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Old 29-04-2015, 23:19   #241
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Re: The criteria of "blue"

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Originally Posted by Jon Eisberg View Post
Absolutely...

In all these skeg vs. spade debates, one thing I think many proponents of the former tend to underestimate is - given the overall depth and narrowness of most skegs - it can be very problematic to fabricate a structure of high strength and rigidity from fiberglass, with the problem of forming a proper layup at the bottom of a skeg formed from a female mold, way down where the highest loads will be seen...
Cool pictures. Having no boat, nor even an hour of sailing, and having been told to "shut the ... up" (more or less) because of that, I hesitate to open my mouth again. All I can claim is that I am reading voraciously about this and many other subjects. The reading, contrary to popular opinion, does not appear to be the "opinion" of the author, but rather what is understood about the issue.

So a spade, being entirely free hanging can have the shaft offset into the interior of the rudder. This allows the spade to be balanced such that the water flowing over it does not push it to one side or the other. This allows the full spade to be very light to steer, even when turning hard.

That "push" is one of the problems of the keel hung rudder. When the rudder turns either direction, the water flowing against it pushes back, making steering hard. A skeg hung rudder doesn't have the shaft offset either, so it cannot be balanced either. So it is harder to steer than the spade IF the spade has an offset shaft, though (apparently?) not as hard as the keel hung rudder.

All of that, btw came from a 25 year old worthless book that I made the mistake of buying before asking the considered opinion of the old salts on this forum. Complete with diagrams and pictures showing how and why each of those things are true (according to that 25 year old book at least).

So the full spade rudder OTOH has a weakness, that large seas pushing sideways on the boat will apply enormous lateral pressure on that spade rudder. Since the rudder is "hung" on a shaft coming through the hull astern, if the lateral pressure is high enough the shaft bends at the point where the shaft exits the hull and enters the spade. If the pressure is large enough, and the shaft is strong enough, the entire ass end can be ripped open. Something has to give. Both of these things have occurred apparently. Given that this was mentioned in my 25 year old worthless book, it is impossible (for me) to say whether modern materials and engineering has entirely fixed this problem.

The ONE large benefit of the keel hung rudder is that it can have a bushing at the very end of the rudder shaft, at the bottom of the keel. This makes the likelihood of the shaft bending remote, and the likelihood of the aft end being ripped open remote. Furthermore, the lateral pressure simply causes the rudder to swing sideways, and said pressure simply slips past.

OK so someone just a few posts back validated (or at least concurred) with what I had read in my 25 year old book about the steering issues that can occur with the skeg hung and spade rudders.

With drawings and diagrams, the book discussed how, when a boat keels over, the shape of the hull changes. The rudder comes up, and in fact (apparently) the fin keel and the skeg / spade start to "fly" aerodynamically (or hydro-dynamically), which together with the keel shape change causes the nose to point windward. This can cause the boat to literally dump the sails and come to a halt if not actively managed. With no forward motion, no water flowing over it, now the rudder is useless, you can't steer until you adjust the sails to get back under way. So specifically in bad weather, the spade and skeg hung rudders both make the boat more skittish at certain angles of attack. This seems to be a problem mostly when the boat is sailing up wind and keeled over.

The full keel (not fin) has an enormous area relative to the fin keel and tries to keep the boat on course. This is precisely why the fin became so popular, because it "steers better" - in most cases. But not all.

OK, so that is all book knowledge. AFAICT it is not "opinion" but an explanation of the physics behind what actually can and does happen. Of course, I will stress again that I don't own a boat, nor even have any sailing time so who am I to try to bring this information to the table eh?

I also assume that everyone here already knows this since I have been told that there was nothing I could say that anyone on this forum didn't already know. I suspect however that some of us junior types might enjoy this discussion.

I am also reading the Pardey's "storm tactics handbook". I fear recommending it too highly since I also failed to get the approval of the salts on the forum before buying this book. However at least the Pardeys do appear to have enough experience that maybe their "opinion" will be looked upon favorably?

And BTW they discuss how a following sea crashing on a boat can put gigantic pressure on the rudder, causing it to slam sideways. Of course their solution is to "Lay up early, Lay up often" to paraphrase. I am still trying to wrap my mind around that whole "following slick" thing but they swear by it. A fascinating book for me. The idea of dragging a parachute through the water to slow the boat down when laid up is cool.

And of course, "laying up" entirely removes the problems of the rudders since the boat is no longer moving (twitching) and the seas aren't slamming against the rudders sideways.

OK, so if modern physics, materials or design make any or all of that stuff above moot, please feel free to discuss, in technical terms, how so. This truly is just my understanding of a rather complicated set of ideas, which I am trying hard to assimilate, so that I may become (willingly) one of the Borg.
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Old 29-04-2015, 23:54   #242
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Re: The criteria of "blue"

jwColby...Quite a reasonable treatise... however... we all like what we have... Otherwise we would make a change and get something we did like... I'm happy with my boat otherwise I wouldn't have kept her for 21 years. She is moderate fin keel with a spade rudder...
My previous was a Vertue... full keel with a rudder hung off the back.. very secure.... if you have a full or long keeled boat its the way to go... in fact its the only way you can go

I've done a few downhill miles but have never had the need to hang a drogue off the back.. just lucky I guess. When the wind is coming from where I want to go I have hove to and even shock horror lain ahull a few times.

One thing I have never experienced is seas slamming my rudder from abeam...ie the side.. once again.. just lucky I guess.

If you do heave to ( what you I think are calling 'lay up') that is when your rudder may cop some grief from getting slammed.

In my opinion one reason spade rudders get a bad press is that many are to be found on yachts with high aspect ratio fins.... its the fin that is the issue... not the rudder.

Moderation in all things...

A 'before' photo...and also having the propellor somewhere near the rudder is also a bit of a plus when ship handling
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Old 30-04-2015, 00:01   #243
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Re: The criteria of "blue"

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Originally Posted by jwcolby54 View Post
That "push" is one of the problems of the keel hung rudder. When the rudder turns either direction, the water flowing against it pushes back, making steering hard. A skeg hung rudder doesn't have the shaft offset either, so it cannot be balanced either. So it is harder to steer than the spade IF the spade has an offset shaft, though (apparently?) not as hard as the keel hung rudder.
Most skeg hung rudders are in fact semi balanced... as are most spades.. its just that spades tend to be 'more' balanced.

My boat has been in the yard for 8 of the last 9 months.... I have seen the good, the bad and the downright fugly..I 've seen boats of all configurations that I would happily go to sea in... likewise I have seen an awful lot more... of all flavours... I wouldn't leave the dock in.
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Old 30-04-2015, 01:01   #244
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Re: The criteria of "blue"

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jwColby...Quite a reasonable treatise... however... we all like what we have...
I understand that. I am not making any attempt to say one is better than the other. Just that each has very different characteristics from the next, and none of them are perfect.

To be brutally honest, I think that I recommended a book with a title of "Desirable and Undesirable Characteristics of Offshore Yachts", and that landed right in the middle of a bunch of "old salts" who have said over and over, "it ain't the boat, it's the crew", or as Ms Muldaur would say "It ain't the meat it's the motion".

Now that book title seems to suggest that yea, perhaps there are good and bad characteristics to offshore yachts. And so those who have made the claim that there is no such thing, are feeling a little "challenged".

And yes, that 25 year old book has taught me more about a boat than every post from these old salts combined. Times 100. And in spite of all the protestations, not a single post has said a single actual thing that says "the information in chapter X, page Y is wrong. Never mind "because of this reason..." NOTHING. My guess is they haven't even read it.

I'll be more brutally honest and say that by and large, none of the old salts have added anything of value to the thread, in spite of their protestations that "we won't listen anyway". Well actually, there has been a very interesting discussion of offset hatches and hand rails.

What I truly find puzzling is why these "old salts" are even participating in the thread. They claim that this is so hashed out in other threads, such a worthless topic, and yet here they are, 15 pages later, not contributing anything technical but nastily suggesting that those of us with no experience should just go away.

I will nastily suggest that some of these folks should take a valium and chill. Go sit on their yacht and get into their inner space, contemplate their navel. I don't even own a boat and yet I am enjoying learning new stuff and having fun with this stuff.
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Old 30-04-2015, 02:57   #245
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Re: The criteria of "blue"

I am sure we are all aware that in order for 'Criteria' to be meaningful, .....testing conditions must be very well defined.

If we make high quality build materials, execution, systems and good seamanship ALL assumed constants, ......then the design decisions on "scantlings, hull form, weather deck, rigging and static stability become the major testing Criteria.

But what about the testing Conditions?

If we tested for 'Survivability' then that might favor the design with the heaviest scantling for a given material's use ..... But how does that weight penalty affect weather deck dryness in normal trade wind conditions?

If we tested for stability then what about dangerous G-forces with excessive beam on a given hull design or a design that produces high speeds?

Also the dynamics of ocean passages and wave forms makes this an even tougher criteria decision as does the reality that those blue water passages represent a relatively small percentage of your enjoyment onboard and you will prioritize creature comforts into the mix.

For those searching for the Holy Grail...it is what makes our chosen craft so personal and distinctly human.

We fall in love with that lady...warts and all.... and learn to keep our boat and all on board within their designed comfort level.

The enthusiastic research and hunting for that special lady is a trait we all have in common and should not become a judgmental weapon.
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Old 30-04-2015, 04:20   #246
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Re: The criteria of "blue"

What are these ship models?

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The first pic is from the amazing archives of Maine Sail:








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Old 30-04-2015, 04:46   #247
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Re: The criteria of "blue"

Does this get the BWA ( Blue Water Approved) tick?

The day before you could see daylight where those silverish bits are but somebody tacked some patches over them before I came back with my camera.

So..its steel.. its not a spade..in fact its essentially well secured to the stern post top and bottom.
I think the boat was ferro... well 'ferro' stands for steel or iron or some such so she ticks all the boxes... BWA and set to go....
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Old 30-04-2015, 04:55   #248
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Re: The criteria of "blue"

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I understand that. I am not making any attempt to say one is better than the other. Just that each has very different characteristics from the next, and none of them are perfect.

To be brutally honest, I think that I recommended a book with a title of "Desirable and Undesirable Characteristics of Offshore Yachts", and that landed right in the middle of a bunch of "old salts" who have said over and over, "it ain't the boat, it's the crew", or as Ms Muldaur would say "It ain't the meat it's the motion".

Now that book title seems to suggest that yea, perhaps there are good and bad characteristics to offshore yachts. And so those who have made the claim that there is no such thing, are feeling a little "challenged".

And yes, that 25 year old book has taught me more about a boat than every post from these old salts combined. Times 100. And in spite of all the protestations, not a single post has said a single actual thing that says "the information in chapter X, page Y is wrong. Never mind "because of this reason..." NOTHING. My guess is they haven't even read it.

I'll be more brutally honest and say that by and large, none of the old salts have added anything of value to the thread, in spite of their protestations that "we won't listen anyway". Well actually, there has been a very interesting discussion of offset hatches and hand rails.

What I truly find puzzling is why these "old salts" are even participating in the thread. They claim that this is so hashed out in other threads, such a worthless topic, and yet here they are, 15 pages later, not contributing anything technical but nastily suggesting that those of us with no experience should just go away.

I will nastily suggest that some of these folks should take a valium and chill. Go sit on their yacht and get into their inner space, contemplate their navel. I don't even own a boat and yet I am enjoying learning new stuff and having fun with this stuff.
I saw what you refer to jwcolby54. Just ignore the old "salt" - Notice the use of the singular!
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Old 30-04-2015, 05:10   #249
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Re: The criteria of "blue"

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Actually I never made mention that either one was or was not a blue water boat. My point, and only point, was that one sailboat had properly (in my opinion) prepared and reduced sail, while the other (maybe for fun) had too much canvas. That, was my point.
Yeh, you are quite right. I am not sure either. Think I must have had some info ratling about in my head left over from some body else's previous post. Woops. Sorry for miss quote.
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Old 30-04-2015, 05:30   #250
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Re: The criteria of "blue"

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Nope.... Not an accurate assessment at all. Would you like to have an "Old Salt" splain it to you? Someone who's owned and sailed boats with spade and skeg hung rudders. Or... do you already know it all... from a 25 year old book which was written before most of the modern boats with spade rudders were designed.

Looks like another fellow has made a good suggestion about hand holds.
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On second thought... forget it. You guys won't listen anyway.
We will listen Ken. Don't worry. Splain it to us please. Would love to see your take on fluid dynamic theory.... Here is a reference page on hydrostatics to help you but not sure you will need it with your wealth of knowledge. Fundamentals

Can't wait for this.. So excited.
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Old 30-04-2015, 05:37   #251
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Re: The criteria of "blue"

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Cool pictures. Having no boat, nor even an hour of sailing, and having been told to "shut the ... up" (more or less) because of that, I hesitate to open my mouth again. All I can claim is that I am reading voraciously about this and many other subjects. The reading, contrary to popular opinion, does not appear to be the "opinion" of the author, but rather what is understood about the issue.

So a spade, being entirely free hanging can have the shaft offset into the interior of the rudder. This allows the spade to be balanced such that the water flowing over it does not push it to one side or the other. This allows the full spade to be very light to steer, even when turning hard.

SNIP...
When you're done with DESIRABLE & UNDESIRABLE CHARACTERISTICS..., you really owe it to yourself to get Bob Perry's book... A wealth of information conveyed in Bob's typical straightforward fashion, not to mention a very entertaining read...

When Bob Perry speaks about the relative merits of skeg-hung vs spade rudders, I think its worth paying attention. After all, he's the guy who practically invented the things, everyone thought he was nuts when he split the underbody, separated the rudder from the keel, and hung it on a skeg with the Valiant 40, and then had the nerve to call it a Bluewater Performance Cruiser :-)

Quote:
It wasn't so long ago that people thought I was being radical and reckless because I put a skeg hung rudder on a cruising boat.
He's written quite a bit about skegs over on Cruising Anarchy, here's a couple of comments in response to the following:

Quote:

Back in the '70s I worked in Bob Derecktor's yard in Dania and one problem we noticed with skegs was getting them strong.

The skeg would flex before the rudder shaft, so it was more of a fairing piece than a rudder support.
Bob P:

Quote:

I found the same thing. GRP skegs are very hard to build and there is many a rudder out there holding the skeg on...


Skegs are a hard shape to laminate when they are integral with the hull mold. You just can't get your arm down there to do any careful laminating. You need a broom stick to shove the glass into the bottom of the skeg. When I designed the Valiants and thre Lafittes I made the skegs independant of the hull and bolted and glassed on. This made it easier to lay up the skeg but it was an expensive detail...



I hesitate to even try to tell you how they laminated up deep skegs. Not sure you would believe me...


On a boat over 40' a skeg prevents you from having any balance to the rudder. I like some balance to relive some of the pressure on the helm. I'm working with nthe owners of a 60 plus foot boat that has a full skeg and they have helm balance issues. Having a skeg makes it only worse. Much worse...



That design study was an attempt to stretch out my Esprit 37 and gain some boat speed.

Would I change anything today? Yes, probably everything. I'd start by removing the skeg...


Are spade rudders stronger? I wouldn't generalize like that. Some are and some aren't. There are some real structural advantages to a carbon blade and stock combo as it can be made monocoque as one unit without the different combination of materials needed to make a steel stock grp blade rudder. Certainly on a welded alu or steel boat the skeg can be very strong.
Even on a metal boat, however, skegs can still fail, as Evans Starzinger has noted:

Quote:

...there was an aluminum Paine boat, where the Paine drawings clearly showed the skeg was supposed to be brought up thru the skin and tied to the frames, but the yard in fact just welded it to the outside of the skin. This was an 'expedition' boat and when the boat was in a rather remote place some of those skin welds popped and the skeq became wobbly - not good!
Bob Perry, again:

Quote:
A quick look around at a variety of boats including the latest H-R's will show you that the spade rudder is here to stay. It's a better rudder.
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Old 30-04-2015, 05:50   #252
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Re: The criteria of "blue"

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In my opinion one reason spade rudders get a bad press is that many are to be found on yachts with high aspect ratio fins.... its the fin that is the issue... not the rudder.

Moderation in all things...
Exactly... Few expressions sum it all up better, when it comes to assessing the suitability of a design for offshore...

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Originally Posted by El Pinguino View Post
A 'before' photo...and also having the propellor somewhere near the rudder is also a bit of a plus when ship handling
Yup, another hugely advantageous feature, IMHO... One of the biggest downsides to the trend towards saildrives, they are often placed so far forward of the rudder that the prospect of generating an effective quick burst of propwash can be essentially eliminated...

No need for bow and stern thrusters on my little tub :-)


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Old 30-04-2015, 06:05   #253
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Re: The criteria of "blue"

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Exactly... Few expressions sum it all up better, when it comes to assessing the suitability of a design for offshore...



Yup, another hugely advantageous feature, IMHO... One of the biggest downsides to the trend towards saildrives, they are often placed so far forward of the rudder that the prospect of generating an effective quick burst of propwash can be essentially eliminated...

No need for bow and stern thrusters on my little tub :-)


But how can that be possible Mr Eisberg? You have no boat experience and are just an internet guy! How can you possibly have a boat? You just have to love modesty. It always wins the day!
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Old 30-04-2015, 07:11   #254
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Re: The criteria of "blue"

I do not buy the argument that people without boats or people who do not sail are lacking anything when it comes to discussing things blue and offshore.

Imagination is of paramount importance. And there does not seem to be any unjust distribution of imagination between the landlubber and the one who sees (himself/herself) as an old salt.

Experience may count, BUT experience is formed while sailing specific boats on specific waters.

So I say I am 100% fine with blue/offshore whatever visions and prejudices made by each party.

Cheers,
b.
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Old 30-04-2015, 07:12   #255
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Re: The criteria of "blue"

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Funny, and just goes to show how easily you can misjudge a guy's character based on internet postings alone. Then again, "Gasbag" implies a bull*****er, as in full of hot air, etc. which doesn't seem to fit. Maybe Herb M. just meant that you were "prolific."


That moniker derives from the original days of the CRUISING WORLD Bulletin Board, back when Herb was the editor of the mag, and basically served as the 'moderator' of the forum... I got into a pissing match with some lurker there, and he branded me the "#1 Gasbag of the CWBB", and, somehow, it stuck... :-)


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Speaking of Mason 44's with gargantuan Garmin's, one fitting that description recently showed up at the dock at Little Creek, VA. Also well kept like the one in your photo, and somewhat newly purchased by a retired pilot from NH. He was just returning from the PR & the BVI's on his way back to Maine. He said he had bought the boat in Newport last year and that it had been on the market for awhile. Thought you might know the boat and its PO. Got to tour the interior and it seemed pretty narrow & cramped for a 44'. Only a 12' beam, of course, but I also wasn't wild about what seemed to be an overly compartmentalized layout. Like the 43, it was stunning on the outside, but what can I say, I'm an admitted pushover for traditional boats.

I'm the same, 3 of my Alltime Dream Boats from afar have always been the Alden 44, the Cambria 44/46, and the F&C 44...

But upon having the chance to finally go aboard each, they became lowered a bit in my estimation :-) I have no doubt they all sail like a dream, and I'd still own any of them in a heartbeat if I could, but they really are a bit cut up and relatively 'cramped' down below...

If there is one thing I could request re many of the OPB's I get to sail, it would be a Moratorium on Pedestal NavPod Proliferation... It's ridicuous the extent that some of these Erector Set Clusters are being taken to these days...

I loved this Cabo Rico 42, a wonderful all around boat... But this array at the helm, unbelievable... This is the eye-level view forward, when seated behind the wheel atop a couple of additional cushions. If I lined it up just right, I had a clear view of the horizon thru that 3/4" slit between the plotter and the bank of instruments :-)





Absolutely mind-boggling, the extent to which this cluster-f impeded the utility of the cockpit... And at night, fuggeddabouddit, the only solution when you actually wanted to be able to see, would be to simply drape a beach towel over the whole stoopid thing :-)









But again, based on what I'm seeing out there these days, that's probably just me...

Or, perhaps the distortion of a wide angle lens... :-)
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