Surface Prep for Antifoulling Paint

[Border Line]

Hello,

My 1990 Sea Ray 310 is going to need a good dose of elbow grease next season prior to lauching. Since I will have plenty of time to do the work myself, I was hoping some of you more experienced do-it yourselfer's could guide me in the right direction.

My question revolves around what is the best way to remove the many years of previously painted antifouling paint. It's in pretty bad shap, some areas are chipping in large chunks, other just waiting to come off. It's fairly obvious that the previous owner was happy just to keep painting over the imperfections time after time.

I want to start with a clean slate... So what are my options to remove all these layers (years) of paint. Can I use a chemical, or do I have to sand the whole surface. What grit of sandpaper should I use??? Etc etc...

Any advise or help would be appreciated...

Thanks,

Richard

 

[Warren]

Richard my suggestion is to get some positive referrals in your area on soda blasting the bottom. You will need to ensure that the contractor is familiar with marine paint removal and you will need to be present to ensure that the job is done right. This is a much better (and safer to your health) option than sanding!

A inexperienced contractor can do serious damage to gelcoat - but you want as much of the paint removed as possible - so a delicate balance is required. It is better to leave a bit of paint for sanding than to remove gelcoat. When the paint is gone you will have a clean slate. Four or five coats of Interprotect or equivalent can then be applied followed by an antifouling paint of your choice (in consultation with the epoxy base coat supplier) for a perfect, long-lasting bottom treatment.
Good luck!
Warren

 

[fwebster]

Media blasting is one method but the guy doing it must be experienced enough to know when enough is enough or you can do serious damage. The other issue with media blasting is the cost....it runs about $20/ft. here and makes a terrible mess so be sure you are not liable for the mess or damage to neighboring vessels in the boat yard.

The other approach is hand sanding with 80 grit paper/sanding disks so you can see when you are approaching the gelcoat. You need to end up with a lot of the white showing..........this isn't just a "light sanding job".

After paint removal, prep and prime according to the instructions provided by the maker of your bottom paint.

 

[Salty Dog - LI]

Rich,

With the help of my brother, we stripped the bottom clean on my 1990 Sundancer 270DA when I bought it 3 years ago. The old bottom paint was on thick and chipped/rough. I know that fiberglass is actually porous and will blister over the years. Read the articles from Interlux on fiberglass degredation!

The job is a little messy, but worth it! Sand blasting or soda blasting can take off the gelcoat, and then you have a bigger problem! I used 6-7 gallons of Interlux Interstrip to take off the layers of bottom paint with a 4-6 inch taping/spackling knife. It takes several applications, working a 3'x3' area or so at a time. The waterline needs to be taped with wide painters tape to protect the clean gelcoat above the waterline. We wore Tyvek suits to keep clean, and organic respirators because of the chemicals (the stuff is nasty- you don't want to breath it- read the warning labels!). We wore old shoes and chemical resistant gloves because we knew we'd get stuff on them (and we did). We had drop cloths under the boat so we didn't get any stuff on my concrete driveway (it won't come off!) We poured the stripper in metal coffee cans, and used cheap paint brushes to apply the stripper. We then scraped the old paint into a cardboard box, using the edges to clean the scraper. The stripped paint dried to brittle paint in the box for disposal in the trash. We were careful not to scratch the gelcoat. Once we got most of the old paint off, we used 202 and rags to clean off the smudged paint. Then came the 2 Makita palm sanders with 80-100 grit paper to sand the gelcoat somewhat clean. Any found blisters should be grinded out and repaired (they'll just continue to grow and you'll have a bigger problem!). When the hull is finished, one more cleaning with 202 to get the dust and grease off, We peeled off the old painters tape that got scratched up, ran a string line and measured/pencil marked a new waterline, and then carefully taped down new painters tape for our finished water line (slightly above the old water line- I ended up with a bottom paint line 2 inches above the actual water line!), then 4 coats of Interlux Interprotect barrier coat(rolled on) to the tape. I alternated white and gray coats so I could see the full coverage. Then I put on 1 coat of green Interlux Micron Extra, followed by 2 coats of Black Micron Extra. This bottom paint is the most expensive ablative paint, but it lasts 2-3 seasons! I did the job 3 years ago, and all I do each spring is paint a fresh coat along the waterline for 3-4 inches (or what shows down to the chimes), touch up any paint chips from contact with floatsom, and I'm done! The Interprotect is a barrier coat that will seal the fiberglass and prevent water intrusion. It cures like fiberglass. The bottom paint layers may chip off, but not the Interprotect (I see gray every time if the bottom paint chips or scratches anywhere). The Micron Extra is ablative paint and will melt away. When I see green, I will know it's time to put on 2 more coats of black! The important thing is to follow the instructions for prep and application times. When we started the first coat of Interprotect, we had to keep going every 3-4 hours with the next coat and put on the first coat of Micron Extra by the end of the day. We started at 7AM, and finished at 7PM! (The coats won't bond if you don't follow the time schedule!) Then I had time to put on the last 2 coats of Micron Extra- 1 coat per day. After the paint dried, I peeled away the painters tape, which also breaks off a clean waterline! By the way, don't get bottom paint on the outdrive gimbel! (or you'll get electrolysis and eat away the outdrive!) Tape off around the gimbel! The outdrive gets painted with Trilux 33 (better than the spray paint).

I have 4 boat stands to go along with my 2 keel stands, along with a small 2 ton hydraulic jack, so I can lift my boat carefully as needed to slide the keel stands or boat stands around to work on the spots under them after I finished the rest of the hull. For my 27 foot, I only needed the 3 points to keep my boat upright (2 stern boat stands on the rear corners, and the bow keel stand). I used the hydraulic jack with a wood block to slide in another bow keel stand position using interconnecting concrete blocks and 2x6 treated planks. Then I had the second set of boat stands to put next to the first set to move out the first boat stands (one at a time) to strip and paint those areas through each step (striping, 4 coats Interprotect, 3 coats bottom paint). With caution, we were able to get it done (I'm a safety consultant, so I don't take chances!). The marinas may use their travel lifts to lift the boats and do the spots under the stands (or they may not and the boat owners will never know!). I worked on many a sail boat racing hull in my earlier years. The finish on the hull was important if you wanted to win races! I ended up spending about $900 on Interstrip, 202, Interprotect, and Micron Extra paint, but I have a perfect bottom finish that has lasted into a 3rd season (and hopefully a 4th!). My hull is sealed from water, and I increased the value of my boat (a boat coated with Interprotect barrier coat paint and Micron Extra paint is a great selling point!).

When I finished, I threw away the tyvek suits, painters hats, shoes, and drop cloths! The job took 2 weekends to strip and sand, and 1-2 weekends to paint, but it was worth it in the end! I saved a lot of money doing it myself. Check with your boat yard to see if they will allow you to strip and paint your own boat. Some have rules against that. They may say they have to do it! I have the luxury of having my boat in my driveway. I did a FWC conversion on my engine 2 seasons ago, and an upper engine re-build last spring. This spring I'll be replacing my interior headliner and new upper deck pinstripping. I have a boat hauler move the boat each season for $175 each way! I charge myself for winter storage and maintenance!

Best of luck to you!

 

[RonF]

Salty Dog - LI,

Wow, thanks for the detailed description. You really did it right, no corners cut. Alternating the colors was a great idea. I'll be looking at a job like that in a yeae or two, but I will have to find a yard that will do it correctly for a fee.

 

[comsnark]

Well. . . I have a 28' and the dealer charged me $1000 (maybe a bit less) to roll on one coat of the cheapest bottom paint on the planet. They charged extra to poorly paint the outdrives. Thus started what was to ulitmately to be a short buisness relationship. I do not want to *imagine* what it would cost for the dealer to do a complete job; and can't imagine them getting it right.

I think I want to hire Salty Dog to do my boat next year when it comes time to strip it. You will come down to Jersey, right?

 

[Border Line]

Thank you all for your feedback.

I love these Forums, as I was really hoping to hear from someone who actually had done the job themselves, and not only did I get a response, but lots of quality details... (thank you Salty Dog)

I've always beleived that if you can offered the time, as long as you do your research first, the best option is to do it yourself. I'm not saying that there are not good contractors or boatyards out there that will do a great job, it's just that nobody will put the TLC in your project like you can, and you always run the risk of having a bad experience like Warren had.

Thanks again for all your great feedback...