Swing Keels anyone ? - Page 2 - SailNet Community
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post #11 of 20 Old 08-22-2006
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Of course, along with swing keels, there are lifting keels, which have many of the same benefits, but are a slightly different design, with different problems and flaws.

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post #12 of 20 Old 08-22-2006
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I have a 38' Irwin with a swing keel, it gives her a draft of 3,1/2 ' up and about 9' down. We sail out of Corpus Christi Tx. and the shoal draft opens up quite a bit of the gulf coast area that would otherwise be un passable.
She's a fairly long modified fin keel, and sails pretty well to winward with
the board up feels tighter with board down, hard to see difference since we're in blue water before we can drop it. The cable goes thru a stuffing box with a derlin pushrod, leakage is minor stuffing box stuff. Art.
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post #13 of 20 Old 08-22-2006
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A friend of mine (in fact, the chap who bought my P-27 with a wing keel -- God forbid -- call the Coast Guard NOW!!!! Those wing keels sail BACKWARDS!!!!!) has bought a Southerly 110 that, at last report, was on a ship headed for Baltimore. I promise a full report once he takes me for a sail.

For you wing keel-a-phobes, check out the Southerly Yachts site http://www.southerly.com/ Way cool seeing a big boat flat on her belly waiting for high tide.

And Jotun, you're right that centerboards/swing keels/ lifting keels all add a tad more complexity to things and are one more thing that can break or go wrong. But that usually isn't the end of the world either. I know of an Irwin 42 that lost two centerboards (one off Hatteras, one in Back Creek Annapolis.) After the second CB fell off, the owner decided not to replace it because it was more trouble than it was worth.
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post #14 of 20 Old 08-22-2006
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(By swing keel I am assuming that you are using the definition that I grew up with, namely a fully ballasted centerboard carrying a large percentage of the boat's ballast, and that is predominantly external to the centerboard trunk in all positions. If you mean otherwise I apologize in advance for any confusion)

While I am a big fan of keel- centerboard boats, I am not a fan of swing keels. The problem with a swing keel is that is extremely difficult to get decent support for the keel when it is the partially raised postion through fully lowered position. They work reasonably well on small boats, but are quite vulnerable as the loads get higher. Structurally it is extremely difficult to design a full strength method to lock the swing keel in the down position and dangerous if they are not locked down.

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post #15 of 20 Old 08-23-2006 Thread Starter
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swinging isn't what it used to be

Quote:
Originally Posted by Jeff_H
(By swing keel I am assuming that you are using the definition that I grew up with, namely a fully ballasted centerboard carrying a large percentage of the boat's ballast, and that is predominantly external to the centerboard trunk in all positions. If you mean otherwise I apologize in advance for any confusion)

...
Jeff
Since I grew up Southerly for one (maybe only?) started producing a fully retracting swing keel circa 1980. It has a single pivot point. The keel and the grounding plate/trunk it retracts up through are cast metal. In the fully down position it does not swing forward, only aft. As I said before, the keel retracts up under the raised salon, so it does not protrude into the cabin otherwise. They include an inspection window in the salon. Vessel size if 35-46 feet. Their 46 footer draft range is 2'9" to 10'10".
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post #16 of 20 Old 08-23-2006
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Best of all worlds for trailerable boats.

I used to have a Macgregor 21 with a swing keel of about 200 lbs. I too had problems with cable breakage. If I hit a stump or a rock, the keel would swing up then snap the cable when the keel swung back down.

I liked being able to beach the boat and I could use the weight of the keel as a temporary anchor in shallow water. Still, the cable problems outweighed the advantages.

For 15 years, my backup boat (can't seem to sell it) has been a 26' Macgregor with a 45 lb swing keel. The boat is water ballasted so the keel only needs to be heavy enough to sink. The keel is attached to the boat with a length of line. There is no winch since the keel is so light. To raise the keel, you pull up on the line then make fast to a cleat in the cabin.

This boat has been great for me because I like to travel. It trailers and launches easily (I only need to back down to 20" of water to float it off)and is surprisingly stable under sail. I would recommend any water ballasted swing keel boat to anyone who wants to sail a variety of waters, deep or not.
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post #17 of 20 Old 08-23-2006
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"I have a 38' Irwin with a swing keel, it gives her a draft of 3,1/2 ' up and about 9' down."

Actually you have a keel/centerboard boat. A swing keel si something different and in my opinion not as desireable.

Respectfully,
Jeff
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post #18 of 20 Old 08-23-2006
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combo keel

I also have a combo shoal draft/swing keel on my Rhodes 22. Comes in handy on the lakes and coasts here in FL. July 4th we were on the lake and wanted to go to the next lake over to watch the fireworks You wouldn't beleive the looks we got after I lowered the mast at the nearest dock, hoisted the 70lb board and we motored down the tiny canal to the other lake. Quite a few dropped jaws. Only one motor boater asked what kinda water we draw. 20 inches Almost caused some crashes due to people looking back at us but still heading forward. Of course If I was headed offshore I would want a Full Keel. And a bigger boat.
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post #19 of 20 Old 08-23-2006
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Quote:
Originally Posted by Jeff_H
(By swing keel I am assuming that you are using the definition that I grew up with, namely a fully ballasted centerboard carrying a large percentage of the boat's ballast, and that is predominantly external to the centerboard trunk in all positions.Jeff
Like Jeff, I also think of a swing keel boat as one with a heavily ballasted centerboard.

In addition to the weaknesses that Jeff lists, the retracting mechanism also has to be meticulously maintained. If the cable or winch or other critical part snaps suddenly, dropping the heavy keel, it can rip the bottom of the boat apart, sinking the boat. But, I've never heard of such a catastrophic failure occuring when the mechanism was well-maintained.

A swing keel isn't a bad design when well-maintained and used for it's intended purpose. Swingers are intended to be sailed on inland lakes and small bays, and in mostly fair weather, where the waves are usually less than 2 feet. If used in that manner, it's extremely unlikely that a boat will get knocked down so severely as to endanger the boat. The risk is in using it in heavy weather conditions, when it isn't designed for that use.
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post #20 of 20 Old 08-24-2006 Thread Starter
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pounding bottoms

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Originally Posted by Sailormon6
Like Jeff, I also think of a swing keel boat as one with a heavily ballasted centerboard.

n addition to the weaknesses that Jeff lists, the retracting mechanism also has to be meticulously maintained. If the cable or winch or other critical part snaps suddenly, dropping the heavy keel, it can rip the bottom of the boat apart, sinking the boat. But, I've never heard of such a catastrophic failure occuring when the mechanism was well-maintained.

A swing keel isn't a bad design when well-maintained and used for it's intended purpose. Swingers are intended to be sailed on inland lakes and small bays, and in mostly fair weather, where the waves are usually less than 2 feet. If used in that manner, it's extremely unlikely that a boat will get knocked down so severely as to endanger the boat. The risk is in using it in heavy weather conditions, when it isn't designed for that use.
Hmm. Seems to me with some technology this bottom pounding issue can be minimized. After all, if movement of the keel doesn't have to be fast then it can be designed to be slow even in steep seas. Perhaps some hydraulics could be used to dampen the motion. Hydraulics have their own maintenance issues I know, but if the goal is a skinny beaching draft it could be worthwhile.

I'm going to drop by the Southerly slips at the Annapolis show to ask a few questions. They've been producing large cruising swing keel sailboats for over 25 years so it's hard to believe that the bottoms drop out as has been suggested.

It will also be interesting to see what the price is now. With the exchange rates the last few years they showed some enormous increases which left the 45 footer at about 600K USD.

As far as the definition, I believe it is correct about the swing keel having heavy ballast, whereas the centerboard is light enough to kick up easily in a grounding. I would be very concerned about the reduced righting moment in an unwanted swing keel retraction in any knockdown scenario. That's even more incentive for a dampened keel movement.
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