Winged Keels

[CptCrunchie]

Originally Posted by Dave_S

....The wings will significantly change the boats reaction in the swell.

As the boat moves from level to bow up, the drag below your pivot point increases resisting the bow rising and when you crest the wave you will come down earlier so not as high. As the boat transitions to bow down the drag will pull the bow down and it will bury the bow deeper.

Hmmmm..... I'm pretty sure that's what I wrote in the second last paragraph of my OP. You be the judge.

Originally Posted by CptCrunchie

Then there's what happens heading into big seas. My thinking is that the wing would hold the bow up over the crest, and only once the keel neared the crest would the bow come down. Then, once that happened, the wing would hold the bow down to push it through the next crest .....versus the bow riding over it.

I'm no expert either, it just makes sense to me that it would do that.

[sailorboy1]

So much over thinking. Lots of boats have a wing keel (my 6.4’ draft boat has a wing keel) for fluid dynamics. But a shoal wing keel boat is about draft. I’ve had a shoal draft wing keel and it sailed as well to wind as my deep draft boat. The biggest difference is my deep draft boat handles gusts better, but not really a reason to lose any sleep over.

So a big wing keel is about a shoal draft boat that still sails well. Who cares if it heaves to well etc., ...... it’s about draft (I haven’t heaved to in over 8 years)

[Jim Cate]

(I haven’t heaved to in over 8 years)

But then, as I recall your frequent posts, you haven't done much offshore sailing in those 8 years, and heaving to is primarily an offshore tactic.

And for all these anecdotal reports that wing keels sail to windward just as well as their deep conventional keel sisters... well, they are just anecdotes with ns of one. The PHRF ratings, based on many, many race results show that in general, the wing keel boats are a bit slower around a race course. May not be a big difference in some models, but there none the less. Only the individual sailor can decide if the differences are important to him in his application.

And finally, it is interesting to note that AFAIK, no serious racing boat has been designed with a wing keel for many years, so I must doubt that there are any inherent advantages in their performance. Apparently the drag added by the wings compared with a bulb is enough to rule them out.

None of this means that a shoal draft keel with wings isn't a reasonable choice for shallow water sailors.

Jim

[CptCrunchie]

Originally Posted by Jim Cate

But then, as I recall your frequent posts, you haven't done much offshore sailing in those 8 years, and heaving to is primarily an offshore tactic.

And for all these anecdotal reports that wing keels sail to windward just as well as their deep conventional keel sisters... well, they are just anecdotes with ns of one. The PHRF ratings, based on many, many race results show that in general, the wing keel boats are a bit slower around a race course. May not be a big difference in some models, but there none the less. Only the individual sailor can decide if the differences are important to him in his application.

And finally, it is interesting to note that AFAIK, no serious racing boat has been designed with a wing keel for many years, so I must doubt that there are any inherent advantages in their performance. Apparently the drag added by the wings compared with a bulb is enough to rule them out.

None of this means that a shoal draft keel with wings isn't a reasonable choice for shallow water sailors.

Jim

Well stated, Jim. Thank you.

Since Wifey and I are in no big hurry (as compared to racing), we have pretty much decided to go with the winged keel boat. We just have one boat to check out in Mexico, and another in Hawaii. Besides, I'm more of a close reach than a close haul sailor anyway.

[Uncle Bob]

Originally Posted by CptCrunchie

All you experienced wing keel sailors, I have a question that only you can really answer.

We are still mulling over the wing keeled boat I referenced in the OP. So far, I am encouraged, and will likely put in an offer.

Yesterday, I spoke with an older sailor about wing keels, a guy who said he knows a lot about them, but admitted he has never sailed one. We got talking about heaving to in big seas.

I started out heaving to with the genoa and mainsail, but quickly discovered it is far more comfortable for me, and far less stressful for the boat to heave to on just the mainsail. I have since done this in all sea states, and much prefer it to using 2 sails and/or a drogue.

This old salt said that heaving to on a wing keeled boat will be a challenge, because as the wave rolls under the boat, the leading wing will catch the wave as the wave breaks. This will make it roll the boat and either bring the boat up through the wind, or force it to roll sideways into the trough.

While I know very little about the effects of a wing keel heaving to, I don't see how it would go through the wind because the angle of the rudder would never let that happen, and it can't roll into the trough because the sail would be powering up.

What say you?

I would say that this says it all about this source of information.

[Dave_S]

Originally Posted by CptCrunchie

Hmmmm..... I'm pretty sure that's what I wrote in the second last paragraph of my OP. You be the judge.



I'm no expert either, it just makes sense to me that it would do that.

If you read it carefully I am disagreeing with you.

I am saying at low speeds you will get SFA lift with much more drag. At 6° AOA nose up you will have huge drag 1.5m below your pivot point this will RESIST the bow lifting. It will be pulling the nose down (so far so good but). As you crest the wave you start to angle nose down the drag will pull the nose down harder and your bow will bury deeper....very not good. That's where you lose most of your speed, pushing through water.

I'm no expert but that seems to make perfect sense to me.

You won't have enough speed to make enough lift to push you further upwards as your thinking, I don't know the numbers but I'd guess at 5:1 against. So rethink of it as drag not lift and see what you think.

[sailorboy1]

I love when I give direct experience on something based on years of personal use and get told I'm all wrong. I can save everyone a lot of trouble: If I typed it, it's wrong!

[SaltyMetals]

I had a Bene Oceanis 400 (hull#1) for almost 15 yrs (that is 40 ft /12m for you guys in the US) which had a winged bulb. draft 1.8 m. (6ft).

Frankly i never really noticed any drawbacks at all, only the advantages of being able to get into places (or over sand bars) which boats with a longer keel could not manage. If you really want to get into the heavy weather considerations i suggest you read Fastnet Force 10 by John Rousmaniere and Heavy Weather Sailing by Adlard Coles. Yes, there is a difference, as you will understand when you read those two books. The example taken is a long-keeled boat compared to a deep fin keel where the former will slip sideways down a large wave but the latter is locked by the deeper keel and likely to get tumbled over. While i have not read anything about winged keels I would imagine that the wing will also lock the underside of the boat in the water and will then get tumbled but i am just guessing, i am not an expert in heavy weather.

But if you are cruising then any different performance in normal sailing compared to a deep fin keel is not going to bother you. I was very happy with my winged bulb, apart from the odd occasion when i hit mud.
Andrew
"Genial Bee"

[Group9]

Originally Posted by sailorboy1

So a big wing keel is about a shoal draft boat that still sails well. Who cares if it heaves to well etc., ...... it’s about draft (I haven’t heaved to in over 8 years)

I sail a lot in shallow waters, so shoal draft means a lot to me. I suspect that most of the people with no use for shoal draft winged keels, don’t.

[Jim Cate]

Originally Posted by sailorboy1

I love when I give direct experience on something based on years of personal use and get told I'm all wrong. I can save everyone a lot of trouble: If I typed it, it's wrong!

SB, you posted

"I’ve had a shoal draft wing keel and it sailed as well to wind as my deep draft boat."

This is your subjective experience, comparing two unidentified boats performance. IIRC, your previous boat was a Cal 39... a rather different design than your current Hunter. I dunno which one had the wing keel, but using such disparate designs to show that wing and deep keels sail to windward equally well is not a compelling argument.

PHRF ratings, while not an absolute data set do show that wing keeled versions of the same designs generally perform a bit poorer overall... larger sample size, somewhat more objective analysis, so I personally find this a better metric than what you posted.

So, the inference isn't that you are "all wrong" in reporting what you experienced, but that it doesn't contribute very much to the discussion... at least in my opinion. The discussion of how the hydrodynamics of wing keels actually affect the way a boat reacts to wave trains is interesting, even without years of personal experience.

And of course I agree that in some venues, shoal draft, however achieved, is a great convenience.

Jim

[Ken Fry]

Originally Posted by Jim Cate

PHRF ratings, while not an absolute data set do show that wing keeled versions of the same designs generally perform a bit poorer overall... larger sample size, somewhat more objective analysis, so I personally find this a better metric than what you posted.

Yes, the PHRF ratings are a good yardstick, based on a large sample size.

Typically, a Catalina 25 with fin keel rates 225. A Catalina 25 with wing keel rates 231. (6 seconds per mile is a very small difference, but the wing keel is slower.) The weight addition and location of the wings helps recover some of the righting moment, and the wings can have a slight endplate effect, which can reduce drag, if other things were equal.

But other things are not equal. In an optimized winglet design, as on the Americas cup boats, performance can improve. But in production boats, where draft reduction is the primary reason for the wings augmenting a short keel, the tradeoffs rarely improve performance -- and PHRF ratings show that.

It takes a racing Catalina 25 about 12 minutes to go a mile. That is 720 seconds. So the 6 second difference translates to less than one percent difference in overall performance.

In cruising, that is certainly not enough to make a winged keel a bad choice, and in many locations, it can be the best choice for draft reasons when combined with the simplicity of avoiding a swing keel or centerboard.