Barrier Coat Project

[Benny]

Hi All - I'm seriously thinking of barrier coating my bottom - I mean her bottom - uh, I mean the boat's bottom and just got off the phone with a company who will peel off the gel coat for me and then I will do the barrier coat and bottom paint - he recommended Interprotect from Interlux paints as a good system.

Has anyone gone through nthis process and do you have any advice etc?

I don't have a blister problem but the gel coat is crazed in some small areas. Thanks in advance for the info.

[knottybuoyz]

Hey Benny

I did our 25' express cruiser a few years ago with Interprotect. It's not hard to work with just follow the instructions. I'm assuming you're not going to take all the gelcoat off? The yachtpaint.com web site has good instructions on prepping the surface for barrier coating. Be careful once you get your hull stripped that some of the crazing isn't actually spider cracks. They're potentially problem areas that barrier coat will not fix.

Get good rollers when applying the epoxy barrier coat. The cheap foam type from the big box stores won't work. The epoxy components will eat the foam right off the roller handle in only a few minutes. The best ones I found were the short nap rollers from TimbrMart.

Doing that job outside is almost a must. The fumes from the epoxy paint is noxious and dangerous. A good respirator and tyvek suite (or sleeves) is essential. The stuff gets everywhere!! We followed up with XXX anti-fouling and that's nasty stuff too. Don't ever sand it, the dust will kill ya!

It's a good job for the DIY's as long as you take time to read the instructions!

Good Luck!

Rick

[Benny]

Thanks Rick - yes I did plan on peeling all the gelcoat as it is crazed in several areas - is this a problem? I took off a patch last year of about 18 inches by 30 inches along the strbrd side of the keel which peeled easily with a putty knife and the hull surface under it was a kind of fuzzy or hairy texture. There may have been a less than topnotch repair done to this area in the past. I then patched it with fiberglass resin and primed and painted it along with painting the rest of the bottom. The boat is outside so no prob with enclosed fumes.

[delmarrey]

Like Knottybuoyz says, check out the cracks. Look on the insde of the hull (bilges) where the cracks are to see if the hull is working. A reinforce maybe in the works.

As for the coating, don't mix up more then 4 liters at a time. By the time you get that on it'll start to cure in a 20º C day. If cooler you'll want to put it on thin otherwise it'll run. Three normal coats is good enough.

Port and Stbd.........................._/)

[knottybuoyz]

That almost sounds like a case of de-lamination caused by a poor bond between the gelcoat and the layers of glass/resin or as you say, a crappy repair job. That's not good. You should probably sound the hull before you start.

NAUTICALweb - Delamination: is it serious, doctor?

Surveyors Service 2

Fiberglass Repair by Don Casey

Take a walk around the boat with a small light hammer (you know those kind with the teflon heads) (or a twoonie) and knock on the hull. You'll hear the difference when you strike a void. Take a sharpie marker and draw a circle around where you hear the void. Do this over the whole hull. If there isn't any widespread delamination you won't need to strip the whole boat. If there's voids under the gelcoat you'll have to remove that and repair the area. Depending on the extent of the voids you'd probably be better off fixing rather than stripping as it's a lot less work and expense.

Stripping all the gelcoat completely from the boat is a big job! You're in for a treat for sure. Using Interprotect to rebuild up the proper depth required before painting is going to be a big job too. I think you might get 1 ml per coat and you'll probably need 5-6 to completely fill the weave of a stripped boat. A 1 Gallon kit only covers 300 sq ft and costs about $80. That'll set you back a few bucks!

http://www.yachtpaint.com/USA/hotlin...t_bulletin.pdf

Personally I'd prefer to fix any voids, prep the hull in accordance with the barrier coat mfgr's recommendations, 1 coat of barrier coat (it can take up to 2 weeks inbetween coats with Interprotect) and repaint. Stripping to the glass is an extreme measure and isn't guaranteed to ensure a proper or long lasting solution. I've seen some paint/gelcoat failures and they're not pretty!

[delmarrey]

This is the best roller I have found for epoxy. (I not endorsing W M!) It's EZ to clean and doesn't over saturate.


http://www.westmarine.com/webapp/wcs...key=SiteSearch

[knottybuoyz]

Originally Posted by delmarrey

This is the best roller I have found for epoxy. (I not endorsing W M!) It's EZ to clean and doesn't over saturate.

How do you clean it after using an epoxy based paint like Interprotect?

[delmarrey]

First wipe/squeeze off as much epoxy as possible with rubber (nitrile) gloves.

Submerse it in a sealable container (1 gal. paint can) of (1 liter) MEK. Shake it up for a couple minutes. Replenish the container and do it again, three times is usually good enough. The gloves will not hold up to the MEK for very long. And do this out doors with a respirator.

The used MEK can be poured in to plastic soda bottles. Let it settle for a few days and the left over can be used for pre-rinsing/cleaning or thinning. The epoxy settles to the bottom leaving just a few contaminates in the MEK. When I rinse out brushes I use the used MEK first and finish with clean MEK, which goes right back into the soda bottles. It's recycling (environmental) and saves $$$$ in MEK.

Unless one does a lot of epoxy work (like myself) it might be cheaper to just buy new rollers.

PS Don't use Acetone! It evaporates too fast. MEK is used for desolving/cleaning rubbers in die molds and thining.

[Benny]

Thanks Rick and Delmarrey for the input - the company which would strip the gelcoat does it regularly at my marina and I've seen the bottoms of other boats when stripped and then the owner does the barrier coat. The stripping cost for my boat is $1200.00 CAN and the cost of the barier coat would be about $800 for 10 gallans.

The hull was sounded and metered by a surveyor last year who reports no delamination. I think the crazing may just be the result of a louzy repair or louzy gel coat job. The boat has had hull repairs done in the past. There are no cracks inside the boat so I think it's just a surface problem.

So what I'll probably do is a real close inspection of the bottom and determine if those small areas are only isolated and will just repair them separately.

[irwinsailor]

We did our blister job using the WEST system. It was a great deal of work.

[Tom967]

Having had my boat on the hard for 7 months with all sorts of projects..and learned from pros..You have a fairly simple job...First..If bottom paint still on...Have it sandblasted off..What would take you two weeks..a sandblaster have all the old paint to gel coat in 40 minutes...Now sand your bottom...a few hours with palm sander..Buy a gallon 2 part 3M vinylester fairing compound..You trowel it on with putty knife..One to 2 days...It sands easily...giving you a nicely faired protective bottom.."Never worry about blisters again"..now prime bottom with Petit protect..Then bottom paint..

[AnchorageGuy]

benny, Before you apply any barrier coat the bottom of the boat must dry out thoroughly. That means an overall reading with a moisture meter of less than 3%. Otherwise whatever you apply will blister and your problem will be worse than before. The dryer the better. The crazing in the gelcoat can allowed moisture into the glass unless the boat has been out of the water for some time. This is the leading cause of barrier coat failure.