boats that are designed with car aerodynamic method?

There we go !! why are you guys alway quoteiing the high speeds and yachts ? its the 35 to 60 mph bracket that most small power boats fall into . drive down the road and put you arm out the window with you hand flat against the wind feel the push !! now turn you hand around 90 degress so your hand is paralel with the ground feel the differance !! aerodynamics is needed in everything even tall buildings . The chinese have some massivly tall buildings and some are shaped towards the prevailing winds and have wind generators built into them !! and even on a day where theres no breeze at grond level the turbines are spinning not fast but spinning a high percentage of there tall buildings are rounded and hardly ever any sharp square corners any more .
You talk about the family car and traveling down the road , now days they are much quieter than the old box'y shapes they are more stable on the road than the ever were ! theres vertually no air noise at all,and there body shapes help press them down onto the road to keep more traction . slowly they have changed shape and we have been acustom to the change but boats have never changed designers have this thing embeded and ground in there minds how they should look at its like a mental block . if anyone does step over the line they are ridiqualed and get pointed at . wake up people change has got to happen weather you like it or not . Big boats are lumbering things like sick fat elephants ! they are terrible things !! the only time you see pointed parts on a aeroplane is reall high speed . most planes that travel at around the 500 to 800 mark have rounded fronts that are aerodynamic .
I got a small boat design once and superimpossed a wing shape over the top ! it took a while to come to grips with the shapes but by the time i changed a few things more in keeping with the aero thing ,wow it turned into something rather nice and much differant !!,the shape starts at about chine level and from there up i changed
I am 110% for the aerodynamic changes of boats . why do we keep getting fore decks and side decks on little boats ?? running board on cars vanished way back !,square fronted cars vanished even further back . boats have never changed !! get with it !!

 

Okay, then the progressive rise in freeboard in recent decades is in direct defiance of your ability to grasp the reality of the actual resistance figures? We're all nuts, and you have it figured out . . . Can't wait to see your next production run.

 

( Why wouldnt it make sense ????)

(yes !!,using air pressure !! so with boats that same air pressure can be used in reverse to lift as well !! )

(Yes you are right !!!! they do need lift but is the ordinary boat designed i such a way that it will take any kind of advantage and have any kind of lift ?? )

 

your home work assignment !!

Just as a excise try designing a boat in the thought mode of aerodynamics from the chine up and see what you come up with !!.
try it !!
top speed in the 50 mph bracket !!!
boat length 25 feet !!!
a cabin boat or open boat !!
single outboard !!!

Oh forgot to mantion you need to close all the books that you copy from and start with a pencil and a blank sheet of paper
Let the mind flow let the mind go to places its never been feel the force !!
May the force be with you !!
You sure as hell are going to need something !!

 

Tunnels, I'm not sure of your background but once again, run the total resistance numbers and see where air resistance figures in. It's a number, but not one to be particularly concerned with. How many HP do you lose in a 30 knot wind, compared to maintaining the plane you're scooting around on? What do you get, a couple , a few. Wheeee, glad we worked that through. If you're blasting along on 200 HP at 40 knots and you sudden place the boat in a vacuum, how many more knots do you get, 2, maybe 3, wow, we should all just sit up and rethink how we're done things, because 1% to 3% of the total resistance number just isn't enough to get all pissy about, unless you're racing similar craft and an "edge" is the only thing keeping you from winning. Yep, there's some aerodynamics at play, but losing a few HP to a relatively high Cd isn't a concern in the big resistance picture, when discussing typical pleasure craft, most of which (the extreme vast majority) operate below 40 knots. The a huge difference between a perceived issue and one that actually come to play after the numbers have been crunched. Water resistance, from the various forms of drag are, far more (by an absurdly large margin) important then the comparatively easy breeze the air makes. The viscosity difference alone should make you realize why.

 

If aerodynamics is not a issue at any speed ,then why isnt the family car still looking like a model T ford ? so brick fly Faster than bullets ?? admit it you dont want to change ! where do i come from !! the fibreglass boatbuilding industry !!! since 1972 !

 

The two attached graphs show the air resistance as a fraction of total
resistance for a monohull, catatamaran, two trimarans, two SES and a
hovercraft (ACV). All vessels have a displacement of 1200 tonnes.

It is clear that air drag does not play a significant part for the pure
displacement vessels except at very high speeds.

Air drag was estimated using the frontal area of each vessel. It is not clear to
me how you could reduce this frontal area without comprising the volume and
cargo-carrying capacity of the vessels.

I agree with PAR that a NA's focus should be on many other aspects of design
and operation before spending much time considering air drag.

 

How many cars do you see with their wheels running on wishy-wasy water..and how many on a solid road??!!

 

You are all dead from the neck up !
Big truck filled in the gap between the back of the cab and the trailer units they fit a wind deffector on the roof to give better air flow and reduce drag to improve fuel comsumption . High speed trains are aerodynamic . i regularly travel in the trains here in China between Shanghai and Suzhou they cruise at 294 plus km hr the fastest one i been on was 340 kmhr going to Najing . theres no whind noise at all it like flying at ground level !!.

Sorry you can live in the past and do the same things every day !! me i want change !! change for the better !! big boats and ships have massive windage like as in huge !

my main interest is small boats !!!big boats dont interest me much at all . I done my time and made more yachts over the years than i want to try and remember they to dont hold much interest either !!
Tunnel boats are part way there ! some one ,one day of going to get the bright idea to take everything a few steps further thatn where they at now !!

 

Could you show us your estimates of the air drag of vessels that you are interested in?
At a minimum, I'd like to see the proportions of wave resistance, skin-friction, and air drag at the speeds of interest.

 

I'd love to have the luxury of designing a yacht with 4 contact patches, totaling less then a square foot, as the primary resistance issues to contend with. Yes, at high speed aerodynamics can play a role and some consideration was given a recent high speed design of my own, but only in as much as to offer clean edges, for air flow to release at near 100 knots. Other wise, the hull form was hydrodynamicly contrived.

Automotive styling is mostly aesthetic and perceived ideas, of aerodynamics employed for the consumption of the market it's aimed at. A sport sedan may look "swoopy" but in fact is an aerodynamic pig. The better Cd figures, used in the automotive industry, produce shapes only a hybrid can love. Take a good look at the most extreme solar/electric cars and you'll see little resemblance with these exceptionally aerodynamically "clean" shapes and the products rolling of the assembly lines. These cars rely heavily on these clean shapes, mostly because the hamsters running around in the cages that propel them, need every ounce of savings they can get. Most cars kiss off real aerodynamics, for perceived aerodynamic styling exercises (the C3 previously mentioned, is a classic example of this). The market doesn't have any more clue about aerodynamic realities, then a few in the discussion here. I used to have a 1971 C3 and drove it over 130 MPH more than once. It was not particularly stable, but good fun.

In fact, the automotive industry has previously gone through similar aerodynamic trends, again mostly based on public perception of what this might be. Jet nozzles on 50's era cars, wings, fins and spoilers, the rounded art deco shapes used a generation previously where the same thing. These "marketing trends" trickled down to the marine industry as well. They didn't do a damn thing for aerodynamic efficiency, but did help sell cars and boats.

It's not really a debate, unless you ignore the actual numbers.

 

some where long ago i read about th shape of the engine cowl in the mercury out board and the amount of resistance it caused . wasnt to long after that mercury changed its whole shape and appearance of the outside of there outboard"s The wind resistance figure was quite high .
Flowing lines and smooth shapes with rounds and no sharp corners to cause turbulance have got to be better that what we have and see everywhere , Let just look at one small part of every boat ! the deck edge where the hull meets the deck ! it has never changed since as far back as i can remember its a 90 degree shape with a belting of some sort .end of story!
The transom is another part thats just cut square and thats it !! good place to hang all manner of junk !! ladders motors boardring platform and its exstention that is happening more and more . the plate form size is getting rediculous we havd a boat sitting in our factory that has a exstension as well as what the boat has and its big enough to hold a crowd of people not just one of two . cabins have lots square corners and the side decks we really dont need them at all

 

Tunnels, if you actually understood aerodynamics, you'd understand that those hard, crisp edges are desirable, from this point of view, not as you perceive. Rounded shapes cause wind to stay attached, which at high speed isn't necessarily what you want at certain places on any specific shape. Ever seen a F1 car with rounded shapes? There are some, but mostly they're not and for good reasons, of which you don't understand.



Lots of hard, crisp aerodynamic edges at work here. Yep some rounded shapes, but mostly hard, crisp edges. The same applies to boats. Maybe you should speak what you know, instead of bantering around guesses and assumptions about something you don't really have a good grasp of.

 

That's all just sensible attention to detail, but you have not given any
indication of the magnitude of the air drag compared to other quantities.

It's a matter of how much time and effort should be invested for the possible
gains in efficiency, given a finite design time and finite resources.

If you supply something more than anecdotes and abuse I might believe you.

 

is it possible for a jet fighter plane to sit on the runway with it hand brake on and the jet at full absolute maximum power ??
Deck edges are one of the worst places for vortexs and turbulance .
just like the wing tips of aircraft !!and how long agao did you start to see wing tiplets of airplanes ??
what is the simplest way of killing lift on any air craft wing ??
Boat front screen corners are another place that does the same as the deck edge .
the bow shape on just about every power boat and the topside panels are all fighting in differant directions !!!

Why does a tunnel boat get lots lift from the tunnel when a catamaran get almost non ?? why dosent a catamaran work better than a tunnel boat ?? how much lift is also genetared from the deck any ?
very little ?
or non what so ever ??
and why ??