Cruisers Yacht hull delamination advice appreciated

[rourkeh]

The issue with your delamination would be bad enough if it was the only problem you are facing. But these sort of problems are indicative of extremely poor quality control, and I would bet if you sound the entire hull you will find other hollow sounding areas where the chemical bonding or layup is starting to fail. Over time this delamination will continue making the areas you are fixing now look minor in comparison. Very rarely (read never) do manufacturers make small, isolated mistakes like you are seeing now. Walk away before the financial loss become catastrophic.

[HappyMdRSailor]

Boy Oh Boy...

What a mess huh???

I offer the following assumption:
If - A:
The entire skin was prepped and bonded with the same method from start to finish...

Then - B:
The entire skin bond must be suspect and repaired, not just sections that have delaminated...

I would try and see if the injection method will work... Core sample the worst area see what you have.... injection repair said section... Take ANOTHER core sample of the repaired section and see what happened... I would even go so far as to do destructive analysis on the (many) core(s) to verify your core to skin bond of the injected repair... 2" holes are easy to repair...

I only offer this, as minaret thinks it is a possible option... The only other way I see is the expensive way... Reskin the boat... possibly saving the core, possibly not...

I am at best... an amateur composites dood... Bantering my ideas...

[HappyMdRSailor]

Originally Posted by rourkeh

The issue with your delamination would be bad enough if it was the only problem you are facing. But these sort of problems are indicative of extremely poor quality control, and I would bet if you sound the entire hull you will find other hollow sounding areas where the chemical bonding or layup is starting to fail. Over time this delamination will continue making the areas you are fixing now look minor in comparison. Very rarely (read never) do manufacturers make small, isolated mistakes like you are seeing now. Walk away before the financial loss become catastrophic.

And this statement has extreme merit...

[minaret]

Originally Posted by HappyMdRSailor

And this statement has extreme merit...

Based on past work on these boats, I'd agree with that statement. Had dealings with the factory on that one, and it wasn't reassuring.

[darylat8750]

I'm not a real fiberglass man but it's the internet so I'll put in my 2 cents worth anyway.

The boat is in Green Bay with very low hours so it's been out of the water most of it's life and already has serious issues. It is very possible that much larger issues are waiting to be reveled with more time of immersion. I would be very concerned that after this part of the hull was fixed the same type of issue would present it's self somewhere else. If I were intending to use this boat myself I would be inclined to take out everything that goes through the hull, strip off the entire outer shell and after checking the bond of the core, replace as required. I would also take off anything that is attached to the hull inside and out and make sure there is no rot in the core at each location and carefully re-bed every screw. Someone mentioned trying to get an outer shell from the factory. I don't know how that would work but if so it may make sense.

[Cadence]

Maybe I'm getting in a crass mood? I can't see any solution worth the time, money and effort. The only real solution would seem to be strip the outer hull replace what core needs it and lay up a new outer skin. I wouldn't try that without an inverted hull.

[jimbunyard]

Originally Posted by Three Sisters

If your boat is outdrive equipped it may be a good time to remove both of them to survey the surrounding transom core.

To inspect the transom core entails pulling the gimbal housings, which entails pulling the engines. Given the glasswork already eminent, it might be easier just to drill strategically placed cores around the drives.

Originally Posted by Cadence

Maybe I'm getting in a crass mood? I can't see any solution worth the time, money and effort. The only real solution would seem to be strip the outer hull replace what core needs it and lay up a new outer skin. I wouldn't try that without an inverted hull.

Inversion would be a big job, not impossible but perhaps unnecessary. Seems much simpler to build a jig to support one side, rotate the hull 70-80 degrees, repair the exposed side, switch the jig to the other side, rotate and repair the other side.

[Cheechako]

Originally Posted by mealsonreels

Hello,
I bought a 2002 Cruisers 3572 as a project boat. The boat is in great shape, but for whatever reason there are large sections of the hull where the outer glass skin is separated from the core. These areas start about 5 feet back from the front and continue back to just in front of the engine room.
I've been advised of a couple different methods of repair. Some say to drill holes and inject resin to fill the voids, then anchor the repair with screws until the resin cures.
Others say to skin the areas in sections, inspect the core, and glass the sections back on. All the delam is below the waterline so it's all covered by paint.
I'm favoring the second method of taking off 3 foot wide sections of the hull from the waterline to the bottom, making sure the core is ok, and re glassing the sections back on with thickened epoxy. A vacuum bag or screws would be used to hold the section in place.

Has anyone done a project like this? Any advice would be appreciated regarding how to cut the sections, split the parts of the skin from the core that are still attached, and how to anchor the piece while it's curing.


I've had a fair amount of experience with doing fiberglass work on boats. Also, the boat is inside my shop with a controlled environment.

Thank you

I had this done on a boat I had. On that boat I would not do it again. The reason is the outer skin of the boat was thick enough to have been an uncored boat anyway. I could have thought of the core as insulation. Even the inner skin was fairly thick on that boat. So $30000 later I had a freshly painted boat with the gaps filled with epoxy, but it was probably unnecessary.
But if your boat doesn't have a thick layup, then the core being attached is a part of the structural design.
BTW, to inject the epoxy ..... inject in the low hole and fill until it comes out the upper hole further up the hull. You need an air or electric operated injector... or you're going to have forearms like Popeye!
Some manufacturers are better than others, but fiberglass shrinks.. a lot... over time. I'm a non believer in cored hulls over time lasting. Some do I guess... but I think it's trouble waiting to happen.


BTW, this boat was resold again last year ...21 years and two owners later... and surveyed fine.

[mealsonreels]

Originally Posted by Cheechako

I had this done on a boat I had. On that boat I would not do it again. The reason is the outer skin of the boat was thick enough to have been an uncored boat anyway. I could have thought of the core as insulation. Even the inner skin was fairly thick on that boat. So $30000 later I had a freshly painted boat with the gaps filled with epoxy, but it was probably unnecessary.
But if your boat doesn't have a thick layup, then the core being attached is a part of the structural design.
BTW, to inject the epoxy ..... inject in the low hole and fill until it comes out the upper hole further up the hull. You need an air or electric operated injector... or you're going to have forearms like Popeye!
Some manufacturers are better than others, but fiberglass shrinks.. a lot... over time. I'm a non believer in cored hulls over time lasting. Some do I guess... but I think it's trouble waiting to happen.


BTW, this boat was resold again last year ...21 years and two owners later... and surveyed fine.

How large was the area of delam? Was the core dry? Any guess as to why it happened in the first place?

[Cheechako]

Originally Posted by mealsonreels

How large was the area of delam? Was the core dry? Any guess as to why it happened in the first place?

Most of the boat. Worse in some areas (Beam) and not much in others. Dry core. Probably the balsa wasn't wetted enough with resin prior, hulls shrink and change shape over time, so a gap occurred. Balsa soaks up resin like a sponge, so if you don't put a lot on on in the first place you end up with a dry laminate. Fortunately the boat was only cored to ~6" above the waterline.... which is probably why it was a thick layup in the first place, they just laid up a hull and then cored it above the waterline.
It was discovered on survey, I paid half the agreed price for the boat and went forward.

[Cadence]

Originally Posted by jimbunyard

To inspect the transom core entails pulling the gimbal housings, which entails pulling the engines. Given the glasswork already eminent, it might be easier just to drill strategically placed cores around the drives.



Inversion would be a big job, not impossible but perhaps unnecessary. Seems much simpler to build a jig to support one side, rotate the hull 70-80 degrees, repair the exposed side, switch the jig to the other side, rotate and repair the other side.

I built one 48' upside down and turned it over with chain falls and a hell of a cradle . Anything is possible. A nice guy,I know, tried building upright, a disaster. I only had to glass the top of the skeg up side down about drove me crazy.

[Three Sisters]

Originally Posted by Cheechako

Most of the boat. Worse in some areas (Beam) and not much in others. Dry core. Probably the balsa wasn't wetted enough with resin prior, hulls shrink and change shape over time, so a gap occurred. Balsa soaks up resin like a sponge, so if you don't put a lot on on in the first place you end up with a dry laminate. Fortunately the boat was only cored to ~6" above the waterline.... which is probably why it was a thick layup in the first place, they just laid up a hull and then cored it above the waterline.
It was discovered on survey, I paid half the agreed price for the boat and went forward.

Viking yachts were known to build with this method. The advice bantered about was/is to pay close attention around portlights, engine room vents and such.

Always admired the exterior design used for the cabin.

[Zach]

If you go with the injection route:

Co-Poxy offers an slower cure tropical hardener than most other brands, that stretches the open working time of 460 minutes at 77f. That means you have a longer shot time before you have to move injection sites and you get more resin in before it starts to set up.

I use West Systems for most hand layup and wood work, but sometimes other brands have some novel solutions.

[Dymaxion]

Would a vacuum infusion approach be suitable for fixing this delam? Thinking a series of small holes in line a few inches apart could serve as the infusion or vacuum channels. Rows of holes aligned vertically, say a foot between rows. I'm assuming this is a manufacturing related delam, no wet core.

[UNCIVILIZED]

In order to Truly test the integrity of the core, as well as the quality of the bonds of the core to the skins (on both sides). What needs doing, is to attach a high pressure vacuum clamp (like a suction cup on steroids) to a section of the skin. Then the cut through the full depth of the outer skin, in a specified radius around the clamp.

Followed by which, a machine, exerting a powerful straight line pull, perpendicular to that section of hull, is attached to the clamp, & switched on. Where upon it pulls with ever increasing force, until the pre-cut section of skin comes off of the boat’s structure (hopefully with a loud bang), with or without core or core fragments attached to the skin coupon.

What you want in such a test, ideally, is for there to be severly torn/sheared pieces of the core to be attached, both to the excised skin coupon, & to the hull’s inner skin. As this indicates that the skin to core bonds are good on both sides. Because the core tore/sheared, under the heavy load applied to it, vs. the skin to core bonds failing.

Whereas, if you have core that is primarily intact, on one skin or the other. Then the skin to bond strength is poor. Primarily on whichever piece of skin has little core attached to it, in that area of the boat anyway. And thus, you likely have a seriously major repair on your hands.
If, in fact, it even makes sense to do so from a dollars to recoupled costs standpoint, when selling her type perspective.

Also, you can look at the condition of the kerfs in the core, in sections of the hull, in & around the area of the test coupon, to see how well they are/were filled in during the vessel’s construction. Which, of course, is another indication of build quality.

There’s more detailed information on this type of test in Professional Boatbuilder magazine. Including the tools & techniques involved. Plus more details regarding what such tests reveal. In addition to other recommended tests for questionable core bonds in boats.

And I hate to sound negative, but then again, they’re not my words. For when considering a boat, & or a refit, Nigel Calder states: “If there’s any question that there are structural issues, just walk away”.
A Refit Reality Check | Cruising World

PS: For a "quick peek" at inverting a boat in order to work on her outer skin. There's a video series on YouTube, where a Cal 40' is getting a TOTAL overhaul/refit. And they invert her as part of this. Albeit, basically just to properly refair her bottom. NOT to do a full on structural rebuild of her hull.
Inverting a boat for that, along with the necessary level of internal hull & bulkhead supports, so that the hull shape stayed true, would be HUGE. As would be the (literally) thousands of man hours which would go into refairing her, after the structural rebuild work was done.

https://www.youtube.com/watch?v=TxHG...itzFHsqu1pxDAO