Repairing bubbles in ply?

[aprayinbear]

:?:

Not long after building my first boat I found several bubbles forming where the ply partially delaminated. The bubbles were only on one side panel of the boat. I used standard BC exterior ply which I epoxied, taped and then applied numerous coats of exterior paint. As they didn't continue growing, I've continued using the boat and forgot about the bubbles. Now that it's getting warmer, I'd like to repair the bubbles.

Any suggestions for how to repair? Has anyone else had this problem in the past?

Duffy

 

[Kayak Jack]

First thing is to find out how many layers deep the bubble originates. Something is likely to be degenerating down there, and trouble is probably forming.

If it is moisture under the outer layer of paint, you're exceedingly lucky. Sand it out and repaint. If it's a layer deeper, you may have to cut out a piece of wood - glass & all - and replace it.

If it's the latter case, I'd drill holes at the corners of the affected area, use a keyhole saw or hand held, electric jig saw and cut out the bad wood. Once it's out, carefully inspect the edges to make sure you got all the decay out and are back to solid wood.

Lay a piece of cardboard up against the side, and draw a pencil line around to get the shape of the needed patch. Cut a patch from something of the same thickness as the original material.

Lay glass over both the inside and outside, cutting a piece that overlaps about 2" on all sides. IE: make the glass patch 4" wider than the hole.

I'm a bit fussy, and use only Okoume mahogany plywood. More skillful builders can use lesser wood. I'm not only fussy about strength, I'm not a skilled craftsman. I have to use the best stuff to make up for my ham-fistedness.

Other builders will provide more advice, some of which may conflict with mine. Listen to them.

 

[oldsparkey]

If the bubbles are not some moisture under the paint.........

You could follow Jacks way with making a templet but you will have the templet when you cut the piece out.

Mark the area , then using a 1/16th drill bit drill several holes in the wood in a line and touching each other along the line you have marked. Now using a very fine hand saw cut the rest out.
The cut out piece becomes the templet , put it on the good wood and mark around it , cut that piece out by cutting just outside of the line (the line is the cut area in the boat. If you have done this correctly the new piece should fit in the hole nice and snug , if not then some light sanding will do the trick.

This is the same process for putting hatches in the deck of a kayak. Then do like jack said and glass the repair overlapping the glass on the good wood outside or past the replaced piece.

Chuck.

 

[Kayak Jack]

Thanks, Chuck.

Actually, I meant to also say to roughly sand the area around the hole after the bad chunk is removed. Sand back about 3" all around the hole. This will provide something for the new epoxy to grab on to.

Mix up some thickened epoxy with wood flour to about the consistency of peanut butter. Wipe clear epoxy (unthickened) on all edges of raw wood, and all over your new patch. Artfully gob on some thickened epoxy around the edges of the patch so it serves as a gasket between the patch and parent material.

Now, install the patch as I said above, with a large piece of glass inside and outside.

You must wear vinyl or latex gloves while working with epoxy. don't get it on your skin, and if you do remove it. Do not remove it with solvent as that will wash chemicals into your skin.

 

[Kahuna]

You can

You can also get a syringe and drill a small hole in the bubble and fill with epoxy. Maybe not as asthetic but it works. My two cents worth. :lol:

KAHUNA

 

[sheena's dad]

aprayinbear;

It sounds as if your problem might be a void in your ply that may have been holding some moisture in it still when you applied your epoxy. Since the boat's already built, you should probably stick to Jack's remedy of using the 'dutchman', as that would be your best alternative. Drilling a few small holes and using a syringe type glue applicator would work also but you'd have to ensure you were able to have a way to clamp the bubble(s) flat while the glue dries. I've had similar problems in the past with some furniture projects because of void in the ply.

Also, as Jack suggested, be sure to rough sand around the hole as well as the inside edged both the cut out and the insert to ensure you get proper wood penetration with your epoxy or glue. It will provide some extra strength to your repair.

Sheena's Dad

 

[Kayak Jack]

Whenever an outer coating raises or bubbles up from the inside - the outer coating is still integral and unbroken, only swelled up - there is something wrong down deeper. No cosmetic fix will work.

If your arm seems to have an extra elbow, don't bother with a band aid.

Another example of that is paint on a vehicle bubbling up, but the paint isn't broken. This is from corrosion UNDER the paint. Often, it is caused by water still in the air lines used for painting at the factory. Someone may not have cleaned out the air-water separator on the line, and spray gets onto bare metal, and painted over.

If wood has moisture in it, you will likely get the same effect.

 

[aprayinbear]

bubble update



Just a quick update...... I'm almost finished repairing the bubbles in my boat. Each of the bubbles I cut into seemed to be around a void in the second ply layer. I didn't discover any rot once I cut inside. Sooooooo..... at each location I cut out a football shaped hole over the void. Next I painted on a thin layer over each cutout, filled the void with epoxy and flour past, covered with a piece of fiberglass tape and finished with a saturating coat of epoxy. tomorrow I'll sand smooth and paint. Probably won't be invisible, but not bad either.

Makes me think twice about using exterior ply, then again unless I was making the boat for someone else, I'd probably take the risk.

Thanks for the advice,
Duffy

 

[Kayak Jack]

Duffy,

You just hit on my point. Some builders here get away with using cheaper materials. I personally think that is penny wise and pound foolish. Some (all) other builders are more skilled than I am. I HAVE to have the best materials to make up (somewhat) for my hamfistedness.

AND - hull integrity is pretty important once you pull away from shore. I'm not a really great swimmer either.