crack in bilge fiber glass

D

dchurch3

New member
I know this topic has come up before. I am hoping someone who has dealt with it will contact me so i can get some advice and find out how they handled it. I noticed today (I have a 2007 25' C-Dory) a crack in the fiberglass in the bilge that extends under the water tank (no idea how far back it goes. I have attached a photo so members can tell me what they think. Is the next layer down still fiberglass or is it the balsa. it was hard to the touch. Is this cosemetic or is it a big deal. My bilge is dry. The boat has been on the trailer for the last two months. Im putting a photo of it in my album. Im wondering if i can still use the boat for another couple of weeks or does boat use need to cease until its repaired.

My Album is C-Cruiser
 
photo_1.jpg


Here's the pic from the album.
 
:oops: Apologies! I should not skim the thread!!! :oops: :oops:

Dave, since you're that close to Les, I think I would drag it up there for a quick look. The photo makes the crack look deep.

edit: Or what Dr Bob recommended in the comment below :idea
 
Is the water tank aft or under the bunk? (I thought by 2007, they were aft, with no holding tank. Earlier boats had the tanks under the bunk, with a holding tank aft.

In the photo it looks as if it was aft. It is possible that the "crack" is some mat which has not bonded well and was a secondary addition.

However to be safe, you need to grind it down and see what is under--unlikely that it is structural, but also unlikely that it is "stress crack" which occurs in gel coat. I would take a Dremel took and "V " the crack, and then probe, if there is balsa under this, then you need to put more layers of glass over this (with epoxy, for a better secondary bond). If it is wet, then there may be water in the core--and this becomes more serious.
 
Bob,

The water tank is all the way in the stern below the motor well. The crack ends in the picture (between the fuel tank and water tank in an open bilge space and extends under the water tank towards the transom. no idea how far. the sruface layer has definetly delaminated and can easily be broken off with my finger. the next layer down is hard and not wet. But I do not have enough experience to know if the surface layer is a liner and the next coat underneath is fiberglass or if i am looking at balsa. What do you think?
 
To answer your real question, use the boat until you haul it, if it's only a few weeks and then follow Dr. Bob's advice. If you don't see any hull damage on the outside when you get it on the trailer, it's probably a simple fix.

Charlie
 
I was also trying to figure out where it is. Is the darker circle above (where the hose leads to) an area where the hull core has been removed and which makes a little sump for the bilge pump to fit in? Not that that matters for the crack, necessarily, but that would make me think the tank is under the cockpit sole and that is the inside of the boat hull itself? (Of course correct me if I'm wrong; I'm not that familiar with the 25.)

Not that Dr. Bob needs anyone to confirm his knowledge, but I'm thinking the same thing: I would want to physically investigate to see what is going on there. By appearances (which can be deceiving, especially in photos), that looks like a "real" crack (vs. stress or spider cracking in gelcoat). If it's a "real" crack, then it may lead directly into the balsa core, in which case you'll want to take care of it sooner rather than later.

One thing I like to keep in mind while checking these things out, is... can I find any cause for it? In other words, is there anything besides the crack that I want to take care of? If you re-fiberglass the area can be made very strong, which may easily withstand any stress that might happen again; but I still like to see if I can figure out why something failed/cracked/shifted/etc.

Sunbeam
 
dchurch3":2qcf3v5t said:
there is not a crack - just a surface that has cracked
Click to expand...

I'm not sure I understand this.... do you mean that you know there is a subsequent layer of fiberglass below it? Can you see edges of maybe an added layer/piece of cloth that has cracked? Usually in a section of fiberglass that was laid up together (in other words, say an original layup comprised of three layers of cloth plus resin that were "made" together), one layer doesn't crack independently of the others. Not saying it can't happen, just that I don't commonly see it. An added layer though.... is another story. Maybe it's the edge of something starting to de-bond?
 
i guess one of my questions is does anyone here know the hull construction. When i look in the bilge i see a gray fiberglass surface that has bubbled in one area and I chipped off a piece of it (you can see the missing piece in the photo). It appears to be a thin fiberglass surface. The next layer down is not cracked and appears solid. It is yellow or brown and hard. I am wonderdering if that is more fiberglass or that a bilge liner was adhered to or if it is balsa? Can anyone describe the assembly?

Is this cosemtic and simi urgent - or is the structural and very urgent?

the outside hull is hard and does not show any signs of damage.
 
dchurch3":c2d9e08l said:
I chipped off a piece of it (you can see the missing piece in the photo). It appears to be a thin fiberglass surface. The next layer down is not cracked and appears solid. It is yellow or brown and hard. I am wonderdering if that is more fiberglass or that a bilge liner was adhered to or if it is balsa? Can anyone describe the assembly?
Click to expand...

I can't tell you exactly how the 25 is constructed in that area, but if it helps, fiberglass resin that has cured can be a brownish-yellow color.

I can also tell you how the hull of the 22 (and presumably the 25) is generally laid up (may not be specific to your boat). The hull is laid up in a female mold. So built "from the outside in."

1) Gelcoat sprayed into mold (this ends up being the shiny outside or bottom of boat).

2) Layers of fiberglass cloth (or other similar reinforcements) are laid in and saturated with resin.

3) A balsa (or other) core layer is laid in - probably around an inch thick - maybe a bit more.

4) More layers of fiberglass cloth are laid on top of the core and saturated with resin, excess resin is removed (squeegeed or some other way) (this layer could look yellowish brown, as the resin can cure that color).

5) Some sort of inside finish is applied. Some builders spray on gelcoat (which will end up looking more like paint and not super shiny like the molded gelcoat), some paint it on, some use paint.... it varies. I think the C-dory is some sort of applied gelcoat but not sure. This (if gelcoat or paint) could be the grey layer.

Layers 1-4 should be put on in close enough succession that they form a chemical bond, but... if some layers are added later for some reason (even later in the build process, maybe after the weekend, etc.), then they have to rely on a mechanical bond. Polyester isn't the best at secondary bonds (our boats are mostly built with polyester, as far as I know), so maybe something is de-bonding and cracking?

If your crack was all the way through layer #4, you would be down to the balsa core. However, you might not know it, because usually some resin/putty/slurry is used between the core and the adjacent fiberglass layers to sort of help "mush" it in and get an all-over bond without dry spots. So you could be seeing that (could be yellow-brown cured resin), and have a crack all the way through layer #4 but no currently obvious balsa because you are seeing resin/slurry (hardened of course). Of of course it could be something much more superficial - hard to tell without laying hands on it, or maybe seeing high-res photos that would enable major zooming. Can you clean the area to make it more obvious what's occurring?

Or, maybe layer #5 is simply lifting (the painted or sprayed on gelcoat layer) and you are seeing the top of the fiberglass (layer #4) and not the top of layer #3 (core)? What is the brownish patch to the left of the hose? Is that where more gelcoat has come off of the fiberglass maybe?

Just to be clear, I'm not saying I know you have a serious problem - I just can't tell. Sometimes something can look alarming and be nothing, or some dirt, or etc. But.... it does look like something I would want to get to the bottom of.

*********

Edited to add:

I looked at the photo some more and am thinking out loud:

1) If I'm seeing it correctly, that corrugated hose leads to a through hull - maybe for the bilge pump? Or maybe that's the pump itself at the end of the hose? It looks like that is in a circle about the size of a dinner plate that has no core (it's depressed). Maybe it is a mini-sump for the bilge pump, or an area of closed out (removed) core for a through hull? If that's the case, the way it could have been made is to have cut an area the size of a dinner plate out of the inner skin and then remove that core. Then new fiberglass (secondary, mechanical bond, probably)[ would have been laid into the depression and up over the side of the cut out core and onto the top. Maybe it would have overlapped the "virgin" hull by 6" or so. If this is the case, there would have to be an edge of that new top fiberglass layer. With a secondary bond in polyester is not uncommon to have it start to peel up at an edge. Could your "crack" be that edge?

2) What about that structure that looks like an angle supporting the tank? That looks like fiberglass. Is there a large layer of extra fiberglass extending out from that to help anchor it? If so it could be the same "secondary/mechanical" bond situation as I mentioned in #1 just above.
 
This picture is the best I can do, but it shows the hull form and where the balsa core is laid. To me, it appears that the crack is in the main structure, that is the top layer of glass above the core. So the first advice above was to take it to someone who is familiar with the C-Dory and fibreglass repair. If Les Lampham is near, go there. This is not a do-it-yourself job, unless your an expert. I'm not. We had a crack in the transom and I had someone repair it that did that for a living. And even then they had to do it twice. Find someone who does small boats, like Les.

Hull_side_5_5jpg.jpg

Boris
 
Tortuga":2ohrakn7 said:
photo_1.jpg


Here's the pic from the album.
Click to expand...

Some perspective; water tank is to the left (stern-side, centered under splashwell). black hose is for the bilge pump which is in the upper right corner (centered into the bilge). The issue will be how far back the crack goes under the tank. The tank is not removeable; it would have to be cut up (sawzall) and removed in peices.
 
It looks like it may be only the interior gelcoat cracking and elaminiating from the fiberglass underneath. I have the same issue in a boat I own and it is a cosmetic issue, not structural. I think what you feel under it is fiberglass.

If the fiberglass itself were cracked, I would expect a more "jagged" appearance to the edges. Gel Coat is brittle and it cracks more easily than the glass underneath.

What has caused this needs to be investigated. It may be just bad adhesion of the gel coat to the fiberglass under it. It could be flexing of the hull that has caused the gel coat to come loose and subsequently crack. I'd bet on the former as more likely.

I would probably use the boat for the next few weeks and then have the area looked at.
 
I happened back across this thread while searching for something else (polyethylene water tank repair), and wondered what was determined. After our poring over the photo and description and our "Internet sleuthing," I'm curious! dchurch3, did you ever get this resolved, and if so, would you care to share the information?

Sunbeam
 
Sunbeam, if you're really curious, send him an email with a link to the thread. He doesn't post that often so perhaps he doesn't monitor that often either.
 
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