HATCH COVERS IN BERTH

To be clear, it's not a lot of flexing. But there does not appear to be any core in this area, and it sounds like other boats also have the core stop a few inches in front of the cabin bulkhead. I have no idea how thick that fiberglass is in the bow. I do know that this area takes a lot of beating in waves though. The foam I removed is "hard". That is, it would add additional support or strength to the bow in the area it reaches. While the foam did not fill the entire void, where it did fill would be a solid backing inside the hull that I would think would add overall "structure" to what appears to be fiberglass and gelcoat only. The flex is not a lot. But I can push hard with my hand and see the hull move if ever so slightly. Where I'm pushing is between the sides where the berth bunk material mates, and the keel. This is not aluminum. Hit hard enough by a pounding wave, I would think the fiberglass could be cracked. Then again, I'm not a boat builder or structural engineer. Right now I'm just very leary about how much support was removed from that area with the removal of the foam. A lot of speculation and opinion has been given in these forums. I just don't know what the qualifications of the writers are. What I would like to know, is has the actual boat builder been asked or given answers regarding this area and the removal of foam. If the newer boats that are coming with the storage compartments and hatches already installed are built in the exact same way, without additional strengthening or core in this area, then that would certainly encourage continuing to fabricate the older boats in this way. I just want to know that when I'm offshore in the Great Lakes with the pounding chop that I can trust my boat to take a good wave smack and not crack. This probably has a lot to do with my lack of much experience with this boat so far, and not being a structural engineer. Colby
 
I don't think that hitting a wave and cracking the fiberglass in the bow area will be an issue. A wave will hit a large surface area and the force will be distributed. Also the shape of the hull will deflect a large portion of the wave energy.

A bigger issue is hitting something hard in the water (e.g. a log or other debris) while moving at a good clip. Again while the shape of the bow area will deflect some of the energy, the force of striking a solid object will be much more concentrated and more likely to cause a hole.

Another thing to consider is that the C-Dory boats have been built with pretty much the same hull design for something like 30 years now. Seeing where a number of these boats go, I would think that if there were any issues with the hull strength or design it would have shown up by now.
 
I think about the log or obstruction issues, as I also boat in some of the major rivers. Hoping that all my concerns are for nothing. Having the additional storage will be nice, and since I've already started the work, it'd be nice to know I haven't opened up a can of worms or made a lot more work for myself! ;-)
 
ssobol":2z5m5r8c said:
If the hull is designed to flex in this area (perhaps to soften the ride a little) and I put something in there that limited the flexing, I might end up with cracking of the FG around where my structure attaches.
Click to expand...

Granted, it's good to keep stress risers in mind (so as not to create them), but I feel pretty confident in saying that no fiberglass hull is designed to flex. I say that because flexure weakens the layup. Every time the boat flexes, it puts weakening stress on the laminate. Now, that's not to say that some flex in a boat means it will break up, but just that I haven't heard of any boat designer putting flex "in" on purpose for any reason. At least not in a boat built with "normal" materials (vs.some special exotic ones that I'm not familiar with).

When fiberglassing stringers (fore and aft "beams") or bulkheads into a boat, one generally runs the tabbing a decent distance out to the sides, which helps to prevent a point load (and oftentimes a bulkhead itself doesn't even touch the hull, or has foam at the point of contact, so it's the spread out tabbing that's doing the work).

Sunbeam
 
In the end, I decided to just use the cutout section as the storage cover. Only thing left to do now, is see how the hull handles stress without the foam...

Finished_Storage_Cover.jpg

I put storage here and in the same location on the other side.
 
I am installing a bladder water tank in the front vberth area at this time.
I did tab two small pieces on the sides of the center bulkhead to divide the area for support for the tank. I stopped both pices a little short of the hull so as to not point load.
Plan on posting pictures.

Jerry C Nile C22
 
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