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View Poll Results: FULL or FIN
Full Keel 67 67.00%
Fin Keel 33 33.00%
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Old 14-01-2008, 08:04   #1
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FULL verses FIN

In terms of crossing oceans, which is safer/better? a full keel or a fin?

Is there any credit in the idea that a fin keel will get you there faster, so you have less chance to be caught in a storm? or that you could out run a storm?

does a full keel provide enough extra saftey to be worth the sacrifice in preformance that you would gain in using a fin keel?
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Old 14-01-2008, 09:36   #2
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The open ocean is the least likely place one will lose their yacht. It is groundings, reefs and land in general that are the things to worry about. The ability to manuever is the most important.

The vast majority of cruisers sail fin keeled boats. The belief that full keels are safer is a bad hangover from the past.
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Old 14-01-2008, 10:13   #3
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There was a big discussion on keels in this thread that might be of interest... http://www.cruisersforum.com/forums/...ard-10109.html
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Old 14-01-2008, 10:28   #4
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The vast majority of cruisers sail fin keeled boats.
Ken, with all due respect, you seem to be making many blanket statements in your replies that I just can not agree with. And certainly this statement.
I do agree with your opening statment however. But the last sentance of that, are you also suggesting that a full keel means you have poor manuverability??

The one thing I love about my full keel boat is, I don't get pushed around like the flat bottom fins in the marina when berthing and having a side wind. When I sail, I don't get pushed sideway's the same either. And I can spin the boat within the boats axis when manuevering with engine power. Maybe I turn through a tack slightly slower, but being single handed or just the two of us, I don't want to tack any faster anyway.
OK, my view and maybe it is just my view, but I truely don't believe you can outrun weather. Unless it is perhaps a tropical cyclone. These tend to be small in physcial area they take up, rather than a larger frontal system. But you still have to know with plenty of advanced information of it's path so as you can make adjustments. Maybe you can put a further 20-50miles a day between a fin and a full keel, but un less you are a round the would racing boat, the difference is not that big and most of the time, will not get you out of a weather system.
Sure there are advantages and disadvantages to fin and full in their sailing ability and handling.
We did a lot of research before buying our boat. And had the wonderful fortune of talking to a couple that were caught in the 95..? storm that caught many sailing from NZ upto the Islands. What we found was, the majority of boats that sailed right on through were full keel boats. Several of them were FC, but I don't think the fact of them being FC was the reason. I am sure there must have been some Fin Keelers that made it to. But the comment I got was that in major sea's and wind, it is hard to slow the Fins down and keep them comfortable. So it is imperitive that you tow drogues and sea anchors. I want to make clear here, this is not my experiance as I don't have open ocean experiance yet, it is what I was told by the couple who went through it.
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Old 14-01-2008, 10:33   #5
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Originally Posted by chad.lawie View Post
In terms of crossing oceans, which is safer/better? a full keel or a fin?

Is there any credit in the idea that a fin keel will get you there faster, so you have less chance to be caught in a storm? or that you could out run a storm?

does a full keel provide enough extra saftey to be worth the sacrifice in preformance that you would gain in using a fin keel?
Losing a rudder at sea is a consideration. It may be a small possibility but if it happens to you, the statistics matter little.

I think that your real consideration should be spade rudder vs hung rudder. Some fin keel boats have substantial skegs that help support the rudder well and also allow the vessel to track better.

The stresses placed on the rudder durring long ocean passages are tremendous. Running downwind is where I find the big difference in full vs fin keel. I have done many deliveries on both type vessels. I find that full (and modified full) keel boats track far better than fin keel boats. In fact, in big following seas, fin keel boats keep me a little on edge. I think that a fin keel (spade rudder) vessel is far more likely to broach than a full or modified keel.

I think that getting to the other side safely and comfortably is far more importand than speed. Although, speed does limit your exposure. I don't think that a fin keel boat is necessarily faster than a full keel boats in long ocean passages. They may be faster on the race course but cruising is not racing. Getting there safely is far more important than getting there fast.
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Old 14-01-2008, 11:22   #6
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Full keel boats are safer everywhere, especially close to hard objects. Running a full keel boat aground vs a fin keel is much less likely to do any real damage. The fin keeler just may dislodge his keel and/or unprotected rudder. Rudder mounted on a skeg? the skeg bends jamming the rudder. The protection that most full keel boats provide for the rudder is not to be under estimated. Full keel boats are not inherently slow. I just spent Sat sailing in 20+ and there was NO 30' Catalina that could keep up. Up wind or off. Three tried... And my boat is only 19' on the waterline! I had a double reef main and the 130 headsail reefed to 100%. What else can I say?? Ever sail upwind in a good seaway in a flatbottom fin keeler? I have and the pounding wasn't nice. This was a Hunter 34. I take my little full keel Cape Dory 25D out in the same conditions and guess what, no pounding. Wet as hell, but that's why I have a dodger. I hide under it and watch the spray pass overhead! .. Having a tiller, I can sit and steer from under the dodger.
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Old 14-01-2008, 11:30   #7
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Having a centre boarder that has done serious ocean sailing, (built in France now in New Zealand via Alaska) says something for its ability to cope. It does have a shallow full keel with a transom hung rudder, when manoevering I drop the main centre board either partially or completely depending on the depth, she turns wherever I want her to go, probably the same as a fin. Serious wind can undo the plan until you can get up to speed, otherwise the main board is only used on the wind, the aft one is used when running down wind. although I have experimented with both boards in varying sailing situations.
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Old 14-01-2008, 11:35   #8
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Delmarrey said it all:

"There was a big discussion on keels in this thread that might be of interest... Center board vs keel vs twin keel vs twin centerboard"

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Old 14-01-2008, 12:48   #9
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If you were to group all the sailboats made in the last 30 years together, you'll notice that the "blue water" boats have long, full(ish) keels, and lots of ballast way down at the bottom. Club racers and weekend coastal boats have fin keels with much less ballast relative to their sail area and length.

Damage to a full keel and protected rudder is almost unheard of. And if you do sustain damage, it would have been about 100x worse if you had a fin keel / independent rudder.

If you already have a fin keel, chalk it up to one of those items you wish you didn't have, and learn to live with it. Every boat has some things you would otherwise do differently, and the keel and rudder are no exception. There are plenty of people who are making do just fine with fin keels, but if you had an option and all other things are equal, in my opinion you would be foolish to not select a full(ish) keel, if you are intending to do a lot of heavy weather operations.

One thing I haven't seen anyone mention yet is heaving to, which (from my experience) is quite easy on a full keel, and essentially impossible on a fin. In fact, I have two videos on heavy weather sailing. One, by Rasmussen(spelling is off), discusses heaving to. Another, based on fin keel boats, totally writes off the idea of heaving to, and focuses on running off.

So beyond the integrity of your hull and rudder, there are noticeable differences related to safety and manuevering based on your keel design.
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Old 14-01-2008, 14:01   #10
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I have a full keel. I've never considered anything else. that big full keel has always made me feel safe. Can anything be said about how the full keel disperses the weight more evenly about the boat? as opposed to a fin keel putting a lot of weight in a smaller area, stressing the hull more?


I had never considered heaving to being an issue with the different designes... it would be interesting to hear more about that from people with experience.

I will check out that other post about keels. I hadn't seen that!
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Old 14-01-2008, 14:19   #11
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Here's an article written by one of our members Jeff H

It's a good read with lots of good info.

First of all your question seems to be about appendages. In principle Appendages keep a boat from making leeway. They come in many shapes and sizes. Keels are supposed to be a fixed appendage and centerboards generically are moveable appendages that occur on the centerline but centerboards are just one kind of moveable appendage. In more detail:

Keels:
The earliest form of a keel was simply the backbone of the boat extending through the bottom planking. (Like a Viking ship) That works OK with running and reaching sails but when you try to point toward the wind you slip side wards at great speed. As sails and rigs were invented that allowed boats to point toward the wind the keel was extended below the boat either by planking the hull down to a deeper backbone or by adding dead wood (solid timber below the backbone. A planked down keel permitted the space between the planking to be filled with heavy material (originally stone), which served as ballast keeping the boat from heeling. After a while it was discovered that there were advantages to bolting a high-density cast metal ballast to the outside of the deadwood and interior ballast dropped out of fashion.

Full keels:
These earliest keels pretty much ran from the point of entry at the bow, to the aft most point of exit at the stern. Those are full keels in the fullest sense of the word.

They have some advantages; they theoretically form a long straight plane, which keeps a boat on course better (greater directional or longitudinal stability). If you run aground they spread out the load over a larger area reducing the likelihood of damage. Once really planted they keep the boat from tipping over fore and aft. They are easier to haul and work on. You can spread out the ballast over a longer distance and so they can be shallower for the same stability. You have a greater length to bolt on ballast so it is a theoretically sturdier and simpler connection.

They have some disadvantages; a larger portion of the keel operates near the surface and near the intersection of the hull and keel, which are both turbulent zones. They also have comparatively small leading edges, and the leading edge is the primary generator of lift preventing sideslip. Because of that they need a lot more surface area to generate the same lift. Surface area equates to drag so they need more sail area to achieve the same speed. Long keels tend to be less efficient in terms of lift to drag for other reasons as well. As a boat makes leeway water slips off of the high-pressure side of the keel to the low-pressure side of the keel and creates a turbulent swirl know as a tip vortex. This is drawn behind the boat creating drag in a number of ways. The longer the keel, the bigger the vortex, the greater the drag. So they need more sail area again to overcome this drag. To stand up to this greater sail area the boat needs more ballast and a stronger structure, which is why long keelboats are often heavier, as well. (Of course, then the spiral starts again as more sail area is needed to overcome that additional weight as well. It is the classic weight breeding more weight design cycle) Full keels tend to be much less maneuverable.

Fin keels:
By the classic definition of a fin keel any keel whose bottom is less than 50% of the length of the boat is a fin keel. Fin keels came into being in an effort to reduce drag. Cut away the forefoot or rake the stem, as well as, move the rudderpost forward and rake it sharply and pretty soon you have a fin keel. Today we assume that fin keels mean a separated rudder (skeg hung or spade) but in fact early fin keels had the rudder attached in a worst of all worlds situation. They offer all of the disadvantages of both full and fin keels, but with none of the virtues. Unknowing or unscrupulous brokers will often refer to boats with fin (or near fin) keels as full keel if they have an attached rudder.

Fin keels with separate rudders seem to be the most commonly produced keel form in the US these days. (I could be wrong, there is a resurgence of full keels these days)

Fin keels have some advantages as well. They have less drag as explained above so they typically make less leeway and go faster. You can get the ballast down lower so in theory they are more stable for their weight. They are more maneuverable. They take better advantage of the high efficiency of modern sail plans and materials.

They have some disadvantages as well, many of these have been offset or worked around by modern technology but at some level they are still accurate critiques. They have less directional stability than long keel boats so the tend to wander more under sail. Since directional stability is also a product of the dynamic balance between the sail plan and underbody, in practice they may actually hold a course as well as a full keel. In general though you can expect to make more course adjustments with a fin keel. It is sometimes argued that the lower helm loads requires less energy to make these corrections so a fin keel may also require less energy to maintain course. This I think is a product of the individual boat and could lead to a debate harder to prove than the number of angels that can dance on the head of a pin.

Fin keels are harder to engineer to withstand a hard grounding and when aground they are more likely to flop over on their bow or stern. (Although in 37 years of sailing, I have never heard of anyone actually experiencing this.) Fins typically have deeper draft. They are easier to pivot around and get off in a simple grounding.

Shoal keel
A shoal keel is just a keel that is not as deep as a deep keel. Today the term seems to be applied mostly to shallow fin keels. Shallow full keels seem to be referred to as shoal draft boats. A shallow fin is a tough animal to classify. Like a fin keel with an attached rudder, I really think it has few of the advantages of either a deep fin or a full keel and has many of the worst traits of both full and fin. This can be partially offset by combining a shallow fin with a centerboard, which is a neat set up for shoal draft cruising.

Bulb Keel:
A lot can be done to improve a shallow fin. One way is to add a bulb. A bulb is a cast metal ballast attachment added to the bottom of the keel. They concentrate the ballast lower providing greater stability and sail carrying ability than a simple shallow keel. Traditionally bulbs were torpedo or teardrop shaped. They have been re-contoured to provide some hydrodynamic properties. Recalling the discussion on tip vortex from above. Shallow keels need to be longer horizontally than a deeper fin in order to get enough area to prevent leeway. This means that a shallow longer fin would generate more tip vortex and more drag than a deeper keel. The bulb creates a surface to turn the water aft and prevent it from slipping over the tip of the keel thereby reducing tip vortex. This does not come free since a bulb increases frontal area and surface area.

Wing keels
Wing keels are a specialized type of bulb keel. Instead of a torpedo shaped bulb there are small lead wings more or less perpendicular to the keel. These concentrate weight lower like a bulb and properly designed they also are very efficient in reducing tip vortex. There has been some discussion that wings increase the effective span of the keel when heeled over but this does not seem to be born out in tank testing of the short wings currently being used in production sailboats. Not all wings are created equal. They potentially offer a lot of advantages, but they are heavily dependent on the quality of the design and I really think that many wing designs are not really working to their potential.

Then there is the whole grounding issue. In 2002, the Naval Academy did a study of keel types and grounding. They found that the popular perception that wing keels are harder to free is accurate. In their study, wing keels were extremely harder to free. Straight fins were much easier to free, especially when heeled, and the easiest keel to free was the bulb keel.

Keels that are not really keels:
Swing keels are ballasted centerboards and drop keels are ballasted daggerboards that are ballasted beyond what it takes to submerge themselves. They are really forms of centerboards. More on these in the discussion on centerboards.

Keels that are keels that move.
I said in the introduction that keels do not move. That used to be true. We now have canting keels, which can be pivoted from side to side. They are best designed to be light fins with heavy bulbs that can be canted to windward increasing the effectiveness of the righting aspects of the keel. Just one problem, a keel canted to windward losses efficiency to prevent leeway so they really need other foils to keep leeway in check. I frankly do not like the idea of a canting keel. I think canting keels are too complex and potentially problematic.

Centerboards:
Centerboards are appendages that can be raised and lowered on or near the centerline of the boat. They can rotate up into a trunk or rotate below the boat. Daggerboards are a type of centerboard that raises vertically or near vertically in a trunk. Swing keels are a type of rotating centerboard that actually contains a substantial portion of the boat’s ballast. They may be housed in a trunk like a Tartan 27 or 34 or hung below the boat like a Catalina 22. In the case of the Tartan 27 or 34 they are more frequently referred to as a Keel/ Centerboard (abbreviated k/cb). A swing keel is intended to act as a fin keel when lowered and allow some sailing in the partially raised position. My biggest problem with swing keels is that most do not have a positive lock down. In an extreme knockdown they can slam up into the hull greatly reducing the boat’s stability. This is a pretty rare occurrence and usually requires big wave action combined with a lot of wind, but I have experienced it out in the Atlantic.

A drop keel is a daggerboard that actually contains a substantial portion of the boat’s ballast. These are easier to lock down but can be more easily damaged in a grounding. They generally have better shape than a swing keel and can be more robust, but not always are.

Other appendages: (besides the rudders)
Bilge keels (or twin keels for our English friends) are a pair of keels (usually fins these days) that emerge on either side of the boat and angle out. They offer some advantages. If you let the boat dry out the boat can stand on the two keels and wait the next tide. There are dubious theories about increased efficiency since one is vertical like a good leeway resisting foil and one is canted like a good stability inducing foil. With computer modeling there has been greater success in approaching that theory on large bilge keel boats. While bilge keels do allow shallow draft though, they extremely difficult to free once aground since having the two keels on the ground prevents heeling the boat to get free. In practice bilge keels have enormous wetted surface creating a lot of drag at lower speeds, and produce two very large tip vortexes creating a lot of drag at speed.

Keel Centerboards are a wonderful choice for coastal and offshore cruising. Properly designed they offer nearly the performance of a fin keel, and yet permit access to shallower venues. They can be partially raised to precisely control the center of lateral resistance and therefore offers the ability to have a very neutral helm and great tracking in a wide range of conditions. Properly constructed they have proven to have a long service life. Keel-centerboard boats really proved themselves offshore during the late 1950’s and into 1960’s.They fell out of popularity with the advent of the wing keel in the early 1980’s. The downside is that they are a little harder to maintain, and because the ballast is closer to the center of buoyancy they require more ballast and so end up requiring a higher overall displacement, a higher ballast to displacement ratio, or are more tender, or some combination of the three.

Bilge boards (for the scow guys), are a pair of centerboards that angle out of each side of the boat. They work well on scows but I’ve never been able to really figure out scows anyway. Seriously, You raise the windward board and lower the Leeward one on each tack and because they are close to vertical they can be small and efficient. I still don’t get the scow thing.

Last but not least- Leeboards. Leeboards are foils that are bolted to the side of the hull like on Dutch Jachts and Herreshoff Meadowlarks. Phil Bolger’s sharpies use them a lot as well. They have some advantages but they drive me nuts. They are vulnerable in docking and ideally are raised and lowered on each tack also. Some are raised to be hinged feather so they do not need to be raised.
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Old 14-01-2008, 14:24   #12
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Please read Jimmy Cornell's World Cruising Survey. That vast majority of cruising boats have fin keels.

Heaving to is very easy with a fin keel. I have done it several times.

The potential for rudder damage is not reduced with a full keel. Dashew covers this in depth. If you do suffer a grounding in a full keel boat, the chance of getting free is much smaller than a fin keel due to surface area & friction.

The most dangerous part of any sailing anventure is when the boat gets close to land. The ability to easily manuever at slow speeds is a huge advantage.

As for being safer under way, this is a relic of history. The argument that a full keel is more stable is more often offset by its slow response. A full keeled boat is much more likely than a fin keeled boat to roll than recover its course.

What used to be the accepted truth has been refuted by science and experience.
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Old 14-01-2008, 15:01   #13
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I am sorry, but the fact you give are completely wrong. Please read Jimmy Cornell's World Cruising Survey. That vast majority of cruising boats have fin keels. .
Hang on Ken, Jimmy Cornell's 2 editions of World cruising Survey only cover the boats (the ones that responded) in his own 2 round the world rallys. I have read the first book and really only remember about 10 respondants.
His rallys are quite expensive and take just the most cashed up echelon of cruisers often with new Swans or Oysters. I had the impression there were very few 'standard cruising boats' if theres such a thing LOL

His current outting with World Arc Welcome to World Cruising Club: World Arc will again be similar with the boats listed here Entry List for World Cruising Club: World Arc showing that they are not your average gunkholers
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Old 14-01-2008, 15:01   #14
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you did not mention the modified full keel which has a protected skeg rudder. also the keels can be molded into the body or bolted on .. there's a difference.
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Old 14-01-2008, 18:51   #15
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Ken, with all due respect, you seem to be making many blanket statements in your replies that I just can not agree with. And certainly this statement.
I do agree with your opening statment however. But the last sentance of that, are you also suggesting that a full keel means you have poor manuverability??

The one thing I love about my full keel boat is, I don't get pushed around like the flat bottom fins in the marina when berthing and having a side wind. When I sail, I don't get pushed sideway's the same either. And I can spin the boat within the boats axis when manuevering with engine power. Maybe I turn through a tack slightly slower, but being single handed or just the two of us, I don't want to tack any faster anyway.
OK, my view and maybe it is just my view, but I truely don't believe you can outrun weather. Unless it is perhaps a tropical cyclone. These tend to be small in physcial area they take up, rather than a larger frontal system. But you still have to know with plenty of advanced information of it's path so as you can make adjustments. Maybe you can put a further 20-50miles a day between a fin and a full keel, but un less you are a round the would racing boat, the difference is not that big and most of the time, will not get you out of a weather system.
Sure there are advantages and disadvantages to fin and full in their sailing ability and handling.
I agree with this 100% having owned both fin and full. I would much rather manuever a full keel boat then a fin keel especially in a cross wind. (along with the other afformentioned attributes.)
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