Winter Boat Bottom Work

[PGUTIERREZ]

Good morning, My Catalina 36 is 20 years old and sailed on the upper Mississippi River where winter temperatures easily go to minus 25 - 30 F. Due to my boat's age and boat bottom condition after haul out, I am considering maybe having the boat bottom soda blasted during the cold winter months. By having this done during cold months, then when warm May temperatures arrive I would paint a few layers of epoxy barrier coat followed by VC17 or similar. The boat is stored outside and has an excellent winter cover that goes down to waterline stripe. Should I have any concerns about the boat bottom being exposed to the cold after being soda blasted or paint striped? For example, soda blasting / paint stripper would be applied on a warm winter day any time December to March at 40 F or higher. Boat bottom has had multiple layers of VC 17 and I feel it is time to get the boat soda blasted, bottom re sealed with an epoxy barrier coat followed by VC 17. This work would be done on the hard. Boat would be sitting 3 - 5 months out side exposed to minimal moisture and very cold (minus 30 F is probable).
Alternatively would consider using a stripper. Anyone have experience using paint strippers in cold temperatures ? Should I be concerned about having a soda blasted or paint stripped "raw" boat bottom when boat is stored outside, and most of the winter snow getting deflected by my very excellent winter cover.
(I am sending this request to a few other sources of information such as Catalina Yachts, Pettit Paints, Jamestown Distributors for their input). Please share your experiences on cold temperature boat bottom preparation where the raw boat bottom will be exposed to very cold winter temperatures.

 

[Davidasailor26]

Having the boat sitting in the cold after stripping shouldn’t be a problem. Depending on when you plan to apply the barrier coat and paint you may have some additional considerations. First, although the air might be warm enough to apply epoxy or paint it’s possible that the surface of the bottom itself won’t be. You need both the air and surface to reach the minimum application temperature and stay above it during the curing time. This is especially difficult on the keel that takes longer to warm up. Also, the barrier coat will probably have a maximum period of time between application and over coating before sanding is needed. The barrier coat instructions should specify what that maximum time is. But if you plan on barrier coating during a warm day in December and then not being able to paint for a few months you might have trouble. Finally some paints have a maximum time after application before launching. I don’t know if VC-17 has that issue but it’s worth checking their instructions.

 

[dlochner]

The more time the bottom is bare and exposed to the weather, the better as it will dry out even more. That's a good thing.

Now, about VC 17. As easy as it is to apply, is as hard as it is to remove. Don't waste time and money on a chemical paint stripper. It won't work. VC 17 is not your normal paint, it is a layer of copper powder suspended in teflon like finish. Paint strippers won't touch it. Solvents, like acetone, alcohol and others will soften the paint and allow it to be smeared around, however doing this causes more of a mess than a bare bottom.

The only way to remove large areas of VC-17 is mechanically, with soda or glass bead blasting or lots of 36 grit sand paper. In high wear areas, like the leading edge of the keel and rudder, the paint is thin because it wears away. However, in low wear areas, like the flat areas behind the keel the paint builds up and becomes a sheet of copper. When the sand paper hits it, the copper burnishes and becomes a polished copper sheet before it begins to come off. A few years back I spent the better part of the summer under the boat removing VC-17. In the end I had collected 5 gallons of paint dust and used several hundred 36 grit sanding disks.

I'll never go back to VC-17. This year I used Petitt Hydrocoat Eco. It is copper free bottom paint that is about the most environmentally sound paints on the market. At the end of the season there were no zebra mussels, some alga on the top of the wing, and some slime. A hose, a soft brush, and about an hour had the bottom looking as pristine as a new coat of paint. The attached photo shows the bottom before it was washed. There is a lot of scum on the unpainted side of the waterline and on the port side of the rudder. (The port side faces south and is exposed to a lot of sun light.)