[2574]
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Imagine two identical yachts except one has 1.9m draught on a fin keel and the other has 1.75m draught on a wing keel. Would you anticipate much difference in any aspect of sailing performance?
Wing keel vs fin keel
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langstonelayabout
Well-known member
Very little difference, but it depends on the designs of the deep fin and wing keels.
Koeketiene
Well-known member
My previous, previous boat was a wing-keeler (38' with a draught of 1.6m).
All my subsequent boats had a draught in excess of 2m. (Current boat 36' with a 2.05m draught).
Draw what conclusion you will.
The main aspect of sailing performance affected is how well the boat performs to windward.
Also seakeeping in a blow.
westhinder
Well-known member
Difficult to judge, there are so many variables that affect performance. You would have to test two identical yachts alongside one another, top crews on board both so that you can be reasonably sure each boat performs at its potential.
FWIW, reports suggest that the deep keel and wing keel versions of the Starlight 39 and 35 pretty well match one another.
FWIW, reports suggest that the deep keel and wing keel versions of the Starlight 39 and 35 pretty well match one another.
John 32i
Active member
We thought having a wing keel here on the East Coast would be a good idea but we just couldn't get close enough to the wind....one day we did a pirouette in Harwich Harbour! Got a similar boat with a 2M draught now...sails much better; just a compromise as to where and when we can go to 
Catalina36
N/A
Can't comment on a comparison but my current boat has a wing keel with 1.2m draught on 36 feet. Its first voyage was a delivery trip from Boston Massachusetts to Falmouth then on to the buyer in Holland and the delivery crew left a letter praising its handling. The design is apparently popular in Holland where shallow water is common.
Since I bought it in 2005 I've constantly been impressed by its speed versus other boats which must in part be due to lack of drag I guess. I often sail under genoa alone. Offwind or even finely on it, it regularly keeps pace with similar-sized boats which are under full sail. Upwind I've not noticed it failing against other boats either - closeness to wind is more a function of sailplan not hull form. Leeway is a different matter and again I've not noticed a problem. When heeled the keel deepens and forms a "hook" whereas a straight keel when heeled is able to slide to leeward no matter how deep it is - the more the heel angle, the less the grip whereas a wing digs deeper. Aircraft design has developed into putting fins on wingtips to eliminate tip turbulence and improve lift, perhaps there's a connection.
That said, it depends what sort of sailing you do. There's no doubt that a deeper keel gives a deeper CoG and probably a surer passage in rougher conditions - I reef the main at 20 knots or rounding up becomes a problem, but I don't make a point of doing long trips in open water in more than 20 knots. Horses for courses.
Since I bought it in 2005 I've constantly been impressed by its speed versus other boats which must in part be due to lack of drag I guess. I often sail under genoa alone. Offwind or even finely on it, it regularly keeps pace with similar-sized boats which are under full sail. Upwind I've not noticed it failing against other boats either - closeness to wind is more a function of sailplan not hull form. Leeway is a different matter and again I've not noticed a problem. When heeled the keel deepens and forms a "hook" whereas a straight keel when heeled is able to slide to leeward no matter how deep it is - the more the heel angle, the less the grip whereas a wing digs deeper. Aircraft design has developed into putting fins on wingtips to eliminate tip turbulence and improve lift, perhaps there's a connection.
That said, it depends what sort of sailing you do. There's no doubt that a deeper keel gives a deeper CoG and probably a surer passage in rougher conditions - I reef the main at 20 knots or rounding up becomes a problem, but I don't make a point of doing long trips in open water in more than 20 knots. Horses for courses.
Seven Spades
Well-known member
We had a Starlight 39 with a winged eel and it never slammed. I suspect the the keel helped drive the boat through rough water. We always thought that when the weather was tough it just got going. Lighter boats are often stopped by powering into waves. the shallow draft was useful but off putting in areas where a fin keel might sink into the mud at low tide.
AndrewfromFal
Active member
I sailed a GK29 that had been retrofitted with a tandem keel (wing keel with 2 vertical elements holding the wing). The thing sailed like a rock and never slammed going upwind, and had great stability (especially when compared to a normal fin keeled sistership) especially when running in a heavy seaway, - given it was a classic 70s IOR type hull of the kind prone to death roll in such circumstances, - this was impressive and most welcome. Conventional GK was quicker in light airs (as had less wetted surface), but as soon as the breeze got above about 12 knots, she took off.
HissyFit
Active member
Although a wing keeled boat is intended to get into shallower spots, the warning is that if you do go aground the trick of heeling the boat to lift the keel off the bottom won't work, as you will be digging one wing further in. I think that will depend on the profile of the ground.
There is a theory that the hydrodynamic profile of a wing keel could be designed to give different performance characteristics, by providing lift.
There is a theory that the hydrodynamic profile of a wing keel could be designed to give different performance characteristics, by providing lift.
Frogmogman
Well-known member
Shortly after Australia II had won the America's cup, Huey Long is reputed to have told Ted Turner that he was thinking of fitting a wing keel to Ondine.
"Well Huey" Turner replied "You could fit me with wings too. But It sure as hell wouldn't make me an Angel".
"Well Huey" Turner replied "You could fit me with wings too. But It sure as hell wouldn't make me an Angel".
Sharky34
Well-known member
Whereas, as has been said on previous similar threads, it is difficult to get a wing keel off the putty, if it runs aground.
Why are they popular in Holland, hardly reknown for deep waters?
fredrussell
Well-known member
Well, my Parker 31 has a draft of 1.8 metres AND a wing keel. Not boats with a reputation for dawdling around, but, that said, I’ve heard of more than one that has had its one tonne lead wing recast into a bulb for the performance boost.
HissyFit
Active member
The extra wetted surface area of a wing keel could be a negative.
TSB240
Well-known member
Our version of the Hanse 301 is a shallow draft 1.1m lead keel with wings. The fin version is cast iron and draws 1.7m . Both boats have approximately the same ballast and displacement.
I don't believe there is a significant difference in wetted surface. I have the same handicap as the fin version.
My favourite anchorage in this very tidal area has a pool with 1.2 m on lws! It is never occupied by fin keel boats.
I have run aground on a number of occasions. The wing has a slight dihedral angle which allows a small degree of heel before the wingfront edge digs in. Useful when drying out alongside a harbour wall. Heeling and weight on the bow will help to get you off should you get on the putty.
I tend to only push my luck taking short cuts over any sand banks on an incoming tide .
We can lose an inch of water every minute of the ebb at half tide here. This will guarantee a parking spot for any keel type for the next 6 hours!
I don't believe there is a significant difference in wetted surface. I have the same handicap as the fin version.
My favourite anchorage in this very tidal area has a pool with 1.2 m on lws! It is never occupied by fin keel boats.
I have run aground on a number of occasions. The wing has a slight dihedral angle which allows a small degree of heel before the wingfront edge digs in. Useful when drying out alongside a harbour wall. Heeling and weight on the bow will help to get you off should you get on the putty.
I tend to only push my luck taking short cuts over any sand banks on an incoming tide .
We can lose an inch of water every minute of the ebb at half tide here. This will guarantee a parking spot for any keel type for the next 6 hours!
Catalina36
N/A
Oddly enough I've never been close to finding myself on the putty. Try watching the depth sounder. It has a handy little device called "alarm" which you can set at any depth which suits you and then it goes beep to wake you up.
anoccasionalyachtsman
Well-known member
Slightly embarrassingly I've been 'him in charge' on a few wing-keeled boats when the driver has erred on the shallow side. They're no harder to get off Solent gravelly mud than a fin.
@HissyFit, if you consider the shift of the centre of buoyancy with heel I'm pretty sure that heeling will reduce draft with a 'normal' production boat wing, albeit maybe not at quite the same rate as a fin. Again, never seemed to be a problem for me.
(Accidentally tagged JumbleDuck - thrown by the yellow in both your avatars - sorry).
Sharky34
Well-known member
Lucky you.
Catalina36
N/A
If that's beyond your means, there's a thing called a "broom handle".
Sharky34
Well-known member
Laminar Flow
Well-known member
We had this discussion a while back, I believe.
Meanwhile I have found out more about the Delft keel study done in a test tank.
They tested a total of 7 keels, two of which were a deep trapezoidal and an elliptical keel. The deep keels had a span of 2.29m the rest were shallow keels including two variants of winged keels with a span of 1.38m. The two wing variants consisted of a fairly long model with short wings and a shorter model with long wings.
These were tested on a 3m long model of a 63' yacht.
To separate hydrodynamic effects from stability, all calculations were done for the same RM.
The results were calculated in hours sailed on an olympic course and for wind speeds of 15 and 25kts.
Deep keels (both): 15kts 3.96 hrs; 25kts 3.52 hrs
Wing long body: 15kts 4.04 hrs; 25kts 3.60hrs
Wing short body: 15kts 4.01 hrs; 25kts 3.53hrs
It should be noted that the reduction in depth of keel under the boat from 2.29m to just 1.39m is quite significant and that the short body, wide wing model is nearly as good as a much deeper fin in the higher wind speeds. This coincides well with the observations made by previous posters on this tread.
Sadler yachts made comparisons of various keel designs and it was noted that the wing keels significantly enhanced directional stability.
The German yachting magazine, "Die Yacht", tested two Contest sister ships, one with a wing and the other with a fin. The fin was found to be quicker in light going. The wing seemed to dampen the ship's motion in a seaway.
My brother owns a Catalina 28 with a wing. He cannot discern any particular difference in performance from the previous C&C 27 with a fin. He does complain that the Catalina is shorter rigged. This is entirely subjective of course and for a more valid comparison I would look at the Delft numbers.
Meanwhile I have found out more about the Delft keel study done in a test tank.
They tested a total of 7 keels, two of which were a deep trapezoidal and an elliptical keel. The deep keels had a span of 2.29m the rest were shallow keels including two variants of winged keels with a span of 1.38m. The two wing variants consisted of a fairly long model with short wings and a shorter model with long wings.
These were tested on a 3m long model of a 63' yacht.
To separate hydrodynamic effects from stability, all calculations were done for the same RM.
The results were calculated in hours sailed on an olympic course and for wind speeds of 15 and 25kts.
Deep keels (both): 15kts 3.96 hrs; 25kts 3.52 hrs
Wing long body: 15kts 4.04 hrs; 25kts 3.60hrs
Wing short body: 15kts 4.01 hrs; 25kts 3.53hrs
It should be noted that the reduction in depth of keel under the boat from 2.29m to just 1.39m is quite significant and that the short body, wide wing model is nearly as good as a much deeper fin in the higher wind speeds. This coincides well with the observations made by previous posters on this tread.
Sadler yachts made comparisons of various keel designs and it was noted that the wing keels significantly enhanced directional stability.
The German yachting magazine, "Die Yacht", tested two Contest sister ships, one with a wing and the other with a fin. The fin was found to be quicker in light going. The wing seemed to dampen the ship's motion in a seaway.
My brother owns a Catalina 28 with a wing. He cannot discern any particular difference in performance from the previous C&C 27 with a fin. He does complain that the Catalina is shorter rigged. This is entirely subjective of course and for a more valid comparison I would look at the Delft numbers.
