Fin Keel vs. Full Keel

[Rayallyn]

I have been looking and researching many boats Morgans included. I was going to take a trip down to New Orleans and check out a Triton
28 ft. pearson triton sailboat
But with the cheapest airfare of $718.00 round trip forget it. I did not expect to find it worth investing but was thought it was worth a shot until I saw the airfare.
Just got a reply from a guy who has a Columbia 68 I was interested in the price just jumped up because of the season. He is now trying to sell me a Bayliner Buccaneer 24 at a good price. I can afford that and maybe name it,"topsy Turtle"

[speedoo]

Are you in New England? I don't think you need to go very far to find a boat. Here's a nice clean looking Ericson 29 on ebay in Massachusetts:

eBay Motors: 1974 Ericson 29' Used Sailboat - MA (item 360152725475 end time May-09-09 15:00:00 PDT)

It's being sold by a charity at auction so it can probably be bought pretty cheap. Do a search on ebay and you'll find lots of boats.

[Rayallyn]

Yes I have been watching her and a few others on ebay. Seems my bids are always out bid by $10.00 to $100.00 dollars even when I bit within the last minute. I think some people have a program to automatically bit or something. Anyway now that the season has started there is a lot more bidding and people willing to pay more then I think or want to risk. I'll just keep putting more money away and selling off what I do not want or need on a boat and someday my ship will come in. I just recently made a couple of offers on two boats but it seems what I am getting back is the boat is worth more now then a month ago because it's boating season.

Thanks for link anyway I appreciate it.

Ray

[speedoo]

Ray... did you see the Pearson Triton on ebay? I think it's in Maryland.

eBay Motors: PEARSON 28 TRITON /ATOMIC 4 (item 260403962846 end time May-10-09 04:27:20 PDT)

[keelbolts]

A full keel boat doesn't necessarily have more wetted surface. My boat, Favona, has a full keel with a 6' draft on a 24' waterline. A friend of mine had a C&C 32 with a swing keel and we used the same amount of bottom paint. Not a scientific study, granted, but useful to know. It's easy to see that a full keel boat would have more wetted surface than a fin keel if the only difference is the keel, but it's not so clear when comparing a narrow wine glass, full keel and a beamy fin keeler.

On the subject of windward ability, I can't imagine conditions in which a fin keel could out perform a full keel to windward. Running down wind - sure, but to windward - never. Going to windward is all about using resistance to lateral motion to create forward motion. It's, in a great part, about square footage of lateral surface. I have sailed fin keelers that pointed pretty high. The problem was they wouldn't go there. A fin keel, with its separate rudder isn't going to create lift. a keel hung rudder with a little weather helm does create a foil shape that provides some lift. I don't believe you get a lot of lift out of either one.

In the 20 some years I've owned Favona, I have never been beat to windward.

[speedoo]

Originally Posted by keelbolts

A full keel boat doesn't necessarily have more wetted surface. My boat, Favona, has a full keel with a 6' draft on a 24' waterline. A friend of mine had a C&C 32 with a swing keel and we used the same amount of bottom paint. Not a scientific study, granted, but useful to know. It's easy to see that a full keel boat would have more wetted surface than a fin keel if the only difference is the keel, but it's not so clear when comparing a narrow wine glass, full keel and a beamy fin keeler.

On the subject of windward ability, I can't imagine conditions in which a fin keel could out perform a full keel to windward. Running down wind - sure, but to windward - never. Going to windward is all about using resistance to lateral motion to create forward motion. It's, in a great part, about square footage of lateral surface. I have sailed fin keelers that pointed pretty high. The problem was they wouldn't go there. A fin keel, with its separate rudder isn't going to create lift. a keel hung rudder with a little weather helm does create a foil shape that provides some lift. I don't believe you get a lot of lift out of either one.

In the 20 some years I've owned Favona, I have never been beat to windward.

Look, I'm not going to knock full keel boats, but if they truly were better to windward, why do all racing-designed boats sport deep fin keels with deep spade rudders? I think it is very well established that if you want a boat that points high, give it a deep fin keel with an appropriate shape, maybe a bulb at the bottom for additional stiffness, a spade rudder and a tall rig.

[keelbolts]

I was talking about windward performance only and the racers can't count on always going to windward. I'm not an expert on keel design, but I guess that, given an equal area, a deep fin keel would do fine. Remember, it's about square feet. A 6 foot fin keel will never beat a 6 foot full keel to windward. It's quite possible that a 12 foot fin keel might.

In any case, Rayallyn is looking for a cruiser and I think a full keel with an attached rudder is very simple and reliable - good attributes for a short-handed cruiser. Also, their motion is much more seakindly - another excellent attribute for a boat you're planning on being on for extended periods.

The full v. fin keel debate will probably rage on for as long as there are sailboats. I've done a good deal of reading on the subject, but, do to my swiss cheese-like memory, I'm mostly relying on experience here. I've owned and sailed a classic boat for years and I've sailed on fellow classic boat types' boats and friends with more modern designs and there's no question, in my mind, and most of theirs, that the full keel is superior in most ways.

Remember, too, that the fin keel/spade rudder boats regularly get spanked when the weather turns nasty. For one thing, most of them can't heave to.

I don't have a blanket dislike of all fin keels, my new boat has two of them.

[Southern Star]

Speedo is correct - a properly designed fin keel will actually create lift and hence, improve your ability to point. That being said, full keel boats are often far better balanced. With proper sail trim, my old Folkboat and Alberg 30 could be sailed to windward without touching the helm in virtually any conditions - heading up in the puffs and off in the lulls with such perfection one would have thought that the Flying Dutchman was at the helm.

Rayallyn, in the price range that you are looking at I wouldn't worry about fin versus full keel. I would try to find the biggest boat I could afford that has a reputation for a good design and solid construction; I would look for one that has good rigging/sails and is in good structural/mechanical condition, and pay little attention to cosmetics, electronics and 'extras'.

When you find something in your price range that interests you, ask boat-specific questions on this site: there are past/present owners of most makes and models here and, if not, at least recommendations from those who had some familiarity with a particular boat, or the ability to point you in right direction. Good luck in your search and in your new life!

Brad

[keelbolts]

I'm going to have to look that up. I worked on and flew aircraft for several years so I think in those terms when thinking of foil shapes and lift. You can't get lift out of a symmetrically shaped airfoil so why would you get lift form a symmetrically shaped keel. It might hold you up to windward, but a foil that would create lift on one tack would not be able to do so on the other. Am I missing something here? I'll look it up & report back.

I had a Folkboat. What a sweetheart. Twenty years later, I still wonder if I shouldn't have kept her.


I think I found out what I'm missing. I found a tutorial on keel design and I note that they show diagrams, I don't remember what we called them in structures classes back in school, that indicate lift forces at the keel, but that lift is apparently dependent on the keel's meeting the water at an angle. That's not what I understand as lift. If I stick my hand out the car window and angle it slightly it will rise, but my hand hasn't created any "lift", it was simply blown up by the wind. An airplane wing creates real lift, with the wind straight on it, by treating the wind that passes over and under it in different ways. Using the nautical definition of "lift," the front door to my house would create lift if shoved thru the water at an angle.

[Amgine]

Lift is the sum of forces which results in a force perpendicular to the oncoming flow. This is true in aerodynamics and keels.

[Fishman_Tx]

Originally Posted by speedoo

Ray... did you see the Pearson Triton on ebay? I think it's in Maryland.

eBay Motors: PEARSON 28 TRITON /ATOMIC 4 (item 260403962846 end time May-10-09 04:27:20 PDT)

yep eBay's a good place to watch. We bought a '73 Bristol 34 for $5700. She's got the modified keel (3/4?). Needs minor work, but couldn't beat it.

[bob perry]

Keelbolts:
Your boat makes leeway on the wind and reaching. This creates an angle of attack for the foil and that's where the lift comes from despite the foil being symetrical.

[speedoo]

Originally Posted by bob perry

Keelbolts:
Your boat makes leeway on the wind and reaching. This creates an angle of attack for the foil and that's where the lift comes from despite the foil being symetrical.

Thank you Bob. I've heard/read this explained before but never so concisely and easily understandable. And this also helps me understand why deep keels provide more lift and hence help a boat point higher.

[keelbolts]

I'm nowhere near stupid enough to argue with you about keel design, so anything I say here is about clarification for me. I can see how water working on the keel at an angle would lift the keel, in the same way that when I stick my hand out of the car window it is blown up or down. I think my confusion is founded in semantics. An aircraft wing, buy its asymmetrical shape, creates lift while a boat keel is lifted? Did I get that right?

[bob perry]

Keeel:
I'm not sure.
Think of it like this: Going downwind when you are making zero degrees of leeway there is no lift on the keel. The moment you head the boat up and begin to put a sideways wind force on the boat the boat will begin to make leeway. It's this angle of leeway that creates the angle of attack on the keel and provides the left. It's exactly the same as when you have your hand out the window and you tilt the forward part of your hand up. You have created the angle of attack. Asymetrical foils do work better but you need two ( one for each tack) and they need to go up and down. Yes, you are correct, the asym aircraft winf foil creates lift thru it's geometry and not it's angle of attack. The shape of the foil provides the angle of attack.