Would your keel joint survive a full speed impact? - Page 2 - SailNet Community
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post #11 of 37 Old 01-02-2012
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All this talk is about the keel and hull the standing rigging takes a beating too
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post #12 of 37 Old 01-02-2012
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Quote:
Originally Posted by davidpm View Post
this is very scary. How do you survey for this, or do you just pass on all encapsulated keels?
Personnally, I do generally pass on encapsulated keels, preferring a bolt on keel assuming that the connections are properly engineered. That is a very big assumption, since the design of keel connections vary widely and some are just not as good as others. But also, bolt on keels require more long term maintenance, ideally being removed periodically so the keel bolts can be inspected and the joint recaulked. To me this is a matter of a trade off between something which can be maintained but which requires more maintenance vs something which is lower initial maintenance but which ultimately cannot be rebuilt properly.

But if I were to consider buying a boat with an encapsulated keel, I would want to check for delamination. A good surveyor, let alone a reasonably astute amateur can tap out a keel encapsulation envelope for delamination. A large enough delaminated section to be problematic is pretty easy to hear, let alone feel.

About ten years ago, during in an earlier discussion of this topic I went through a yard, tapping on encapsulated keels with my bare knuckles. I took notes and don't recall the exact percentage, but my recollection is that roughly half had delaminated areas that were larger than 18" in diameter and some where completely delaminated and would flex when simply pushed on. During that period I spoke to a couple yacht designers and a marine composites engineer who did work for yacht designers, and the sense was that depending on the size of the boat, an 18" dia. delam was at the point where it impacted the ability of the boat to safely absorb the next impact.


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post #13 of 37 Old 01-02-2012
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Hit a rock at 5 1/2 knots cutting a corner to closely years ago rounding into Marblehead harbor from Peaches Point. No leaking, no damage. Still have the same boat 15 years later...Chris Craft Apache 37 sloop with a cast iron fin keel bolted to the hull. When I pulled the boat that fall, there was a very small chunk missing off the leading edge that I fared smooth.

BTW, great sailing day across the Chesapeake Bay yesterday (New Year's) from Galesville.
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post #14 of 37 Old 01-02-2012
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There is a J-54DS for sale up on Lake Erie that reportedly hit a sandbar at full throttle. She made it to port, but I'm told had substantial damage that has since been repaired. Unfortunately, given the glut of boats on the market, I'm sure she will be the last 54DS to ever sell.


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post #15 of 37 Old 01-02-2012
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You had the repair done in China?

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Originally Posted by tommays View Post


It took a rather large truckload of money as 7' keels seem to be quite the lever
It looks like you paid with a (small) truckload of yuan.

Finishing our major refit. Our trip to Newfoundland is off because it is too late. Hoping to go to the North Channel instead.
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post #16 of 37 Old 01-03-2012
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Quote:
Originally Posted by Jeff_H View Post
But if I were to consider buying a boat with an encapsulated keel, I would want to check for delamination. A good surveyor, let alone a reasonably astute amateur can tap out a keel encapsulation envelope for delamination. A large enough delaminated section to be problematic is pretty easy to hear, let alone feel.

About ten years ago, during in an earlier discussion of this topic I went through a yard, tapping on encapsulated keels with my bare knuckles. I took notes and don't recall the exact percentage, but my recollection is that roughly half had delaminated areas that were larger than 18" in diameter and some where completely delaminated and would flex when simply pushed on.
I'm assuming that tapping on good keel sounds solid and hurts and delaminated sounds hollow and does not hurt as much.

18" seems like a very generous allowance. Wouldn't any delamination probably mean water egress and water, at least salt would mean more delamination as freezing and rusting continued?
How exactly are these keels filled. I've heard of chunks of iron or lead set in concrete was one method.
In old Catalina 30's they had a plywood shoe in the bottom of the stub keel. The top of the glass in the bottom of the bildge has to be removed, the plywood dug out and replaced with glass.
Would a repair on a encapsulated keel be simililer in that the bottom of the bildge would have to be removed but then the whole keel would have to be excavated?
It sounds like wet deck core work. Probably not expensive to do ones self but a really big nasty long job.

Last edited by davidpm; 01-03-2012 at 02:48 PM.
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post #17 of 37 Old 01-03-2012
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In looking at the encapsulated keel with the bloody nose above, it seems that there is a relatively small cover of glass on a long lever. As I discussed in previous posts, I hit a rock (or something) doing full speed under power, 6 knots or so, with my old Alberg. It was a couple of years ago on Lake Champlain when the lake was terribly low. Talk about Aw S%^t moments! It took a good chunk out of the glass, which is > 2" thick at the bottom of the keel. I was surprised, in doing the repair that the lead in these type designs is seated on top of some 3/4" balsa core material. The balsa, I'm sure, distributed the impact by depressing and allowing the glass to break rather than having the impact go directly into the lead. It was also easy to just dig out and replace some of the balsa with new to regain the hull shape. Having to work overhead, the repair was a PITA but not catastrophic nor very expensive. It was just time consuming building up that many layers of glass (heavy roving mostly) feathered out 20" or so from the gouge. There was no sign of any stress or distortion in the bilge above the impact and the sloped angle of the keel no doubt allowed the boat to ride up and over whatever I hit. (I think it was probably the buoy mooring which I was too close to.) So, I guess the type of encapsulated hull design has a lot to do with what happens when meeting a rock.

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post #18 of 37 Old 01-03-2012
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down, the I28 is built like a brick *house, it isn't easy to break one. But AFAIK there is no keel designed to take hard impacts without structurl damage to the boat. Either you tear the keel off, or the hull lets go, the amount of force involved in a "head on" collision is going to wrinkle the boat. Even if you kept the keel on, the rig would probably be damaged and the bulkheads come untabbed--on any boat.

Hit a concrete divider with a Mercedes, and you'll still total the car. Build the car strong enough to break the wall, and you've got a tank instead of a car. Tanks don't sail well. And the I28 doesn't do so well in ghosting conditions, as it is.
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post #19 of 37 Old 01-03-2012 Thread Starter
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Hello,

I am impressed with how the I-28 is built. You are right. The 1/2" thick steel keel stub plate is an indication of that. This thread has opened my eyes to the distribution of force one should expect when hitting a solid obstruction with the keel. It isn't a very heavy boat at 7,000 pounds. Almost half of its mass is the lead and that is raked backward at a fairly good angle. "Some damage" should be expected if you smash into something but I will expect to "survive" an accident like that if it ever occurs. There would certainly be a tendency to "ride up" on impact. The likely hood of the keel breaking away is probably very small.

It isn't impressive until things start to blow then the I-28 is a special little sailboat.

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post #20 of 37 Old 01-03-2012
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Quote:
Originally Posted by Minnewaska View Post
There is a J-54DS for sale up on Lake Erie that reportedly hit a sandbar at full throttle. She made it to port, but I'm told had substantial damage that has since been repaired. Unfortunately, given the glut of boats on the market, I'm sure she will be the last 54DS to ever sell.
I know the boat. She didn't hit sand-- she hit rocks under power at considerable speed. Impact was enough to tear the engine and generator off their mounts. Yes, it was repaired, at over $200k in costs, but it's not a boat I'd buy.
Correction: It may not be the same boat. There is a Yachtworld listing that is not the boat I'm referring to.
Same story, though.

Mark Smith
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio

Last edited by msmith10; 01-03-2012 at 04:44 PM.
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