SWING KEELS GOOD or BAD? - SailNet Community
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post #1 of 16 Old 01-31-2013 Thread Starter
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SWING KEELS GOOD or BAD?

Was looking at Boats for Sale and ran across a 25' O'Day with a 2'10" draft. Owner said it was great for shallows...etc. but then made the comment it had a center board, '... no swing keel to mess with,' implying it's a bad thing?

So, if one is in shallow waters is a swing keel a good thing or a bad thing?

Pro's? Con's?
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post #2 of 16 Old 01-31-2013
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Re: SWING KEELS GOOD or BAD?

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Originally Posted by wannabsailor View Post
Was looking at Boats for Sale and ran across a 25' O'Day with a 2'10" draft. Owner said it was great for shallows...etc. but then made the comment it had a center board, '... no swing keel to mess with,' implying it's a bad thing?

So, if one is in shallow waters is a swing keel a good thing or a bad thing?

Pro's? Con's?
Every thing on a boat that is designed to move need some level of maintenance.

Swing keel is a more complicated design than center board.
More complicated more maintenance or parts to break.

But boat design is full of trade off's

A center board take more space inside and might be a little bit more awkward to operate.

I wold not let a single feature of the boat put me on/off.

If you need/want a shallow draft boat - why not have a look at it?
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post #3 of 16 Old 01-31-2013
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Re: SWING KEELS GOOD or BAD?

The various swing/cb/shoal draft options out there have their place, in some areas they are essential.

A swing keel will generally 'kick up' if you happen to get to shallow with little or no damage, most daggerboards when down will not. The swing keel may offer more options with helm balance and tweaking the balance of the boat over a daggerboard.
The pivot pins in swing keels can be a pain, but usually only if their upkeep/maintenance is neglected.

I'd be looking for a swing keel if I was expecting to routinely sail in shallow water.

Ron

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".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
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post #4 of 16 Old 01-31-2013
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Re: SWING KEELS GOOD or BAD?

IMHO fewer moving parts underwater is better; when I was looking for a Catalina 25, I didn't even look at the swing keel models.

Failure mode 1: the cable breaks while the keel is down and you are stuck in deep water.

Failure mode 2: the cable breaks while the keel is up and the keel (1900#) swings down until it hits the stop (which might not). This could let the green monster into the people tank.

Failure mode 3: The boat surfs down (or falls off) a wave and the keel retracts a bit; at the bottom of the wave, the boat stops but the keel keeps going. See #2 above.

Centerboards aren't as problematic, but I still prefer a solid keel.

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post #5 of 16 Old 01-31-2013
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Re: SWING KEELS GOOD or BAD?

Wannabsailer,
The O'day 25 is a great boat. It has a regular keel with lead ballast and a swing centerboard that swings up into the keel, not into the boat. Doesn't take up any room in the boat.
Some boats have a swing keel. The keel is the ballast and heavy. It swings up into a trunk in the boat. Due to the weight you need a winch mechanism to raise the keel.
Back to the O'day, even with the centerboard up, you have a keel with 1800lbs of lead as ballast. It sails fine with the CB up except for some slipping when pointing into the wind. I know. When I got mine the centerboard was stuck in the up position due to marine growth the first few sails.
The CB on the O'day weighs about 65lbs so it does not need a winch to raise it. It has a rope pendant connected to the CB by a shackle. Some pre 80 models did have a winch in the cabin but mine has the pendant running to a cleat in the cockpit.
I think swing keels let you get into shallower water but that is because the keel is up into the boat and so is the ballast. The O'day set up may not let you in as shallow water as the others but the mechanics are simpler and don;t take up cabin space.
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post #6 of 16 Old 01-31-2013
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Re: SWING KEELS GOOD or BAD?

Take a look at the ballast to displacement ratio, and how low the cg of the ballast is. I don't know where you sail, but if it's in salt water you might want to pay attention to this.
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post #7 of 16 Old 01-31-2013
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Re: SWING KEELS GOOD or BAD?

There are three things here:
Swing keel: Outside the hull, no centerboard trunk in cabin, heavy and gets the weight lower that the others, draft when up is the width of the keel. Very common on trailersailers like Catalina 22.
Centerboard: Weighs less, not significant in stability, has nothing below hull when it's up, easier to trailer launch and can go into shallow water. Common on dinghys and smaller boats also sharpie type boats. Trunk in the cabin takes space, trunk can be fouled with stones when beaching.
Keel centerboard: Has keel like stability, shallower than a full keel, draft is usually greater than a swing keel. No CB trunk. More common in the larger trailersailers like Catalina 25.

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post #8 of 16 Old 02-01-2013
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Re: SWING KEELS GOOD or BAD?

I'm new to all this, but I enjoy learning, so when I bought my Catalina 25 I started reading up on this a bit. I'm not an expert, but the following is my understanding. Like Ward said, each form of movable keel has its advantage and disadvantage. A swing keel, like on the Catalina 25, carries a good bit of the balast of the boat in the part that swings. In the Catalina 25, that's something like 1200 or 1500 lbs of balast that hangs down. When the keel is down, you move 1500 lbs (or some portion thereof) up to 5 feet from the boat. This significantly improves the boat's righting motion, and gives her characteristics more similar to a fin keel. Don't get me wrong, I'm not saying that it's "just like" a fin, but the boat tends to behave more like a fin than a shallow draft full keel. The down side is that you have to raise and lower 1500 lbs. And, if the winch, cable, turning ball, swage fittings, pivot bolt, or other part of the lifting mechanism breaks, you have 1200/1500 lbs of steel that will come crashing down and smack into the keel trunk, which in many cases results in the boat sinking, or at least rapidly taking on water. It is rare to see this happen, but it is an important to know about and monitor this as a failure mode.

With boats like the O'Day, you have a very light weight centerboard that swings. 65 lbs crashing into the keel trunk is going to do a lot less damage than 1200-1500 lbs. Of course, the down side is that the balast is moved much higher up in the boat compared to a fin or swing keel. If you think back to high school physics classes where you talked about leverage, moving the ballast closer to the center of rotation/center of gravity on the boat means it takes more balast to counteract the rotational forces imposed by the sails - that is, you need more balast to improve the boat's righting ability if you're not going to put the weight on a long fin keel. The swing centerboard still improves the boat's pointing ability, so it isn't a useless part of the boat, and the mechanisms to control the centerboard are simpler and eaiser to inspect and maintain.

Some boats use dagger boards. Though you typically see these on smaller boats like Sunfish, there are some very large boats that use these. The problem with a dagger is that it won't "kick up" when you run aground, where the swing keel and swing centerboard will do that.

Hope this helps!

- Jim
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post #9 of 16 Old 02-01-2013
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Re: SWING KEELS GOOD or BAD?

Living and sailing around Florida, where shallow water and shifting sand banks are an issue, I think a swing keel is a wonderful thing. That's why I used to have a San Juan 23, which has essentially the same arrangement as the O'Day 25.

Find an unexpected sand bar? The swing keel just pivots up and the boat gently comes to a stop. Pull the keel up the rest of the way and back off or sail away. Easy peasy. With a centerboard it would hit the sand hard and stop suddenly, possibly even doing some damage. If you were heeled over when it hit, then the centerboard is now digging into the sand and holding the boat heeled over. If there isn't any damage, then you pull up the centerboard (with some difficulty if you were heeled when it hit) and go on your way.

Yes, the swing keel includes a pivot point and pennant arrangement that adds a bit of complication. Still, in the 8 years that I owned the San Juan, I never had even one single problem with that. I do not consider it a significant issue, and feel the benefits of a swing keel well outweigh the minor drawbacks. In fact the sailing dinghy that I own now has a swing keel, and I specifically looked for that versus the more common dagger board in boats that size.
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post #10 of 16 Old 02-01-2013
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Re: SWING KEELS GOOD or BAD?

By the way, if the O'Day's 2'10" draft is accurate, it's only 2" deeper than the Catalina 25. There are also wing keel models that don't need a lot of water. They sort of split the difference between swing and fin keels. They are fixed, but shallow draft (the Catalina 25 with a wing is something like 2'11"). Their pointing ability is better than the swing keel models with the board up, but not as good as a fin keel. But, they don't have any lifting mechanisms to worry about.

- Jim
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