Late 1980's Chopper Gunning - Resin Rich?

Hello Everyone,
Working on a repair job late 1980's production small day-sailing sailboat.
I see gelcoat resin on the outside, I see woven roving on the inside, between the two seems to be a thick, resin-rich mass with many air bubbles and only a small amount of fiber. Would this be a 'wet' chopper gun application? This does not look anything like mat or the backside of classic composite furniture from 'back in the day'. The gelcoat seems to be 8-10 mils (.25mm) and the woven roving is maybe 18oz / .031" thick (.8mm). The 'in- between is a good 60 mils (1.5mm), maybe a bit more.
Thoughts? Thanks!

 

Professing zero expertise, but a guess.

https://www.tapplastics.com/product/fiberglass/carbon_specialty_fabrics/coremat/93

 

Using this for the missing layer and taking the weight per sq foot in Vectorlam against the sq inches of my sample comes to within a percent or so.
I think we have a winner.
Thanks for the suggestion!

 

Hard to be sure about the method,it could just as easily be CSM that has been broken down by a paddle roller.Even pictures won't help that much.There is a tendency for chopper guns to be set up for a resin rich laminate as the surplus resin may cost less than the time taken to consolidate a drier laminate.Is there an owner's group for the type of boat in question?That may be the best way to get to the truth.

 

Thanks. I have reached out to an active forum and to the manufacturer. We have the ability to section and take pictures at work. Here is one for kicks, it's the middle layer that has me confused:

 

@ondarvr knows it all well

 

It might even be air bubbles as a result of mixing with a paddle in a drill.There are many possibilities.Whatever process was used,the boat is still here 35 years later,so it can't have been all bad and may not have been bad at all.

 

It looks like the typical poorly rolled skin coat, not uncommon at all.

Resin rich can be good for cosmetics and blister prevention, but a resin rich laminate is commonly from just poor workmanship.

The fewer fibers, and farther they are from surface of the part, the less chance there is of blisters, plus the surface profile tends to be better. But in this case the numerous air bubbles could cause, or contribute to blistering.

Not that blisters always result from air bubbles or fibers, but they frequently go hand in hand. There are so many variables that play into blisters and print through you almost can't name them all.

 

Thanks Everyone, I really appreciate the input.

 

It doesn’t look like chop to me, it’s coremat.
Many years ago I did some experimenting with very loose layers of chop as a core material, shooting it resin light, letting it kick off without rolling, applying another layer of chop, then covering that with fabric while wet to try to flatten it out.
The idea was to maintain some airspace in the chop, using the strands to hold the fabric layers apart.
I’ll be the first to say that it was not a success, the chop being very hard to apply in an even layer, and the last layer (roving) being extremely hard to roll out over the contours.

 

This may be a case of two nations separated by a common language but I don't see anything I would recognise as coremat in the samples.This is what we call coremat:



Or the bulkier version:



This,on the other hand is what we call Rovicore and it may possibly be in the laminate shown,but if it is it didn't come out of a chopper gun. https://www.compositesone.com/wp-content/uploads/ROVICOREbrochure2019.pdf

 

KapnD, Wetfeet- thanks.

Is it just me or does the laminate seem 'unbalanced' with one heavy fiber layer (woven roving) and then either a core or fluffy resin preceded by gelcoat?
Would it make sense to do repairs in a more balanced fashion where the core would have some fiber on both sides? Or skip the core and use multiple layers of fiber?
I suppose the veil is not an issue if the repair is working from the inside out and gelcoat goes on last...

 

Normally coremat and similar products are used behind the skin, and in this pic I don't see anything between the gel coat and the resin rich, and air bubble rich layers.

Cormat having no strength in itself would crack rather easily if it was directly behind the gel coat.

But.....you never know how a boat from the 80s was built, they used all sorts of products incorrectly to build boats as fast and as cheaply as possible. The crews were also poorly trained, so even if the boat was supposed to be built well, the crew that day might do just about any random thing to finish by the end of their shift.

 

I don't see a core that I would recognise.As I posted earlier,it has lasted this long so must be fundamentally sound,if not perfectly laminated.There is a possibility that the slapdash laminating was done to meet a production target and thus qualify for a bonus payment.That is often the catalyst for a hurried job with corners cut.Without seeing the area where the repair is to be done it is a bit difficult to offer advice about the best way forward.

 

The pieces shown as cut-outs are 4+3/8" [11cm] diameter access holes I cut into the bottom a comfortable distance (enough to swing a sabre saw) in from bow and stern off to one side of the keel. I have a PC fan pulling air out from one hole and both are offset with a cap so is doesn't take on rainwater. Since the bottom has other cracks and holes along its keel and lower edges I decided to leave the nicer-than-average deck alone for now. These two areas will not be hard to fix, they are nearly flat. It seems like most of the repairs I have seen online for these, the cut out area is re-attached over a lip (sometime a cut-off batten) fastened inside hull and then a minimal glueline and repair to the gelcoat. Not quite a 1:12 grind and build-up and fairing situation.