Lagoon 380 de-lamination

[Be Free Sailor]

Hi, does anyone have experience with what feels/sounds like de-lamination of the hull skin?
The hull above the waterline is balsa cored (Lagoon 380) and I am guessing the balsa core and GRP skin has detached, for some reason.
No visible damage, inside/outside.
According to the boatyard, the repair will be made from the inside, by removing the cabinetry and cutting out the inside GRP shell and balsa core, before rebuilding everything back to "like new" from the inside.
Did anyone experience a similar issue, and how did you have it fixed? And could the cabinetry be put back together, without any visible marks?
I am thinking, maybe it could be repaired by a "vacuum infusion" of resin, from a couple of small drilled holes in the outside GRP skin?...
https://files.fm/u/wx9d5733d
See the video link, where you can "hear" the cracking sound while I press on the affected area of the boat.
Input appreciated!

[Sand crab]

I'd repair that from the outside, it's way cheaper like 10 times cheaper. Unless that's separated from the bulkhead inside then it becomes a big job. If it's a small area then your idea of injecting epoxy sounds great but you might be able to forego the vacuum infusion part. You can buy epoxy in a caulking tube with mixing nozzles. Drill a hole and squirt some in and later on sand and paint. It's a DIY job for less than a boat buck. If it's bigger then destructive analysis might be required. Parlay Revival on YouTube purchased a hurricane damaged L450 and did some extensive hull repairs. All from the outside. Later on they discovered bulkhead issues and then had to dismantle the interior. It was a massive refit and you don't want to go in from the inside unless there is no other way.

[aqfishing]

As that is a gelcoat finish(?), I think it would be very hard to get the finish to match the rest of the vessel if you were to repair that from the outside.

Doing it from the inside will also give you a better idea of the condition of the vessel and the extent of the damage.

It should not be too hard to put the cabinets back together again without any blemishes.

Go with a professional boat yard and get it done properly.

My 2cents.

Eugene.

[Sand crab]

Lagoon likes to assemble the cabinets which may contain bulkheads as a modular unit and drop them in place in a puddle of goo. The cabinets, paneling and everything else are screwed together from the back side beforehand so taking them apart is really a hassle. Older 380s might be constructed differently. You can see this in vids of the factory. Once again go look at the Parlay vids of the bulkhead replacement. It was absolutely horrible. An L450 was on the hard next to him doing the same thing. On the positive side they had an ace gel coat color matcher The boat was in Panama and a local there really knew his trade and the results were amazing. He mixed the paint and Parlay/Colin applied it. Eventually the OPs boat will need some more extensive cosmetic hull repairs due to dock rash and/or miscellaneous scrapes because sh*t happens Deal with the color match then.

[Searles]

Big question is ,is it delaminate from the inside skin or the outside skin ,verry important before going any further .⛵️⚓️

[Be Free Sailor]

The cabinetry, I believe is "screwed" from the backside, as Sand crab mentioned.
I have previously removed the small shelf above the desk of the owners cabin, and even this small task turned out to become somewhat "destructive", as I had to cut the screws holding the shelf. These screws must have been secured from the backside of the shelf, before the whole desk-area was installed at the factory.
I consider Lagoon a boat "factory", because they "assemble" boats, rather than "build" boats.
I agree it would be great to view the damage, by working from the inside, but my concern is if/how the boatyard can do this, without damaging the cabinetry.

[catsketcher]

That is a big area of delam. I think you may find when they pull it apart it may be more area than you think. I don't know why you got some delam with no visible damage on the outside - that is strange. There should have been some large impact that caused the core damage and core to skin failure. Or the boat was built with a dry area at this location.

It would be nice to know how thick the gelcoat is too. Then you could have some thickness to play with to work it from the outside if you wanted. If there is only thin gelcoat then it would be harder to fair the repair in. A bit of filler on the outside of a hull is great for repairs.

If I was you I would be more worried about the why than the how. Losing such a large area to delam on a overbuilt cruising cat is a worry - why did it let go?

[Tetepare]

Face it, cabinets will get small dings. That’s nothing concerning the major work that you’re facing. First I’d get an expert to determine the possibility Extent of damage

[LittleWing77]

Originally Posted by aqfishing

As that is a gelcoat finish(?), I think it would be very hard to get the finish to match the rest of the vessel if you were to repair that from the outside.

Doing it from the inside will also give you a better idea of the condition of the vessel and the extent of the damage.

It should not be too hard to put the cabinets back together again without any blemishes.

Go with a professional boat yard and get it done properly.

My 2cents.

Eugene.

I'm with Gene. If you have a professional yard recommending that you conduct the repair from the inside, there must be a reason for effecting the repair that way.

You need to properly discuss/investigate the why and how - as well as Tetepare says above in Post #8, an expert assessment of the problem.

LittleWing77

[Sand crab]

Originally Posted by LittleWing77

I'm with Gene. If you have a professional yard recommending that you conduct the repair from the inside, there must be a reason for effecting the repair that way.

The boat yard is not necessarily looking out for the OP interests. How big is the problem area?

Modern Lagoons are made with Alpi panels and wood trim. Alpi is a synthetic wood product in many colors and veneers which kinda looks like wood. But it's only kinda. The point is that product is unobtanium in the US. So re-fabricating interior trim is difficult. Where's the boat?

[Be Free Sailor]

The boat is from 2016, and she is currently located at a small boatyard in Spain. I have no personal experience this yard, and I have no references from other cruisers. I would be feeling better, using a boatyard from which I have positive personal experience.
The boatyard in Spain does not have carpenter and/or GRP specialists, but an external GRP "professional" was aboard to inspect and assess the repairs needed.
The affected area of "hull flex" is about 100x60 cm (3x2 feet).
I am suspecting it to be a dry area, from the time of production, and not delamination as a result of "impact" or an "incident".
If it was a dry area from manufacture...it could be more serious than "just" needing a repair?
The boat had 2 "incidents" the past year, none of which I expect would cause delamination of a structurally sound / well built hull;
Last year the boat rode its fenders quite hard overnight, against a concrete wall, with swell and wind pushing the boat onto the fenders.
And second "incident" was during the recent haulout with a travellift, during which the rear sling was mistakenly placed 60-80 cm forward of the structural engine-room bulkhead, and right on top of the delaminated area.
The area of delamination was observed/determined a few days after the recent haulout, during "hands-on" hull clean/polishing.

[aqfishing]

Have you contacted Lagoon to get advice? Maybe they can recommend a repair centre?

[Tetepare]

If that yard doesn’t have the expertise go elsewhere. They will only fudge it up, and it sounds like they know neither what they’re looking at or how to determine what the issue is.

[catsketcher]

My vote is for the noght against the concrete to be the cause. THis sideways loading across a panel would be a much higher load case than the "along panel" loading of the travel lift.

This makes me worry about the core. If the night on the concrete is the cause then you may be up for core failure rather than skin delam - and this is more common. So the skins might not have come off the core, rather the core may have exceeded its ability to handle the shear loading and broken down. Core failure like this is how monos fail cores in race boats. Large flat areas up front, getting slammed when beating to windward and falling off waves. Then the cores fail and the boat needs work.

I wouldn't know what has happened until the area is opened up. If it was me I would hope there was a bit of gelcoat thickness for me (fairing the edges of laminate) and then fix it from the outside. That way, if the failure is larger than thought, you can follow it easier without worrying about bulkheads and furniture.

cheers

Phil

[Sand crab]

If you do decide to do repairs from the outside. A series of holes about 15 cm (6") apart should do. Drill them about as wide as you need to get the epoxy nozzle in there. Once you establish the depth of the core try to drill only that far. You will be able to see if the inner laminate still has a good bond. If the core and the inner laminate is still decent then you don't have to drill so deep. If the core is fractured you can make it strong again with the epoxy. Epoxy has been used for a long time to strengthen and repair damaged and/or rotten wood so you are not doing anything that hasn't done before. There are penetrating epoxies made for this. They are very thin and the balsa wood will soak it up and be stronger than before. Many epoxies give off an amine blush which is a waxy like substance that interferes with a potential second coating. Normally you would wash or sand that off before a second coat but you can't do that here. You can either use a blushless epoxy like System 3 or just do the whole job at once. Blush won't be a problem on a wet on wet application and you will have a really good bond. This is the preferred way and just about any epoxy will do. You could for instance do a first application of penetrating epoxy (if needed) and then follow up with something thicker. Like I posted before there are many caulking tube type epoxies out there. Some use a double barrel caulking gun while some will fit a regular gun. Buy at least 10 of the mixing tips because the glue will set up in there if it's a really fast hardener. You can also premix the epoxy and pour it into your own empty caulking tube. Buy extra tubes but you won't need mixing tips because you already mixed it by hand. Epoxy tends to get everywhere so mask the area off before you start drilling. It heats as it cures so initially it will get runny and want to drip out of the holes and down your boat so mask all the way down. You could fashion little plugs to stick in the holes right after you fill them but they will be there forever if you don't pull them out when the epoxy is tacky. The next day chisel off any big globs of epoxy. Epoxy doesn't do well in the sun so you'll need to paint or gelcoat it. You can paint just the epoxy and go sailing today or you can sand it down and make it real pretty and go sailing later.
Good Luck