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What Kind of a Keel do you Have

15K views 98 replies 30 participants last post by  Minnewaska 
#1 · (Edited)
Fin keel, full keel, long keel, stub keel with centre board, bilge keel, swing keel, lifting keel,bilge keels, canting keel, water ballast, centreboard, daggerboard, chine logs, bilge boards, foils, Multi hull with any of the above. And whatever I missed.

Why do you like what you have.

In this vid I am using "Chines" for lateral resistance. My Sharpie can do the same. The benefit is very shallow draft, the negative is you don't really get much in the way of lift, so you can't point as high as some boats.

 
#3 ·
Swept, shoal depth, fin keel, with a modified bulb. Perhaps one can make it out in my signature below.

Best all around option for us. Reduces draft to 6.5ft on a 54ft LOA, expanding anchorage or harbor choices. Improves maneuverability (along with the spade rudder) in tight quarters. Does a reasonable job holding off leeway, but I’m sure the standard 9ft keel would have performed better.
 
#5 ·
Too bad this wasn’t an actual poll. Would be interesting to see the raw data.

Mine is a full keel (I mean FULL!). Moderately-deep, encapsulated.

Like: Excellent at tracking and maintaining a line. Very easy on the helm. Strong; can’t easily be damaged. Protects rudder/prop. Doesn’t snag any wayward fishing gear. Sits well on her keel so easy haul out or dry out.

Dislike (even though you didn’t ask): Not very maneuverable, so docking is challenging. Not very efficient up-wind. Lots of wetted surface so takes a bit more time to get moving. Also costs a lot more in bottom paint.
 
#6 · (Edited)
Leeboards on the CF dinghy.
Bulbed fin on the Outbound.
Keels should be appropriate to the use of the boat. Pure form follows function. Keels need to be thought of in terms of the totality of the boat-canoe body, other appendages, house, sailplan. If the boat was drawn by a skilled NA it has the “right” keel for that boat. Likes or dislikes should refer to the boat in most cases as what keel it has is the natural evolution from the design.
Believe there is little or no correlation between keel type and tracking. There is between wetted surface however and type.
There isn’t between type and risk of damage with some outliers such as daggerboards on multis v fixed keels.
With IP going under other than heritage yachts pure full keels will gradually disappear. They made sense when building in wood but not for performance.
When I give up long range cruising I want a Lyle Hess 32. Totally illogical but beautiful. Totally contrary to current thinking but perfect in design for that style of boat.
 
#11 ·
My yacht (O'day 22 :) has a stub keel with a centerboard. Usually, we have pretty thin water, so having a minimum draft of 18" is super helpful. We are now at record high water, so....

I'm still making friends with positioning the board for the most efficiency on any point of sail.
 
#14 ·
Crab crushing full keel on a canoe shape underbody. Solid, forgiving in grounding, easy to check for integrity, good tracking, protection for rudder and prop, very stable when on hard, almost horizontal shaft angle giving better fuel efficiency. Negatives are: slow, takes a lot of bottom paint, hard to maneuver in reverse.
 
#40 ·
I have just a basic fin and a skeg hung rudder.

My dream is a Southerly with a lifting keel. The ability to explore with one of those would be smashing.
My Clearwater 35 has a weighted swing keel, like the Southerlys, but it also has a swing rudder. With the "landing gear" retracted, as shown in the thumbnail, the draft is 2 ft. With the keel down, the draft is 6 ft and the rudder draft is about 3' 10".

This boat has inboard shrouds, allowing tighter genoa sheeting angles, and with the elliptical keel, she goes to weather with the best of them. This boat is not tender, due to form stability, weight discipline in the design, and 5000 lbs of lead ballast. Half of the ballast is glassed into the slack bilge and the other half is encapsulated in the leading edge of the keel.

The headroom under the coach roof is 6'3", but the keel trunk goes all the way up to the coach roof, splitting the main cabin.

So, there are some compromises in the design-primarily in the location and size of the keel trunk, but the advantages of variable, shoal draft are downright addictive. Harbors are larger, shortcuts are available, and gunkholing options are greater than with the traditional 35 footers.
 

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#16 ·
Bolt on LEAD keel

Keel off:


Keel on:
 

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#18 ·
One of our boats has two mini keels (one on each hull), 4' draft, crash bulkheads forward and rear, can be set down on them without additional support needed, rudder and saildrive protected well. Sails well, but not stellar upwind - better than a Morgan OI, but worse than a Hunter fin keel.

The other boat has daggerboards in each hull, 4' draft when up (hull is only 2', but rudder is 4') and 7.5' draft when down. Needs additional support when on hard, less protection for rudder (saildrive has a protective skeg in front of it). Stellar upwind - probably equal to or better than all but racing design monos (JeffH would beat us upwind).

Mark
 
#19 ·
My Cal 29 has a fin keel, stubby by current standards, but a lot like the famous Cal 40s. My 21 ft Dovekie has leeboards. What you have is all about what the boat is intended to do. Typically sharpies have a single centerboard of two boards port and starboard to get the boards out of the centerline of the cabin/cockpit area. So sharpies are about shoal draft. The fin keel is about a speedier hull than a full keel. The full keel is about a more stable tracking, and less vulnerable design for cruising.
 
#22 ·
Synergy has a moderate draft, moderate area fin keel and moderate rudder design.
PIC00003 by ,

[URL=https://flic.kr/p/2gF8nHQ]
Farr 38 by https://www.flickr.com/photos/22254080@N08/,

The pros and cons are that she sails well in a broad range of conditions, has a lot of stability allowing me to carry an efficient sail plan without reefing or furling through an extremely wide wind range, points well, and is shallow enough that she does limit my cruising ability. The difference in draft between the rudder and keel generally protects the rudder from damage. The counterbalanced rudder results in extremely light helm loads which makes use of a vane steering possible and also means that the autopilot uses less amps. While she does not track in the traditional sense, she does balance so she can steer herself or I can steer with the main sheet rather than the rudder (as I had to do when the steering linkage failed)

Jeff
 
#25 ·
I don't think a narrow stern should make you squirrely down wind necessarily.
Squirlly down wind is more likely a balance issue IMO.
The narrow stern definitely contributes to squirrelly behavior down wind especially in conditions where a boat is rolling. When a boat has pinched ends and it rolls, at the extreme edges of the roll the shape in the boat in water becomes a sharply curved wing turning trying to turn the bow of boat strongly towards the side that is out of the water. The rudder correction required to prevent a broach combined with the asymmetric hull form in the water tends to increase the amount of rolling.

This was exacerbated by the large girth spinnakers of the IOR era (and lesser extent CCA era) that tend to cause 'excitation rolling' that greatly increases roll angles. Excitation rolling is caused by the spinnaker rolling sideways through the air and its edges alternately creating aerodynamic forces that pull the boat towards the side and so add to the kinetic forces causing the roll until a broach or death-roll occurs.

If you look at reasonably modern designs from the past 20 years they typically have broader transoms. Those broader transoms do several things that avoid the problems of a pinched stern. First of all, as they roll they develop more symmetrical water lines that tend to move to leeward reducing the rounding lever arm between the lateral center of resistance and the lateral center of effort of the sails. But more significantly they also dampen roll as they increase the form stability as they heel. The result is that they roll slower through a narrower roll angle reducing excitation.

Jeff
 
#26 · (Edited)
Skinny sterns can do great in big following seas, put a sail on them and the dynamic changes. But a boat with a skinny stern and highly variable CLR should do fine. Wind surfers are a good example. As far as that goes, so is my sailing kayak. And my Bay Hen.

The nature of many keel boats prevents you from getting the weight back far enough or the CE far enough forward to make skinny sterns work down wind, but that is not a hull shape issue, it's a balance issue IMO.

 
#27 · (Edited)
Skinny sterns can do great in big following seas, put a sail on them and the dynamic changes. But a boat with a skinny stern and highly variable CLR should do fine. Wind surfers are a good example. As far as that goes, so is my sailing kayak. And my Bay Hen.

The nature of many keel boats prevents you from getting the weight back far enough or the CE far enough forward to make skinny sterns work down wind, but that is not a hull shape issue, it's a balance issue IMO.
Its not about solely the stern itself, or that the stern is 'skinny'. In fact traditional life boards were double-enders since the it was thought that doubleenders did well in surf. In the case of a boat with a pinched stern, it is the combination of a wide beam hull form along with the pinched stern that created the problem. The reason that the term 'pinched stern' is used in the first place is to contrast the stern with the beam of the boat.

The reason this is true is that there is a huge difference in the change in shape when heeled between a long narrow hull form like a Kayak, or the planning hull form of a surf board, or the barrel sections of a traditional double-ender, and the pinched transom hull forms of the IOR era.

It is not really a balance issue in the usual sense (keel too far forward or aft relative to the longitudinal center of effort) since the turning moment when downwind is the offset between the center of drag, and the center of effort of the sails times the drive force, combined with the rotational force produced by the shape of the hull in the water.

Jeff
 
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#28 ·
I think we are agreeing, but I am not sure. It isn't really the narrow stern causing the directional instability. I have no doubt there may be other proportions at play that may be causing the squirley feeling, including the rotation.

Some multi hulls can feel like they are tracking on rails. Multiple, long skinny hulls provide for much of the directional stability. Nearly everybody has sailed a hobie 16. They don't even have boards.

I am not sure what kind of boat Whalerus has, but I wouldn't be surprised if part of the challenge with getting her to track down wind has as much to do with racing rules interfering with boat design as it does the breadth of the stern.

The trend in racing dinghies is even stronger. They have reached the point where they are darn near useless for anything but racing. Which I think might be partially responsible for the resurgence in cruising dinghy popularity. Fine sterns and Lug sails seem to pretty well represented in that category :)
 
#29 · (Edited)
Some multi hulls can feel like they are tracking on rails. Multiple, long skinny hulls provide for much of the directional stability.

I am not sure what kind of boat Whalerus has, but I wouldn't be surprised if part of the challenge with getting her to track down wind has as much to do with racing rules interfering with boat design as it does the breadth of the stern.
I don't think we are talking about the same thing. Long skinny hulls do not change shape as much as when they heel as a beamier boat tends to do. When you couple a pinched stern with a beamy hull, the heeled hull form changes really dramatically and as such that the boat becomes much more prone to roll steering. Its exactly the opposite as what happens with something like a kayak or something like a beach cat.

The reasons that modern boats have wide transoms is that a moderate heel angles the shape of the boat in the water is closer to the shape of catamaran in the water and so tracks better and does not roll steer as much. When heeled these boats tend to end up with largely symmetrical shapes that are comparatively narrow in width and low in wetted surface.
Synergy stern by https://www.flickr.com/photos/22254080@N08/

Although this is too much of a heel angle to be ideal, (sailing into a building wind, and depowering after a mark rounding) I think that the picture above illustrates how narrow the waterline becomes and the shape of the hull in the water (look at the windward side of the boat). When heeled this produces a relatively symmetrical hull in the water with the centerline of the water plane offset to leeward and with the rudder still remaining fully in the water.

By way of comparison, this is a picture of IMP (a Ron Holland designed IOR era boat showing her pinched stern). Imp-flossing her rudder by https://www.flickr.com/photos/22254080@N08/

If you look at the picture it is easy to see that the windward side of the submerged hull is a fairly flat curve while the leeward side is sharper wider curve, tending to turn the boat to windward.

Jeff
 
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#30 ·
Thats sailing upwind :) I am thinking you like her a bit flatter when running?

I think you are right though. We aren't really talking about the same thing. I am talking about strictly hull form, but with your boat its almost impossible to contemplate your boat without the context of a keel. Its part of the package.

I am thinking more along the lines of maybe a Michael Storer design where the hull itself can be reallistically considered without any board/keel what soever. Long, narrow, hard chines, and very much a modern design.
 
#32 ·
Thats sailing upwind :) I am thinking you like her a bit flatter when running?

I think you are right though. We aren't really talking about the same thing. I am talking about strictly hull form, but with your boat its almost impossible to contemplate your boat without the context of a keel. Its part of the package.

I am thinking more along the lines of maybe a Michael Storer design where the hull itself can be reallistically considered without any board/keel what soever. Long, narrow, hard chines, and very much a modern design.
Two separate topics, the first had to do with a boat being squirrelly when sailing down wind. I chose the two photos of the boat with a pinched stern and a boat with a wider stern to illustrate why a boat with a pinched stern would be squirrelly due to the shape of its water plane as it rolled from side to side. I thought that the pictures sailing upwind would be the best way to illustrate the shape of the water plane in a way that would make it easier to visualize the change in shape as the boat rolled.

Topic 2: I am a big fan of Michael Storer's Viola 14 design with the batwing rig. I have no use for lug rigs. In my mind they offer no useful advantages and come with a real problem of excitation rolling downwind.

Jeff
 
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#31 ·
Just as a further point of reference, this is a Karma, a recent Mills design.
Heeled Mills Design-E https://www.flickr.com/photos/22254080@N08/

I think you can visualize how narrow, symmetrical and low wetted surface the submerged hull would be even at this small heel angle. (BTW for the record, I am not a big fan of the current crop of wide beam boats.)
 
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