While in the middle of my 5.2 make over, I have removed the hull cover to reglass a cross member. I noticed a crunching sound as I was pressing against the outside of the hull, towards the bow. It's a pretty large area.
I've looked in, as far as humanly possible, and see no delamination, but this seems like it's the only possible answer.
I am thinking that I could pour the expanding foam in the hull, which would take about 6 cubic feet. Will this do the trick? I know it will expand, which is what I want it to do, but I can't physically put my arm in there and feel around for any delamination.
What are my options?
In Christ

Expanding foam may warp your hull shape. It expands with quite a bit of force.

Extra weight in the bow probably wouldn't be the best addition either.

Glad to know.
How about drilling holes and using a syringe and adding more epoxy between the outside layer and inside glass?
Would that be a correct route, or just sell her and get another cat?

That works -- at least it worked on the deck of my Laser. But it makes it a lot heavier.

And using expanding foam is not good, because then there are pockets in your hull that accumulate water, and there might be no way to get it out.

The technique that I have HEARD about, but never actually done, is to drill a bunch of holes over the delam area. Put one or two molly bolts in strategic places. Then squirt epoxy into the holes between the delaminated sheets. Then tighten the molly bolts and wipe off excess epoxy. After it has dried, remove mollies anyway you can, and gelcoat.

That is it in a nutshell. Good luck.

Try adding a couple of extra fiberglass crossmembers. Get a cardboard roll (like from Christmas wrapping),fit it in between the hull sides and fiberglass in. This will add minimum weight and maximum support.

The problem with injecting resin between the core and skin of a delaminated area is that it doesn't fix the underlying reason for the delam in the first place (usually caused by a bad bond to the core, often because the core face was contaminated before laminating).

Alternatively, and usually a more permanent/sturdy fix for delamination, depending on the side of the delamination, is to grind the affected area away (including one skin and all the foam), leaving just one intact skin remaining.

Vac bag a new core into place, fair the core with a torture board to the surrounding skin, apply new second skin with suitable overlap on the surrounding skin, fair again with torture board and paint.

It does depend on how big an area the delam is though. If it is smaller than the size of your hand, injecting resin may easier, but it may not fix an underlying problem with the core to skin bond.

Having said all that, a crunching sound may indicate that the core has been smashed during a collision...in which case the original core to skin bond in that area is fine, but injecting resin may still not repair the damage well because you can't see the extent of the damage.

If you've got the facilities and skillz, replace the core, it is the solution with the least chance of failing.

what year is that 5.2? If it's pre-1984 then there's a good chance that it is NOT a foam core boat but is solid fiberglass. There is a tube stringer that runs the length of each side of each hull and it may have either separated from the hull or degraded completely.

Whether it's foam core or not, you probably need to remove the deck to get a really good understanding of what's happening. If you can reach inside with a digital camera, it might also enlighten you a bit as to the problem.

Here's some inside shots I took of the Team Seacats I20 as I was inspecting all the structural areas before a Tybee 500. It was impossible to put my eyes on these areas but the camera extended through a port hole worked wonderfully.

If you cut the deck off neatly an inch in from each side, you can then grind off the old foam put new divinacell or similar foam underneath the old deck then use divinacell foam to make bulkheads to sit just under your deck. Glass in more foam under your edges you cut to make a lip then when thats dry glass your old deck back in. The decks will be solid as for little extra weight.
regards

Screw it.....

Jake:
She's a '77 model. It would be virtually impossible for me to build extra cross members because I don't have the tools to get into such a tight area.
It looks like no foam core, from what I can tell.

Definitely no foam core in there. If it's crunchy, you definitely need to do something. There was a thread on here about how to remove the decks from the 5.2. If you are gentle with a chisel, hammer, and putty knife, you can usually neatly separate the decks so you have full access to the inside.

Jake:

I've got the deck removed already. The problem is that it is not possible for me to get my arm into the effected area with out cutting the entire top of the hull off. My arm is too short and the opening is too narrow. If I tried to open the hole more, I would be tearing into the sides of the hull.

OOoooohhhhh... did you say it was in the very tip of the bow? Can you take some photos?

Jake:
It's from the tip of the bow and stretched almost to the beginning of the deck cover. I don't have a camera. All I have is this silly camera on my phone. I'll try to take some pics.
Thanks

Simply brilliant! I predict that idea is going to save my a lot of grief over the years!

It's a great trick - I have a whole bunch of photos of hull innards from over the years. The fun thing is when the screen saver on the computer picks them up and mixes them in with the pics of kids, cats, and dogs.

hi all, had skipped this thread as the title didn't grab me

choloemac, do some searches on this forum for; nacra 5.2, deck removal and also look for posts by airborne and gree

your 5.2 is, like theirs and mine, solid glass, as jake says no glass there

sounds like your problem is forward hull stringer de-lamination and you'll need to lift off the forward decks with chisel and putty knife to re-bond the stringers on and add bulkheads to prevent them coming off again

the hulls are build of woven glass cloth and the stringers were made of random chop glass laid over cardboard tube formers. state of the art in it's day but in retrospect the chopped mat glass was a bad choice as it's heavier for less strength than woven glass and wasn't bonded well enough

given 30 years of banging and flexing the stringers sound like they have twisted free of the hulls. if i remember rightly the rigging you have is from airborne's 5.2 after the port hull snapped off forward of the beam and torpedoed the starboard hull. airborne says that there was dirt in the glass where the stringers should have been laminated meaning they must have been loose for some time and without them the huge length of unsupported hull twisted off in waves with 2 on traps

think gree ended up with the starboard hull and mast of that boat and used the hull to practice deck removal so he could do a cleaner job on his own 70's 5.2. pretty sure he's doing that work now...

i've been worried about my own solid glass 1982 5.2 as there is no way to see inside the forward half of the hull to check the stringer bonding. but with my hulls in the garden at the moment i've notice that in the morning ice has formed on the night's condensation in such a way as to show exactly where the stringers are bonded underneath. theoretically if the stringer had de-laminated from the hull this effect would be patchy........so i'm guessing that my gently used japanese 5.2 hasn't started de-laminating yet

will try to dig up the other threads

eric e

all here

http://www.catsailor.com/forums/sho...;amp;page=0&fpart=1&vc=1
http://www.catsailor.com/forums/sho...;amp;page=0&fpart=1&vc=1
http://www.catsailor.com/forums/sho...;amp;page=0&fpart=3&vc=1