NEW bottom

[RT Firefly]

Greetings,
In anticipation of getting our "new" (to us) boat, a question about anti-foul (AF). Hull is 2015 vintage (World Cat Glacier Bay edition) and has always been lift kept. She'll stay in the water 365 in her new home.

Is there any disadvantage of having an epoxy barrier coat applied before her first time with AF? Local marina suggest one barrier coat and one coat hard AF.

Never had to deal with a "virgin" bottom before. Thanks.

 

[twistedtree]

Yes, definitely do a barrier coat. Newer boats have epoxy or vinyl-ester outer layers to prevent moisture absorption, but I wouldn't could on it. A barrier coat is easy to do.

 

[RT Firefly]

Greetings,
Mr. tt. Getting quotes from 2 yards. One yard says, as I note above: (1 coat epoxy+1 coat AF). Other yard says 2 coats epoxy +? coats AF
First yard says they only put 1 coat epoxy as there is a possibility of blistering between layers. Are more coats preferred?
Thoughts? Thanks.

 

[rslifkin]

How many coats of barrier you need depends on what barrier coat is used. I'd go by what the datasheet says.

A coat of contrasting color hard antifouling is a good idea to show when the ablative paint has worn through in some areas and needs touching up.

 

[psneeld]

Never heard of blistering between epoxy coats. If it did that I would suspect application error.

I would go with manufacturer recommendations (say Interlux barrier Interprotect 2000 and use ALL the recommended coats or thickness. I would then apply an Interlux ablative/self polishing antifouling (again to the manufacturer's recommendations NOT the yards). I have been using Interlux products for over 40 years and have had better results with ablatives rather than Petit or anyone else's.

The alternative to Interprotect and any other "barrier" coating would be 6oz cloth and epoxy as a barrier. But as on my own terrible trawler hull, I did both because I ground off the bottom. If still original gel and in good shape I would just stay with the barrier coat(s).

Do you know if any vinylester coats were used in that boats layup? Back as early as 2003 some manufacturers were starting to use vinylester outer coats to help resist blistering (that's probably just the earliest I know about).

If so, then a barrier coat may be overkill.... but always use the maufacturer's recommended coats and antifouling paint recommendations...never a yards unless they are one of the best and I had a long talk with supervision to verify they ACTUALLY knew what they were talking about.

!st coat a different color is also a good idea and very standard. Not sure it has to be a hard coat as much as compatable.

 

[Greg QS]

Follow manufactures instructions on barrier coat. Normally multi coat systems. Since the hull is fresh best time to do it. Also dont do hard bottom coat. Leads to build up and then needs to be stripped over time. You will loose your barrier coat when stripped. Use ablative. 1st coat a different color. Add 2-3 coats of your final color afterwards . Normally figure 1 coat lost per year. 3 coats = 3 years and no build up over time. It can come out of the water and be re launched with no problems. Hard cannot. Hard lasts 1 year. You can run the ablative as long as you want till you see the alternate color coming through; then you know its time to re paint.

I did mine last year. 1 coat black 3 coats blue . You will still need a yearly haul to do zinks, props, shafts, thrusters and through hulls. Or regular diver cleanings. Anyway the more paint the better to stretch the times between paint jobs.

 

[rslifkin]

!st coat a different color is also a good idea and very standard. Not sure it has to be a hard coat as much as compatable.

I agree that it doesn't need to be hard. Compatible is key. But if you can use a compatible hard paint it should avoid concern for ever wearing through to the barrier coat.

 

[Comodave]

Hiven the somewhat different hull style I would call Interlux and ask them how much epoxy barrier coat paint is needed. They will tell you the number of gallons to use, not coats because my coat is likely a different thickness coat than yours. In the past I called and they said use X number of gallons, then keep coating until the paint is used up. You are looking for a designated thickness and the number of coats is irrelevant. I could do 4 really heavy coats and it may take you 6 coats to get the same thickness. Also 1 or even 2 coats is NOT adequate. Probably will need 5 or even 6 coats to get the proper thickness. Timing is critical, you want to apply the next coat when the previous coat is thumbprint dry. Meaning that when you stick your finger into the drying paint you can leave a thumbprint but not get paint on your finger. That way the next coat will stick to the previous coat. If you let it dry completely then you need to sand before the next coat.

It is a lot of work to do it correctly and the yards just want to get the boat out the door. That is why they say 1 or 2 coats is good enough. Ask Interlux how much and listen to them not the yard. The yards have not spent millions researching the paint.

Also make sure they property dewax the hulls before starting using the 2 rag method.

The last boat I did a barrier coat on took 6 coats to use the recommended number of gallons.

 

[psneeld]

Found this on World Cat web site...may have to call them to check when they started....

"The first step in building a boat with a beautiful, smooth, durable hull exterior is using the highest quality gel coat and applying a 100% vinylester barrier coat to the mold. The gel coat provides a beautiful surface that will last for years, and the barrier coat protects against blistering and enhances the cosmetic finish of the gel
To create a powerful barrier between the gel coat surface and heavier glass material, a fine mat fiberglass “skin coat” is laminated into the hull before the build begins"

Be careful when discussing "ablative paints"....there are several variations.

One I used both on my trawler and commercial boats was a bit different than many. It was Interlux Fioberglass Bottomkote NT. Much cheaper and just as effective and many others (depending on vessel usage and water conditions). Its main issue was out of the water for even just a couple days and it needed recoating or sanding prior to launching.

If your boat is going to sit for months in Florida without moving...then ablative may not be your best bet unless you have a diver clean it in moths of little or no use. At that point, if you have a diver in mind, you may want to ask what he/she recommends as a diver can wear off ablatives pretty fast if they aren't used to them (and with diver cleaning constantly they are even less necessary from what I gather)

 

[Comodave]

Found this on World Cat web site...may have to call them to check when they started....

"The first step in building a boat with a beautiful, smooth, durable hull exterior is using the highest quality gel coat and applying a 100% vinylester barrier coat to the mold. The gel coat provides a beautiful surface that will last for years, and the barrier coat protects against blistering and enhances the cosmetic finish of the gel
To create a powerful barrier between the gel coat surface and heavier glass material, a fine mat fiberglass “skin coat” is laminated into the hull before the build begins"

That is fine and good but since the boat is blister free why not do a proper barrier coat job and keep it that way.

 

[SteveK]

That is fine and good but since the boat is blister free why not do a proper barrier coat job and keep it that way.

The way I reads what PS found that hull may already have a built in barrier coat.

 

[Comodave]

The way I reads what PS found that hull may already have a built in barrier coat.

That may be the intent of the layup, but if you feel lucky go ahead and roll the dice. The cost of a good barrier coat will pale in comparison to fixing a blistered hull. The bottom is nice now, why not do whatever you can to keep it that way…

 

[BruceK]

RTF, you need a primer, the selected antifoul will have a specific primer undercoat.
Have you checked with the builder whether vinylester was used in the build? As psn says, that may obviate the need for a barrier coat and the specified primer may suffice.
Perhaps the barrier coat also acts as a primer.
The builder may have recommendations on primer, barrier coats, and antifoul products.

 

[O C Diver]

Barrier coat is measured in mils of thickness. You don't want to put it on thick because you won't know where it's thick enough and where it isn't.

On Slow Hand, Sean sandblasted the bottom down to gelcoat. Then he put 4 thin layers of barrier coat on with a roller. The barrier coat used came in 2 colors, gray and white. By alternating colors, he could make sure that there were no missed spots. While you may not be as OCD as me, doing 2 coats and alternating colors, allows you to make sure you have full coverage.

Here's a link to the post with pictures:

https://www.trawlerforum.com/forums/showpost.php?p=385779&postcount=220

Ted

 

[Comodave]

You want it the proper thickness.

 

[DDW]

According to the literature, if you want it to be a moisture barrier, you need sufficient thickness, and that won't be one coat. If you are wanting it to be a tie coat, then one coat is ok but you need to make sure the yard does the antifouling within the specified time window. It's like 3-7 hours but depends on temperature and also what's going on top. The main thing that is going to make it fail is lack of sanding and cleaning before the first whatever goes on. A lot of yards aren't very good about that.

 

[Pete Meisinger]

Three coats of the barrier paint is pretty normal. Many painters change the color of the middle coat slightly so the owner knows how much is left.

pete

 

[mvweebles]

You want it the proper thickness.

The data sheets I recall give a specific mil thickness so I agree. RT Firefly - if the yard quoted just a single coat, either there is a misunderstanding or they are lazy or they are misinformed.

I think it was Comodave upthread who said figure out how many gallons and apply that. I would only add that it should be with a low-nap roller so coats are relatively thin.

Good luck and congrats.

Peter

 

[RT Firefly]

Greetings,
Mr. DDW raises an interesting point (Post #16). Moisture barrier or "tie" coat. I was non specific when I asked for epoxy+AF. The yard that quoted 1 coat+1 coat and stated they would apply the epoxy THEN while the epoxy was still "tacky" they would apply the AF. Perhaps they were quoting for a "tie" coat?


I don't know what I don't know...yet.


I'll give World Cat a call and ask what they suggest. Stay tuned. Thanks

 

[DDW]

Honestly on a properly built modern fiberglass hull the barrier coat is of questionable value. It sounds like they are using it as a tie coat, and are aware of the time restrictions. Just make sure they sand properly before they lay on the tie coat. I've seen them sand enough but then not clean the dust off (just hosing or vacuuming it isn't enough), or not sand enough so there are still shiny spots, or both. Personally, I'd inspect it when they thought it was ready for coating, looking for any missed (shiny) spots, and run my fingers on the surface to see if any dust was left. Or wipe with a Swiffer dusting cloth and see what comes off. People call me OCD about this stuff, but I've never had adhesion problems on my bottom paint, either.

 

[psneeld]

That is fine and good but since the boat is blister free why not do a proper barrier coat job and keep it that way.

I see a lack of understanding vinylester chemistry, history and effectiveness in water intrusion prevention and adhesiveness in too many posts.

 

[Comodave]

I understand the vinylester resins and blisters, but my point is that he has a pristine hull in the boat now, why not do a barrel coat. It certainly won’t hurt and who knows it may help. Small cost in the scheme of buying a boat and it could save tens of thousands of dollars in the future. Our last boat had blisters and the PO spent $18K to have it peeled and repaired and that was about 20 years ago. Hate to think of the currency price…