Proper Prop

No Ken you're not**** ...at least from me and probably no one else. I expressed my opinion on yacht design until Marin called me stupid and no one else seemed to have an opinion.
Marin lives in his little box of the best things and if one suggests there could be something wrong w it (Rocna, GB, Boeing, or the people on his dock) he comes at them like a steam roller of words. He thinks all his stuff is perfect and all the rest of us should have, do or think the same or we're not very bright. I've been arguing, bashing and bantering w Marin for years and now I'm going to respond to the idea that it's just not worth the effort. When he told 2bucks talking to him was like talking to a 2 year old Johm should have unplugged him for a month or so**** ....but he didn't. I'm personally going to disconnect from Marin forever. If you like**** ..this thread is dead.

Oh I just noticed. My words at the bottom of my posts seem to apply.




-- Edited by nomadwilly on Friday 18th of February 2011 10:28:14 AM

nomadwilly wrote:

I'm personally going to disconnect from Marin forever.*

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Eric--- I'm not sure how all of this escalated so fast.* I have never (I don't think) disagreed with your position on power vs. hull design vs. speed.* Where we have differed is with your opinion American Marine made an error in the choice of their hull design vs the power they put into it.

You have been viewing it from the perspective of a hull designer.* In that regard I don't find any fault with what you've been saying.*

But what I believe has been left out of the picture is the marketing aspect of building production boats.* American Marine's market turned out to be people who wanted to go faster than displacement speed when they wanted to.* As available engines got more powerful, AM put them in their boats because the hull design could make use of the power.

Now I don't deny there might be a better hull design for this particular market, which is comprised of people who want to go faster to get there and then efficiently slower when they get there.* You mentioned the afterbody of the GB would have benefited from being lengthened, for example.

So on the one hand you've been talking design theory-- and so far as I can tell you've not been wrong--- and I've been talking marketing.* When it comes to selling products, be it boats, planes, cars, you name it, designers often--- and to hear our aerodynamicists talk it's always --- have to compromise the ideal design to gain market appeal. I expect you know that as well as I do.

Most boat buyers--- like most car buyers--- have little understanding about the actual design aspects of a boat.* Most of them have not even heard the word hydrodynamics.* And while they may have heard the term hull speed or displacement speed or semi-displacement, they would be hard pressed to say what they are and why.* Instead they ask how fast will it go, and how good is the ride, stuff like that.* Most GB buyers--- given the high cost of the boats--- probably didn't even ask how much fuel does it burn?* Well, they probably did but they probably didn't care what the answer was.

So when you have buyers who don't want a boat that "rocks around a lot," what do you do?* The full-bodied, efficient displacement hull is most likely going to "rock around a lot."* So you don't use it even though it may actually be the best hull to use with regards to efficiency.* When you have a customer base who asks, "Can I go faster if I want to?" that's what you have to design to if you want to sell boats to these people.

So I don't see an argument here between us, just two different views of what GB did.* You believe they erred in their hull design vs power formula in terms of optimum efficiency and I believed they succeeded in meeting the demand of their market.* In my opinion, we're both right.* Would you agree on that or no?

As to my thinking all my "stuff" is perfect, I think I've made it plenty clear that I think the Ford Lehman 120 is rubbish, and the GB design is aesthetically very much wanting by my standards.* I'm not a big fan of Grand Banks at all, actually, outside of their build quality.* We own one because it made sense to buy one and being out on the water in a less-than-ideal boat is better than not being out on the water at all.* I think the Rocna is world's better than the anchor we had, but I don't think it's world's better than* every other anchor on the planet because I have no way of knowing that.* As I've stated, the times we've used our Fortress it's done exactly what it was supposed to do and I would not want to give it up.* In fact, for what we use it for a Rocna would be crap.

But the last thing I would ever call you--- or think about you--- is that you're stupid.* There are a couple of people who participate in this forum who I think are--- or at least ignorant--- but you're certainly not one of them.* You've had more boating experience than I will ever have, and you've probably forgotten more about running a boat in all sorts of conditions than I will ever know.* We may come at things from different perspectives--- you from an engineering and design position and me from more of a marketing and sales position--- but I have never thought you to be a fool for using design reasons to oppose marketing reasons.* It is proably the number one ongoing conflict at Boeing.

And speaking of Boeing you were spot on with one thing--- if someone has a misperception or is just plain wrong about the company I work for or our products, yes, I am going to come at them like a steam roller of words




-- Edited by Marin on Friday 18th of February 2011 01:56:56 PM

Well Marin I sorta didn't think you'd make the effort but I'm glad you did. The part I continually didn't seem to get was the marketing angle. Not rocket science at all. I'm sure your'e correct that people were clamoring for boats that would go "faster" and there were those that didn't and to market two different hulls, one that just went slow (with most or all the transom out of the water) and those that went slow or more than a tad bit faster (like the SD hulls GB actually built). So they would have needed to make a special hull just for the few that would want to go only slow. It's not correct from a standpoint of design but a no-brainer for marketing. I was only talking about design and did not address the marketing issue at all. If I had been head of GB (or AM) at the time, and if I was a good business man I may have done the same thing. However I prolly would'nt have done the single engine boats at all. But who knows. Actually GB was probably the least guilty of all the Asian trawlers for this sin. Most of the other trawler builders made many more single engine boats in semi-disp/semi-planing hulls than GB. Clearly engineering took a back seat to marketing. I can see how my engineering bias was frustrating to you. Efficiency was not the element of my criticism. It was appropriateness or correctness that got me.
An ironic thing about this is that I was actually considering the GB36 in single engine configuration when I was shopping. There's so few FD boats I was actually considering one of the boats I've been criticizing. Can you believe that**** ...I have a hard time with that myself. Actually I considered the GB 36, Monk 36, Albin 36, Sundowner 36, IG 32 and other similar boats all with what I consider an improper stern. Of course it wouldn't be an insurmountable problem. One could just change the shape of the stern.
Marin wrote:
"So I don't see an argument here between us, just two different views of what GB did.* You believe they erred in their hull design vs power formula in terms of optimum efficiency and I believed they succeeded in meeting the demand of their market.* In my opinion, we're both right.* Would you agree on that or no?" Yes I agree but would like to change the words "optimum efficiency" to proper design. Your post says you care and so do I and it WAS a misunderstanding. As to the "stuff is perfect" I've got to hang my head a bit here Marin. I'm sorry**** ... but it is true you could often just say "our boat" or our anchor ect. And lastly Boeing is just fine and it's good always to see someone that believes in their work and a big part of that comes from believing in the company you work for.

Sincerely, Eric

Whew!!* I think we all feel better now.* Thanks guys, I know you are both very passionate about boating and there is your common ground.* As I said before, lets shake hands and go have a beer, I'm buying.**** KJ*

ps lets have some fun on this forum for a while.**i.e. my posting on*woodies, ya gotta agree, wooden boats are really cool!

nomadwilly wrote:

I agree but would like to change the words "optimum efficiency" to proper design.

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Works for me.* In the eyes of a designer,*a design is either "proper" for the designer's intended purpose or it isn't.*

While I know you're not all that interested in aviation examples, from your perspective as a design guy, you would probably have been interested in the HUGE knock-down, drag-out*debate that surrounded the initial design-- by which I mean exterior configuration-- of what is now the 787 but started out code-named"Yellowstone" and then called the "7E7."*

The original configuration had been inspired by two things--- the 747 and a dolphin. Yes, you heard right, a dolphin.* I made a very expensive airshow video featuring three kids in different countries around the world wirelessly drawing the plane*together in real time on tablet PCs.* When the young girl who took it upon herself to design the fusleage drew the upper body line, one of the other kids said, "Cool.* That looks like a dolphin."* Then the girl, who was sitting in glass dome in a huge*aquarium surrounded by all kinds of fish looked at what was swimming in front of her and said, "Yes, and the tail could look like a shark!" And she drew it that way.

Of course what they were drawing was the actual design of the 7E7 at the time, and the fusleage did indeed look like a dolphin and the tail looked like a shark.* The marketing people were ecstatic because the plane would have* a) looked absolutely stunning and blown away pretty much everyone who saw and rode on it, and b) totally differentiated the 7E7 from our competitor.* The design was a brand managers' wet dream.

BUT.... the engineers looked at all this and said, "Well, we can do that but do you realize how expensive it's going to be to*actually*make the plane?* And how hard it's going to be to make the aerodynamics work to meet the goal of maximum efficiency?"*

And the airlines*looked at it and said, "Cool, but look how hard it's going to be to stretch the fuselage to make a larger capacity version when we want one," and "It's going to cost HOW much?"

So when you look at a 787 today, there's no dolphin fuselage, and no shark tail. It is-- like everything else except the 747 and A380-- a straight*tube.* It did keep the very efficient (and fortunately for the marketing folks) very pretty wing.

So "proper" design won the day over the marketing department, and probably rightly so.

-- Edited by Marin on Friday 18th of February 2011 06:49:48 PM

Good story Marin and relevant to our (whatever). I've always marveled at the ugly "tube" shape the fuselage of modern transport aircraft and assumed it was that way because it was easy to manufacture. I remember an older transport aircraft that didn't conform to a tube at all*** ...and it was beautiful. It was the Lockheed Constellation. And I've even flown in one. Not totally beautiful but a nice piece of aviation sculpture. So yes I do wonder how those nice flowing lines survived the engineering gauntlet. Speaking of engineers do you know David Higgins? He's in "structures".

In the "old" days, aerodynamic design often incorporated a sense of aesthetics even if the aesthetics weren't the ideal design. The Constellation, which was designed during WWII to be a bomber, is such a design.

There is an element of aerodynamic design you've probably heard of called "area rule." I don't pretend to understand it--- the only commercial transport still in production today that incorporates area rule is the 747--- but it often resulted in a more curvaceous fuselage. Whether area rule played a role in the design of the Constellation I don't know. But I agree, it's a beautiful plane.

I think planes today all look the the same for the same basic reason that most cars all look the same. Everybody's using the same numbers. Manufacturing costs, aerodynamics (in planes and cars), efficiency---- everybody's trying to get the best return on investment. The pressure to keep costs down and sell the highest volume steers everybody who's making the same thing into the same numbers.

That beautiful boat you posted a photo of in the Woodies discussion would cost an arm and a leg to make today. There's no way you could manufacture that design and sell it for an "affordable" price. Like Aston Martins, there's a limited market that's willing to pay the high cost of something of that quality and style. And the smaller the market, the more you have to charge per item to make any money with a quality, no-compromise product like that boat.

So how do you produce a boat at a cost that will get you a decent profit and appeal to the widest number of buyers to assure that profit? You design it to be easy (aka inexpensive) to produce.* And when*producibility takes center stage that starts forcing you into some basic design concepts. So Bayliner/Meridians resemble SeaRays that resemble Carvers that resemble your-example-here.*

I'm not saying it's wrong or the products are bad, just that the reality of the market starts driving the design. It's why Hondas look like Toyotas look like Nissans look like BMWs.

And Boeing's and Airbuses are straight tubes. (A big advantage of a straight tube is that it's easy to stretch or shorten, an important consideration when designing an airliner and probably the main thing that killed the 7E7's lovely dolphin design).

That's my take on it all, anyway.

Yes and that's what happened to the Alaska State ferries Malaspina and Matanuska. They were like the Taku when first built but got a significant stretch later. When Mr Fales started making the Willard copy w a Willard mould he made a few boats and then cut the mould in half and added 2'. I'd really like to stretch mine 3' but it's way too much work.
When one "rotates" during take off in a jet it's a bit of a rush but take off in a Lockheed Constellation comes after 10 or so minutes of high (or max) power run ups and if you're sitting near the wing you get to watch the huge exhaust ports in full flaming glory and feel the tremendous power. Then you turn on the runway and stop. Then all 4* 3,350 cu in
18 cyl engines build to an incredible engine roar that pulls you down the runway. Rotation is gentle and climb out is long lasting. Engine vibration isn't much much it's probably 10 or 20 times as much as a jet. The last time I flew on a jet it was a Boeing that had a very curved and smooth transition from wing to winglet. And the winglet was quite tall. I miss flying can anyone tell?

nomadwilly wrote:

The last time I flew on a jet it was a Boeing that had a very curved and smooth transition from wing to winglet. And the winglet was quite tall. I miss flying can anyone tell?

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That would have been a NextGen 737.* You'd like the story of how those blended winglets came to be--- Boeing's aerodynamicists at the*time*fought them tooth and nail.**They are*based on a truly proper design by the world's best designer, who you can think of as either*God or Evolution.* The proper design is the condor wing. (The two photos are frames from a video I just finished putting together.)

PM me if you want the story of the 737's winglets which has some humor to it.* I won't subject the forum to it.




*


-- Edited by Marin on Friday 18th of February 2011 10:32:11 PM

Marin,Notice how the turbulence from the birds head goes alongside "the fusalage" instead of over the top of the wing where the greatest lift is created. My last ultralight (Lazair) had curved winglets * *....and a 36' span * quite a wing. Re; the pics * *..actually I think eagles have more curved tip feathers * *...and there's a special name for them but I can't remember it. Yes I'd like the story if it's not much trouble. Thanks.

nomadwilly wrote:

*
Re; the pics * *..actually I think eagles have more curved tip feathers * *...and there's a special name for them but I can't remember it.

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They're called primaries.* I don't know if eagles can curve their primaries up more than condors.* The average wingspan of a female bald eagle is about 7 feet.* The winspan of a condor can be almost ten feet.* But the birds have the advantage over Boeing in that their winglets--- in fact their whole wing-- is totally variable.* The bird can modify the airfoil, change the drag, change the wingtip vortices, change the lift,*anything*it*needs to do in order to fly the way it wants to fly.* In the same scene the two shots above were lifted from the same bird bends its wingtips from up to*down at an even greater curve*and holds them that way*for awhile before curving them back up again.* All this without flapping at all.* The other impressive thing to watch in the video is what the bird does with its tail.* It goes from "full tilt" in one direction to full tilt in the other in an instant--- like watching the extreme movements of the stabilators of a fighter on final approach to a carrier.

I bet a sailboat could make much better use of the wind if it could do this......

*


-- Edited by Marin on Saturday 19th of February 2011 12:06:08 AM

"I bet a sailboat could make much better use of the wind if it could do this......"

For ???

Sure the racing guys might be able to use it to harm a competitor at the mark, the turn point, but a cruiser?

The use of really efficient sails is done on the iceboat , and unlimited catamaran circuits.

San Fran will host the 2013 Americas Cup races in Huge cats , that will be interesting.

One reason most carrier aircraft use control surfaces differently is they are by design airodynamicaly UNSTABLE, the transports are stable.

This is to allow the war aircraft to jink and perhaps avoid missles , that are still use conventional flight rules.

The Russians lead in this field .

"Then all 4* 3,350 cu in
18 cyl engines build to an incredible engine roar that pulls you down the runway. Rotation is gentle and climb out is long lasting."

The 3350 is 3 Rows , ao its 3x9 or 27 cylinders each. The Connies have PRT's power recovery turbines instesd of turboes to capture exhaust energy. The 3350 has a 2 speed shiftable supervharger , so the PRT's 150hp each 3 per engine are simply shaft connected to the crank.

Amazing what they could do in the 1940's , but few got to 2000 hours with out replacement.

The Connies simply reach flying speed and behin to fly.

The transport wings* need a specific angle of attack , hence the rotation.

-- Edited by FF on Saturday 19th of February 2011 05:06:39 AM

FF wrote:The 3350 is 3 Rows , ao its 3x9 or 27 cylinders each.

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The Wright R-3350 is a twin-row, 18 cylinder radial, 2 rows of 9 cylinders each.* The P&W R-4360 is a four-row, 28 cylinder engine, four rows of seven cylinders each.* I don't believe any of the major aircraft engine manufacturers ever made a three-row engine.

*

I believe the biggest advantage of the primary feathers is that they are slotted so that the main wing turns into 6 or 7 little tiny wings. The tip vortice is broken up into many really small ones so the overall vortice is greatly reduced and the slots between the feathers make the wing loading at the tip very small and extremely resistant to stall. The slots and vortices aids greatly to the birds ability to maneuver in turbulent conditions (where they fly much of the time) and the primary feathers also increase the effective span and add very little structural loading so as to maximize effective span, minimize the sink rate and maximize their ability to soar**** .....and that of course enables them to find and get***** ...DINNER.

Years ago Boeing was the prime conractor on a NASA project to develop an infinitely variable (within limits at each end) airfoil. The plane used was a fighter--- I want to say F-15 but I could be mistaken. One of our producers was assigned to support this project at Edwards AFB. As I recall, the mechanism to alter the airfoil shape was a mechanical nightmare and the whole idea never really worked. I think the final conclusion of the project was "If we could vary the shape of a plane's airfoil in flight we could fly as efficiently as the birds do." Which I think everybody already knew before they spent the bazillion dollars on the experiment.

Which I guess, to bring this back somewhat to topic, is why variable pitch props on boats is a great idea. I get the impression the problem is not so much with the propeller itself, but with the control system which, on the scale needed for small recreational boats like ours, isn't practical or cost-effective. Plus the boater would either have to know how to use it correctly, or it would have to be automated to eliminate the problems a boater who didn't know how to use it correctly could cause.

Now, that's what I call a proper prop!***

on the scale needed for small recreational boats like ours, isn't practical or cost-effective. Plus the boater would either have to know how to use it correctly, or it would have to be automated to eliminate the problems a boater who didn't know how to use it correctly could cause.

About $7000 (and up)in added expense on a new build.

Weather the $7K could ever be regained by extended engine life and better fuel consumption is really a matter of the vessels use.

At 200 hours a year , probably no chance , for a Passagemaker venturing out beyond the brown water , probably.

For the venturing motor sailor folks it would be really EZ to justify.

I Stand corrected on the 3350 cylinder rows.