What barrier coat to use...

[Bob Todd]

I know you might just as well ask what method makes the best coffee, because I'll probably get as many different answers.My bottom is being sandblasted today. I intend to use an ablative paint afterward. I was leaning toward Interlux barrier coat. Comments? Suggestions?Cheers,BobNonsuch 30 ClassicLazybones

 

[Daryl]

Barrier Coat

I've used VC Tar, a West Marine Epoxy Product and Interlux 2000. I like the epoxy and Interlux 2000 better. The stuff gets hard like concrete and did not come out very smooth but that made the bottom paint stick on there well. (Not the best racing finish but best for cruising). The Tar took a long time to cure and was deformed a bit by the straps on the travel lift. I'd say that finish was smoother than the epoxy and more suited for a recing finish.

 

[Ed Schenck]

Interlux 2000E

Interlux may have a newer product now. I did mine with 2000E in the spring of 2000. As Daryl states, it is a very hard 2-part epoxy paint. Unlike his experience mine seemed very smooth to me. Not as smooth as the gelcoat but very nearly so. I put on five coats by the book. I had no blisters and it was suggested that I really did not need a barrier-coat. But I just liked the idea of a waterproof hull. And with a modified-epoxy anti-fouling paint(Trinidad SR) I have a hard and fast bottom(on the boat).

 

[Affinity]

Interlux 2000/2001

I have used the Interlux 2000/2001 (ck to see if there is a newer better product) successfully. It requires five coats. To make smooth do a couple of things of which there are several options. Put on six coats and sand lightly. Use a very short nap roller and really roll the stuff out. Another option, after the five coats put on a hard paint and sand that before putting on your ablative. If you don't race, just put on five coats and put on your ablative before the last coat of barrier coat drys and then a second coat of ablative. Best of luck.

 

[Bob Todd]

I intend to...

...spray the barrier coat on.

 

[jprieto]

Bottom Paint

Bob: A post about 3 months ago said that a Chesapeake Bay sailor had used an epoxy copper bottom paint for the first coat, and two ablative bottom paints of a color different from the next two coats. Then every year at haulout he lightly abraided the showing bottom ablative coat with a nylon scrubber. The show- through of the first coat's different color allowed him to identify the few spots which needed touchup with ablative paint. He said his bottom paint had lasted for 4 years and he figured he would probably get 5 years out of it before he had to redo the bottom. The Bay is a very challenging place for boat bottom paints because of various pollutants, so I'd say his scheme is a good one, and we will use it this spring on a new boat.

 

[Bob Todd]

WJ...

I planned on doing exactly that. I've always thought it was a great idea.Cheers,Bob

 

[Gord May]

Epoxy

I prefer the WEST System Epoxy Barrier Coat system - http://www.westsystem.com/See the Basic Users’ Manual - http://www.westsystem.com/webpages/userinfo/manual/and also “ Gelcoat Blisters: Diagnosis, Repair & Prevention” Publication #002-650But if using “Interlux”:After cleaning (sandblasting, in your case) and DRYING out the hull apply “Interprotect” #1000/1001 or “Epiglass HT” #9000 Epoxy Resin Sealers.Then apply “Interprotect” 2000E/2001E or 3000/3001 Epoxy Barrier coat to a finished (dry) thickness of at least 10 mil (usually 4-5 coats). Pay careful attention to maximumdrying times between coats - or you will have to sand.Finally apply anti-fouling paint.HTH,Gord

 

[filthy liberal scum]

Interlux is the way to go

I did my 79 back in 1991 with the 1001 primer and 5 coats of 2001. havn't seen any reoccurence of any blisters to this day. however i might add that i removed the gel coat by sanding with a high powered 7" sander. comp to todays peelers. from everthing i've read on the issue is, sand blasting isn;t the way to go. you can't get all the impurities out so as to get a good clean and dry substrate. Dry is the key. when blistering first became a big issue back in the late 80's and 90's some companies were doing the sand blasting thind but a lot of them were coming back after a few years needing it to be redone. some company in new england was recommending peeling and was giving a 10 yr warrenty with their job. i did a slightly different method and have gotten about 14 yrs and still no signs of reoccurence.

 

[Gord May]

Soda Blasting ?

Capn Jim makes a good point about sand blasting (surface & environmental contamination).I've used (actually, specified & supervised) "Soda Blasting" on "live" high voltage electrical apparatus, and wonder if anyone has any experience with it on boat hulls?Seems like a possible solution, to me.Gord

 

[filthy liberal scum]

one item i forgot

by sand blasting you are mostly roughing the surface and clearing surface contaminents only. to dry quickly and thouraly the gel coat needs to be removed. with the gel coat removed the end grains of the glass are exposed enhancing the ability to dry quickly and to be able to clean sustrate properly. from what i've heard and witnessed it can take months or longer for a hull to dry properly without going to extreme measures such as tenting and dehumidfying. my theory is if you're going to do it.Do it right and do it only once. it's a lot of work and money to be redoing it after only a few years. also the second time around its even worse considering how hard the epoxy is.