Keel of Adelie 16

Sail Boats 15' and up. Please include the boat type in your question.
jbro5000
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Keel of Adelie 16

Post by jbro5000 » Thu May 11, 2017 8:54 pm

I presume that the study plan claimed positive stability to about 135 degrees applies with the centreboard (CB) in the fully down position. In this regard the indicated draft is 35 inches which is significantly greater than the half-way lockable position for the CB.

However, from the plans it and building notes it appears that the CB does not have a locking device for the fully down position. Also the plans do not indicate how the CB could be locked or easily raised if lowered below half way.

While I note the points made about initial stability and cambered deck, if the CB is not locked in the fully down position then stability will be adversely adversely affected and there is a risk that the CB will retract involuntarily and lose its righting capacity.

For your clarification please.



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gonandkarl
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Re: Keel of Adelie 16

Post by gonandkarl » Fri May 12, 2017 1:08 am

Hi,
I am a builder of an AD14 and have built the centreboard weighing over 60 kg where the biggest lead weight of the 3 is at the most downward part of the lowered swing keel.I assure you it keeps the boat upright. Builders like Salvatore have made a winch to easily pull the keel up which I will also build for my boat. Have a look at his building thread it is
Adelie16 from a land down under and he has sailed the boat lots of times in different wind situations. If you are building an Adelie sail boat it is in my mind like building the VW beetle of the sea it will not let us down. So much of a convinced fan of the design who hopes to splash the boat this summer. For proper answers to your questions wait for Jacques the designer to answer.
Greetings from Karl
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Salvatore
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Re: Keel of Adelie 16

Post by Salvatore » Fri May 12, 2017 3:51 am

G,day Jbro5000

It's not just the CB that gives the AD16 such high stability it is also the lead that is placed in the bottom of the boat. I have been in strong winds and there was a situation where the main sheet was in tight and I was sailing to windward a strong gust of wind from another direction forced the boat right over, to almost 90 degrees (the main sheet was jammed in the pulley) I had to hang on to stay in the boat, as fast as she leaned over she popped back up again. One of the top reasons I chose the AD16 design was because of this stability factor. I wanted a boat that was going to be extra safe for me and my friends.

I am not sure why you are concerned about the draft when the CB is down, if you are running with the mainsail up all the way plus a Jib or spinnaker etc you are going to be in deep water. The CB has a unusual shape to it that would allow you to be able to pin it in place. I have never used that design feature.

If you are planning on using the boat in open waters and a wave rolled the boat over, because of the way the boat is designed it would be very unstable in the upside down position, it will role back over. the boat is over designed structurally and even with the keel jumping in the full position it would not fail. Even if the boat was upside down an the CB was in the fully closed position it will role back upright again this has more to do with the shape of the boat than the position of the CB

Regards Salvatore
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Re: Keel of Adelie 16

Post by terrulian » Fri May 12, 2017 8:43 am

Jbro's concern is that the keel, when the boat becomes inverted, will retract into the hull because of gravity and because there is no lock to prevent it from doing so. Once that happens, he fears that the boat's ability to right itself will be eliminated. This is not necessarily hogwash. I own a Catalina 22 with a folding keel, one of the most popular boats ever built, and it in fact does have a screw operated by hand that clamps the keel in the extended position for this exact reason. It can be secured when the keel is all the way down so that in the event of a capsize the keel will be prevented from acting as Jbro describes. The designer put that there for a reason. (I don't use it and in fact have removed mine. Some Catalina 22 sailors think this is not advisable but this isn't a Catalina 22 forum.)

This is definitely a Jacques question. My guess is that an actual capsize is extremely unlikely if you are sailing in reasonable conditions (under 30 knots, less than four-foot seas, for example), but Jacques has no doubt done the math on the righting moment. The far more important concern in the event of a knockdown is: do you have your hatchboards and seat lockers secured? If not, the boat will fill with water and all bets are off. Do you ever sail with your hatchboards not just up but locked? I admit I've had them up in a pouring rain but never secured, in my entire life.
Last edited by terrulian on Fri May 12, 2017 8:53 am, edited 1 time in total.
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Re: Keel of Adelie 16

Post by Jaysen » Fri May 12, 2017 8:52 am

I guess I'm confused by the keel mechanism. Is the keel position "down" with the action provided "lifting"? this is the only way I can see the keel falling in an inverted situation (I don't have the plans and I'm only familiar with the screw type tony mentioned).

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Re: Keel of Adelie 16

Post by terrulian » Fri May 12, 2017 9:09 am

How is the keel raised and lowered on the Adelie?
On the Catalina the keel is raised by a cable that goes to a winch, and I'm imagining that this is so on the Adelie, but don't know. If it is, then Jbro is correct that once inverted, the keel can't be held in the extended position since a cable won't support it.
The screw on the Catalina is merely a clamp that secures the keel when in the down position, not a mechanism to raise it.
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Re: Keel of Adelie 16

Post by Jaysen » Fri May 12, 2017 9:16 am

Then I know a third mechanism (from a Soverel). There is screw mechanism (threaded stainless rod) that creates a hard connection to the keel. It is "break away" for hard impact but solid otherwise (did not break away when we got to close to a mud flat). I'll see if I can gain access to the boat and get a picture. I'm not 100% that it is original though. I didn't study it all that closely since I was more interested in getting the sails up.

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Re: Keel of Adelie 16

Post by terrulian » Fri May 12, 2017 9:53 am

Yes, there are several different configurations, also on big cruising boats. All have their pluses and minuses as do all things on boats. Or a least most. I think a sound hull is mostly always a plus, for example. :D
Last edited by terrulian on Fri May 12, 2017 7:30 pm, edited 1 time in total.
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Re: Keel of Adelie 16

Post by gonandkarl » Fri May 12, 2017 10:51 am

Hi,
The Adelie design has no seat lockers where water could get in and the hatch boards and top one can make lockable without any problem then with a full capsize it will right itself chop chop and you must just hope that you were attached to a lifeline and be back on board over the rudder in a minute. The swing keel is lowered with a cable and also lifted by it with or without a winch. There is a lock ( stainless steel peg ) for the keel in the up position. In a full capsize the keel will crash back into the centreboard case which has a long angled side at the impact and I am sure it cannot damage the centreboard case because it is not only glassed double on each side to the bottom of the boat but also double glass taped to a bulkhead ( frame C ) where the open part of the centreboard case is on deck and not in the cabin which stays watertight. I think it is one of the safest designs in the 14/16 foot boat class.
Greetings from Karl
All pictures of Micro Petrel AD14 and FS13 :

http://gallery.bateau2.com/index.php?cat=87433

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Re: Keel of Adelie 16

Post by terrulian » Fri May 12, 2017 11:11 am

Karl,
Although damaging the trunk is an issue, the main thing is the righting moment, i.e., whether in the up position the keel would supply enough righting moment to bring the boat back on its feet. This has to do with the distance between the center of gravity and center of bouyancy, a calculation only Jacques would be qualified to address. I've been in a lot of gales and never ever had the spreaders touch the water on any boat except a dinghy (dinghies don't have spreaders but you take my point) but it certainly can happen. Of course some of this has to do with timely reefing :doh: That said, huge seas can in some circumstances cause pitchpoling and capsizing. But you aren't going out in that stuff, right? 8O
In regard to the lockers, no opening is about as safe as you can get. However, there is still the matter of the companionway hatch. If the boat has suffered a knockdown, water can enter the cabin if the boards aren't in or aren't secured. Again, an issue only in very extreme conditions.
Tony
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