Crack in floor panel

[Jampit]

I have a Beneteau Oceanis 311 which has developed a crack in the salon floor running across below the galley sink. This had occurred while the boat has been out of the water in a cradle during the winter. While the survey done hast year said the hull etc. was sound, This area showed some reinforcing; namely a layer of Grp mat, it is this that has failed.(Epoxy/ polyester??) I would now assume that some damage had occurred previously, but I don't know for sure.
The hull appears to be unaffected on a visual inspection, (but is covered by anti-fouling at the moment.)
The crack widens to about 10 mm max in the middle.
The door under the sink sticks and the island unit may be warped.
Has anyone had a similar problem?
Would it be safe to launch and see if the crack closes before attempting a repair. The boat is not at a marina so is floated off the cradle and would take a little time to get back out again.
Any advice welcome.

 

[Captn TJ]

A few questions;

Is the crack in the pan (liner) or the hull? B boats are typically built with a complete hull liner or pan on the inside of the hull.

You mentioned a glass mat - is that a repair or can you see the roving from the layup of the hull?

How was the hull supported during layup? If the crack wasn't there before layup perhaps the boat wasn't properly supported.

Regardless 10 mm is a big crack and one to be concerned about. I'd definitely remove the bottom paint in the area and have a qualified yard or surveyor examine

 

[Jampit]

The crack is in the liner which has had a patch put over it at some time. It is this which has failed- I can see the edge of some roving/mat here, so as I said, it looks as if this has happened before. Although the hull was supported both at the sides and fore and aft, the additional props were removed for a while blocks were removed to let the cradle go back onto its wheels. This would be a normal change for any boat, but !!??!
I will get a photo tomorrow.

 

[Captn TJ]

Jampit

Picture would be great - but from the description should still be a concern. The pan or liner is bonded to the hull so the question is then why the movement?

Could be that the pan wasn't bonded or properly tabbed in during construction. Or was the boat run aground which loosened the pan?

If it was my boat the first thing I'd do is drill an inspection hole in the pan to ensure that there is no crack in the hull. I'd drill a small hole and use a scope. If no crack then I'd feel a bit more comfortable but still a bit concerned.

I'd also follow that section of the pan along the hull and see if it's loose. If that's the case the solution may be as 'simple' as getting it rebonded.

 

[Jampit]

I suspect that your idea that it may have been run aground at some time may be correct, In case I wasn't clear (I'll get a pic tomorrow) the smooth top surface of the liner had been overlaid with a glass mat, indicating that some sort of repair had been carried out, however I have not (yet) been able to see if the bond between the original liner and the hull was intact- I didn't know about that- so thanks for that bit of information!
I appreciate your advice and have someone coming to look at it.

 

[Jampit]

Further examination indicates that it is the bond between the liner and the hull which is broken(the hull is ok). I am told that the liner is actually the main bulkhead/stringer at that point and it too is cracked and would need a major repair. The survevor said that it seems most likely that when the additional supports were removed to lower the cradle, the full weight of the boat was supported by the keel. unfortunately, the long overhang towards the stern was not supported at that time and that probably caused flexing which in turn caused the damage. Beneteaus are not happy sitting on a cradle with the weight on the keel only! This information is too late for me and certainly I was not told this by the previous owner- who supplied the cradle- at extra cost!

 

[Captn TJ]

Further examination indicates that it is the bond between the liner and the hull which is broken(the hull is ok). I am told that the liner is actually the main bulkhead/stringer at that point and it too is cracked and would need a major repair. The survevor said that it seems most likely that when the additional supports were removed to lower the cradle, the full weight of the boat was supported by the keel. unfortunately, the long overhang towards the stern was not supported at that time and that probably caused flexing which in turn caused the damage. Beneteaus are not happy sitting on a cradle with the weight on the keel only! This information is too late for me and certainly I was not told this by the previous owner- who supplied the cradle- at extra cost!

Ouch that is an expensive lesson in hull supports! Fortunately the hull doesn't have a crack so it's 'just' bonding the pan liner to the hull. Since this was patched before do you have recourse against the previous owner for the expensive cradle and non disclosure? Maybe the boat yard as well?