Hull void/de-lamination

[Stanleywester]

I've got a 1976 Catalina 22. New to me. It's generally in excellent shape for it's age and I've had it on the water for a few days this winter but it's back on the hard now. I've recently discovered that I missed something before I purchased it; which may be a major issue.

This hull is one of the ones that had the plywood stringers either side of the keel trunk (and as usual they're waterlogged - it's on my list to deal with). However, this is a different and more terrifying issue. On the port side, about 6" aport/above of that plywood stringer, visible inside the aft dinette access cover there's a giant bubble of fiberglass. It runs from the lazarette bulkhead to the dinette foot-well which is at least 24" in the fore-aft direction and 18" the other direction. It knocks hollow, and I can put pressure on it with my palm and deflect it downwards at least 1/4". I haven't pushed harder for fear that I would crack the fiberglass. Knowing the thickness of the fiberglass hull, I would estimate that it's about 1/3 of the thickness of the hull which has popped, but without drilling exploratory holes, I can't confirm this. Without removing the dinette sole, I can't tell if it also exists under the dinette. I also can't tell if it exists further abaft (in the port lazarette) as this area seems to have an extra layer of smooth finished glass over it.

I can't see any reason this should have happened. I don't believe there's any wooden layer sandwiched between fibreglass layers (or am I wrong about that?); I thought the hull was 100% glass/resin. So I can only assume it's layers of glass that have separated from each other. There's no thru-hulls anywhere near it, the boat doesn't take on water from below (though it does take on some rain - also at the top of my list). I can hear (I think) some difference when I knock on the hull from outside, but I'm not exactly sure what I'm listening for or how the placement on the trailer may be affecting the sound of my tapping.

Before I start drilling exploratory holes through the separated layer, I wanted to post to see if anyone else has dealt with this sort of apparent de-lamination and how they did it... without removing the deck and removing the entire cabin sole... yikes. Or if it's advisable to ignore it...

I've attached photos, though the bubble is so big that it's almost impossible to see in the photos. I have a video of me knocking and depressing it, which I'll upload if anyone thinks it's worthwhile?

Thanks in advance to anyone willing to chime in.

 

[LakeShark]

You might want to circle the suspect area in your photos as the bubble is hard to see and the video would help too I am sure. Based on location is there a trailer bunk that may have depressed the hull causing some "oil canning" and creating the bubble? As for the hull make up you are correct it is all fiberglass with no plywood in the lamination. If there are no noticeable cracks on the outside of the hull and your certain it is delamination from the inside you may be in for a large repair that might not be worth it IMHO. If you are near any active fleets within the Catalina 22 association I would reach out. The early hull numbers are often turned into race boats and guys have done everything to them to make them fast and smooth. Likely someone will know more about the issue. Also the Catalina 22 face book page is far more active these days than this forum so you might find additional help there as well.

At the end of the day if I bought it to sail it and not race it I would likely wait till it got worse or started leaking. If your taking to the ocean though or planning to sail hard then I would start exploring the extent of the damage. If its too severe then I would find a hull in better shape and transfer over the best component's from both boats and scrap the bad hull. Sorry for the bad news.

 

[dlochner]

It appears that the hull has been patched. The edge of the patch is visible where the arrow is pointing.

If it has been patched, this is mixed news. The good news is what you are seeing and feeling may just be the result of the resin failing to adhere to the hull due to a poor layup and repair. The bad news, we don't know why the hull needed patching.

Notice the gelcoat or paint on some of the roving is also missing. This could be from normal wear and tear or it could be from sanding before applying the patch.

At this stage of the game, I'd be inclined to remove the bottom paint and barrier coat (if any) on the outside of the hull. Look for evidence of damage. What you might find is missing or mismatched gelcoat or fairing compound that would indicate a repair. If you have access to a similar vintage C22, take a look at the same area, is there roving? Does the lay up look similar?

Let's give the forum a day or so to respond, see what the brain trust comes up with. I think there is an active Catalina 22 class association. They would be another good resource.

 

[LakeShark]

One other thought, Did the hull sit with water in it for an extended period of time? This may also cause delamination but you would likely see it in other areas as well.

 

[Stanleywester]

Thanks for the replies thus far!

Here's the video:

Hope you can hear the difference in taps. It's also tricky to see the deflection but it is there.
Photo with raised area circled attached. At a rough guess, it is right above the trailer bunk. I can measure this today and report back.
The exterior hull looks smooth and fair; and not oil-canned (presently). I suppose sanding off might be the thing to do as you said.

Yes, it will be ocean only... not racing, just pleasure sailing.

There's doesn't seem to be a nat'l association here (west coast of Canada) but I might try the facebook group.

One other thought, Did the hull sit with water in it for an extended period of time? This may also cause delamination but you would likely see it in other areas as well.

The PO had the boat in the water at a marina for 5 months straight last winter. I've only had it in for 4 days this year. I'll do a thorough inspection of the inner hull and see what I can see.

 

[LakeShark]

If I were to guess I would say there was a good chance it bounced on the trailer bunk pretty hard going down the road. The taping defiantly sounds like a void but I would tap form the outside as well and see if it matches up. Either way it may be a slightly weaker part of the boat but I would sail on it particularly if its to be trailer sailed as you would notice any larger issues when you hauled out after each trip. As for the Association the Facebook group is a great place to start and there is a Tech manual with tons of information in it available here: https://www.catalina22.org/


Also if you do a search on this forum some years back I believe there was a guy that scrapped a hull and cut it into sections with lots of pictures so you could see a cross section of the hull.

 

[LakeShark]

Bingo Found it

Cut up hull pictures for reference

I purchased a different trailer for my 1977 last year and when I went to pick it up the owner had this 1974 Cat 22 hull in pieces that he could then place in a dumpster. I took the opportunity to get some quick pics for future reference on the build of our Cats. Please note the flotation foam in...

forums.sailboatowners.com

There are tons of pictures here and the only plywood is the transom area. You can ignore the foam as it was a dealer add in some boats to make them "unsinkable". Problem was the dumb stuff absorbed moisture and never provided enough positive flotation so it was later abandoned as an option.

 

[Stanleywester]

Yeah, I had looked thoroughly at those photos to determine how my hull was made, as that cut up hull was a similar vintage. What was surprising is that on that cut up hull, the hull thickness appears to only be about 1/8" to 1/4"?! Is that really the case. On the bottom of the hull, where I drilled for a new seacock, there was almost 3/4" of fibreglass there! (underneath the waterlogged plywood). In those photos, even the bottom glass looks very thin, not like what I found when I drilled through at all....

Not sure how I missed this....
There is an approximately matching depression on the exterior of the hull. I'm wondering now if when I press on the bubble inside, I'm actually flexing the entire depression in the hull. You can see the depression at about 52 seconds into the video.

 

[LakeShark]

Yeah, I had looked thoroughly at those photos to determine how my hull was made, as that cut up hull was a similar vintage. What was surprising is that on that cut up hull, the hull thickness appears to only be about 1/8" to 1/4"?! Is that really the case. On the bottom of the hull, where I drilled for a new seacock, there was almost 3/4" of fiberglass there! (underneath the waterlogged plywood). In those photos, even the bottom glass looks very thin, not like what I found when I drilled through at all....

Not sure how I missed this....
There is an approximately matching depression on the exterior of the hull. I'm wondering now if when I press on the bubble inside, I'm actually flexing the entire depression in the hull. You can see the depression at about 52 seconds into the video.

Yup the hull is not that thick and while I have never cut up a boat I do know from sailing my own hard (racing and heavy weather sailing) that you can flex the hull at times coming off waves. This past summer while cruising the apostles I had so much sail up and speed that we surfed down the back side of a wave and submarined the bow into the next wave taking water all the way into the cockpit.

Boat recovered just fine though and Lake Superior mellowed out a bit after that. Likely that depression was from a broken bunk or something at one time or another. I would check the Catalina 22 Tec manual (reverenced earlier) for proper bunk alignment and likely hope it flattens back out in time or with some summer heat. Otherwise I would not worry too much until it becomes a larger problem but I do like to live dangerously at times

To check your theory have someone look underneath while you push on the hull to see if it moves.

 

[Stanleywester]

To check your theory have someone look underneath while you push on the hull to see if it moves.

Thanks, working on that now!

 

[dlochner]

Yeah, I had looked thoroughly at those photos to determine how my hull was made, as that cut up hull was a similar vintage. What was surprising is that on that cut up hull, the hull thickness appears to only be about 1/8" to 1/4"?! Is that really the case. On the bottom of the hull, where I drilled for a new seacock, there was almost 3/4" of fibreglass there! (underneath the waterlogged plywood). In those photos, even the bottom glass looks very thin, not like what I found when I drilled through at all....

Hull thickness varies with the amount of stress that area of the hull will be subjected to. The thickest areas are the parts supporting the keel it then tapers up to be fairly thin. If your Cat 22 had a ¾" thick hull from the keel to gunwale, it would be at least 2 to 3 times as heavy and no longer a trailer sailor.

The deck skins are also fairly thin, but typically have a plywood, balsa, or foam core to build up thickness without adding much weight.

 

[pclarksurf]

Reading with interest--- the one place I have yet to throw a grinder is on the hull itself, but based on my '73's experience in overall glass layup and general construction: I don't think I'd be all that concerned actually.

I would straight up grind the bubble out to solid glass-- granted take a small sample in the middle of the bubble as an exploratory view, but my guess is you find mass behind you-- and the only way to fix this in my opinion is grind and fill it back with glass and resin (you'll be better than new).

Not an example of the hull of course but look at this straight on view of the cockpit sole (deck skins similar). Voids and generally sloppy layup are par for the course with our inexpensive production line boats.

And think about that --50 years! she's going have some imperfections by now....

and @LakeShark nailed it with the cross section: I assume this is all but exact on your problem section: Question then becomes are the two layers deviating from themselves or do you just have a bubble in the inner skin?

 

[Stanleywester]

So, there is no void. When I press on the bubble, the matching dent on the outside flexes. Don't know if that's good news or bad. I also regret testing it by pressing on it, as I can hear fibers grinding when I did so. I guess this is "oil-canning". What's the standard procedure for dealing with it? If any...

Force it to pop out, resin down a sheet of G10 as a stringer, and glass over it?

Or sand the outside down to the glass, fill in the indent with a mass of glass/resin, new gel coat, new bottom paint?

Or ignore it...

 

[pclarksurf]

If it's straight oil canning (common) then either ignore it (assuming you have remediated root cause--- aka don't let it continue unabated)

or you could attempt to "spring" it out and attempt to reinforce the new shape with a combo of Glass (if that will hold it) or a broad backer if necessary. I wouldn't go any further than that.

 

[LakeShark]

@Stanleywester I think @pclarksurf nailed it on this one. If it does not bother you then I would leave it. In fact it may even pop itself back out in the summer heat one day. Just be sure the bunks are good on the trailer and properly supporting the hull in the right places.

 

[Stanleywester]

Thank you all kindly for the advice. This forum and the folks here are genuine treasures!