Are our grids glassed to the hull or bonded

[pbyrne]

Just watched a horror story on YT where a band new Hanse 418 was run aground and it need the interior removed, and 40K GBP to repair it.

The grid was/is 'bonded' aka glued to the hull not glassed to the hull, and between the shape of the keel and the shape of the hull (flat, making a 90 degree angle between keel and hull) there was a LOT of leverage, and the grid was separated from the hull, and the keel dropped away from the hull a bit.

Absolute mess.

This got me thinking, it's when not if you run aground, and how are are boats built?  I guess a follow up is who builds a modern boat that can take a grounding and not need 40K of repairs.  I looked at Hallberg Rassy and even they say they 'bond' the grid. https://www.hallberg-rassy.com/resources/how-a-hull-is-built

I did a quick search here and I didn't really find anything so I thought I'd ask.

[KeelsonGraham]

There's nothing wrong with bonding per se. The technique is used is composite airframe manufacture on commercial,aircraft. So, perhaps a better question to ask is how good was the bonding process,

[waughoo]

Our C34s dont have structural grids like the example you saw on YT.  Thus it isn't a concern with the c34.

[pbyrne]

There's nothing wrong with bonding per se. The technique is used is composite airframe manufacture on commercial,aircraft. So, perhaps a better question to ask is how good was the bonding process,

Agreed.  However in the sailboat, FG context, generally speaking, is this technique sufficient to deal with a grounding, which can be expected at least once over the lifetime of the boat.  These boats weren't just damaged in a way a DIY'er could fix it, if they were cars they would have been titled 'salvage'.  Fixable, yes, but pretty much professionally only.

This doesn't sound like a technique that makes sense for a boat that will run aground.  It sounds like building it to a price, using a spec that is unrealistic. Not badly, just not including the fact it will be run aground.

So far I've seen 2 examples on YT, (Beneteau, and Hanse) that after a grounding needed substantial work and money ($10,000s), as the grid separated from the hull, and damaged the interior from flexing.  I'm not saying you cannot do it 'well', as from what I can tell the larger Catalina's use a bonding for anything over 35ft. (http://www.sailplace.com/wp-content/uploads/2016/02/Catalina-Tech-Brochure.pdf).  And I think our Catalina's are well built. IMHO, I would be a bit surprised if the large Catalina's suffered as much from a grounding, but I have no evidence.

What I'm asking is, in general, should you be prepared for significant repairs with this build technique?  2 of the world largest boat builders have well documented proof that in the case of an inevitable grounding, the boat is not safe to sail.  I believe both of the boats are Class A Ocean, which I don't think includes how many times you can whack into the bottom, however, I think I'd think twice before going too far from support.

It would be nice to have some better information on how durable the boats are.   How many people at the cockpit table is nice to know but... 

[pbyrne]

Our C34s dont have structural grids like the example you saw on YT.  Thus it isn't a concern with the c34.

Being curious about that is what lead me down that rabbit hole! I was pleased to see that construction wasn't with a grid to be honest...  See page 4 http://www.sailplace.com/wp-content/uploads/2016/02/Catalina-Tech-Brochure.pdf

[ewengstrom]

Recently I discovered some cracks in the fiberglass tabbing of the stringers in our 1988 C34. The bilge always has a bit of water in it and last winter I made a concerted effort to keep it as dry as possible. I'd vacuum out the water only to discover a small puddle or two developing at the base of the second stringer. Upon very close inspection I find there are a few cracks in the tabbing, when the bilge had water in it this water apparently got thru the cracks and soaked the core material and would weep out when the bilge was dried out.
Fast forward to this spring when I had to get a hose to the bilge area so I reached under the floor and drilled an oversized hole thru the stringer with the thought of sealing the coring material to prevent further moisture from getting to the core....the drill went thru the glass (about 1/4" FRP laminate) and immediately went thru to the other side....the core is MUSH....a very very wet oily MUSH.
So while the brochure in the above post covers the construction methods of newer Catalina yachts, it don't believe it was meant to cover every model back to the beginning. 

I'm concerned about this problem but I know it's existed for a long time now and I'm keeping a very close eye on the affected area and it doesn't appear to be getting worse.
I'll be contacting Catalina to see what they can offer in the way of repair advise and over the winter of 2023/2024 I'll be pulling the boat and addressing this issue along with a few others.
I'll want to get a thread going (I honestly haven't looked to see if there is one out there already) to cover this repair in case something like this shows up in someone else's boat.