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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation
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Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


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  #1  
Old 01-28-2001
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Best type of keel

I am looking at a new cruiser in the 40 -50 ft range. I have the choice of a Fin keel or Wing keel. Any suggestions. We will use this vessel to sail the coast from NC to the Fl Keys as well as some island hopping in the Caribean.
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Old 01-29-2001
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Best type of keel

Judging from your crusing area, you may need the keel that draws the least.
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Old 02-02-2001
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Best type of keel

In terms of sailing ability nothing that we know of sails better than a properly designed Fin keel. They have less drag and they typically make less leeway and go faster. You can get the ballast down lower so in theory they are more stable for their weight. They are more maneuverable. They take better advantage of the high efficiency of modern sail plans and materials.

They have some disadvantages as well, many of these have been offset or worked around by modern technology but at some level they are still accurate critiques. They have less directional stability than long keel boats so the tend to wander more under sail. Since directional stability is also a product of the dynamic balance between the sail plan and underbody, in practice they may actually hold a course as well as a full keel. In general though you can expect to make more course adjustments with a fin keel. It is sometimes argued that it takes less energy to make these corrections so a fin keel may also require less energy to maintain course. This I think is a product of the individual boat and could lead to a debate harder to prove than the number of angels that can dance on the head of a pin.

Fin keels are harder to engineer to withstand a hard grounding and when aground they are more likely to flop over on their bow or stern. (Although in 37 years of sailing, I have never heard of anyone actually experiencing this.) Fins typically have deeper draft. They are easier to pivot around and get off on a simple grounding.

Shoal keels:
A shoal keel is just a keel that is not as deep as a deep keel. Today the term seems to be applied mostly to shallow fin keels. Shallow full keels seem to be referred to as shoal draft boats. (You guys notice that as well) A shallow fin is a tough animal to classify. I really think it has few of the advantages of either a deep fin or a full keel and has many of the worst traits of both full and fin. This can be partially offset by combining a shallow fin with a centerboard, which is a neat set up for shoal draft cruising. In fact if I was cruising in your area keel-centerboarder might be my first choice.

Bulb Keel:
A lot can be done to improve a shallow fin. One way is to add a bulb. A bulb is a cast metal ballast attachment added to the bottom of the keel. They concentrate the ballast lower providing greater stability and sail carrying ability than a simple shallow keel. Traditionally bulbs were torpedo or teardrop shaped. They have been re-contoured to provide some hydrodynamic properties. These are also referred to as Sheel Keels(named for the man that invented and patented one version of this idea).

Since shallow keels need to be longer horizontally than a deeper fin in order to get enough area to prevent leeway. This means that it would generate more tip vortex and more drag than a deeper keel. The bulb creates a surface to turn the water aft and prevent it from slipping over the tip of the keel thereby reducing tip vortex. This does not come free since a bulb increases frontal area and surface area and there still has more drag than a normal depth fin.

Wing keels
Wing keels are a specialized type of bulb keel. Instead of a torpedo shaped bulb there are small lead wings more or less perpendicular to the keel. These concentrate weight lower like a bulb and properly designed they also are very efficient in reducing tip vortex. There has been some discussion that wings increase the effective span of the keel when heeled over but this does not seem to be born out in tank testing of the short wings currently being used in production sail boats. Not all wings are created equal. They potentially offer a lot of advantages, but they are heavily dependent on the quality of the design and I really think that many wing designs are not really working to their potential.

Wing keels have all of the negatives of a a fin keel in terms of difficulty of attachment and risk in a gounding. They dramatically loose lift in a chop. When you run aground (especially if heeled over) they are much harder to free. They are being way over sold in terms of performance. Depending on the model they typically have PHRF ratings 15 to 30 seconds a mile slower than the regular keel. That is significant.

Jeff

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Old 02-03-2001
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Best type of keel

Jeff you didn''t mention centreboards in your analysis.I have always been intrigued with Hood''s centreboard designs (eg the Bristols). How would you compare them to the others in terms of suitablility for extensive cruising?
Are Hood''s cboard designs significantly better than S&S and C&C who occasionally did them?

Thanks for your help/
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Old 02-03-2001
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Best type of keel

Keel centerboarders are a good option in the 40 to 50 foot range. (My Dad currently owns a Brewer 12.8 cutter which is a 42 foot keel centerboarder) They can offer good upwind ability with the centerboard down and good downwind ability with the centerboard up. You can partially raise the board to balance the helm and they can be raised to reduce risk of tripping when hove-to in rough going.


Keel centerboard arrangements are not without their own unique problems. They typcially require more maintenance. They can get stuck up by growth clogging the trunk or stuck down after a grounding. They can slam shut in a really bad knock down. To get any real performance out of them you need to play them up and down with the conditions.

In terms of performance, keel centerboarders need to be heavier for the stability as a Fin keel boat. They typically have shorter rudder lengths meaning more drag or less steerage. The centerboard operates in the tip votex of the keel meaning that you need more wetted surface and drag for the same lift.

As to who designed the best keel/ Centerboarders I don''t think you can say that any of the three were always the best. In my mind, the S&S designed Tartan 34 is one of the best K/CB that I can think of. The C&C 41 and 45 were also very good K/CB boats. I am not a big fan of Hood''s K/Cb''ers but that is more about the design of the rigs and their sheer weight which really hurts a K/CB boat worse than a fin keeler.

Jeff
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Old 03-01-2001
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Best type of keel

As far as centerboards go, it really depends on what your''re doing with the boat. I''ve had two centerboard boats (a Tartan 27 and a C&C 37, my current boat), and there are annoyances and advantages to them.

Both boats grew lots of critters in the centerboard shaft area. You can put paint on a brush or cloth on the end of a stick and put it up there, but it''s not easy, pleasant or neat to do. Nor does it guarantee a critter-free centerboard anyway. Taping a razor to a stick to scrape the beasties out is no fun either (you have to squint or wear goggles, to minimize the chance of them falling in your eyes while your bent under the boat in an awkward position, and they will fall in your mouth too unless you can do this without breathing or wear protection).

On my T-27, the pennant once pulled out from the centerboard when the Fiberglass rotted away. It wasn''t a huge problem for me that I couldn''t get the thing back up, but I did have to get the board pulled out and have a new pennant glassed in eventually the next time she got pulled out of the water. It''s just one more moving part to break.

On my newer boat, the C&C 37 K/CB, there are again plusses and minuses. My gripe now is completely self inflicted. Simply put, after getting a better performing boat than the T-27 I started club racing for the first time, and loved it. So, with 20/20 hindsight as I am trying to re-do the bottom this year I realize that the centerboard will be a constant source of annoyance to me. We''re going to have to put the boat on a TravelLift just so we can wet sand the fool thing, never mind keeping it clean and fair during the season. With the complete clarity of hindsight I know my next boat will have a fin keel.

I can not complain about the performance of either boat as a coastal cruiser & weekender, which is still the primary reason we bought both boats. The C&C is a solid performer and a pleasure to sail, even to windward. You can feel it go faster and point better when you drop the board.

If you''re coastal cruising and gunkholing a centerboard can be nice too, and you can''t complain about having an extra margin of safety in the shallows.

Just don''t get hooked on racing.
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Old 04-10-2001
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Best type of keel

Actually, for gunkholing I don''t think you can beat a bilge-keeler. For a few photos of mine, see --

http://albums.photopoint.com/j/AlbumIndex?u=1231924&a=9316678&f=0
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Old 05-22-2006
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Keel Centreboarders

Does anybody out there know how people stop a big centreboard slamming shut on a bad knockdown? I have a 35ft Keel Centreboarder (like Finisterre), but her board is rectangular and the casing is all below waterline, so I don't wanna go putting pins in. A friend suggested friction brushes.
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Old 06-14-2006
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thisis just a test
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Old 06-18-2006
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Its a trade off But I'd go for a Better Sail Anytime

Did a run down the East Coast ,thru the Bahamas and down the Caribbean Chain to Trinidad. We were limited in the Bahamas in anchorages due to our draft of 6'2". However many times we Thank God as the anchorages
or seas were rough. Beneteau's with their wing keel were the worst rocking rail to rail............And if the went aground......they were stuck!!!!
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