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Old 12-01-2010, 12:46   #76
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"Bolted on keels becomes a question mark after I'd say maybe 5 years."
Depends on how well they are engineered. Along with how strong the hull attachment is. While stainless steel (keelbolts and kitchen knives alike) impressed lots of buyers in the past 50 years, for keel bolts monel ($$) or bronze (can't sell the sizzle onthat, it sounds old fashioned) are probbaly better bets, they just won't fail the same way. Then there's Beneteau's system, with a cast iron keel that they literally bolt onto the hull using "regular" bolts that can be replaced one at a time rather than sistered or cut out. Doesn't SEEM to be as good, but apparently works just as well, and being able to swap them out certainly makes preventive maintenance simpler.

But bolts in general are passe in the modern world. All you need is 3M 5200 or a similar adhesive, properly applied. In theory you could make the hull seamless, just glue the keel on, and if you could tear it off it would tear a piece of the hull off with it. Of course the downside to adhesives is that there's just no way to eyeball them and be sure they were put on and cured right. "Ooopsie".
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Old 12-01-2010, 12:58   #77
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Glue on the keel? Is that actually done?
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Old 12-01-2010, 18:19   #78
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I don't think any boatbuilder is doing it, but I've heard form folks who tried to drop their keel after a PO had glued it on. And had to cut it free.

:-)
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Old 12-01-2010, 18:58   #79
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Sure this has been noticed in the cases of failure so far discussed it wasn't the bolts that failed it was the hull. The structure and distribution of the loads is where the failure is. In the cynthia woods case the keel appears to still have bolts and backer plates intact. It took the hull with it. But a very small section. Similar to the boat on the beach. Have to wonder why the loads arent distributed better. Id think if the keel is ripping out of the boat it should leave more damage around the area of attachment. Seems like bad engineering.
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Old 12-01-2010, 19:21   #80
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Absolutely. Doesn't matter how perfectly the keel is bonded to the boat - whether bolts, glue or thumb-tacks... All your perfect bond is doing is perfectly transferring the stress to the hull itself. So it's the strength of the hull area at and around the keel join that matters. And its ability to distribute and absorb loads.
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Old 12-01-2010, 20:37   #81
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It is often impossible to distinguish between "bad engineering" and "built to a price". Or other spec.

In boats, cars, or even shirt buttons and the thread holding them on.
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Old 13-01-2010, 02:45   #82
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Seems like bad engineering.
I can't agree - the boat is designed, amongst other uses - to race. A cruiser-oriented owner may require that the keel remain structurally intact after an 8 knot grounding. A race boat built to that criteria would not be competitive.

If we were to look at all the keel failures on race boats and racer/ cruiser boats such as this J-boat and discount:
- those that fail because of a grounding
- those that fail because of modification
- those that fail because of lack of maintenance

How many would be left? - I have no idea, but it would not surprise me in the least if the proportion of bolt on keels that just "fall off" is somewhere in the region of one in a million.

I think that is good engineering
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Old 13-01-2010, 09:01   #83
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the boat is designed, amongst other uses - to race. A cruiser-oriented owner may require that the keel remain structurally intact after an 8 knot grounding. A race boat built to that criteria would not be competitive.

If we were to look at all the keel failures on race boats and racer/ cruiser boats such as this J-boat and discount:
- those that fail because of a grounding
- those that fail because of modification
- those that fail because of lack of maintenance
But racing boats aren't the only one loosing keels. Look at all the pics on my previous post. Even bolted on cut-back keels on cruisers are falling off. I certainly agree with you on your 3 points as inherent causes of failure, but this is NOT keel/keel bolt failure: this is HULL failure and it seems to be happening at an increasingly alarming rate. Perhaps we're seeing the flaw in fiberglass.
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Old 13-01-2010, 09:16   #84
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Im with sea hunter on this one. THe keels in the pictures show the hulls cleaning seperating at the immidiate area of contact with the bolts intact. Suggests to me that the load is not sufficiently being transfered. Getting picked up and dropped 8 feet onto a sand bank could blow the keel through the boat. I would hope that the load is transfered to a larger area better. Doesn't seem like this would add alot of weight or expense and the weight is near the right place
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Old 13-01-2010, 21:04   #85
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this is NOT keel/keel bolt failure: this is HULL failure and it seems to be happening at an increasingly alarming rate. Perhaps we're seeing the flaw in fiberglass.
I don't disagree - whether the keel rips off, leaving the bolts, the bolts stay in the keel and are ripped from the hull, or a section of hull is pulled out with the keel - it still has the same result - the keel comes off.

The point is WHY does it comes off? I would like to argue that in the vast majority of cases it comes off because the keel is being put through something that was never in the designed to experience or accommodate in the first place (grounding, poor maintainance, modification)

Of the examples you had in your previous post, the only conclusion I could find of why the keels failed was for the Cynthia Wood, where USCG stated that the failure was due in large part to repeated groundings and improper repair.
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Old 13-01-2010, 21:14   #86
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Breakaway keels are an interesting design concept. But they need to do more work on the concept to eliminate the hole in the bottom of the boat when the keel disappears. It would also be nice if they could have another keel slide into place when the first one disappears.

Sort of like a lizard that sheds his tail and grows a new one when a predator grabs his tail.

Once they perfect these design flaws, I might consider a light displacement, go fast, fin keel dropping monohull.
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Old 13-01-2010, 21:27   #87
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....Once they perfect these design flaws, I might consider a light displacement, go fast, fin keel dropping monohull.
Just as so might also some be willing to trade their Sailboats for self-righting multi-hulls....
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Old 13-01-2010, 21:39   #88
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Just as so might also some be willing to trade their Sailboats for self-righting multi-hulls....
Self-righting multihulls are a great idea, but I would prefer a design that didn't turn over at all.

Years ago there was a multihull named Roge Wave that flipped over, and the famous French skipped said that heavier catamarans have less risk of flipping over than light displacement racing cats. I took his advice and filled Exit Only up with thousands of pounds of cruising gear to the point that I had to raise the waterline. I never worried about wind induced capsize on board Exit Only. Wave induced capsize is another issue. If I ever get in an ultimate storm on Exit Only, I will fill my bilges with seawater to increase our weight and decrease capsize risk.

The only self-righting catamaran I have ever heard of was trying to break the New York to San Franciso via Cape Horn sailing record. The racing cat was in a big storm and flipped over. A short time later another big wave came along and flipped it back up to its normal position. More work needs to be done on this concept!
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Old 13-01-2010, 21:46   #89
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Do you remember those remote control cars they advertised for children a few years ago>? They had wheels that were big enough to touch ground whichever side they were on... seems like they had cockpits on the top and bottom too.

Maybe you could just have a retractable rig... then when the capsize happened, you just go below and crank a handle... the mast pokes up through the (now) topside...

Tough walking on the decks painted with bottom paint all the time...
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Old 13-01-2010, 21:49   #90
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Since cat owners love to boast about how they might flip but they never sink, what about a cat that sails just as well regardless of which way up it is? Like those monster truck toys with huge wheels which flip over and keep driving...

You'd need symmetric hulls, a big centreboard which would double as a wing sail when the cat is flipped over, and carpet on the ceiling... Oh and your giant domestic fridge/freezer would become a freezer/fridge in one orientation...

I'm off to the patents office.


EDIT: darn, looks like SV Faith has beaten me to it. Hope I can run faster...
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