcoat but however get down close two where a signle pass with a DA and 80 grit would do the rest. I've searched the forums here however wasn't able to find much mentioned about the method. Does anyone here have any experience with this method? If so any feedback would be greatly appreciated. I'm taking all the necessary safety precautions. I have a full face respirator (3M 7800) and other necessary items to ensure that none of it is inhaled or comes in contact with my skin. I trailer the boat and plan to coat with Interprotect 2000 and VC Epoxy.

Thanks.

 

[MTboatguy]

Re: Wet Sandblasting

Re: Wet Sandblasting

Wet blasting takes a lot of practice to know when to stop before causing damage...if you choose to go this route make sure you have some material of a similar nature to practice on until you get it right, I have seen guys blow holes in both boats and fiberglass car bodies using a wet blaster..

 

[Joker757]

Re: Wet Sandblasting

Re: Wet Sandblasting

Thanks for the feedback boatguy. I just finished half of the boat. That's 25 linear (approx 120 square feet)feet of bottom surface in about an 90 mins. Of course there's no way around sanding. I'm unable to get under the chines or the keel. Pretty much any surface that parallel with the ground will have to get the old fashioned way. I went with the finest sand they had (60/80). I probably could have gone more agressive with a 30/60 grit but didn't want to take any chances. This worked like a charm. No damage or pitting of the gelcoat. In fact the surfice profile isn't quite up to standard to paint. Would have had to sand it anyway to scuff it up enough for the barrier coat. What I did was not try and get every speck of paint off. Took about 10 50lb bags to do the one side. Getting the rest off (chines, keel and random spots) will be a day job at most. Then I'll rinse and wash and let it dry for a couple of weeks before I address the small areas of gel coat damage that was already there from normal use of the boat. My plan on these spots is to feather out to bare glass, coat with resin then fill with Interlux Watertie eqpoxy filler. I'm talking about a few small gouges in the gel coat only. No structural damage. Please chime in if it seems I'm missing something. I'm always open to suggestions from those that have done this before.

 

[Joker757]

Re: Wet Sandblasting

Re: Wet Sandblasting

pics

 

[Yacht Dr.]

Re: Wet Sandblasting

Re: Wet Sandblasting

Nicely Done Joker .

Yup just a quick cruise over with some 80 on a da and a little hand sanding and your good to go.

I dont know about waiting weeks for it to dry..seems much.

You also dont need the epoxy filler from what your saying..

If there just small little scratches .. feather out and be done with it.. chips fill with some 3m vinylester marine filler..fair be done with it .

Your putting on 5 coats of Interprotect 2000 right ? Your barrier is in that .. raw glass and everything..

Your talking about VC Offshore right ? ( salt water application ).

YD.

 

[Joker757]

Re: Wet Sandblasting

Re: Wet Sandblasting

Nicely Done Joker .

Yup just a quick cruise over with some 80 on a da and a little hand sanding and your good to go.

I dont know about waiting weeks for it to dry..seems much.
want to be 100% sure that I'm not trapping any moisture after driving water into the gel coat. How long do you think would be long enough?
You also dont need the epoxy filler from what your saying..

If there just small little scratches .. feather out and be done with it.. chips fill with some 3m vinylester marine filler..fair be done with it .

Your putting on 5 coats of Interprotect 2000 right ? Your barrier is in that .. raw glass and everything..
was going to do at least 4 to 5 coats alternating colors (black/gray)
Your talking about VC Offshore right ? ( salt water application ).
yes. but after thinking about it I may go with the Micron CSC. I don't want to have to do this again and though maybe something that would wear away and not build up. What do you think?
YD.

I just finished up. So in all it took me about 5hrs to do the entire boat. I was really dreading the thought of doing it the other way and did a lot of research. The finer grit was a bit slower but gave me better control. Also made sure to stay away from the corners to prevent blowing throught the gel coat. Took about 15 bags of sand at $4/ea plus $120 for the pressure washer and atachment. Cheaper than the 6 to 8 gals of Aquastrip I was going to have to use at $60/ea. Just need to use a little common sense, take your time and don't try to get it perfect. There's no getting around the sanding so you can get it perfect then. When you see the black fading away move on. Keep the wand moving and you'll be ok. I'll post more pics as this progresses.

 

[Yacht Dr.]

Re: Wet Sandblasting

Re: Wet Sandblasting

" was going to do at least 4 to 5 coats alternating colors (black/gray). "

Interprotect only comes in Grey..and White..not Black ..

Forget about Micron.. use VC 17 .. only comes in 3 flavors.. red,blue and grey.. ( they all lay on looking like a copper penny but is the best BP I know of ) .

You can apply some red VC first over your 2000..and then some Grey....when you see red then its time to apply more VC Hint Hint....

YD.

 

[Joker757]

Re: Wet Sandblasting

Re: Wet Sandblasting

" was going to do at least 4 to 5 coats alternating colors (black/gray). "

Interprotect only comes in Grey..and White..not Black ..you're right. That's what I meant.

Forget about Micron.. use VC 17 .. only comes in 3 flavors.. red,blue and grey.. ( they all lay on looking like a copper penny but is the best BP I know of ) .

so will the VC17 wear away?
You can apply some red VC first over your 2000..and then some Grey....when you see red then its time to apply more VC Hint Hint....

YD.

Thanks again for your guidance. Much appreciated.