Is a blue hull "wrong" ?

[CJStokes]

The hull of "Aquarius" was painted a deep blue 2 1/2 yrs ago. Small bubbles have appeared in some areas and I have been told that this is due to the fact that the dark hull retains the sun's heat and this causes condensation which causes the bubbles....If necessary I will paint white but she looks so fine in blue. Any comments ?

[On Vacation]

We need more info. to get a better idea of what we are dealing with. Is it a wooden hull, glassed over wood, alum. painted with a two part poly paint, stuff like that? Pictures?

[CJStokes]

Aquarius is '76 vintage, mahogony ply. Not sure when she was last taken down to wood and I've owned her 5 years. There must be a few layers of paint on the hull (I've put 1 on and had the blue done for me - think it was a couple of layers of "normal" hull paint). I am informed that the boat received some kind of West System treatment in the early 80's but not sure if above or below water line and if this would make any difference?
Thanks

[Donn]

My guess is that whoever did the blue for you, didn't do it right. There are boats around here with blue hulls that do just fine. Yes, they do transmit more heat to the interior of the hull, but any color, if correctly applied to a hull, will last.

[imported_Conrad]

If the boat was spray painted the bubbles could be caused by water drops that came through the gun along with the paint, the result of poorly maintained filters. When the sun heats the surface the trapped water drops expand as they change to water vapor, causing blisters or bubbles in the paint film. Often as not they will go away as the hull cools, only to reappear as it warms up again.

The same can happen with a brushed surface if it isn't completely dry when painted- a little residual dew, or moisture from a final wipe-down with a damp cloth.

Given the hull is plywood, and has been painted before, I doubt the cause is moisture in the wood, or moisture moving through the wood. To check, sand a small bubbled area with some 220 grit sandpaper on a flat block, working slowly to cut the tops off the bubbles. If you see wood under them, there may be moisture that hasn't had a chance to work it's way out. Most likely you'll see the previous paint job/color. This suggests there was moisture contamination on the surface or in the air supply when painted. The cure is to simply sand the surface smooth, cutting all the bubbles open and fairing back their edges, then repaint after making sure everything is completely dry.

Bubbles like those described will appear in all colors, but the darker ones speed the process since the heat absorbtion differential is greater. Planked hulls are more likely to exhibit bubbles than ply hulls since the seams and structure of the wood offer a greater number of paths for moisture to work its way under the paint film, but even they can be painted successfully if done properly.

Finally, some paints, even when supposedly cured, will react with high levels of water much like the osmosis process affecting fiberglass. If this is the case with the paint you used, the bubbles will only be found below the waterline, or at the waterline, and almost never on those surfaces that are usually dry or not immersed. If this describes your situatuion, the only solutions are to change paint brands, or keep the boat drier, i.e. stored on a trailer of lift as opposed to always in the water.

[On Vacation]

Many plywood hulls have a dark color on them. Blisters can be a number of reasons. Most of the time it is either moisture that has gotten behind the finish paint, or improper bonding of the topcoat to the undercoat, for various reasons. Many issues of lack of sanding in the prep work, to the wipe down.

Try popping the blisters and patching the blister areas first before painting the whole hull. When popping the blisters, see if you may have some brown ozzing out or soft wood. Report back. What type of paint was the finish coat? Was it sprayed or brushed? Was it the same paint of your one coat? If it was a diferent paint, what was the two brands?

[CJStokes]

Penultimate (white) coat was rollered on by myself. Can't remember brand of paint, Last (blue) coat was sprayed on. I'll burst a blister next week and report back. Sounds like the colour is not the problem but the way it was applied or similar?

[imported_Conrad]

If when you cut the tops off the bubbles you see white, it's an application problem. Next time change the filters, drain the compressor tank, and add a "pumpkin" paper filter at the spray gun. If you'd paid us to do the job, we'd be setting up a time to repair it for you, for free, since a pro has no excuse for this kind of failure.

If you see wood, it was damp when painted. Sand back as far as you can, spending extra time on the bubbled areas, let it dry completely, and try again. The second time should do it!

[Scott Rosen]

Two and a half years is a long time for any paint job to last. You may not have any problems at all, except normal wear.

If the bubbles are forming under fastener heads, then moisture could be getting in from the inside of the boat and working its way through the path of least resistance, i.e., the fastener holes.

The only paint job that can reasonably be expected to last over two and a half years without needing a recoat would be a two part linear polyurathane like Awlgrip, applied over an epoxy base.

[WFK]

Hi Chris; The blisters will tell you at what layer the problem lies. If you pop a few of those buggers and it show's that it's right down to the epoxy, then I'd say you have a bonding problem between epoxy and what ever primer was used. If that's not the case then I'd go with Conrad and erster,...them guy's know ther stuff!

Bill

[Joe ( Cold Spring on Hudson )]

Oyster
.
Member # 5154
posted 12-29-2002 02:00 PM *** ** * * * **
------------------------------------------------------------------------
We need more info. to get a better idea of what we are dealing with. Is it a wooden hull, glassed over wood, alum. painted with a two part poly paint, stuff like that? Pictures?
--------------------
Foolish pleasure is a boat, but some are owned by fools. WHO CARES :mad:

[JimConlin]

Years ago, Maine lobstermen thaough that having anything on a boat painted blue was unlucky.
Could that be it?

[Ken Hall]

Not wrong...back in '93 at a marina in Fairport Harbor there was a pretty little carvel sloop, vintage 1920-23, with a blue hull. Neat it was. smile.gif

[ 12-30-2002, 10:05 AM: Message edited by: Ken Hall ]

[CJStokes]

Scott, paint looks real fine on most of the hull (except the small blister area) so this must mean that its a 2 part poly paint ? If this is so how long before she will need re-painting again ?

[Scott Rosen]

I've had blisters in two-part paint. One of the problems with two part is that it is much more water and vapor resistant than regular oil based paint. That means that any moisture under the paint cannot be dispelled through the paint film and hence a blister can form. What I've done in the past to prevent the blister from growing larger is to poke a pin hole in the blister at the very edge. That allows the water or vapor to escape.

Chris, if poking pin holes in the blisters stops them from growing, then you could get quite a few more years out of the paint job. Before you do that, though, you should be absolutely certain that the blisters are not a symptom of a bigger underlying problem. If the blisters are forming around fastener heads, then you need to find out how and why water is getting into the fastener hole.

[CJStokes]

Thanks. I'll be spending a few days on her after New Year so I'll go see. I do appreciate your comments