Barrier Coat Question

[karista]

When the boat was new (1990) 4 coats of VC-TAR Barrier coat was put on. It held up well until the last haul out when I had about 4 blisters on each side which were repaired. Now my diver tells me that there is 1 blister on each side. The boat is scheduled to be hauled for new paint in the fall. I planning to have the paint and VC-Tar removed to the gel coat and 5 coats of Interlux 2000E barrier coat applied (about $5k ). Could I simply have the paint removed to the VC Tar and then apply the 5 coats of the Interlux 2000E on top of the VC-Tar?

[KWKloeber]

Thoroughly sand the VC tar w/ 80 grit to ensure a good physical bond.
Then apply 2000E atop the VC tar.

Be sure you have all the VC-17 (if that was your anti-foul) is off before the 2000E goes on.

Ken

[Stu Jackson]

Before you do anything, what size blisters?

[karista]

Before you do anything, what size blisters?

Quater Size although one was quite large about 1 " in DIA!

[karista]

Thoroughly sand the VC tar w/ 80 grit to ensure a good physical bond.
Then apply 2000E atop the VC tar.

Be sure you have all the VC-17 (if that was your anti-foul) is off before the 2000E goes on.

Ken

Ken
The yard is doing the job and they plan to use their Water/Vapor blasting system to blast the paint and VC Tar off. So there will be no sanding required. So I am not sure how smooth the VC Tar would be if they only blast off the paint. I guess if it needs to be rough sanded than I may as well have them take it down to the gel coat as then its protection would be compromised.

[KWKloeber]

What bottom paint is on there?
Sanding for physical adhesion won't compromise the barrier protection, per se, but does remove some of the thickness, but the 2000E replaces what's lost.
ie, it;s unnecessary to remove the VC Tar except to spend more money - YBYC. 
The gel should be rough sanded for better physical adhesion.

[Noah]

Bernie- i would just grind, fill, and prime those two blisters and reapply new bottom paint. Messing with  barrier coat IMO is unnecessary, based upon two blisters or even a dozen...

[scgunner]

      Wow, eight blisters, you're breaking my heart. Every four years when I haul Top Gun to do the bottom I find a minimum of 400 blisters and that's on a good haul out. No, I don't have a barrier coat, it wasn't very common back then. I just drill then out with a wood bit, let dry out, fill with West Systems, sand smooth, prime, apply bottom paint and it's good to go for another four years. I've been doing it like this for 29 yrs.

[Noah]

If your "zit popping ritual" hasn't gotten old by now, guess there is no reason to blast and barrier coat. Doubtleful even 400 dime size blisters would cause hull failure, as they most likely they are just surface, but IMO it would kinda make it a pain to sand and paint and to have a fair/fast bottom. To each his own.

[mark_53]

I'd have to agree with Noah. 2 blisters is no reason to spend $5K. I had about 9 this year. Grind out, fill, prime, and paint.

[scgunner]

    Noah,

      It's not kind of a pain, it's a real pain in the a**. Four hard days every four years vs. 5 to 8 thousand dollars(depending on who you talk to)for a barrier coat. At this point drilling and filling is still less painful than writing that check.

[Rick Roberts]

When we dropped the keel this year and I ended up redoing the whole bottom. Stripped it back to the gel coat and used a product called **Amercoat 235** as a barrier coat. It's used for oil rig structures and under water pipes. It's a fraction of the price, its stronger and thicker. Much superior to any other marine product that I have seen!!

But if you only have a few blisters, I don't think it worth redoing the whole barrier coat. I compare blister to rust on a car... Yeah it looks funny but won't really affect the performance or sink your boat. Unless it's the size of a pamplemousse...

[Ron Hill]

Benrd : I agree with Ken.  I'd blast off the paint and then only scratch up the VC Tar so the new Interlux 2000 will adhere.
There is a real problem with blasting thru the old barrier, but not blast into/thru the gelcoat!!!!

My thought

[karista]

Benrd : I agree with Ken.  I'd blast off the paint and then only scratch up the VC Tar so the new Interlux 2000 will adhere.
There is a real problem with blasting thru the old barrier, but not blast into/thru the gelcoat!!!!

My thought

Ron
I decided to follow Noah's advice and had the yard simply repair the blisters they found. They ground them off and then laid a layer of fiberglass matte followed by a layer of epoxy to each blister, which then they sanded down and applied a barrier coat over the repaired area.
I called Interlux and they told me that the  VC Tar barrier coat MUST be totally removed before the Interlux 2000 barrier coat can be applied.

All this may all be meaningless as I don't know whether the boat or my house will still be there, once I am able to return, we live on one of St Petersburg barrier Islands, (Tierra Verde), no one currently is allowed back in after Irma went thru last night. We are in a Hotel currently w/o power.

[Ron Hill]

Benrd : I'll crank up the "prayer wheel" and surely hope things are salvageable.

Best of luck, A thought