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Old 15-12-2012, 03:44   #16
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Re: Fin Keel Strength ?

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Originally Posted by donradcliffe View Post
I felt so much safer after I read your post. Then I read this...

Keel failures prompt call for oversight
These are racing boats. I don't think these are representative of modern production boats.
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Old 15-12-2012, 04:45   #17
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Re: Fin keel strength?

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Originally Posted by goboatingnow View Post
That's a production boat with a short fin keel. Not fit for the ocean according to some.
Interesting is that towards the end they stopped their attempts at crashing the boat in to the seawall because the crew was getting to much shaken up.

Again drives down the point: Most boats are build strong enough that the crew usually runs out of stamina before the boat is in any danger...
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Old 15-12-2012, 12:04   #18
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Re: Fin Keel Strength ?

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Originally Posted by donradcliffe View Post
I felt so much safer after I read your post. Then I read this...

Keel failures prompt call for oversight

The boats discussed are at the far end of the racing scene, where failures like this are, while not expected, considered a reasonable risk. The Andrews 70 (maxi racer no holds barred race boat) I oworked on for instance had a keel root that was less than 2 inches wide. This forced massive loads on the bolts and supporting structure since there was so little surface area to bolt too. Which is why we took the keel off at least twice a year to inspect the bolts, and replace the damaged keel bolts when necessary (the boat had 3 keels so we always had a spare in good shape).

However the repair bills on this boat were considered just the cost of doing business. We also broke a mast every 18 months or so, and replaced spinnaker poles about one out of three offshore races. We also carried a spare rudder with us to races, and have a 40' container with extra sails. To compare this type of boat to a cruiser isn't really fair to either boat.

Even given the Andrews max speed program, in over 100,000 miles off offshore work, including hitting a container with the keel at 18knots, we never lost a keel or even came close. The keel bolts actually were never bent, and the structure was never damaged. Keel bolts were replaced typically because the torqu loads we applied would sheer the threads off eventually.
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Old 15-12-2012, 12:22   #19
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Re: Fin Keel Strength ?

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Originally Posted by Stumble View Post
The boats discussed are at the far end of the racing scene, where failures like this are, while not expected, considered a reasonable risk.
Keel problems are not limited to the high end racing boats. I know of two Santana 35's which sank after hitting rocks at not particularly high speeds--the rear edge of the keel just punched up through the hull on impact. I also know of a Chuck Payne design cruiser where the keel support had to be extensively rebuilt, even without grounding. The article is accurate in that the investigations usually turn out into pissing contests between the designer and builder.
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Old 15-12-2012, 17:41   #20
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Re: Fin Keel Strength ?

The problems with bolt on keels is most have no bilge sump. Any water that gets into the boat will end up sloshing around and soaking everything that's against the hull right up to the deck. Have had two boats without a bilge sump and they were both torture to sail on other than daysails in fine weather. As soon as it got crappy out, everything in the boat got soaked from the sloshing water. On one windward passage, ended up with about 6" of water sloshing over the sole. Because of the angle of heel, the bilge pumps couldn't reduce the water below that level. Hand bailing helped only a little. I know some people are going to say their boat doesn't leak. Try crossing the Alenuihaha channel west to east and come back and tell me their boat doesn't leak. I'll own never ever own another boat without a deep sump to trap water that gets in.

On most boats, bolt on keels are not a structural issue. At least when the boats are new and/or properly maintained. Because of water in the bilge, the keel bolts are subject to corrosion. They need to be inspected regularly and replaced when they become degraded.
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Old 15-12-2012, 19:44   #21
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Re: Fin Keel Strength ?

I don't like bolted on keels.

I had a friend who ran aground in his yacht damaging the bolted on keel. Later his keel fell off in a storm while sailing offshore. That pretty much convinced me to avoid externally bolted on ballast.

My comfort zone requires that ballast be encapsulated in a fiberglass hull rather than bolted on externally if I am going to take a monohull offshore.

But then, that's just my comfort zone.

If I saw a100 ton bridge, I would only drive 50 ton trucks across the bridge. I like a large margin of safety because I don't know who built the bridge or the sailboat.

The sea has a way of testing some of our yachts to destruction. I want to make it as hard as possible for the sea to do the dastardly deed.
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Old 16-12-2012, 01:14   #22
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Re: Fin Keel Strength ?

Thanx for all the replies, seems like initial construction, and routine maintenance are the most important factors. Roverhi also raises a good issue with the depth of the hull and sumps, being able to clear out any water. Hadn't thought of that before

Thanx all, Paul
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Old 16-12-2012, 06:28   #23
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Re: Fin Keel Strength ?

I you intend to cruise Blue Water and/or coral islands your safest hull design is full keel with encapsulated ballast. Full keel or a modified full keel with cut out forefoot for added maneuverability and performance is far safer than a fin keel. They have the ability to rise up and over a container if hit and will undoubtedly have a better chance of survival if hitting a reef. Fin keels are known to shear off.

The video shown of a production boat crash test is no indication that is would survive hitting a container or a reef. If I remember correctly the keel never hit the rocks. All boats worth their salt should withstand a soft grounding in sand as shown and hitting that log and float doesn’t prove a thing as to the boats integrity concerning a REAL HIT such as a container or coral.

My suggestion and this only applies to Blue Water, go with a full or modified full keel for cruising. If you are looking at more modern designs and speed and better performance is what you are after consider only fin keels with encapsulated ballast. Also, a rudder hung off a full keel will be there whereas a spade rudder will probably shear off if hit hard. Therefore of you go with a fin make sure if has a stout skeg hung rudder.

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Old 16-12-2012, 06:57   #24
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Re: Fin Keel Strength ?

A fine foil, fin keel will survive hitting things, IF it was designed to do so. See Hetairos recent adventures.

Needles to say, long, full, etc. keels may offer, on average, 'better' chances of sailing on - just look at the keel/hull contact area, load paths, etc..

One can get a fin keel, fine foils boat, that will be both fast and fare well in collisions, but it is not likely to be one of the 'off the mill' boats.

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Old 16-12-2012, 13:19   #25
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Re: Fin Keel Strength ?

It is amazing how many poorly designed, shoddily built plastic boats with bolt on fin keels turn up on the opposite side of the ocean from which they set out... with the keel still hanging down there where it started the voyage. Lots of those voyages were made by fairly inexperienced crews, too, so it might be that the boats kept them out of trouble when they made mistakes of seamanship like grounding or running into things... the things that happen to voyagers.

I'm not a big fan of the current batch of AWBs, but really, their fin keels seem to work pretty well. And a couple of years ago there were two Westsail 32s abandoned at sea because of some sort of damage to hull or rig. I don't remember the details and am not bashing the W-32... just pointing out that selecting examples of failures that have occurred does not necessarily condemn a design or feature.

So, vtcapo, being very sure that your sort of design is the only way to go seems to ignore the THOUSANDS of boats of other design philosophies that are going into "Blue Water" and amongst coral reefs... and returning intact.

Cheers,

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Old 16-12-2012, 13:29   #26
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Re: Fin Keel Strength ?

bolted on keels are all about maintenance and hull strength surrounding the keel attachment. Many yachts are built that way. A fiberglass enclosed keel is way less trouble prone, but bolt on keels really arent noted for falling off. Well some have!) The older the boat, the more likely you need to drop the keel, check the bolts and re-seal. (a big job) Lightly built Production boats often develop a hull crack (smile shaped) either in front or behind the keel from a hard grounding. It can be as bad as breaking the engine bed loose from the hull. Look for evidence inside and out any boat you 're thinking of buying. also, you can google "catalina smile" for more info on this.
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Old 16-12-2012, 15:25   #27
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Re: Fin Keel Strength ?

The fact is that a lot of lives are lost at sea due keel failures and numbers are pointing at fin bolted keels, from respected manufactures llike Beneteau to J boats, Bavarias, or hunter as a example , and here in the boatyard we have 3 boats with keel problems , a Etap 38i , a beneteau with a iron keel and a Kirie feeling , the Etap have a estimate of 23000 $ to repair the damage, the beneteau need a sand blast and new caulking at the joint and the Kirie is a write off ,, the keel is twisted and the hull broken ...

Fact is that many of the incidents with loss of lives can be avoided if the owners or crew perform the repairs after groundings or collisions , sometimes cracks inside just mean a cosmetic thing, sometimes is a warning ... So if you own a fin keel bolted on the best way to avoid a disaster is to check the integrity of the hull around , stub, bolts , stringers ....
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Old 16-12-2012, 17:02   #28
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Re: Fin Keel Strength ?

I was going to say something sarcastic, but I'll just say I like and trust my fin keel skeg hung rudder boat in any color water..
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Old 16-12-2012, 17:17   #29
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Re: Fin Keel Strength ?

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Originally Posted by neilpride View Post
The fact is that a lot of lives are lost at sea due keel failures and numbers are pointing at fin bolted keels, from respected manufactures llike Beneteau to J boats, Bavarias, or hunter as a example , and here in the boatyard we have 3 boats with keel problems , a Etap 38i , a beneteau with a iron keel and a Kirie feeling , the Etap have a estimate of 23000 $ to repair the damage, the beneteau need a sand blast and new caulking at the joint and the Kirie is a write off ,, the keel is twisted and the hull broken ...

Fact is that many of the incidents with loss of lives can be avoided if the owners or crew perform the repairs after groundings or collisions , sometimes cracks inside just mean a cosmetic thing, sometimes is a warning ... So if you own a fin keel bolted on the best way to avoid a disaster is to check the integrity of the hull around , stub, bolts , stringers ....
Cheers.
Got any stat's?.... just interested. I hear of keel failures but havent heard of much lost lives... doesnt mean they dont happen though! A lot of what I hear is the go fast round the world racing boats etc....
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Old 16-12-2012, 17:22   #30
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Re: Fin Keel Strength ?

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(...) hull strength surrounding the keel attachment (...)
+1!

Exactly.

I have seen keels bolted to the hull (sic!!!) (I mean: to the skin ...)

I have also seen keels bolted to a frame.

Hard to imagine a frame mounted keel falls off unless the bolts get sheared (or unless they corrode thru ...).

Many ways to build a box.

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