Visit our Popular Forums

Keith.LiGreci · 20-11-2012, 06:50

Has anyone experienced damage of the plywood transverse structural floors in the hull bilges under the sole level on each side of the internal “skeg hat”.
See attached picture

Jeannius · 20-11-2012, 07:00

Hi Keith... Ouch. Not yours I hope!

No direct experience of the Salina, but the guys at a charter company we both know used to have to regularly replace cracked hatches on FPs because of flexing.

DotDun · 20-11-2012, 07:37

Trying to figure out what caused that.....Do you know of a hard grounding on that keel? Is there any damage on the keel itself? It's make one wonder if dropping off a swell onto a rock might cause this. If no keel damage, I wonder if simply dropping onto hard sand might cause it.

Looking at it, that would be a point of high stress with enough upward force on the keel.

Rapanui · 21-11-2012, 03:51

Our FP Maldives had an incident with a rock before we bought it which delaminated one of the small ply sub bulkheads in the keel area from the skin. We ground it out and relaminated. The surveyor also found that presumably the same impact had delaminated the hull in a couple of patches up to the size of a hand palm. We ground those out with long tapers and relaminated. There was a chunk of keel missing which was replaced in the same way. One advantage of having a solid grp underwater shell.
First check out the keels and rudders for indications of damage. That should then give you a clue as to the cause.
I would suggest you have the shell in the region of the keel area (and any other areas found above) surveyed inch by inch for delamination. The sort of impact that could crack a bulkhead like that is likely to have done other damage. The surveyors tap with a small hammer, good shell rings (doong), delaminated areas don't (duh), areas over bulkhead are very short and sharp (dong). Apologies for the poor fidelity of the sounds but if you do it yourself then practice on a good bit of hull, you will quickly pick it up. It will not work so easily in the sandwich areas above the waterline. I have surveyed 3 100 ft patrol boat decks with faulty layup using this method and apart from being hell on the knees it is extremely accurate and easy, if somewhat tedious.
The same method will also detect if any of the other sub bulkheads, floor supports etc have delaminated which is a possibility.
The good news is that if confined to the solid layup, repairs are relatively easy and will make the boat as good as new

Tropic Cat · 21-11-2012, 04:46

Quote:

Originally Posted by Keith.LiGreci

Has anyone experienced damage of the plywood transverse structural floors in the hull bilges under the sole level on each side of the internal “skeg hat”.
See attached picture

You ask about the floor, but the photo is showing a bulkhead delaminating. Depending on which bulkhead that is, the cause could either be a grounding or improper stresses caused by someone misadjusting the mast.

marvt · 21-11-2012, 06:08

Hi there, we have a Salina 48, hull 47, what is your hull no?

Where exactly is this damage, I cannot find a similar spot? Do you mean keel where you write Skeg?

Is it under the floor boards in the aft cabins?
Tks, Marius

DotDun · 27-11-2012, 15:09

Quote:

Originally Posted by pguillemin

it happened a lot
A New catamaran not fit to sail [Archive] - Multihulls4us Forums

Not sure what you are implying?

Should FP build a boat that can take a very hard grounding without damage? If you drop 30k pounds on a rock something is going to break.

I think the picture speaks to an operator issue, not a manufacturer issue.

Tropic Cat · 27-11-2012, 21:20

Quote:

Originally Posted by DotDun

....I think the picture speaks to an operator issue, not a manufacturer issue.

I have to wonder how you are able to definitively come to that conclusion? The crack told you the "owner did it"???

DotDun · 28-11-2012, 06:07

Quote:

Originally Posted by Tropic Cat

I have to wonder how you are able to definitively come to that conclusion? The crack told you the "owner did it"???

I said 'operator', which could imply a travelift operator that dropped the boat, or a helmsman that hit a rock after dropping off a swell.

The only way to cause a crack like that to that bulkhead is upward force on the keel. I realize the keel is closed cell foam wrapped in fiberglass but I would bet a good amount of money that the keel doesn't provide enough buoyancy to cause the crack without help.

Your conclusion?

Cotemar · 28-11-2012, 06:21

I agree with DotDun on this.
I think the picture speaks to an operator issue, not a manufacturer issue.
The picture clearly shows upward force from the keel making the crack.
The keel box is just to the left in the picture.

kiltym · 28-11-2012, 06:23

Only thing I would add is if it was from keel hitting something, I would expect some cracks along the length of the keel (or keel cavity) as well (in the "gutter" seen in the photo, for example). The keel is in a cavity, not glassed to the boat.

I think there would be additional places where at least bad stress cracks are present, based on the bulkhead cracking being so severe.

Rapanui · 29-11-2012, 02:42

You may well be right that there is other damage which is why I suggested going over the whole structure nearby looking for delamination. However, it also quite possible the crack may be the only manifestation of damage. The FP keel boxes are very strong by design, they are intended to remain intact while sacrificing the keel. In my view, the weakest area in the construction is the over laminated ply part bulkheads. Plywood is itself inherently weak in tension and the polyester lamination does not bond particularly well to ply. However, the energy has to be absorbed by something in what clearly has been a major impact, and rupturing the bulkhead is probably a better outcome than damage elsewhere.

Hopefully the bulkhead has acted as a fuse and protected other structure, but repeat you do need to survey very carefully.