100 Percent Acrylic Bottom Paint Initial Test Results

[Seahorse24]

We placed our project boat in the slip on September 5. Although the boat is on a boat lift, I left about two inches of the rudder in the water for an initial test of the acrylic bottom paint.

After being in the fresh water lake for 55 days the acrylic paint shows no signs of softening. Algae did grow on the painted surface, which was easily removed with a soft bristled broom.

I have photos but can't figure out how to post them using my iPad. I'll post two photos tomorrow using my desktop computer.

The only problem I see with using 100 percent acrylic house paint on the boat bottom is algae growth over long periods of time in the water. It comes off easily with a brush. For people who trailer their boats, you could power wash it off within minutes, if you do not let it dry. Dried algae can be very difficult to scrub off. Been there, done that. The reason we use lifts for all of our boats.

It takes two weeks of no forward movement of the boat for the algae to begin showing up on the surface below water level. I let it grow for 55 days to see how difficult it would be to brush it off. It came off easily. All I had down at the dock was a soft broom.

By keeping our boat on a lift, we will not have to worry about algae growth, but I wanted to address this issue for trailer sailers who leave their boats in the water for weeks or months at a time.

Our sailboat is 44 years old and we wanted none toxic paint on the bottom. Our fresh water lake is the water source for 450,000 people. 80 to 120 million gallons a day are drawn from the lake.

I have no idea how arcrylic paint would hold up in salt water.

You can learn more about our restoration project at this link.
https://sailboatprojectorbust.wordpress.com/

 

[fstbttms]

Are we supposed to know what this "acrylic bottom paint" is? Is it just some random house paint you decided to use?

 

[Seahorse24]

Are we supposed to know what this "acrylic bottom paint" is? Is it just some random house paint you decided to use?

I used Valspar Duramax paint for the top coat, Valspar latex primer, Valspar Non-skid porch and floor paint for the walk areas. All of these paints are 100 percent acrylic. Other companies also make 100 percent acrylic house paints.

 

[fstbttms]

I used Valspar Duramax paint for the top coat, Valspar latex primer, Valspar Non-skid porch and floor paint for the walk areas. All of these paints are 100 percent acrylic. Other companies also make 100 percent acrylic house paints.

Still not sure what you used for bottom paint. And since whatever you used has zero anti fouling properties, why use anything at all on the bottom?

 

[Seahorse24]

Here are the photos.

The sun was shining on the clean side. I cleaned this side before thinking to take a photo, but it looked like the other side before cleaning.

 

[fstbttms]

OK, well I guess I'm not going to get my questions answered...

 

[kito]

??? You used house paint instead of anti-fouling paint on the bottom? Why on earth would you do that? Of course it's going to have growth on it.

 

[Seahorse24]

NOTE for anyone interested in trying this on their boats:

All of the old bottom paint was removed first. We then wet sanded the old barrier coat with 80 grit sandpaper and then cleaned it again with a power washer. After allowing the bottom to dry, we applied three new barrier coats of CM-15 2-part epoxy. I allowed the epoxy to dry for two weeks, then wet sanded that with 80 grit. Cleaned it again and then used Valspar latex primer on top of the epoxy and then top coated the primer with Valspar Duramax. The only reasons I painted over the epoxy was to block sunlight from the epoxy coat and allow me an easy touch up bottom coat if needed. This boat sits on a lift, so sunlight hits the bottom several hours per day.

 

[Seahorse24]

OK, well I guess I'm not going to get my questions answered...

I answered your questions above in a reply. You asked what kind of paint I used, right?

 

[Jackdaw]

The only problem I see with using 100 percent acrylic house paint on the boat bottom is algae growth over long periods of time in the water.

I gotta say, for 99% of the people that is the ONLY reason to use bottom paint. It really serves no other purpose.

 

[fstbttms]

The only reasons I painted over the epoxy was to block sunlight from the epoxy coat...

Why would this be a concern?

 

[Seahorse24]

??? You used house paint instead of anti-fouling paint on the bottom? Why on earth would you do that? Of course it's going to have growth on it.

Our boat sits on a lift and is not in the water when not being used. anti-fouling paint is toxic. Our children and grandchildren swim around our dock. Our lake is the water supply for 450,000 people. If we don't need toxic paint on our boat, I saw no reason to use it in a fresh water lake environment.

Anti-fouling paint is needed for sailboats that remain in the water year around, year after year. The algae goes on them too, but a thin layer of anti-fouling paint comes off whenever the boat is sailed. After two or three years, you have to have the bottom paint redone, a costly and time consuming project. Trailer sailors might be interested in this alternative paint, if their boats are stored on trailers a good portion of the year.

 

[Seahorse24]

Why would this be a concern?

Sunlight over time deteriorates the epoxy barrier coat. Barrier coat epoxy is not not formulated to withstand direct sunlight for long periods of time.

 

[fstbttms]

Sunlight over time deteriorates the epoxy barrier coat. Barrier coat epoxy is not not formulated to withstand direct sunlight for long periods of time.

There are millions of boats that live on trailers or are otherwise drysailed that do not have paint of any kind on their bottoms. I think if barrier coat deterioration were a problem, we'd know about it.

 

[Seahorse24]

I gotta say, for 99% of the people that is the ONLY reason to use bottom paint. It really serves no other purpose.

That is correct. If anyone ever comes up with non-toxic bottom paint that will not allow any type of algae to grow on it, that would be awesome.

 

[Seahorse24]

Still not sure what you used for bottom paint. And since whatever you used has zero anti fouling properties, why use anything at all on the bottom?

I apologize that I have not made it clear what paint I used. I used Valspar Duramax exterior house paint for the bottom paint. That went on over a Valspar latex primer. Both are 100 percent acrylic. Latex is a lot easier to touch up than epoxy. I can touch up the top, sides, or bottom of my boat in fifteen minutes, since it sits on a lift with 90 percent of the bottom exposed. I can get to everything except the swing keel and bottom of the stub keel.

 

[Seahorse24]

Are we supposed to know what this "acrylic bottom paint" is? Is it just some random house paint you decided to use?

Here is a photo of the paint I used for the top, sides, and bottom. I also used a Valspar latex primer ( not pictured) that is also 100 percent acrylic, before applying the Duramax top coat. The anti-skid porch and floor paint was used on the top side in the designated walk areas. You can see it in the photo of the boat below. It is the color of sand. Other paint manufactures also make 100 percent acrylic exterior house paints. Check with the manufacturer before purchasing to make sure the paint is 100 percent acrylic. I had it mixed to an off-white color, which appears white to the human eye. I read not to use a pure white color on a sailboat.

This paint stands up to a 2000 psi power wash, my first test after applying a test section. We have walked on the paint this past year while working on the topside. I have also scrubbed it with soap and water. So far, it appears to be holding up well. I will continue to post more updates to see how this paint holds up over time.

When not being used, our sailboat is stored on a lift, which is located in a cove near our cabin. To our knowledge, it is the only sailboat on the lake that is kept on a boat lift. There are hundreds of sailboats stored in slips at the yacht club, where this boat was stored for seven years, in the water, before we purchased it.

 

[Brian S]

OK, so I understand that you didn't want any form of anti-fouling paint on the bottom, from a lake ecology standpoint.

I don't really understand your motivation for this acrylic latex experiment. I certainly understand a desire to paint worn gelcoat, or horribly stained gelcoat. Normally this would be done above the waterline with alkyd enamels, or polyurethanes, either 1 part, or 2 part such as Awlgrip.

Paint, in and of itself, won't prevent algae, slime, scum, or outright critter infestation. Given you are on fresh water, I imagine zebra mussels, or on our lake, jelly blobs known a bryozoans.

I think most people painting topsides, deck, house, are more concerned with aesthetics of the boat, and generally don't do much below the waterline.

Perhaps the motivation was you felt you could do the job less expensively using the acrylic latex?

I do know boatbuilders who use only acrylic latex inside the cabin for interior fiberglass surfaces.

I once spoke with an Awlgrip rep about the fact that Awlgrip is not recommended for below waterlines. I was working on restoring a wooden boat, and it turns out Awlgrip isn't recommended for wood, unless the wood is epoxy stabilized, because the Awlgrip is so hard that any moisture expansion/contraction of wood would cause cracking. Since the boat, like yours, is not stored in the water except for maybe a week over vacation, pretty much any paint would work on it. (I still haven't finished it to the point it needs paint.)

Well, I guess you can fill us in on what your overarching plan is. Or not. I guess I am curious at how long your exposed paint job will last given weathering, especially UV degradation, vs. other typical marine finishes. Of course, the one thing I've heard is once you paint a boat, you've set yourself up to have to keep on painting it!

 

[Brian S]

Oh, one thing I see from your picture is that the finish doesn't look especially glossy. I think one of the attractions of enamel paint or polyurethanes is that they can be applied for a very glossy finish. Although decking and non-skid areas are probably better in a matte or satin finish, so there isn't as much sun reflection. What were your thoughts on this?

 

[Seahorse24]

OK, so I understand that you didn't want any form of anti-fouling paint on the bottom, from a lake ecology standpoint.

I don't really understand your motivation for this acrylic latex experiment. I certainly understand a desire to paint worn gelcoat, or horribly stained gelcoat. Normally this would be done above the waterline with alkyd enamels, or polyurethanes, either 1 part, or 2 part such as Awlgrip.

Paint, in and of itself, won't prevent algae, slime, scum, or outright critter infestation. Given you are on fresh water, I imagine zebra mussels, or on our lake, jelly blobs known a bryozoans.

I think most people painting topsides, deck, house, are more concerned with aesthetics of the boat, and generally don't do much below the waterline.

Perhaps the motivation was you felt you could do the job less expensively using the acrylic latex?

I do know boatbuilders who use only acrylic latex inside the cabin for interior fiberglass surfaces.

I once spoke with an Awlgrip rep about the fact that Awlgrip is not recommended for below waterlines. I was working on restoring a wooden boat, and it turns out Awlgrip isn't recommended for wood, unless the wood is epoxy stabilized, because the Awlgrip is so hard that any moisture expansion/contraction of wood would cause cracking. Since the boat, like yours, is not stored in the water except for maybe a week over vacation, pretty much any paint would work on it. (I still haven't finished it to the point it needs paint.)

Well, I guess you can fill us in on what your overarching plan is. Or not. I guess I am curious at how long your exposed paint job will last given weathering, especially UV degradation, vs. other typical marine finishes. Of course, the one thing I've heard is once you paint a boat, you've set yourself up to have to keep on painting it!

Thank you for your interest in our boat project. I appreciate all of the questions. First, let me say I don't know much about sailing. I am a retired engineer who has owned power boats since 2001.

Exterior house paints hold up quite well to UV rays from the sun. As to the finish, we could have used a gloss finish, but went with a semi-gloss. That was just my personal choice. As to our overarching plan. Here is my explanation.

We purchased the sailboat from a friend of my son. The previous owner got married and moved. His wife did not enjoy sailing and he needed to get the boat out of the rental slip. We purchased the boat and dual axle trailer for $2500.00. Pulled it from the water and hauled it to our cabin. There it sat under some trees uncovered for two years. My wife told me to either sell it or get in the water.

I looked into the cost of having the boat repainted top to bottom by a professional. That was going to cost more than we paid for the boat. I happened to remember my wife had painted our front door with Duramax paint. She forgot to clean the twelve dollar brush she used. By the time I found the brush in the garage, the paint had dried. I placed the brush into a bucket of water thinking the latex paint would dissolve. After a couple of months of keeping water in the bucket, the paint on the brush had not softened. I wondered if I could use that kind of paint on our boat. I began doing research and to my surprise, people had already tried it. I found this article by a chemical engineer. He died a few years ago, but his article is interest reading.

http://www.simplicityboats.com/latexcarnel.html

After reading that article, I decided to try and paint the sailboat myself. And that is how the project got started. My wife, son, and I did all of the work ourselves. My wife restored the teak and cleaned up the inside of the boat, while I did most of the exterior paint. My son helped apply the barrier coats, because the pot life required faster progress than I could do by myself. I did all of the 100 percent acrylic painting on top, sides and bottom myself. If we could this, than most anyone can do this.

If people have expensive boats and want to pay professionals to have the bottoms repainted, that is the wise choice. I see a lot of sailors on this forum who buy old project boats like ours. Boats they will never get their money back on, if they spend a fortune on a paint job. It does not make sense to me to put two or three thousand dollars into a paint job on an old boat that someone only paid two or three grand for the project boat to start with, especially, if the boat is going to be trailer-ed to a lake for weekend sailing.

I have learned a lot on this site and people here have been most helpful. I thought I could contribute a bit myself, with my engineering knowledge and ability to do research and try new things. This whole project was done to show an alternative paint choice for trailer-ed sailboats that are not kept in the water year around, year after year. We did a lot more than just paint the boat. We replaced the windows, made a motor mount, replaced all of the lights with LED lights, and replaced the lines. So far we have a little less than $3500 in the boat, but two hundred of that went to replacing the bunks on the trailer. Next up, we are going to redo the interior cushions, replace the interior lights with LED fixtures, and hopefully, my son will teach my wife and I how to sail it.

Here is where we document everything we are doing to the boat. https://sailboatprojectorbust.wordpress.com/

I am not telling anyone they should do what I did. I am just reporting on our experiment so people can make their own decision to do what is best for their particular project boat. I'm not trying to change the world, but I am trying to make our water source a little less toxic when less toxic will work fine for our sailboat.

Happy sailing.