Barrier Coating

S

Salish Seaker

Well-known member
Joined
Jun 29, 2017
Messages
180
Fluid Motion Model
C-242 C
Vessel Name
Island Time
In looking at Baz's pictures, I didn't see that any barrier coating was applied before the bottom paint. Is this typical for bottom painting RT's, not applying a barrier coat first? On our C-Dory, this seemed to be the standard practice. We're considering bottom painting our R23, Island Time, and am curious to know what the standard procedure is.

Peter
 
Hi Peter,

Every boat I've owned has had bottom paint, and I have put a barrier coat(s) on all. A contrasting color on the barrier coat makes it apparent when you need to touch-up or repaint the bottom. The reason for the barrier coat has been to lessen the chance of blistering of the gelcoat on the bottom. Some will argue the necessity of the barrier coat based on vinylester vs polyester resins. Even if you don't feel the need for protection from osmotic blisters with the current resins, another reason for the barrier paint is the epoxy-based used in barrier paints: it makes for better adhesion for the actual bottom paint.

Boat hulls come out of the mold with a wax coating. The bottom has to be prepped before bottom painting, including removing that wax. The barrier coat provides a mechanical connection to the gelcoat, and a chemical connection to the bottom paint. I would (and do) still go with a barrier coat; we have had good results with bottom paint, and in a climate that is much more "growth inticing" than the PNW due to our warmer waters. I would go with the recommendation of the boatyard. And, if you are putting your 23 in dry storage or trailering, be sure to pick a bottom paint that will stay effective, even with time out of the water.

Jim
 
My local marina wanted to put on 4 coats of barrier coating before the 2 coats of bottom paint. Most of their work is the commercial fishing fleet here. They were going to charge $5500 to sand, prep and paint. I don't know what system they were going to use.

The dealer I bought the boat from was just going to do 2 coats of bottom paint, no barrier coat. I don't know what system they were going to use.

I used Petit Hydrocoat on a previous boat and it worked well in our waters and I didn't use a barrier coat. The application instructions from Petit don't say anything about using a barrier coat, so I am not going to. They do have a very through sanding/scrubbing/cleaning process of the hull to scuff it up and clean off the wax before applying the bottom paint.

I suspect barrier coats do help but I don't know how necessary they are. Some bottom coat systems might need a barrier coat more than others.

I know this is clear as mud, my best recommendation is to research bottom coatings and after you decide which will work best for you in your area, see if that system requires/suggests a barrier coat.
 
I agree with Jim. There is more advantages to barrier coat then prevention of blisters. Although that is a good advantage. Vinyl ester resin has a good track record of the prevention of water absorption and boat manufacturers that use this resin in below the water line portions of the hull have decreased the chances of blisters and "delamination". I was told that Fluid Motion uses this type of resin in their hulls. Many boat yards still require barrier coating in their process of bottom painting. The thought is the sanding or cutting of the gelcoat with 80 grit paper opens the protective layer up. Bottom paint is not sealant type paint. Bottom paints only bonding is to the coarse cut of the sanding, there is no chemical bonding. The adhesive bond is 100% reliant on the technicians painting procedure of dewaxing the hull multiple times to ensure that all the wax's are not present and the sanding quality is consistent through out the complete bottom. This can be done and the results can be Good. The alternative is barrier coat, this is an epoxy base paint that still requires the dewaxing and sanding or cutting the gelcoat with 60 grit paper but it seals and provides a protective layer that chemically bonds to the gelcoat. After the first layer of epoxy barrier coat is cured another coat is applied no sanding is needed if coated in the proper time window. This second layer bonds and the combination of the two coats form a strong water barrier to stop water absorption sealing the hull. Some manufactures require as many as 6 coats. I used Pettit requiring 3 coats. After the third coat has cured the first coat of bottom paint is applied. This has to be done within a time window so that the paint chemically bonds to the epoxy barrier coat. 2 coats of bottom paint are applied. I used Pettit Vivid which is a hard ablative finish that is good for repetitive launching. I did this application in 2016 and the finish looks as if it was just done. I should get 5 years from this application. When I repaint the bottom sanding with 80 grit will be required to bond the coating to the existing bottom paint.
 
I noticed on the Pettit web page that their new barrier coat product only needs 2 coats to do the job. But the West Marine web site says that you need 3 coats of that Pettit product!!??
 
Thanks for the posting ref from Andrew Custis. I'm satisfied that my 2 coats of bottom paint on my brand new R29 CB done by Everett Yacht Service was as good as it gets for my PNW cruising waters. I'm not concerned a barrier coat(s) were not applied. The wax was very obviously removed (sand well) before the 2 coats of bottom paint were applied.
 
Thank you for all of your great replies. Thanks Red Raven for the link to Andrew's reply. I was interested in the factory's approach to barrier coating and now I know.

Peter
 
ixlr8":14yght4l said:
I noticed on the Pettit web page that their new barrier coat product only needs 2 coats to do the job. But the West Marine web site says that you need 3 coats of that Pettit product!!??
Click to expand...

I think the third coat was over kill. After two coats were applied the barrier coat was several mils thick and a hard sealed finish. I had enough paint left over to third coat and applied it as per the directions. Pettit may have changed the requirements since then. It was my labor the cost was nothing but my time and a bad back ache. The total materials in 2016 were just over $600.00. Barrier coating is common practice in the midwest. The Ranger/Cutwater dealer in the Midwest highly recommended barrier coating. I called the Ranger factory and spoke to Ronnie Gonzales (2016) he told me in the PNW they sand and paint no barrier. I went the over kill route. The hardest part of the process is the Prep. dewaxing and sanding. That needs to be done regardless. The epoxy application is the easy part.
 
If I were to attempt bottom painting myself by paying for a haul out, taking boat to yard, buying the paint and tools needed and then sanding and applying paint and then hauling back to water, I would seriously consider what all this effort might do to my health and especially my back and leg strains. If the back health is marginal or even if it's not the ensuring health issues could be a long term and never ending issue for me that could end up making the boating life unbearable. So, with this I'm of the opinion to let a professional do this work/activity and hire some young people to do the hard back breaking work on my behalf. 🙂
 
Is your boat moored or on a trailer? How long do you leave your boat in the water? I put a ceramic coating on my r23 and I have other boats lined up to be coated, it not only protects the bottom but also the rest of the upper surfaces from staining. I had it on my champion that had a white hull and it kept the bottom from staining when left in the water too. It adds gloss to what ever color you have and prevents oxidation from forming. Let me know if you have any questions. Kevin, 2017 R23
 
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