That is a monster!! Looks sweet!

Ya! Massive beam....

so it will definitely have massive sails ;-)

A sad surprise was waiting for me when seeing my boat last weekend: on a 50cm strip on the front one hull showed strong deformations on the surface. It did not only buckled but it seemed the foam 'shrinked' and therefore shrinked the whole upper part of the hull in this area.

First, I thought the boat yard did a bad repair job of one of the delamination parts they have been working on. But when studying it, it became clear the new damage occured in an area where no repair has been made by the boat yard, although they repaired the areas around it.

The boat has been in the sun now for 14 days and the damage must have happened within the last 7 days. The grey hulls do get pretty hot, so I am pretty sure, heat is the reason for this problem.

Where I don't have an answer to is why the foam shrinked? There was no forces put on the hull yet, as the mast is not stepped yet.

Anyone ever seen something like this or has an idea what happened? I looked carefully at the rest of the boat but this is the only bad spot.

Thanks!

there are these few white dots in the glassfibre layer. maybe they just happened when grinding but it also reminds me on those little holes you do when doing an easy repair job in delamination... maybe this area has been repaired via injection before using a resin not able to deal with the heat the grey hulls nowadays can reach when exposed to sun?

If however this is not a pre-repaired area, what could be the problem?

detail pic of grinded area with white spots

It looks like something hard has been rested on it and moved around a bit which dinted the foam core...

Dunno about the white dots though, it doesn't look like a resin that would've been injected behind the delaminated skin though, because you can't see the white glue behind the laminate.

Other than that, no idea...

What resin did you end up using, was it polyester or was it epoxy? From your photo's the deformation resembles very much the appearance of "shrinkage/deformation" that can occur when polyester resin is used when the percentage of catalyst has been too high when mixing. The highest percentage of catalyst mixed with polyester resin should be 2% IE 20ml of catalyst per every 1kg of resin. Never higher. The normally used percent is approx' 1.5%. The more catalyst above that 2% that is mixed, the more the shrinkage will occur as more heat is generated during the reaction and the associated uneven expansion and corresponding shrinkage with uneven core cooling will happen. The temptation of using a “hot mix” should always be avoided.

thats more of an in mold kinda issue.

What does the foam look like when you grind into it? Is it melted? Is the rippled surface still rigid or is it clearly delaminated and soft? Are we looking at the top or the bottom of the hull?

That looks like a PVC foam and I do have experience melting it (heat lamp too close on a warmish day)...but it took a LOT of heat (couldn't touch it with my hand). Clearly, I couldn't say "without a doubt", but I'm doubtful that the color of the boat had a direct effect on that problem...I've seen black catamarans before with standard construction and they survive. Based on limited exposure to the problem, and while I wouldn't completely rule out some sort of thermal reaction, my first guess that there might be some sort of chemical thing happening, enhanced perhaps with the heat, to distort the foam there considering all the things that have taken place to the boat recently.

Acetone soaking through the glass and into the foam? What kind of foam was it?

Does any standard structural foam react to acetone?

When the boat was repaired could something like acetone used to clean the boat run along the inside of the skin and do its damage slowly. I spilt a rust retardant on my leather car seat several months ago. I wiped it down with a damp cloth and it looked clean. Three weeks later the spill had melted right through the fabric and a month after that it was even worse.
Were the hulls sealed or tight?
Whatever, I feel for you. I would be gutted!

It's not uncommon for for things like this to happen. It's one the main reasons primer or a seal coat is applied before painting. With gelcoat it isn't normally needed. However you've had some sort of reaction of old v new. You might want to seal that area after the repair. I not sure with what. Maybe epoxy primer? Otherwise you could have the same thing happen again. Good luck.

hmmm....I didn't think about the paint. What kind of paint was used?

jake,

the boat was previous painted with a 2 component polyurethan paint, but pretty sure it was grinded away.

the new gelcoat was applied on top of the old gelcoat.
the ship yard has no explanation for what happened.
havent seen the foam yet but it was not soft, it felt pretty stable... from the outside it was more like vacuum bagging... like all the air soaked out of the foam...

I asked now if the shipyard used any chemicals to clean the hulls...

its pretty weird that it just happened so close to all the surrounding repair spots which are just fine...

I guess it shouldn't be the gelcoat. When I melted the foam it looked like this when I ground away the outer shell of fiberglass. The outer glass was slightly sunken in but still mostly rigid (you could tell it was delaminated).

Dear all, thanks again for sharing all your thoughts and personal experiences!

I know a bit more without understanding anything :-(

Aceton was indeed used to clean the hulls (and probably when doing the repairs around the old area which got damaged now). I asked the ship yard to test what happens if they drop a bit aceton on the foam, but have no feedback yet. They say, if Aceton was the problem, than it should have reacted immideately or would have affected putting on the new gelcoat, which was not the case!

Can aceton really run into the glass and foam, remain there (normally it drys out quite quickly, right?) while the repairs are made with epoxy? so later remaining aceton (?) is trapped in the glass or foam? than new gelcoat is applied without problems because the aceton on the outside dried?
than the boat is put into the sun, and the first 7 days, there is no problem? in the second week, temperatures rises very little but somehow... something happens, the foam starts shrinking and pulls the outer layer of glass inside??? (you can really see the glass texture like you normally can see when doing vacuum bagging...)

this all is so hard to believe, as aceton dissappears fast and if the cellfoam was just damaged etc... under heat, you would assume expansion... or delamination... but how could it shrink? and why did it took two weeks to cause this damage?

This is not the only area where repairs had been made, so I am really in fear that other parts might encounter a similar problem over time?

What do you think?

Did the guy that made the repairs for you use a heat gun or heat lamp to try to get the patch to kick faster? It kind of looks like someone was using that technique and wasn't paying attention to where it was pointing...as if they heated up the patch to the temperature they wanted and when they moved the heat source away it was still close enough to heat up the boat and was pointing in the direction of your new problem area...which just so happens to be in-between the new repairs that they did. I doubt very seriously if it was a chemical reaction with the foam…it looks to be some low level of heat distortion. Not as much as Jake experienced...but enough to make it deform.

Regards,
Bob

hi bob,

not sure I understand you right...

the boat was fine when delivered.

it stayed fine for more than a week in the sun.

in the second week it deformed to the current state.

the only heat in that time was the sun warming up the grey hulls...

Hi Dirk
You wrote "First, I thought the boat yard did a bad repair job of one of the delamination parts they have been working on. But when studying it, it became clear the new damage occurred in an area where no repair has been made by the boat yard, although they repaired the areas around it."

That is what I was referring too...When they did their repair the damage was done, the foam was changed once it hit its heat distortion temperature...this often causes the foam to "out gas" When in a cool environment out of the sun the laminate appears normal and the problem is undetectable...when you bring it out into the sun and the laminate heats up, gasses expand and distortion of the panel takes place. This may or may not be the cause of your problem...but it does exist...

Regards,
Bob