Delamination in a Big Way

[Emmalina]

Just hauled out my boat in Thailand and had a weeping hole.. After grinding about a metre square we realised its the first quarter inch of the whole boat has come away from the main structure. A week later I now have a bald boat. It peeled of like orange peel .... I had no blistering or any other sign of this except I bought a moisture meter out of curiosity to test my hull. Has anyone else had this problem? The boat is 30 years old and was built in Hong Kong by a very reputable boat builder. He made 14 of these boats and I have contacted other owners and nobody else has this problem. Its now drying out although all of the bad moisture readings were all on the skin that we peeled off and of course the acid smell of uncured resin/styroid. I am guessing this was just a bad resin day in production .... I am going to reskin with woven strand and epoxy but would like to know how this happened in the first place...
PS you can really upset your neighbours by lending them a moisture meter

[El Pinguino]

Cheoy Lee?
I saw one hauled out in Kettering about 12 years ago , built in early 70s maybe, that was shedding its skin like a snake. Very ugly.

[sabray]

Polyester can dissolve and cloth can absorb water without blistering?

[El Pinguino]

Don't know... just reporting what I saw.... hull looked dry enough , just looked as if there was no longer any adhesion between mat and gelcoat...

[Emmalina]

Guy who built them was David Cheng boatbuilders ltd
After peeling we now have a 20% reading so I am pretty happy with that so we will leave it to dry for a month.

[HansSolo]

We had the same thing happen to the side decks on our hans christian. The chopped mat de-lamianated and pealed up in sheets. Im thinking that it was a off day during layup (not enough resin?) cupeled with water sitting under the old teak deck for almost 30 years. We ended up pulling it up / grinding it off and laying down a layer of 1708 with epoxy
All of the lighter colored areas in the 1st photo were De-laminated. Once we pulled up those loose areas it was dry underneath (soled glass decks, no core) 2nd photo.

[minaret]

Originally Posted by Emmalina

Just hauled out my boat in Thailand and had a weeping hole.. After grinding about a metre square we realised its the first quarter inch of the whole boat has come away from the main structure. A week later I now have a bald boat. It peeled of like orange peel .... I had no blistering or any other sign of this except I bought a moisture meter out of curiosity to test my hull. Has anyone else had this problem? The boat is 30 years old and was built in Hong Kong by a very reputable boat builder. He made 14 of these boats and I have contacted other owners and nobody else has this problem. Its now drying out although all of the bad moisture readings were all on the skin that we peeled off and of course the acid smell of uncured resin/styroid. I am guessing this was just a bad resin day in production .... I am going to reskin with woven strand and epoxy but would like to know how this happened in the first place...
PS you can really upset your neighbours by lending them a moisture meter

Yes, I've seen this before. Was the depth of the delam very consistent? If so, what you are seeing is very likely a boat that was skin coated with a chopper gun on a Friday, and then the layup was continued on Monday with no prep. This is common in production boats, and is not usually a problem due to the nature of orthophthalic resin. However, there are other factors to consider. If this is done in very high heat, or with an external mix chopper gun that is having issues, the chemical bond can be pretty poor. Technical difficulties with an external mix gun can also explain this situation, as it can result in a thin layer of uncured resin at the surface of a layup. Many boats are molded outdoors and contamination issues can be a concern as well.

One boat we did that was like this had a very consistent delam at about 1/2" depth, half way through for much of the layup. We ran a skill saw set to 1/2" depth around the waterline and then athwart ships every couple of feet, then peeled 1/2" strips off the bottom, demoing and rebuilding in sections so as not to have the boat break in half on the stands (80' power). Nightmare to fair. One year, 250k.


Good call on the meter. Sure is true about neighbors, hand a man a moisture meter if you wanna see him cry...

[minaret]

Originally Posted by HansSolo

We had the same thing happen to the side decks on our hans christian. The chopped mat de-lamianated and pealed up in sheets. Im thinking that it was a off day during layup (not enough resin?) cupeled with water sitting under the old teak deck for almost 30 years. We ended up pulling it up / grinding it off and laying down a layer of 1708 with epoxy
All of the lighter colored areas in the 1st photo were De-laminated. Once we pulled up those loose areas it was dry underneath (soled glass decks, no core) 2nd photo.

This is a classic dry chop matt layup. Not enough resin in the skin coat. Chopper gun was not yet calibrated correctly for temp, layup was kicking off before properly wet out and rolled down. This is one of the great flaws with a chopper gun, all the problems tend to happen early in a layup, when they are right against the mold, right where you don't want them. The average operator responds by burying the problem in more chop matt so the foreman can't see what happened. Nobody wants to get fired over a bad part.

[Emmalina]

Thanks Minaret Yes it was consistent all over the hull only took 3 days to peel it all off. Not too worried about fairing as it was a consistent thickness all over and the smell.... Phew!!! Also it was matting not a chopper gun as we can see the sheets,, Maybe as you say a weekend layover. Anyway in Thailand its probably gonna cost about 5k to fix so not too bad.

[Emmalina]

OK thats the worst of it I hope !!!!!

[minaret]

Looks like they skin coated it with matt and then lost the bond between it and successive layups. Should be fine. Did the delam stop at the waterline? Usually you have to chase it above the waterline a ways. In a case like this I wouldn't be surprised if you had to go all the way.

[minaret]

Are you doing lots of fresh water wash as well? Wash with hot water and TSP with a scrub brush, then rinse very thoroughly with a hose. This is to wash off all the salt, styrene, and other contaminants in the layup. It will accelerate drying. We wash once a week for the first month, twice a month for succesive months, when air drying (which we don't do any more).

[Emmalina]

Originally Posted by minaret

Are you doing lots of fresh water wash as well? Wash with hot water and TSP with a scrub brush, then rinse very thoroughly with a hose. This is to wash off all the salt, styrene, and other contaminants in the layup. It will accelerate drying. We wash once a week for the first month, twice a month for succesive months, when air drying (which we don't do any more).

monsoon season at the moment ! lots of rain and the odd pressure wash. No mad rush as dry season starts in november ... if we get a good forecast might try before Thanks for the advice...

[barnakiel]

I believe this may happen in at least these two scenarios:

- the builder started laminating on Friday then took a weekend off, finished the job on Monday ...,
- at a point the boat had an 'osmosis repair' job done by a lousy 'specialist' who added these now peeling layers to the boat ...

Etc.

b.

[neilpride]

Uncured resin, spray gun wrong mix ratio, drunk crew waxing the inner gelcoat instead of the mold ,upset worker pouring wax in the resin barrel,
Friday guys!!! lets finish this thing today!!!