Any advantages of Wing Keels ?

[belizesailor]

Originally Posted by AlanT

I can see the attraction of wing keels if you are going to be sailing in skinny water a lot. But that same skinny water makes it more likely that you will ground out (whatever your draft) and therein IMO lies the problem. If you ground out with a wing keel it is reportedly much more difficult to get off. You have two things working against you 1. Greater surface area creating greater friction/suction to the sea bed, and 2. You can't heel the boat to reduce draft.



~A

Having hauled a few wing keelers out of the mud, I can attest to that as a possibility. We used to call them "reverse danforths".

[BillKny]

A keel is a vertical wing with a high pressure side and a low pressure side. The "high pressure" water "leaks" across the bottom of the keel and creates a horizontal eddy behind the boat. This eddy is wasted energy, and the whole process reduces the pressure difference between the two sides of the keel thereby reducing its effectiveness.

By putting a horizontal plate on the bottom of the keel, this "leakage" can be greatly reduced, and it improves the effectiveness of the lower part of the keel. This is the same principle and reason that modern airplanes have those little vertical tips on the wings.

The reason the "wings" were important on the Australian America's Cup boat was that the keel length was limited by the rules. Adding the "wings" made their keel perform as if it was longer and deeper.

For two keels of the same depth and geometry, one with wings and one without, the one with well designed wings will be better at reducing leeway. There will also be extra weight down lower, which will improve the overall performance of the boat. How much they help depends on a zillion variables.

That additional boast upwind doesn't come for free. "Wings" increase overall wetted area and therefore drag which will decrease performance when reaching or running, especially in light air.

In a lot of designs the "wings" are either badly designed, and/or they are being used to try to compensate--as much as possible--for the inherent performance issues that come with a shoal draft keel.

[jewt]

My previous boat was a 1969 Morgan keel/cb. The keel had a 4 ft. draft and the board added an addition 3 1/2 ft. and 200 lbs. of addition ballast. I owned that boat for 30 years rebuilding the interior twice making 12 trips to the Bahamas, both inside and direct from Beaufort, NC AND collect so many trophy's my wife finally made me move them garage.

For skinny water and performance a K/CB is the way to go

jewt

[Martkimwat]

This is a very biased vote since neither option is really positive, whereas wing keels have several advantages including low centre of mass in the keel (due to the wing having a large part of the weight) and hence stiffer boat for shallower draft, the boat can also dry out upright if the wing is broad enough (Starlight 35/Sadler 35) and also the wing acts as an end plate making the fin more efficient and reducing drag.

[danstanford]

Originally Posted by BillKny

A keel is a vertical wing with a high pressure side and a low pressure side. The "high pressure" water "leaks" across the bottom of the keel and creates a horizontal eddy behind the boat. This eddy is wasted energy, and the whole process reduces the pressure difference between the two sides of the keel thereby reducing its effectiveness.

By putting a horizontal plate on the bottom of the keel, this "leakage" can be greatly reduced, and it improves the effectiveness of the lower part of the keel. This is the same principle and reason that modern airplanes have those little vertical tips on the wings.

The reason the "wings" were important on the Australian America's Cup boat was that the keel length was limited by the rules. Adding the "wings" made their keel perform as if it was longer and deeper.

For two keels of the same depth and geometry, one with wings and one without, the one with well designed wings will be better at reducing leeway. There will also be extra weight down lower, which will improve the overall performance of the boat. How much they help depends on a zillion variables.

That additional boast upwind doesn't come for free. "Wings" increase overall wetted area and therefore drag which will decrease performance when reaching or running, especially in light air.

In a lot of designs the "wings" are either badly designed, and/or they are being used to try to compensate--as much as possible--for the inherent performance issues that come with a shoal draft keel.

Thanks for the explanation, I always wondered how that keel was better when everyone said they were worse.

[Coach Shoe]

In a previous life (mid 1980’s), I worked for a sailboat manufacturer that undertook a significant study to ascertain the differences of various keels in the real world. We built three identical 26 foot boats with the exception of the keels. One boat had a deep draft fin keel, another a shallow draft wing keel and the third had a shallow draft Scheel Keel. Over a period of several months the boats were raced against each other, alternating helmsmen, and in different wind conditions. The boats were raced “blind’....I.e, nobody had any idea of which boat they were on. After a significant data base was built, we tabulated the results. It was news at the time but the results are now common knowledge. The fin keel consistently out performed the other keels.

That said, because I often cruise in skinny water, my current boat has a wing keel and I am more than pleased with all aspects of its performance. Choose a keel that meets your needs.

[DMF Sailing]

I sometimes sail a boat with a wing keel here in New England.

I have nightmares about hooking a lobster pot.

Especially those ones off Provincetown, one of my favorite destinations, that have a flag attached by a short line to the actual buoy. About four feet long. Perfect for hooking.

I presume you are not in lobster country.

[thunderhoof]

Keels with winglets can have an advantage going upwind compared to bulb keels of the same depth when designed to hydrodynamic principles. Most of the wing keels I have seen appear to be intended for visual impact which is not a go fast factor.

[Jim Cate]

Originally Posted by thunderhoof

Keels with winglets can have an advantage going upwind compared to bulb keels of the same depth when designed to hydrodynamic principles. Most of the wing keels I have seen appear to be intended for visual impact which is not a go fast factor.

I'm not competent to comment on this, but wonder why, if it is true, we don't see winglets on serious raceboat designs these days? They seem all to be very high aspect fins with bulb ballast on the tips.

Jim

[thunderhoof]

Jim,
I think all the nasty fouling and damage issues mitigate against "winged" keels. Most classes have enough hull definition to preclude them as well.

[dfelsent]

The lobster buoy thing.
I’ve always had the same concerns.
Both Roger Hewson and Jim Taylor have spent decades sailing in New England.
I would hope they factored trap lines into their wing keel shapes.
Does anyone here have a real story about catching a trap line?

[chriswheat]

Originally Posted by Hudson Force

'beats a CQR for holding in mud and clay!

Sure does! And yes it will keep you upright until Towboat US gets there. I crewed on a delivery one time when we got stuck in Turtle Cove or something like that at Absecon NJ We were in mud and the Towboat captain agreed to pull us off only after we assured him that we didn't have a winged keel.

[belizesailor]

Originally Posted by Jim Cate

I'm not competent to comment on this, but wonder why, if it is true, we don't see winglets on serious raceboat designs these days? They seem all to be very high aspect fins with bulb ballast on the tips.



Jim

No substitute for leverage. Wing keel versions of boats just dont go to windward, especially in moderate to heavy conditions, like a deep fin or deep fin w a bulb.

[DMF Sailing]

Originally Posted by dfelsent

The lobster buoy thing.
I’ve always had the same concerns.
Both Roger Hewson and Jim Taylor have spent decades sailing in New England.
I would hope they factored trap lines into their wing keel shapes.
Does anyone here have a real story about catching a trap line?

As the guy who obsesses over this, I can say that the only trap I've caught was when I was up top wrassling the main in a near gale while a newbie guest was "steering" in a tight channel... he ran over the pot, it got fouled in the rudder, and I got the knife and dove it.

Did not end up cutting the buoy from the trap line. Unwrapped it.

Moral of the story: Don't.

Pictured: Where it happened. Depths in feet. Wing draws 5' 11".

[NY2TLV]

Pros and Cons of the Wing Keel
Wing keels come in all shapes and sizes but the general idea is to have, aside from the vertical fin of the traditional keel, a horizontal foil on the bottom.

The idea for a wing keel came about because of one of the America Cup races. It was introduced to increase performance by reducing leeway when a boat heels and helping the water flow over the bottom. In practice though, the reason for its popularity is because of its shallow draft, not performance.

What are the pros and cons of the wing keel?

Advantages
Shallow draft
Lower center of gravity
Better access during maintenance
Stiffer ride
Innovation

Disadvantages
Can't point as sharp windward
Worse performance overall
Whorter rudders - worse handling
Difficulty getting unstuck when aground

Advantages of the Wing Keel

Shallow draft
The main reason the wing keel gained popularity is that it offers better clearance. The horizontal wing enlarges the keel's surface area and so it doesn't have to go as deep as a fin keel on a boat of the same size has to - the difference can easily be a foot of draft on a twenty-foot sailboat. This is quite irrelevant in the Mediterranean or Adriatic for the most part, also, ocean crossing boats don't have to care, but in the United States, especially around Florida for instance, this can make a difference.

Also, people who sail on lakes might find this useful, especially in this day and age, when quite a few lakes experience lower water levels than, say, twenty years ago. So if exploring shallow coastal waters is something you do, if you find yourself often on lakes, rivers or waterways without much depth, join the gang.

Lower center of gravity
Now this one sounds good but it isn't as black and white as you might wish for - more on that in a bit. Generally, since there is more mass on the lowest point of the keel, you will likely have a lower center of gravity, which adds to stability. You might experience less heeling, which is favorable for performance and comfort for those who get nervous when the railing touches the water. The boat will also rock less, which is something the seasick ones will welcome as well as anybody who manipulates with open liquid containers on the boat - whether that be somebody wanting to enjoy a full cup of coffee or somebody looking to cook some pasta.

Now to relativize this point slightly - it is only valid when comparing boats with equally deep keels. But if you are comparing equally sized boats, one with a fin keel and one with a wing keel, the drafts simply won't be the same. So all in all it isn't a fair comparison since it would only apply for boats of different sizes.

Maintenance access
The ease of access when maintaining a boat isn't really what people look at when choosing a boat. But it is a relevant point nonetheless. You see, when hauled, given the shallower draft, your boat will be lower to the ground, thus easier to access when you want to clean it from the pesky sea fauna and flora, repair it or apply some antifouling paint. Or do any work on its bottom in general.

Whether this one is beneficial for you depends on the kind of equipment you have at your disposal for these kinds of situations. If wooden crates and ladders are what you are using, you will probably welcome having your boat a few feet closer to the ground. If on the other hand, you have some kind of a motorized construction platform, you probably won't care as much.

Stiff ride
Because of the construction design as well as some of the benefits listed above, the ride with a wing keel is a bit stiffer than with the fin keel. Many sailors prefer this, especially the cruiser types, who will appreciate the reassuring ride. If comfort is your goal, or if it is a liveaboard you are looking to purchase, this might be a relevant factor for you.

Support of invention
Wing keel was developed in the pursuit of bettering the boating experience. Whether that worked or not, the important thing here is that somebody took a long-standing design that worked for centuries and decided to improve it. Not with a hi-tech feature, taking advantage of the technological progress, but rather with an idea that is structurally relatively simple. That is a bold move, that should be rewarded because its encouragement can lead to other, similar feats.

So by purchasing a boat like that, you are showing support to improvement and fighting design dogmas that can be great and working, but as any dogma, they should be tested from time to time.

Disadvantages of the Wing Keel
Now it is the time for the disadvantages of wing keels - and not to discourage anybody ahead of time, but there are many. So wing keel supporters, brace yourselves.

Worse performance windward
No way around it. Simple fin keels have better performance windward. Choosing a wing keel will rob you of some 5 degrees since you just won't be able to point as high as you could with a fin keel. Now if you are on a cruiser or a liveaboard, where it is about the enjoyment of the ride rather than being able to go the optimal route, you don't have to care. But if this is a matter for you, think twice before going the wing route.

Worse performance all around
To make matters even a bit poorer, a fin keel boat can point better, because of the larger vertical board area it tracks better, and, as will be explained later, sometimes has a larger rudder. Then there is drag - a wing keel will have higher drag than an equally deep fin keel, again, hindering the performance. So with wings, you can expect worse performance on many fronts.

Now just as was the case with the previous point, this is something many won't care about, because performance isn't what they are in this for, or perhaps it's that the advantages outweigh the disadvantages. After all, the smaller draft is a big deal for many.

Shorter rudders
To address the rudder point stated above - one possible issue with wing keels is that because they can be so short, sometimes the rudders reach deeper than the keel. So if you happen to bump the sea bottom, your rudder will be what takes the punch. And rudders' structural integrity is much more delicate than that of keels. Plus, if you take out your keel, your boat is still operational. If you take out your rudder, good luck getting somewhere without a towboat.

The obvious solution to this is of course shortening the rudder, which is what quite a few models did. But a smaller rudder means yet another performance and maneuverability reduction point on top of everything else.

Getting unstuck
Last but not least, when aground, fin keel is easier to get off. It won't have as large area of contact and because of it being vertical, simple heeling the boat can get it unstuck. With a wing keel on the other hand this won't help you. And as many users of this design testify, in mud, it acts as an anchor, so even a powerful towboat will have issues getting you out. So on one hand you have more clearance because of the shallow draft, but in certain conditions, because of this as well as the rudder issue, you have to pay more attention because when you do touch the bottom, things get ugly.

Application of the Wing Keel
If you find yourself in a race situation where you are limited by the class rules as far as draft goes, wing keel is what you want to go for - this is among the reasons it came to be after all. For cruisers or pleasure crafts, the main benefit is versatility, since you will be able to cruise around in waters shallower than the fin keel folks.

When to Choose a Wing Keel (and when to avoid it)
All in all, get wing keel if you know you will be sailing in shallow areas. If that is not the case though, there aren't many reasons not to avoid it. This is best described by what an unnamed Catalina seller said: if the draft is not an issue, stick with fin keel. It is better overall. If however, you sail in areas where the shallow draft gives you an advantage, consider a wing keel. So as with most things, your choice is up to your personal preference.