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Old 07-04-2010, 05:21   #31
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Originally Posted by forsailbyowner View Post
Dockhead, argue all you want you won't change my mind. I've sailed bulb keels, they suck downwind. No advantages to modified full keel? what about downwind tracking, protected rudder and prop. Shallow draft 3'11" no keelbolts, ability to stand on keel to work on avoiding yard fees. Upon grounding spins around and motors out 90% of time.

I sail more than 90% OF time when offshore(not bays ICW or rivers). If winds are on nose I wait. Let me guess your pig was a thirty something boat your comparing to a 54 ft boat. Maybe you needed new sails or trimming experience on your semi full keel pig, my boat performs just fine as long as I keep the keel down and point no closer than 50deg.
Well, it's your choice and a matter of taste and style, so I'm not arguing with anyone. Glad you like your boat. To each his own!

But don't confuse keel type with bottom type. They're different things. A light displacement cruiser-racer with an almost completely flat bottom will pound, and will have some problems downwind, but that's because of the bottom, not the keel.

A cruising boat needs some depth in the forefoot and some profile to the hull, which does cost some speed but gives a comfortable motion and better tracking. There is no contradiction between this and an efficient bulb keel. Our boat is great downwind -- easily driven yet tracks like a freight train. The autopilot easily deals with following seas.

Naturally, our new boat and old boat are comparing apples to oranges -- the old one a 38 footer from the early '80s, and the new one a 54 footer 20 years more modern. A lot of the difference is down to that; you are right there of course.

But it sounds like our old boat pointed like yours -- well-trimmed it would go decently to 50 degrees apparent; 45 was already starting to pinch a little and worse VMG to windward. That means that with leeway and difference between true and apparent wind we could not realistically tack through better than 110 degrees on the GPS in ideal conditions; usually more like 120 or even 130 degrees. The sheer geometry of that makes it really not realistic to make progress to a destination approximately upwind. So we motored a lot. It felt a bit like having a square-rigged ship. If you are sailing in tradewinds, this may not apply to you. We have not done any tradewind sailing yet, so just mathematically we have a 50% chance on any given passage of having the true wind ahead of the beam which means apparent wind (depending on speed) 70 or 60 degrees or closer which means pointing or a close reach.

Even in our boat in the best case we cannot sail at all in 50% of possible courses when the true wind is ahead of the beam, so for at best 25% of possible courses we have to tack (realistically it's more). The numbers rapidly deteriorate from there, the less you can approach a true 45% course to the true wind.

The other thing was that the large wetted surface of the long keel hull meant that the boat would not be driven in light winds. Downwind in less than say 6 or 7 knots of wind you just couldn't make any progress. Even putting a spinnaker up would make little difference. On with the "iron gennie", yet again, adding a whole other set of circumstances where we couldn't sail.

The new boat is a totally difference experience. Yes, of course, the size plays a big role. The new boat is 46 feet at the waterline; obviously that's a different ball game from what we used to have. But we point to 30 -- 35 degrees apparent even in less than ideal conditions -- even in 30+ knots with only the staysail up which can't really be trimmed very well. We tack through 90 -- 95 degrees on the GPS. The geometrical difference is huge. It means instead of giving up and rolling the sails in and cranking up the engine, we can usually tack to our destination.

The easily driven hull also makes it easier to tack. The boat just goes and goes; we hardly lose a knot of speed while tacking. That translates also to more sailing -- tacking to a destination upwind is a pleasant, rhythmic process without the hassle we used to have, the battle to keep up momentum, and the ever-present risk of getting into irons in light wind.

To each his own -- my own, in this case, is wanting to have the performance benefits of modern keels, even on a cruising boat.
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Old 07-04-2010, 14:05   #32
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the way that i chose a boat was to firstly look at my sailing area,it became apparent very quickly that a boat with a draught of greater than 5ft would be a liability,so that narrowed my choices down to either bilge or lifting keel,i would however consider a wind keeler with beaching legs, for our good friends who are not familiar with beaching legs,then they are generally removable telescopic aluminium poles that attach at reinforced areas and hold the boat in an up right position on the beach.

if i was going to do a tour of the UK i would go for something like a trident challenger or a trident voyager and fit them with beaching legs,they are long keelers with a draught of 5ft or a wing keel boat and do the same,lifing keels also have my attention,if i could afford one id get a Kirie Feeling or if the lottery came up an Ovni,there are also other manufacturers of lifting keels but Kirie has been making them for a long time.


If your boat can take the beach,its a real bonus,you can park her up far away from the mad crowd and sleep without bouncing around.(not to be done on strong onshore winds with big swells)
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Old 07-04-2010, 14:39   #33
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Quote:
Originally Posted by forsailbyowner View Post
I chose a modified full keel. My reasons are ; no keel bolts and associated high load areas associated with such, no worries of crevice corrosion of keel bolts, ability to stand on keel for maintenance outside boatyard, protected rudder and prop, simple shafting, bearing configuration, tracking ability downwind and in rough seas. Have seen quite a few people fixing delamination of hull and surrounding structure along with the keel to hull joint. I feel much more secure knowing mine is an integral molded in part of the boat that acts as a backbone instead of a vulnerable appendage.
What boat models have modified full keels?
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Old 07-04-2010, 17:45   #34
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The truth is that the full keel was invented because it was the only way they could build it strong enough. For a cruiser, a modern NACA foil fin keel coupled to a spade rudder outperforms any other cruising design, on any wind-angle, in any sea conditions.

cheers,
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Old 08-04-2010, 08:35   #35
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The truth is that the full keel was invented because it was the only way they could build it strong enough. For a cruiser, a modern NACA foil fin keel coupled to a spade rudder outperforms any other cruising design, on any wind-angle, in any sea conditions.

cheers,
Nick.
What you say Nick is probably exactally true, and we have to understand that as cruisers, we're a very small minority of the people that purchase and used boats as we do.. liveaboard, cruisers...
50 years ago, the full keel was the normal boat out sailing waters including racers, look at the columbia 5.5s or the echels, or the Morris Bahama.. all were designed as racing hulls but were full keel boats..
In todays market, what sells is the "Racer/Cruiser" which actually isnt really either boat, as its a compromise on both..
With all the boats produced in todays market, how many have a fin keel coupled to a spade rudder.. not many.. unless its a custom design..
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Old 08-04-2010, 09:07   #36
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Quote:
Originally Posted by s/v Jedi View Post
The truth is that the full keel was invented because it was the only way they could build it strong enough. For a cruiser, a modern NACA foil fin keel coupled to a spade rudder outperforms any other cruising design, on any wind-angle, in any sea conditions.

cheers,
Nick.
Here's another agreement on that statement, and in a perfect sailing world of all deep water and no nav hazards this is the design I would have. But in my sailing I do tend to go to spots where the water can get a bit thin so a nice, efficient, deep fin can be limiting. Not to mention that with a shallower draft one can tuck up in a corner of a harbor where the big boys don't fit.

Then I also get into areas where there are impediments to easy transit like rocks, reefs, lobster pots and such that can bend, bang or entangle a spade rudder.

So I decided on a compromise. Semi-shallow, modified fin keel and separate rudder on a skeg. Does not perform as well as the fin/spade combo, is not as protected as the full keel/attached rudder combo. My idea is that I get at least some of the benefits of both designs and not the worst of both.
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Old 08-04-2010, 16:05   #37
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Yep. But Nick is talking from a big boat's perspective. There is a lot of size-generic safety in his boat so he can concentrate on getting the performance.

The same cannot be done in a small hull, so the performance (in the cruising mode, not the Minitransat mode) has to be sacrificed (to some extent) to get more safety.

Reading Seaworthiness by Marchaj gives some idea of why we cannot have a fast and safe small boat.

b.
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Old 08-04-2010, 16:26   #38
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I have a full keel and like it. I'm not in a hurry and occasionally I hit things.

But I do like the idea of a swing keel, such as on the Southerlys, assuming that it gives you pointing ability as well as the ability to beach the boat.
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Old 08-04-2010, 16:30   #39
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Yep. But Nick is talking from a big boat's perspective. There is a lot of size-generic safety in his boat so he can concentrate on getting the performance.

The same cannot be done in a small hull, so the performance (in the cruising mode, not the Minitransat mode) has to be sacrificed (to some extent) to get more safety.

Reading Seaworthiness by Marchaj gives some idea of why we cannot have a fast and safe small boat.

b.
every author has a different idea on how a boat should be built and the size.. Larry and lin Pardey say to go small, Steve and Linda Dashew say go large.. Its just another persons oppenion..
And when your book hits the market, they'll be quoting you too...
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Old 08-04-2010, 16:30   #40
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We have a Centerboard on our 42' Maple Leaf....4' to 7.5' draft. This works very well and shallow draft is great!
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Old 08-04-2010, 16:41   #41
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Yep. But Nick is talking from a big boat's perspective. There is a lot of size-generic safety in his boat so he can concentrate on getting the performance.

The same cannot be done in a small hull, so the performance (in the cruising mode, not the Minitransat mode) has to be sacrificed (to some extent) to get more safety.

b.
The only issues you get into with smaller boats in performance is weight..
To take a small 24 foot performance boat weighing in at around 3k and adding water and stores aboard, you're looking at adding another 1000 or more lbs or 1/4 of the boats weight.. which disrupts the design of the boat..
But a 24 foot boat weighing in at 10k stock, the same stores are only 1/10 of the total weight.. a big difference in % added to the boat..
I would think that up around 30 feet, you'll see a difference as the 30 footers in more of a performance design will take the weight without disrupting the handling of the boat but I guess it all depends on the boat..
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Old 08-04-2010, 22:59   #42
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So far I like my heavy displacement full keel for different reasons, not many of them rational or yet fully explored/experianced: I'm not in any kind of a hurry, I enjoy the long motion , steering doesn't seem to require as much attention, bumping into the bottom, sailing through kelp paddies or in and out of fishing gear don't worry me as much, can get into shallower spots, and can careen her. But, more than anything else honestly, I ljust happen to love the aesthetic of a more "traditional" boat. For these things I accept the compromises of, not as easily driven, can't point as high, slower and less excitement.

I was just reading some Don Street who in his usual, highly opinionated way (translate: fun to read) is dead aginst centerboard boats for many reasons and in the introduction to The Ocean Sailing Yacht Vol. I ,Carlton Mitchell pokes at Street for taking "a few swipes" at his "beloved fat girl", Finisteere and goes on to say that he remains convinced that a "properly dsigned, built, ballasted and handled centerborder...makes the most comfortable small boat afloat"
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Old 08-04-2010, 23:54   #43
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In todays market, what sells is the "Racer/Cruiser" which actually isnt really either boat, as its a compromise on both..
"Racer/cruiser" boats are actually a pretty well-defined type, and this is not actually "what sells". It's a small part of the market. These are boats which are fully capable of racing and with decent if compromised cruising abilities. J-Boats, X-Yachts, Bene First, Salona, Elan just to name of few.

We shouldn't make the mistake of thinking that there is only one type of modern underbody and keel, and that this is automatically the racer-cruiser type. This type is very, very different from that of the best modern pure cruising boats.

Look at the underbody of an Oyster, for example, undisputably one of the very best pure cruising boats you can buy today (and one of the most expensive, unfortunately). It's got a fin keel of course, and with a bulb. It's a robust fin which is not so long or thin as racer/crusers' would be -- it's for good performance cruising, not ultimate performance.

Look at the forefoot -- it's not flat like a racer/cruiser, or even like most French production boats.

Look at the rudder -- it's hung on a full skeg, to protect the rudder in case of grounding and to make the whole construction strong by spreading out the bearing points.


But as Nick said, ful keel boats or long fin keel boats are hardly more than a historical oddity anymore. The only boats still made with them are consciously retro or eccentric designs (Island Packet or Cornish Crabber, say). The fin keel is the standard today because it performs so much better than anything else. Designers make them more or less radical, depending on the purpose of the boat.

Bilge keels and lifting keels are for special purposes -- performace hit being accepted for ability to fulfill that special purpose (getting into really shallow places, and/or taking the ground).
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Old 09-04-2010, 10:29   #44
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Let me add here that I like a design with a center board too. The French built Ovni and the Dutch built Atlantic (both aluminium) are perfect examples of that and both true cruising designs.

Let's not forget the most important feature of a keel: minimize leeway while minimizing drag. It should be obvious that almost any design beats a full keel because it's wetted surface alone puts it at the bottom of the list.

When you design a fin keel you end up with more draft. Dashew had a problem with that because he wanted the Sundeers to be able to sail shallow areas too. This forced him to enlarge the rudder (something he wanted anyway for reasons of maneuvering under power) so that the rudder plays a bigger role in tracking and preventing leeway. The design ended up with a draft of 6'6" at the keel and 6' at the rudder. The original owner of Jedi needed 6'2" and she got a small bulb to compensate for those 4".

This put all attention to the engineering of the rudder because he wanted all that surface area on a high performance spade rudder, no skeg. This lead to one of the first rudders on a cruising sailboat that was one piece incl. the fiberglass shaft. It also has an engineered weak point so that you are left with 2/3rd of the surface area if something needs to break during a grounding.
What I try to say is that a spade rudder can be made just as strong as a skeg hung rudder.



ciao!
Nick.
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Old 09-04-2010, 10:54   #45
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But at some point speed is limited by your waterline, yes? So at that point wetted surface becomes less relevant.
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