Wing keels - good or bad?

[oldbloke]

I used to have a MG Spring 25 which came with the wing Keel as standard. There were various stories/ theories but the main one was that it was the easiest way of putting a lot of iron onto a shallow draft keel. Certainly, along with the twin rudders it would stand up unaided. It was also mentioned that as it heeled the leeward wing going deeper preserved the draft , otherwise the beam hull and shallow draft would soon lever the keel out of the water, also the aft rake of the wings moved the centre of resistance back reducing weather helm. Was it as good as a proper keel? Probably not but 1m draft and not worrying about touching the bottom in a sheltered anchorage worked for me.

 

[thinwater]

A curious side effect. Yes, they draw is slightly less, measured with a ruler. But a wing keel is more difficult to break free if grounded in the mud (think anchor-like fluke), so you actually need a greater safety factor in muddy shoal waters. That is the conventional wisdom in the Chesapeake Bay.

They are a rule-beater more than a practical shallow water advantage.

 

[oldbloke]

There are plenty of Spring 25s that have lived happily in mud berths without sinking or tearing the keel off. It may have happened, Cheasapeake mud can be v gloomy, but I am sure our east coasters would say ours 8s better

 

[Chiara’s slave]

A curious side effect. Yes, they draw is slightly less, measured with a ruler. But a wing keel is more difficult to break free if grounded in the mud (think anchor-like fluke), so you actually need a greater safety factor in muddy shoal waters. That is the conventional wisdom in the Chesapeake Bay.

They are a rule-beater more than a practical shallow water advantage.

Rule beater meaning that they are indeed more efficient in some ways than a conventional keel of the same draught. Any shallow water advantage is offset by shallow water disadvantage. The mud issue, the inability to reduce draught by sending your fattest crew member to the end of the boom and poling him out. Shallow water is not what wing keels are for.

 

[KompetentKrew]

I would not walk away from that one, I would RUN.

If I'm correctly interpreting OP's comment, the joke is that you should, yes.

 

[Geoff Wode]

Actually, no it's not. There are cracks around the keel bolts, two of them are missing, the forward hatch leaks badly, the rig is off an insurance write-off, mice have nested in the sails and it's subject to a contested insurance claim.

Oh dear.

Theres loads on the market at the moment but mostly twin keels. Theres one with new sails on for £7.5k iirc.

 

[Tiger Moth]

I would not walk away from that one, I would RUN.

My apologies, I was being sarcastic. The boat is fine, I was just trying to dissuade anyone else from grabbing it. I should have made myself clearer.

 

[Refueler]

Wikipedia claims that the wings have aerodynamics which pull downwards, increasing righting movement.

Wing keels as well as the Collins were fads that came out trying to re-invent the wheel. Ideas such as using wing profiles to compliment weight and righting moments etc. Like every design - there are gains and losses ...

And like most - they seem to fade away and not become standards.

Any reason to walk away ? None that I can think off ... at least whoever buys will have a conversation piece at club bar !!

 

[MisterBaxter]

Every commercial airliner has swept-up wingtips because they generate a bit more lift for the same wingspan - as I understand it, by controlling tip eddies so that the full span of the wing is lifting. The principle is presumably the same in boats - the very bottom of the keel doesn't produce as much lateral resistance as it could, because some of the water escapes underneath the keel. So a wing keel gives you a bit more lateral resistance for the same size and depth of keel.
In boats there's obviously a second advantage, which is that having an additional big lump of metal on the end of the keel is good for stability.
But nevertheless, if you used the lump of metal that went into the wing to extend the keel downwards instead, you'd get more lateral resistance and better stability than the wing version would provide. But you'd also get a deeper keel, which might be inconvenient.

 

[Refueler]

Every commercial airliner has swept-up wingtips because they generate a bit more lift for the same wingspan - as I understand it, by controlling tip eddies so that the full span of the wing is lifting. The principle is presumably the same in boats - the very bottom of the keel doesn't produce as much lateral resistance as it could, because some of the water escapes underneath the keel. So a wing keel gives you a bit more lateral resistance for the same size and depth of keel.
In boats there's obviously a second advantage, which is that having an additional big lump of metal on the end of the keel is good for stability.
But nevertheless, if you used the lump of metal that went into the wing to extend the keel downwards instead, you'd get more lateral resistance and better stability than the wing version would provide. But you'd also get a deeper keel, which might be inconvenient.

Wing tip additions are to control Tip Vortices ....

We've been using them on models long before the big boys started using !!

 

[scottie]

As I understand it the winged keel on Australia 2 was a way of beating the measurement of draft by giving more draft when heeled. Of course the concept of winglets on tip of jet aircraft seems to be pretty standard now as a way of controlling off the end eddies.
So it would seem off the end eddies can be controlled by winged keel or more often now a bullet. In both cases ballast is lower with obvious advantages.
The disadvantage of winged keel on a yacht would be that if you run aground you can not heel to boat to reduce draft.(but you can't with twin keels)
The advantage is less draft but I think with a penalty of less lateral resistance area and more drag so probably worse up wind performance.
So as said winged keel seem to have gone out of favor although bullet (bulb) keels seem to be the go for performance as said.
If performance is a priority then fin keel possibly with bulb would be best but winged keel might be fine for his requirements. ol'will