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Old 30-01-2009, 11:43   #31
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I think we are in dangerous waters here. There is too much generalizing going on about keel types and their associated performance.

Some of the best tracking boats I have ever sailed have had very short chord fins.
"Chord" is the leading edge to trailing edge dimension of any foil measured perpendicular to the presumed flow. So, chord is the fore and aft length of the fin at any given pint and "span" is the depth or vertical dimension.

I think BCmike has the right approach and Jeff has done a great job of laying out the components of this discussion. Fun discussion.

One of the worst tracking boats I have ever sailed had a full keel.
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Old 30-01-2009, 14:28   #32
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Everything I've read says that a long keel is better for bluewater cruising. Especially if your short-handing as its less strain on the autopilot(whatever type you use).
Everything I've read says that, among those who have cruised and then bought a second boat in order to cruise some more, almost always go with a fin keel on the second boat. The reason is that they want better windward ability. The more people cruise, the more important that seems to become. Not always, but most of the time.

The other thing that is overrepresented for unreformed cruisers is a bias for a metal hull.
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Old 30-01-2009, 15:40   #33
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Everything I've read says that, among those who have cruised and then bought a second boat in order to cruise some more, almost always go with a fin keel on the second boat. The reason is that they want better windward ability. The more people cruise, the more important that seems to become. Not always, but most of the time.

The other thing that is overrepresented for unreformed cruisers is a bias for a metal hull.
That's why I posted that book, it weighs up the different bonus's of various features of a boat intended to be used as a offshore cruiser.
I'm sure that we can at least agree that all boats are compromises between different features...
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Old 30-01-2009, 16:34   #34
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Hiracer, I knew there was something wrong with me. I did all my cruising on a fin keel boat, and wanted a full keel when I bought my next one. Though I too have been on a full keel boat that seemed to slide sideways at an alarming pace, the majority of the boats I tried with full keels had a nice motion, loads of storage space, and most importantly held a line in the water with very little work from the helm.
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Old 30-01-2009, 16:55   #35
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Hiracer, I knew there was something wrong with me. I did all my cruising on a fin keel boat, and wanted a full keel when I bought my next one. Though I too have been on a full keel boat that seemed to slide sideways at an alarming pace, the majority of the boats I tried with full keels had a nice motion, loads of storage space, and most importantly held a line in the water with very little work from the helm.
I am a fan of heavy boats with nice motion, moderate beam, adequate SA/D ratio, lots of storage, and run like on rails. So I'm with you. But you can have all that in a fin keel too.

There are fin keels, and then there are fin keels.

I think many people pay too much attention to keels/rudders and not enough to hull shape and sail balance.

Over simplifying a complex subject can lead to deadends and missed opportunities.
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Old 30-01-2009, 17:01   #36
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Dead ends? Missed opportunities? Again, it's like you're looking over my shoulder.
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Old 30-01-2009, 17:13   #37
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Dead ends? Missed opportunities? Again, it's like you're looking over my shoulder.
My apologies. I could have put it differently.

What I meant is that many choices put on these forums are presented as if they are an either/or choice, when in fact they are not. It's what I call a false choice: either this or that. But if done right, you can actually have both and not choose between this or that.

Bob's example of a fin keel than tracks well makes the point. People assume that a fin keel boat will not track well and a full keel will. As far as a generality is concerned, that might be true. But with respect to any one particular boat it may well be completely false. Thus, the either fin-and-twitchy or full-and-steady is a false keel choice.

That's my point. Don't fall for the false choice. It's limiting when one really needn't be limited.

This is NOT an agrument against full keels. Its an agrument about over generalizing about keels---fin or full.
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Old 30-01-2009, 17:27   #38
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I was just joking.
I actually agree with you. It is a false choice. I think the whole idea of picking a boat based on formula's is a little dicey. I prefer longer passages and longer times at anchor. If I prefered overnighters and marina hopping (and nothing at all wrong with that) I would prefer a fin keel boat for the generally quicker handling.
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Old 30-01-2009, 17:35   #39
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I was just joking.
Oh good. Too bad it went right over my head. Kind of wasted on me.

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If I prefered overnighters and marina hopping (and nothing at all wrong with that) I would prefer a fin keel boat for the generally quicker handling.
LOL

To beat a dead horse even deader: I have a fin keel. She sails pretty well without much helm input. Turns just about in her length if I use the prop walk. But my goodness, I have a huge skeg that encases the prop and backing up is a frigging nightmare. I do not have marina boat by anybody's definition, despite having a fin keel, so where did I go wrong?

But it's all good because for me the whole purpose of the boat is to find santuary away from towns and marinas and etc., just like you I suppose.
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Old 30-01-2009, 19:16   #40
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What about a long fin keel...

Boracay, a Robers Offshore 44, has a longish fin keel. Seems to track OK.

Some of the out of water pics of full keel boats show a keel that is not really bigger on the bottom than Boracay's.
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Old 30-01-2009, 19:58   #41
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I also decided on a bit of a compromise between the full and the fin keel....
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Old 31-01-2009, 09:52   #42
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For my money you can get the best tracking with a boat that has the rudder as far aft as possible. Ray Richards once described it as like the feathers on the back of an arrow. Running those feathers full length on the arrow is not necessary. My own boat has a transom hung rudder. It's a ice big modern foil and as far aft as physcally possible. My boat doesn't track worth a damn. But it's a Peter Norlin design so I don't take it personally. My boat is also 26' long and maybe it's just asking too much for a short boat to track. I am in love with my auto pilot.

As far as backing up goes, after 45 years at this it's still a mystery to me. I have done boats like the V-40 that back up perfectly. Perfectly with total control and minimal prop walk. Then I owned an Esprit 37, pretty much an identical prop.rudder/skeg situation to the V-40 and it was not so god in reverse. It wasn't bad but it sure was not the Valiant 40. Go figure.

I have found that the more stuff you take off the hull aft and keep the hull clean, like a modern racer, then add a big spade rudder you get the best performance in reverse. My newer boats with shorter chord keels and big, semi balnced spade rudders, no skeg work just fine in reverse. My boat backs like a dream.

Boats like Baba 40's and 30's with the prop in a aperture are the very worse. That aperture seems to act like Cort nozzle and just direct the prop stream to one side making backing up a true adventure. The only solution to this, and it's a partial solution, that I have found is the Max Prop. The Max Prop has syemtrical blades. They are the same shape in reverse as they are in forward so they have far beter bite in reverse than the typical asymentrical prop. I did a lot or prop testing years ago and the Max Prop was the clear winner based upon it's low speed and backing performance.
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Old 31-01-2009, 11:13   #43
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THis is the underbody of Rhosyn Mor. She tracks well, and will hold a steady course in pretty much anything, all of which leads me to belive that its not so much the keel/ rudder configuration , but the overall underbody that has the most effect. She is slightly flat, and so pounds, backing up is not a real problem- although there have been days when it has been so AS for heaving to, that seems to be more of a rig issue than an underbody thing..... perhaps?
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Old 31-01-2009, 11:16   #44
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As far as I can see, my two blade prop is symmetrical, but this is from memory. I have a deep fin and a skegged rudder. I don't think my boat backs well, though I have seen someone back a sister ship quite nimbly. I don't use reverse except to kick the stern in and stop forward motion when coming along side for fuel. I don't have much need for nor practice in backing down.

Of course when you are in reverse you are steering the boat with the rudder at the leading edge of motion and that makes control and steering in reverse very challenging. Imagine if your rudder were at the bow!
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Old 31-01-2009, 11:45   #45
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Boats like Baba 40's and 30's with the prop in a aperture are the very worse. That aperture seems to act like Cort nozzle and just direct the prop stream to one side making backing up a true adventure. .
Bingo that's like my boat. The size of the skeg is very, very substantial and the prop is encased in the skeg.

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The only solution to this, and it's a partial solution, that I have found is the Max Prop. The Max Prop has syemtrical blades. They are the same shape in reverse as they are in forward so they have far beter bite in reverse than the typical asymentrical prop. I did a lot or prop testing years ago and the Max Prop was the clear winner based upon it's low speed and backing performance.
Duly noted, thanks. I have a big fixed three blade--for now.

I can live with a boat that doesn't do backwards. I'm not a marina kind of guy anyhow.

I first fell in love with the idea of a skeg encased prop one day in Alaska. We were in bay that had no soundings. Totally uncharted. There was an underwater glacier moraine blocking the entrance. About a month previous, while listening over the shoulder of the intended audience, I memorized the advice of how to enter (local knowedge). We slipped through at high tide with about four feet under our keel through an otherwise unknown slot in the moraine. Once in, it was motoring by braille, i.e., no wind and glued to the depthfinder.

The bay was filled with bergy bits because it had a saltwater terminated glacier. I kept looking at the bergy bits and trying to estimate how much was underwater relative to how deep our prop was. There was no radio communication out of the bay, mountains blocked it, so we were completely on our own. My kids on board were 2 and 6 at the time, and the Coast Guard couldn't get into the bay anyhow on account of the moraine. If the prop hit some ice, we had some serious problems. So it was real exciting. I remember thinking, boy, just to turn the odds just a little more in our favor, I sure wish I had a skeg encased prop. Not perfect insurance, I knew, but every little bit helps.

So now I have one. If I screw up in the marina, that's a correctable problem and certainly far from life threating. But I intend to get back up to Alaska, where I'm sure I'll appreciate that skeg someday.
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