Lagoon 380 de-lamination

[bil56]

repeated shocks are probably the cause of delamination.
the best solution to repair is a vacuum injection of epoxy resin (more fluid), but must be done by competent and careful people
./.

[smj]

I’m guessing one must first determine were the delamination is, between outer skin and core, inner skin and core or both?
Either way I think the correct fix is to grind the delaminated glass of and then re glass.

[catsketcher]

I am not a qualified boat builder, but I have built 4 mulits, one a vac bagged post cured 38ft carbon reinforced tri, one foam cat and two cedar core cats.

Leaving holes in a laminate is not good practice unless under fittings. You have to glass over holes anyway. So even if you go the epoxy route, which I feel is really dodgy on a nice boat, you would need to cover the epoxy holes with 1mm thick glass -then you have to fair it - another 3 mm minimum. This would mean you have a laminate sitting 4mm proud of the current hull sides. This would entail huge amounts of fairing fore and aft and above and below. This idea sounds fast but unless it is on a deck (and you can cover it with thick deck paint) it will take a huge amount of time - fairing is tricky.

In my 25 years of boatbuilding I have never been happy doing a quick fix up job. I have always found it best to dig out the bad stuff until you get to good stuff and then build it properly again - whether I was chasing rot, some weakness in a structure or delam. I once chased down some rot along my stern steps and in the end just replaced the lot on one hull. I never regretted my decision - a good job gives peace of mind long after the effort is forgotten.

It may be worrying to do a good job but it is probably just as quick (or even quicker if you count less fairing) and you will know you have a 100% sound structure afterwards. We don't use epoxy as a core for a reason - it is rather brittle in resin form and surprisingly easy to crack in large volumes, even with fillers. That is why we always glass coves - the epoxy needs to be reinforced with glass. I would be happy using an epoxy insert for a plug for a winch base, but this is over a small distance. Foam is a great core because it is light flexible and tough. Epoxy is lots of wonderful things but it is not tough. I regularly bond temporary things (strongback to the floor is one example) with epoxy dabs and remove them by taping them with a hammer - the epoxy glue just cracks. Great at what it does but very bad for a large area of core.

Rip one laminate away - dig out the bad stuff. Pop new foam in - that is really easy. Then fair to below the current laminate. Then add glass with overlaps onto feathered edges on the good laminate around the repair. Then fair with filler and coat with probably polyester flowcoat. The the flowcoat will need to be sanded and polished to get it smooth. A good builder will make it seamless.

It probably would be easiest to rip out the internal furniture and remove the inner skin and bond to that. The the fairing is drastically reduced. I would then like to be very careful with bonding to the external laminate so that the outside skin is kept fair as the foam is mushed onto the laminate. Watch these guys to see how a really good pro fixes a bad laminate (removing outside skin rather than inside). Witness how the filler in the video just cracked - it aint a proper core.

https://www.youtube.com/watch?v=YO1iqGk1PfM

[Be Free Sailor]

Thank you so much, for all the valuable suggestions and information.
I will be using the input received, when deciding next step forward.

[jason w]

I believe your first instinct is correct and the skins were poorly bonded at the factory.
Outside forces such as the improper placement of travel lift straps could have led to further delamination but it hardly matters now.

I do repairs like this for work and having seen your video I agree with the yard.
If the repair is done from the inside the new core will be bonded against the outside skin and the inner skin can be wet laminated.
Often the outside skin is thicker than the inside so shape retention will be easier and wont require gelcoat repair.
It doesn't appear that anything is wrong with the exterior glass or gelcoat in your video.
I have not seen the furniture in the boat but I would bet it will be easier for a skilled tech to put the interior back together than to try to properly repair and fair the outside let alone matching old gelcoat.

If you choose to do the outside repair expect to see evidence of it forever as matching gelcoat will fade over time as your current gelcoat has and become mismatched.
If you paint the boat (not just the repair)the outcome will last. There is nothing wrong with doing this type of repair from the outside but if you want it to look as though it never happened I think you will be happier with the inside repair.
As for the cost you are trading fairing,gelcoating and buffing for the reassembly of cabinets with some well planned cleats replacing tabs cut away during disassembly and likely no finishing. Without seeing the cabinets its anyone's guess but if I were doing the work I would try pretty hard to avoid exterior finishing.
In either case this repair can be done with vinylester resin and it will bond fine.

Injecting epoxy is amateur at best and without glassing the injection sites will fail. If they do glass the holes they will have to use epoxy as polyester resin shouldn't be used over epoxy. This will preclude the use of gelcoat and mean painting the area. Not really sure this matters. If they choose not to glass the holes the risk of failure is high. This type of failure will lead to bigger problems. We have repaired decks that had previously been repaired this way and it usually means large areas of core replacement. As I think about it now its basically the same job they were trying to avoid in the first place only larger. If you are correct and the skins were never bonded there is no way to properly prepare any of the surfaces. If a yard suggests injection go elsewhere.
I hope this was helpful.
Good luck with your repair.

[redneckrob]

Originally Posted by catsketcher

Watch these guys to see how a really good pro fixes a bad laminate (removing outside skin rather than inside).

I'm not sure I'd consider someone who works upside down applying chemicals without any eye protection whatsoever a "pro"! Attention to detail and doing the parts that are necessary even if somewhat annoying carry through to the entire job.

[ohdrinkboy]

Originally Posted by Sand crab

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?

Looks like there are 2 Alpi distributors in the USA.

https://www.alpi.it/en/distributions/united+states/usa

[Be Free Sailor]

Hi please see new photos, just taken below the aft cabin floorboards, in the location of the fuel tank.
Also some photos forward under the hallway floor.
The fuel tank is located under the floor, inside the cabin where I discovered the soft area of the outside hull skin.
There is a cabinet, on the outer wall, and inside the cabinet I can see some torx screw heads, which I do not think is original to Lagoon 380.
Could it be, this boat had some structural damage, and subsequent repair in the past? Looking at the pictures, I get the feeling this GRP work is not "original" and as the boat came from Lagoon factory, but rather from a later repair of the boat.
Any clues, does anyone have input please?
I will try upload the pictures - hope it works!

[Sand crab]

I think you are right about some work done there in the past. Those funny looking 5 sided pieces have old screw holes in them and the ply that they fasten to has been cut with the edges not quite aligning on the re installation. I suspect the brownish fg is a repair. Those torx screws and cup washers are probably not original. I think you can see a rough cut on the ply when you zoom in on that screw but actually it looks pretty decent for a repair.


FWIW Ohdrinkboy. Just try to find the Alpi you want stocked anywhere in the US.

[Matt Johnson]

And it looks like they tabbed directly over the gelcoat without prepping the surface. I would check other areas of the bilge to see if they are like this too.

[catsketcher]

I'm with Matt - glassing over gelcoat is a huge no-no - incredibly amateur work. There is a dodgy story somewhere in the past - maybe just someone who wanted the squeaking of a small bulkhead to stop in a seaway, but the fix is not good.

[bil56]

I'm with you too, this work is unworthy of a shipyard, or else done by a handyman.
even the color of the resin is weird ...

[jason w]

I agree that the tabbing does not appear original. I don't see any evidence that it is failing nor do I see any evidence that lagoon thought it was necessary at all.
There doesn't seem to be any evidence of prior hull damage which I believe is what we are talking about.
Is any of the interior structure impeding the repair of the hull delamination and can it be reasonably removed and replaced?
I still couldn't say but if the yard believes it can I have to take them at face value.
As far as the rest goes, none of us who buy used boats will ever know their complete history but does any of it matter? If you suspect the boat is compromised by prior repair check the rest of the boat out with the same critical eye you have given to this area and compare.
I Have never looked closely at a lagoon as we don't have a lot of cats in my area but I've seen many monos that belong to the same family and I wouldn't be surprised by much.
At the end of the day you still have a delaminated hull and it still needs to be repaired. One thing at a time and you'll get there.

[Be Free Sailor]

Thank you for all the good responses.
It is very strange to discover these "old" repairs, because I believed to know the full history, after all the boat is only 6 years old, and I have full tracking.
The boat was purchased 2nd hand, directly from the Lagoon dealer in Spain (Catamaranes OceanCat - Charter catamaran - lagoon).
This is the same Lagoon dealer who sold the boat new, to the first owner, and the dealer knows the boat well. However, he did not inform about any previous repairs or damages to the boat.
The boat was originally chartered around Ibiza (exclusively with skipper), only for a few weeks, before it was decided to sell and take it out of charter (it is a 3-cabin owners version, and according to OceanCat it was only chartered a few weeks).
The boat name is "SANSA" and she was in charter with "Goa Catamaran".
She was sold to a friend of mine, who used it until recently when he decided to upgrade, and he signed a contract to sell SANSA to me.
I have owned a Lagoon 380 before, and wanted to go back to this model, after since then having owned a larger Lagoon cat.
The delamination / hul damage was just recently discovered, during my time together with my friend, during haul out and preparing SANSA for the final handover to myself.
We are shocked and disappointed.
My friend reported the hull delamination to his insurance company, and it looks like they accept to cover the repairs of the delamination.
However, at the time of reporting the damage, I had not discovered the "old" repairs under the floorboards, which could be linked to the delamination issues, which were found on the hull right next to the old repairs.
Again thank you for all the support!

[aqfishing]

Good luck.