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CS30 Structural Grid Repair In Bilge

14K views 52 replies 23 participants last post by  Faster 
#1 ·
Greetings,
Does anyone know what the internal composition of the stringers in the bilge of a CS30 consist of? I'm wondering if the grid structure is hollow, or has coring?
Has anyone repaired/replaced sections that were cracked due to grounding the boat?
Many Thanks.
 
#4 ·
Greetings,
Has anyone repaired/replaced sections that were cracked due to grounding the boat?
I know sailnetters are annoyingly conservative and I hate to have to play that cliche but...

Fin keel boats, especially more modern designs, often distribute the keel loads with a some form of lattice in the bilges of the boat. This is because the loads on the keel are significant, more than enough to cause failure where the forces concentrate - especially where the keel meets the hull aft.

A hard grounding at speed stopping a 4 ton boat all focused on that point and hard enough to rip apart the structure designed to support that load? Scary. I would be nervous that as the load transferred to parts of the structure not designed to support it (i.e. the hull laminate, then the bulkhead tabbing, even the chainplates and rigging) there would be damage that's invisible to non-destructive examination.

Do you know exactly what happened to the boat?

Have any photos you can share?
 
#5 ·
I am pretty sure the grid is fiberglass without any wood core. My CS27 is and it pre-dates the CS30 by a few years. The grid is hollow.

Depending on how hard the hit was the damage could be extensive. To repair it properly access is needed which could mean removal of cabinetry.

I was on a 33' Beneteau recently that hit a rock. The damage was repaired professionally - for 26k.
 
#6 ·
Thanks for the reply Mitiempo and Zedboy.

The boat is said to have been grounded on a shoal under power.
The subsequent survey for the insurance claim indicated no damage to the exterior hull, but a deformation of the aft upper end of the keel, and substantial damage to the stringer grid in the aft section of the bilge.
hopefully the attacements of photos i have will load...

Thanks again for your input.
 

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#7 ·
Yeah right no damage to exterior hull. That puppy flexed real nice to deform the keel like that and crack those stringers. Hard to tell what the glass underneath looks like without chipping/peeling off that cracked gelcoat.

My little bit of experience with this tells me the glass can still be flexible even on an older boat - lots of stories of improperly stood (standed?) boats' hulls "popping back out" once put back in the water, presumably with no ill effects.

Whether you could make a claim that everything is still ok just because the stringers look healthy under that gelcoat, and assume things just flexed and took the impact ... I'll let bigger experts than me weigh in. And if the glass looks bad, all bets are off.

My boat is wood ;)
 
#8 ·
Hopefully rugosa will notice this, you might want to PM him.. he worked with CS for a time.

This looks like a pretty serious grounding, and though undoubtedly repairable it's not a small job. A big part of it is determining the actual extent of the damage. The hull skin (apparently intact could have internal damage not visible from outside. I really don't think this is a DIY repair for most of us.. Kinda scary - the boat would have to be nearly free to take this on.
 
#9 ·
That's some serious impact to compress the bend into the keel. CS 27 through 36T were solid glass grids. Expect same on other models. When I worked at CS '78 to '83 we took in a 36T that had grounded in Bahamas and disected it. Lots of fun to tear one apart.:D The damage extended beyond the visible, including delamination (downward tearing) at forward end of bilge, (upward tearing) in way of engine bearers, etc. CS furniture fit was highly consistent so look for uneven cabinet mountings, cabinet and cabin doors that bind or have uneven joints, screw plug pops, tabbing delamination, tanks shifted or off mounts. Split the shaft coupling to get an idea if the engine moved too. Also check steering thoroughly - impact at forward edge of rudder, binding turns (bent stock). The cheapest thing to fix will likely be the impact ding in the keel. Hopefully it is free to a good home.
 
#10 ·
When a fiberglass boat is damaged the cracks are easy. They're obvious and not difficult to estimate. The real, and expensive, part of the problem is delamination. At the top of the trailing edge of that keel, there was enough force to bend the keel and shed whatever coatings (gel coat, paint, epoxy sealer) were in place. When the glass is deflected that far you can bet it's delaminated. my guess is that the delam is probably on the order of 12 inches across and 10 inches fore and aft. Basically, the same goes for the grid. Cracks are cheap, delams, not so much. Forget the surveyor, get a qualified glassman and don't stop grinding until you've reached the perimeter of the delams. Otherwise, it's like building a house on sand.
 
#11 ·
Agree with Faster, and am not even close to being an expert on anything, however I have been around boats and boatyards for a long time. This looks like the equivalent of a broken back with possible massive repair work that may be sound or maybe not. If you got the boat free, maybe worth the gamble, maybe not. Another sound boat that hasn't been crippled might be a better alternative.

Paul T
 
#16 ·
This looks like the equivalent of a broken back
Think about how far the trailing edge of the keel had to deflect up to put that S-bend in it. :eek:
 
#20 ·
The grid is definetly hollow and the damage is significant. As others have mentioned the more serious damage may be what you can't see. If you are really interested in the boat find a marine surveyor with a thermal camera and make sure he is certified to use it properly. This will reveal any lamination damage. The grid is a fairly simple fix .... delamination could cost big bucks to repair.
 
#22 ·
This Sailnet forum is really an amazing tool. To be able to pick people's brains from all over the map with all sorts of prior experiences is invaluable.
Thanks everyone who've taken the time to send their two cents my way.

The repair quote was $35,000. I'm not sure how intrusive the testing for damage was in order to come to this number.

I'm going to take a look at the boat, the repair quote, survey and talk to the yard and form an informed opinion then...
 
#24 ·
Perhaps you could find another un-damaged similar boat for $35,000? Re-sale value on a boat that has been "fixed" may not be so good? Is there something super special about this particular boat other than it being wounded? Just wondering out loud.

Paul T
 
#25 ·
the reason is that "IF" it's repairable and i get it for next to nothing it's exactly the boat i'm looking for.
CS boats are very well built and also sail well. I'd be using it on an inland lake for weekends/evenings.
my budget is limited and i'm looking for my next project to tackle. if it's doable, i welcome a challenge, that's just the way i am....
 
#26 ·
"dabnis"- good points. i realize that the resale will never be comparable to an unbent boat. my justification to buy it would be if i were able to get it for a song, and do the majority of the work myself, i could keep the repair costs well below the 35,000 and have a nice boat when i'm done.
maybe i'm crazy.
 
#27 ·
Not that I know anything about this type of repair but it's a buyers market. There are lots of cheap boats out there for reasons other than having their entire hull structure compromised.

Maybe if it's free, and if the boat is in fantastic shape, recent engine, sound decks, sails... everything else, and you're sailing on an inland lake where the risk of hull failure is less...but there are a lot of boats out there.
 
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