Crack in bildge behind keel

[Ausluke]

Hi all
To we pulled into town of Lefkas Greece today.
Went to anchor off the town quay and found out just before tieing the stern off that the rudder was kissing some rocks/ rubble. After pulling forward slightly and still having the cringe feeling of not enough water under the rudder we pulled off and anchored in an anchorage.

After checking the rudder stock etc from the top side of the boat ( swim is tomorrow’s job) I wandered to the bilges and found a clean hairline crack running east/west. I’m wondering if the keel also touched the bottom. The boat is new to us so I’m still finding her imperfections. I can’t remember a crack on pre purchase inspiration.

None the less it’s there now and I am after thoughts on seriousness of it. Attached is a photo

[Suijin]

None of us can give you a definitive diagnosis. I will say that if your rudder was "kissing" the rocks and you don't even know if your keel was touching that either the crack is pre-existing or your boat is made of paper mâché. So I doubt that your incident caused the crack but I wasn't there.

[Don C L]

Sure hard to see what part of bilge and keel we're looking at there. Is it leaking? When a boat runs aground the keel exerts a lot force up into the hull behind it, which may be the cause of the crack. That was my first thought, but it doesn't sound like what you did so not your fault I bet. It is also a very small crack, I would not be inclined to worry about it.

[JPA Cate]

Suijin's right, can't tell from what we see, but if your keel has more draft than the rudder, it is more likely to have touched the rocks. Furthermore, if it went all the way through, it would at least be seeping. I'd regard that crack as something to investigate, but you will be diving the boat today, and perhaps have seen more.

Some boats flex when they sit on their keels on the hard, and can require fairly extensive repair, but it IS fixable. Don't know about repair facilities in Lefkas, though, maybe one of the people in Europe will be able to recommend a yard. If it is flexing too much, eventually, you will be getting water in there, and tightening the keel bolts won't help. It takes some convincing to get a solid repair done, or make it yourself. In our case, we had to replace a floor and two stringers, as well as the exterior repair.

Good luck with it.

Ann

[Ausluke]

Yes only kissing , talking couple inches of swell. As the boat bobbed up, rudder free, as the boat dipped 2 inches it hit.
Mabe I should put it this way
; there is a crack there now, I will have it repaired for peice of mind. Hopefully it’s not structural.

[Don C L]

It would be helpful to see exactly where the crack is in the hull. It sounds from your description that you rose and settled on the keel with the swell (or maybe both keel and rudder?). And I think you have a bulb down there right?

[Ausluke]

Yes fin bulb. The crack is about 200mm aft of the last keel bolt.

[jimbunyard]

Wellll, I guess that's a 'crack', but it's only in the gel coat. By all means, take a swim tomorrow, (jeezz, it's fkn Greece), but there won't be any external evidence of the 'kissing', other than maybe some abraded paint somewhere...the beauty of FRP construction is its' flexibility...

[Ausluke]

The crack is staggered. As in forward side of crack is slightly lower mabe 1 or 2 mm. Wich is strange. If the bottom hit I would imagine the forward side of the crack to be pushed up. Possibly the weight of the keel hanging in slings? It was put in the water few weeks ago.

[Boatwright]

Serious cracks aft of the keel are often caused by a hard strike at the forward edge of the keel.

Possibly your crack was pre-existing, patched on the surface and reappeared after your most recent incident.

Another thing to consider is the large loads imposed on a heavy structure by a low velocity collision. What seemed like minor bump to you could be a big bump to the many tons of your boat.

Visualize you jumping off a 1 meter bench as opposed to dropping your boat from the same height from its launching slings onto the boat yard pavement.

IMO you need to have the boat pulled and inspected.

[Ausluke]

Have a surveyor coming for a look tomora. Ill post an out come for others if interested..

[NevisDog]

Originally Posted by Ausluke

Have a surveyor coming for a look tomora. Ill post an out come for others if interested..

Thanks, that will help all of us. But won't you have to lift her out of the water first? Can't think why fwd side of crack is lower than aft side. Hanging in slings won't do it, not unless it was already broken from a grounding at speed, and then we'd expect to see weeping??? No point speculating though.

[CarinaPDX]

Sorry this is happening to you. You did the right thing by getting a surveyor on the case. No one can give a reliable diagnosis from afar, but I will offer some guesses:

Your light grounding of the rudder probably didn't cause this - it is in the wrong place. And at the wall on Lefkas it is easy to hit the rudder on the riprap (I always go bow-in for that reason) but the keel should have been over very soft mud. I really doubt your keel hit bottom there.

The location and orientation is exactly what you would expect from a grounding under way (Santana 35's were famous for this sort of failure). I suppose it could also be caused by a grounding at anchor or being set on her keel without adequate hull support but that would imply a pretty light construction.
.
I would have been inclined to dismiss this as a hairline crack in the gel coat, but the different heights on each side of the crack imply damage to the fiberglass beneath the gel coat. The crack is probably located right at the aft end of the keel. One scenario is that there was a grounding that raised the aft end of the keel, causing the crack, and once refloated the mass of the keel pulled down on the forward side.

Again, these are just (somewhat educated) guesses. The surveyor will have the answers.

Greg

[Cheechako]

Is that inside the boat? It just looks like a common gel coat crack to me, often gel is sprayed inside thick to cover rough surfaces cheap and cracks a bit when it shrinks back over time.
Not to worry. Many boats have dozens of those.

[patprice]

As a thought, the crack if new will have clean sides. If old there will likely be dust or similar in the crack.
Get a magnifying glass and have a good look. There may be better ways of doing this.