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  #51  
Old 02-14-2012
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Quote:
Originally Posted by tdw View Post
If it were financially possible I'd have that later model Malo (or Hallberg Rassey) in a flash and given the overall build quality of the beasts I have no doubt that the Malo spade would be stronger than many skeg hung rudders.

While I would never consider a deep fin/torpedo with leading edge exposed arrangement, improvements in underwater design allow us to have faster cruising boats that do not sacrifice their load carrying capacity. It may not seem much but that extra knot or two makes one hell of a difference on even a coastal passage and without doubt enhances the simple pleasure of the sailing.
Fuzzy,

I'm by no means an expert at sailboat designs, but looking at the above photo the first thing that comes to mind is both the prop and rudder could easily be susceptible to damage from something as small as a piece of driftwood, especially if the engine was running hard against the current. In my mind I can readily picture a partly submerged snag washing down the hull, being drawn into the prop, and jamming into the rudder hard enough from the engine's torque to blow the rudder and rip out the boat's bottom. I don't see this as a remote possibility with a full-keel boat and skeg mounted rudder. To me, it just seems like common sense, but maybe there's something I'm missing. And, of course, things like this don't happen when the weather's calm and conditions are ideal. For some unexplained reason, all of these incidences seem to occur during nasty storms and dangerous conditions.

Here's a photo of a friend's 32.5 Morgan which clearly shows it would be difficult to take out the rudder or prop even when hard aground.

Gary
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Last edited by travlineasy; 02-14-2012 at 07:12 PM.
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  #52  
Old 02-14-2012
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If you take advantage of the twin keel being more upright, thus each only having to be half the size of a single keel ,they have no more wetted surface than a long fin keel, and have far less wetted surface than a full length keel.
I hope to experiment with tip shapes, to eliminate the tip vortexes of twin keels. Shouldn't be too hard to accomplish.
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  #53  
Old 02-15-2012
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Between Jeff_H and my fellow barn-door-rudder brethren, I don't have much to add. As a relatively new skipper, I can't tell you how much tight marina's scare me. Jeff is bang on with his technical points above... but the original poster is a self-proclaimed newbie which perhaps gives me a more recent perspective since I've recently gone through the same question and discovery.

In my quest for a boat, I sailed on as many as I could. Three examples,
1) I sailed a Shark 24 numerous times ( http://www.shark24.org/membership/images/plan3.jpg ) which was passable but I didn't like the boat. Tacking was easy enough but required a little time to get through the wind.

2) I then had the opportunity to skipper a J24. This thing quickly and accurately pivoted around a central point. It tacked so quickly that I would often over shoot my intended angles. Quick, easy and I needed very little input to get it through the wind in a second.

3) I settled on my lovely little Contessa 26... a modified full keel with a keel hung rudder. Oh boy. If I though the shark was slow through the corners, the full-keel takes a loooong time. I won't be dicing it up in a match racing duel any time with my baby.

From a newbie perspective, the type of keel & rudder combination drastically affects the handling of the vessel. In a car metaphor, a fin keel is going to be more like a twitchy sports car that will respond to lesser steering inputs (to varying degrees of course) and will require greater attention to your course. A full keel will feel more like a limo... you plan your corners ahead of time and will be more forgiving to newbie-skipper steering input. We often lapse in our ability to sail in a steady course for long periods of time. :-)

As a newbie, a full keel seems easier to steer for long distance without the aid of autohelm, but is harder to dock, reverse and handle in tight quarters.

Another point that wasn't mentioned above is the turning radius. From my limited experience, I've found that the narrower the fin keel, the tighter the turning radius. The Farr 30 (Mumm 30) on which I sometimes race spins on a dime as does the J24. The Shark less so but still quite tight. My longer keeled Contessa likes a wide arc. I suspect this is primarily due to keel shape but I'll leave that as a homework exercise for Jeff_H to explain. ;-)
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  #54  
Old 02-15-2012
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I think you make a choice and with the choice comes a particular set of advantages and disadvantages. I also think that it is quite simplistic to say that full keels are this and fin keels are that. A lot depends on the quality of design of the particular boat, i.e there are some full keels that are very well-designed and some that are not. Same for fin keels, centerboarders, and bilge keelers. If I was a full keel person I could find full keel boats that were terrible to sail and fin keelers that I would love to sail.

I have a skeg-mounted rudder now but have had fins as well. On an earlier boat (S&S designed 29') I was amazed to see how little strength the skeg had when the rudder was removed. The strength of the unit was coming from the rudder shaft, not the skeg. The reason why the rudder was off, was that it had been broken when the boat came down onto the tip of the rudder (it went downward a bit from the skeg) on a sandbar at a harbor I should not have been trying to enter with waves as they were. The force tore the rudder blade away from the shaft which jammed the rudder againt the fairing that came down from the hull. If it has been a spade rudder, I suspect that the damage might have been similar although perhaps less tearing and more bending of the shaft.

Final point - the keel does not exist in isolation from the rest of the design. You can't buy an XYZ 34 with a long keel and the same boat with a modern fin - so what we are getting when we make a choice is the whole package of design choices and compromises.
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  #55  
Old 02-15-2012
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On the bluewater boards, they make it sound like if you aren't in a traditional full keeled boat 40' or better, you are suicidal to sail in anything larger than a 1 acre pond.

The number of fin keeled boats in transoceanic races somewhat belies that. The large number of small fin keelers in the Carribean also kinda belies that.

So I would say any respectable built sail boat thats not too big for your crew to handle, and that YOU can dock comfortably, will take you anywhere you are likely to go as long as you respect it's, and your limitations.

After all how many of us have rounded the capes in winter, or done a Northwest passage, or rounded Antartica?

I prefer sailing in tropical lattitudes outside of hurricane season. That makes it unlikely that I will see anything over a F8 in open water. Even more likely I will be running for the lee of the nearest landmass as soon as a storm is forming in the area, long before the waves build to dangerous levels.

Would a "bulletproof" ship be nice, well yes; but I probably wouldn't sail it as much as I would a light cheap production boat that is easy to dock.
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  #56  
Old 02-15-2012
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Capt Bill, some responses

Quote:
Originally Posted by CapnBilll View Post
On the bluewater boards, they make it sound like if you aren't in a traditional full keeled boat 40' or better, you are suicidal to sail in anything larger than a 1 acre pond.

The number of fin keeled boats in transoceanic races somewhat belies that. The large number of small fin keelers in the Carribean also kinda belies that.

So I would say any respectable built sail boat thats not too big for your crew to handle, and that YOU can dock comfortably, will take you anywhere you are likely to go as long as you respect it's, and your limitations.

After all how many of us have rounded the capes in winter, or done a Northwest passage, or rounded Antartica?

I prefer sailing in tropical lattitudes outside of hurricane season. That makes it unlikely that I will see anything over a F8 in open water. Even more likely I will be running for the lee of the nearest landmass as soon as a storm is forming in the area, long before the waves build to dangerous levels.

Would a "bulletproof" ship be nice, well yes; but I probably wouldn't sail it as much as I would a light cheap production boat that is easy to dock.
Some responses - based on our experiences
1. I think the bluewater board folks need to get out more. From what we see there are more fin-keeled (think Bob Perry, fairly conservative fins) boats that full-keeled boats (lets say attached rudder types).

2. Don't try to take too many conclusions based on trans-oceanic race boats. Their crews are different and so are their priorities 1) make it and 2) win - comfort or ease of handling are way down the list, if on it at all.

3. For extended cruising ease of docking is not much of a priority since you so rarely do it. We docked in Panama, Tahiti, and Australia on a trip from Florida to Australia.

4. You can get more than F8 in the tropics during the recommended time of the year. We got F10 SE of Tahiti.

5. We are circumnavigating Antarctica (and the North Pole too), but will never be closer than around 1800 nm (in South Africa), and it will be in summer, but I still have considerable trepidation about that part of the trip.
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  #57  
Old 02-15-2012
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My first boat had a long keel with rudder attached. She tacked on a dime , whether you wanted her to , or not.
My second boat, with a much longer keel, was not much better, and tacked much quicker than my current boat, with short twin keels. The difference was hull balance; hull shape.
Keel length had little effect on directional stability.
Some race boats, slow to tack, have been said to have 'Excess directional stability." That is due to hull shape, not keel length.
There is no such thing as "Excess directional stability" on an offshore cruising boat; the more the better.
You see fewer and fewer boats cruising offshore with full length keels. Even out there, they are increasingly rare.
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  #58  
Old 02-28-2012
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Quote:
Originally Posted by newbee View Post
We have sold our home and are looking for a liveaboard to learn on in Maine. Here is what we know about ourselves. We love being on the water, and are hardy souls who can share a small space for extended periods of time and keep our sense of humor. We bought a tiny little Hunter 21 last summer as our first "learning boat" and had a blast! We are starting the process of finding a boat in the 29-38 foot range with lots of headroom, a forgiving hull, and a reasonable learning curve. We have a budget of around 60,000$ All advice is welcome! Please chime in!!!!
So far we have considered A Sabre 38 with a fin keel, and any Island Packet between 29 and 32 feet. The bigger IP's are out of our financial reach. The Sabre is a BEAUTIFUL boat, but with our limited experience more than we can handle?
Thanks,
newbee
Hi newbee,
You should post this question as a new thread, rather than in a this unrelated thread. You'll likely get more exposure and more advice that way. Perhaps the mods can help separate the last few posts into a new thread for you?
Cheers,
J.
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  #59  
Old 02-28-2012
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The Hobby Horse action while even at a mooring is one disadvantage on some full keel boats. I was a Bay Host a reasonably protected bay (Leinster Bay, St John USVI), a year or so back, when a Ferry Boat passing a quarter mile away caused one boat to hobby so bad it cause some injury to two occupants who were not expecting it. The major problem is the boat continued to hobby horse well after all other boats were totally stable again... actually for probably 2 full minutes.

I responded to a cry for help and was some 70 yards away and by the time I deployed my dink and arrived some 3 min later I was just able to board the boat which was still having Hobby Horse movements. The two had minor bruises and one a cut to the head from hitting something when thrown down in the cabin. Nether wanted / would allow medical assistance to be called but did show bruises for several days.

Most other boats in the harbour were fin keel boats and Cats but at least one other appeared to be a 3/4 keel but was further up in the bay and did not suffer any significant disturbance.

I've seen many full keel boats similarly effected by swells of a short duration that seem to trip the hobby horse effect. often causing the bow sprints to go under water and most of the Rudders to be exposed while adjacent fin keel and cats had only a minor effect. It would have been Very difficult/ dangerous to effect any forward deck work during these events.

All boats have good and some not so good responses to specific weather/ sea conditions, you can only go with what you feel is best for your type and location of cruising and be prepared for what comes.
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  #60  
Old 02-29-2012
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Quote:
Originally Posted by utchuckd View Post
Can somebody pro/con a full vs. fin keel for a newbie (will learn to sail on said boat) and taking it thru the Caribbean? All I can seem to come up with so far is fin keel is better to the wind, and a full keel will protect your rudder.
Probably the single most important reason why full keel boats are considered blue water has been discussed for over a hundred years, but interestingly enough not yet pointed out on this thread thus far.

Below is a picture taken from the book "Yacht Architecture" written in 1897. Notice that they were quite familiar with fin keels and bulb ballast as they describe in this book. Contrary to popular belief, a very old design.

What they knew back one hundred years ago was that hull form can create a significant amount of righting moment. And these two hulls create radically different hull righting moments. The flat bottom bulb keel creates considerably more hull righting moment than the full keel design because it has a flatter bottom.

So the full keel design is given more ballast. The ratio of ballast righting moment to hull righting moment is much higher in the full keel boat. This causes the full keel boat to be considerably more friendly in rough water. The reason is that the full keel tends to remain upright on waves, yet the flat bottom boat tends to heel with the wave angle.

And as we all know a full keel boat is more comfortable in rough seas. That is well documented in hundreds of years of Yacht design. So if you really want to put a number on "Blue Water", you should look at the ratio of mass righting moment to hull righting moment. The full keel by its very design forces a high ratio.
Bryce
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Last edited by BryceGTX; 02-29-2012 at 01:16 AM.
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